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Concentrations of dialkyl phosphate metabolites of organophosphorus pesticides in the U.S. population.


We report population-based concentrations, stratified by age, sex, and racial/ethnic groups, of dialkyl phosphate (DAP (Directory Access Protocol) A protocol used to gain access to an X.500 directory listing. See LDAP.) metabolites of multiple organophosphorus pesticides. We measured dimethylphosphate (DMP), dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), diethylphosphate (DEP), diethylthiophosphate (DETP), and diethyldithiophosphate (DEDTP) concentrations in 1,949 urine samples collected in U.S. residents 6-59 years of age during 1999 and 2000 as a part of the ongoing National Health and Nutrition Examination Survey (NHANES). We detected each DAP metabolite in more than 50% of the samples, with DEP being detected most frequently (71%) at a limit of detection of 0.2 [micro]g/L. The geometric means for the metabolites detected in more than 60% of the samples were 1.85 [micro]g/L for DMTP and 1.04 [micro]g/L for DEP. The 95th percentiles for each metabolite were DMP, 13 [micro]g/L; DMTP, 46 [micro]g/L; DMDTP, 19 [micro]g/L; DEP, 13 [micro]g/L; DETP, 2.2 [micro]g/L; and DEDTP, 0.87 [micro]g/L. We determined the molar sums of the dimethyl-containing and diethyl-containing metabolites; their geometric mean concentrations were 49.4 and 10.5 nmol/L, respectively, and their 95th percentiles were 583 and 108 nmol/L, respectively. These data are also presented as creatinine creatinine /cre·at·i·nine/ (kre-at´i-nin) an anhydride of creatine, the end product of phosphocreatine metabolism; measurements of its rate of urinary excretion are used as diagnostic indicators of kidney function and muscle mass.

cre·at·i·nine (kr
-adjusted concentrations. Multivariate analyses showed concentrations of DAPs in children 6-11 years of age that were consistently significantly higher than in adults and often higher than in adolescents. Although the concentrations between sexes and among racial/ethnic groups varied, no significant differences were observed. These data will be important in evaluating the impact of organophosphorus pesticide exposure in the U.S. population and the effectiveness of regulatory actions. Key words: biologic monitoring, dialkyl phosphate, general population, organophosphate, organophosphorus, reference range, urine. Environ Health Perspect 112:186-200 (2004). doi:10.1289/ehp.6503 available via http://dx.doi.org/[Online 4 November 2003]

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Organophosphorus (OP) pesticides are among the most widely used pesticides in the United States and are used in both agricultural and residential settings. Approximately 40 OP pesticides are registered with the U.S. Environmental Protection Agency (U.S. EPA) for use in the United States (U.S. EPA 2003). Examples of commonly used OP pesticides are chlorpyrifos (Dursban), diazinon (Dianon), azinphos methyl (Guthion), and oxydemetonmethyl (Metasystox-R). OP pesticides are popular because of their broad spectrum of applications and potent toxicity to insects, their relative inexpensive costs, and their decreased likelihood for pest resistance (Karalliedde et al. 2001). According to U.S. EPA sales data, OP pesticides account for about half of all insecticides used in the United States. About 80 million pounds of OP pesticides are used annually in the United States, with 75% of their use in agriculture (U.S. EPA 1991). Crops on approximately 38 million acres of farmland are treated annually with OP insecticides (U.S. EPA 1991). A smaller percentage of the total OP use has been in residential settings. Whitmore et al. (2003) found that nearly half of U.S. households with a child younger than 5 years of age had a pesticide stored within a child's reach. In outdoor settings in contact with light and water, OP pesticides degrade relatively rapidly. However, when used indoors or as a part of structural treatments, these compounds can remain stable for much longer periods (Fenske et al. 2000) and can remain potentially available for repeated exposure for both adults and children.

Most OP pesticides have the same general structure (Figure 1), a common mode of action as an insecticide, and a common mode of acute toxicity in humans and other animals (Mileson et al. 1998). In vivo, these pesticides are potent inhibitors of the enzyme acetyl cholinesterase (AChE), which breaks down the neurotransmitter acetylcholine. More specifically, the hydroxyl group of a serine residue in the active site of AChE chemically reacts with the OP pesticide or its metabolically activated form to chemically bind the enzyme and prevent it from performing its natural function. In most instances, the original enzyme may be regenerated via a simple hydrolysis, similar to its regeneration after breaking down acetylcholine.

[FIGURE 1 OMITTED]

Most OP pesticides are composed of a phosphate (or phosphorothioate or phosphorodithioate) moiety that, in most cases, is O, O-dialkyl substituted, where the alkyl groups are usually dimethyl or diethyl, and an organic group (Figure 1). For example, diazinon is composed of an O, O-diethyl phosphorothioate to which a 2-isopropyl-4-methyl-6-hydroxypyrimidinyl group is attached. Once entering the body, OPs can be enzymatically converted to their oxon form, which then reacts with available cholinesterase. The oxon also can be enzymatically or spontaneously hydrolyzed to form a dialkyl phosphate (DAP) metabolite and the organic group moiety. In the case of diazinon, diethylphosphate (DEP) and 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPY) may be formed. If the pesticide is not converted to its oxen form, it can undergo hydrolysis to its organic group metabolite and dialkylthionate metabolites (i.e., dialkylthiophosphate and/or dialkyldithiophosphate). For diazinon, these metabolites are diethylthiophosphate (DETP) and IMPY. These metabolites and/or their glucuronide or sulfate conjugates are excreted in urine.

After the National Research Council's 1993 report, which focused on dietary pesticide exposure among infants and children, the advantages of using OP pesticides were scrutinized because of the potential consequences of childhood exposures. Consequently, the passage of the Food Quality Protection Act (FQPA) of 1996 required the U.S. EPA to reassess all pesticide residue tolerances on food and, in this reassessment, to give special consideration to potential cumulative and aggregate exposures to children. OP pesticides were the first class of pesticides for which tolerances were reassessed because of their common mode of toxicity, widespread use, and unknown long-term health effects (U.S. EPA 2003). Because of increasing concern about the safety of these pesticides to children, many OP pesticide uses, such as residential use of chlorpyrifos and diazinon, are being eliminated.

Because exposure to OP pesticides occurs typically by multiple routes and the dominant routes of exposure for individuals vary, quantification of OP exposure is not a trivial process. Therefore, in many epidemiologic studies, markers of exposure in biologic samples have been measured to estimate the absorbed dose (Aprea et al. 1996; Curl et al. 2002; Loewenherz et al. 1997; Lu et al. 2001; Mills and Zahm 2001; Whyatt and Barr 2001). One of the most common ways to assess OP pesticide dose is quantifying six common urinary DAP metabolites. These measurements may provide information on class exposure to OP pesticides or exposure to the DAP itself that may be present in the environment as a breakdown product of OP pesticides (environmental DAP). Although no published studies have documented the environmental presence or biologic absorption of environmental DAPs or their contribution to urinary DAP concentrations in humans, researchers widely recognize their potential contributions to urinary levels largely based on data demonstrating similar environmental exposures, absorption, and excretion for more selective OP metabolites (Barr et al. 2002; Curl et al. 2003a; Krieger et al. 2003; Wilson et al. 2003). In addition, the potential health effects resulting from exposure to environmental DAPs have not been evaluated. Although the DAP measurements provide no specific information about the pesticide to which one was exposed and they may potentially represent exposure to the pesticide itself and/or its environmental degradate, urinary DAP metabolites still provide useful information about cumulative exposure to OP pesticides as a class because about 75% of the U.S. EPA-registered OP pesticides form one to three of these six DAP metabolites. However, these concentrations are often difficult to interpret because reference concentrations are not available.

We report DAP metabolite concentrations in urine samples collected in 1999 and 2000 from approximately 2,000 persons 6-59 years of age from the U.S. general population. Specifically, we report urinary concentrations of dimethylphosphate (DMP), DEP, dimethylthiophosphate (DMTP), DETP, dimethyldithiophosphate (DMDTP), and diethyldithiophosphate (DEDTP). The data we report are representative of the civilian, noninstitutionalized U.S. population and are stratified by age, sex, and race/ethnicity.

Materials and Methods

Study design. The National Health and Nutrition Examination Survey (NHANES), conducted by the National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention (CDC), is designed to measure the health and nutrition status of the civilian noninstitutionalized U.S. population (CDC 2003a). In 1999, NHANES became a continuous survey, fielded on an ongoing basis. Each year of data collection is based on a representative sample covering all ages of the civilian noninstitutionalized population. Data files are released for public use in 2-year groupings (cycles). National population estimates for DAPs as well as estimates for the three largest racial/ethnic subgroups in the U.S. population (non-Hispanic white, non-Hispanic black, and Mexican American) are derived from the first 2-year cycle of the survey, NHANES 1999-2000.

The sampling scheme for NHANES is based on a complex multistage area probability design, which includes selection of primary sampling units (counties), household segments within the counties, and finally sample persons from selected households. In 1999 and 2000, persons 12-19 years of age and [greater than or equal to] 60 years of age, non-Hispanic blacks, and Mexican Americans were oversampled. Low-income white Americans were oversampled in 2000. In addition, in 1999 and 2000, most women who indicated that they were pregnant in the screening interview were selected into the sample to increase the sample size for pregnant women. Data were collected through a household interview and a standardized physical examination, which was conducted in a mobile examination center. Urine specimens were collected from each participant [greater than or equal to] 6 years of age during one of three daily scheduled examination periods (i.e., morning, afternoon, and early evening). Sociodemographic information and medical histories of the survey participant and the family were collected during the household interview.

NHANES 1999-2000 was conducted in 26 locations throughout the United States and included examinations of 9,282 persons. For the DAP metabolites, measurements were conducted on a subset of participants that were selected based on a random one-half sample of children 6-11 years of age in 1999 and 2000, a random one-quarter sample of people 12-59 years of age in 1999, and a random one-third sample of people 12-59 years of age in 2000. Because the subset was a random selection from the entire set, the representativeness of the survey was maintained.

Laboratory methods. During the physical examinations, "spot" or "grab" urine specimens were collected from participants, aliquoted, and stored cold (2-4[degrees]C) or frozen until shipment. Urinary creatinine concentrations were determined using an automated colorimetric method based on a modified Jaffe reaction (Jaffe 1886) on a Beckman Synchron AS/ASTRA clinical analyzer (Beckman Instruments, Inc., Brea, CA) at the Fairview University Medical Center, Minneapolis, Minnesota. Samples collected for OP pesticide measurements were shipped on dry ice to the CDC's National Center for Environmental Health. Urine samples were analyzed for DAP metabolites of OP pesticides using the method of Bravo et al. (2002). Briefly, 4 mL of urine was spiked with an isotopically labeled internal standard mixture and concentrated to dryness using an azeotropic codistillation with acetonitrile acetonitrile /ac·e·to·ni·trile/ (as?e-to-ni´tril) a colorless liquid with an etherlike odor used as an extractant, solvent, and intermediate; ingestion or inhalation yields cyanide as a metabolic product.. The residue was dissolved in acetonitrile, and the DAPs were derivatized to their respective chloropropyl esters using 1-chloro-3-iodopropane and potassium carbonate. The solution containing the chloropropyl esters was concentrated and then analyzed using gas chromatography-positive chemical ionization-tandem mass spectrometry. The DAP metabolites were quantified using isotope-dilution calibration. Metabolite concentrations were adjusted using creatinine concentrations to correct for variable urine dilutions in the "spot" urine samples. Quality control materials were analyzed in parallel with unknown samples. Data were not reported for sample runs in which the quality control materials failed to meet the specifications outlined in the Westgard multirules (Westgard 2002). Both laboratories and methods were certified according to guidelines set forth in the Clinical Laboratory Improvement Amendment (1988).

Covariates. Age was reported at the time of the household interview as the age in years at the last birthday. Age categories used in our statistical analyses were 6-11 years, 12-19 years, and 20-59 years. A composite racial/ethnic variable based on self-reported race and ethnicity was created to define three major racial/ethnic groups: non-Hispanic black, non-Hispanic white, and Mexican American. Individuals from other racial/ethnic groups were included in the total estimates reported in this publication; however, no separate demographic breakdown was provided.

Traditionally, creatinine concentrations have been used to adjust spot urine samples for variable dilution caused by the different hydration states of the sample donor. Because age group, sex, and race/ethnicity all affect the creatinine concentrations in the urine, creatinine adjustment in diverse populations would not be valid for comparisons of DAP concentrations among the demographic groups. To overcome this limitation and thereby allow for an appropriate comparison of DAP concentrations among the demographic groups, creatinine was also used as a covariate in statistical models. By using this model for DAP concentration comparisons, we appropriately corrected for covariate effects on the creatinine concentrations while eliminating the variability caused by urine dilution of spot samples.

Statistical analysis. Survey-specific sample weights tailored to suit the random subset were used in statistical analyses. Parametric statistics were performed only on analytes for which the frequency of detection was greater than or equal to 60%. Geometric means (GMs), least-squares geometric means (LSGMs), and percentiles of urinary DAP concentrations were calculated using SAS software release 8 (SAS Institute, Cary, NC) and SUDAAN software release 7.5.6 (Research Triangle Institute, Research Triangle Park, NC). LSGMs are GMs that have been calculated using an analysis of covariance. The analytic limits of detection (LODs; defined as three times the standard deviation at zero concentration) were 0.58 [micro]g/L for DMP, 0.18 [micro]g/L for DMTP, 0.08 [micro]g/L for DMDTP, 0.2 [micro]g/L for DEP, 0.09 [micro]g/L for DETP, and 0.05 [micro]g/L for DEDTP. For concentrations below the LODs, a value equal to the LOD divided by the square root of 2 was used (Hornung and Reed 1990). For the statistical analyses of summed metabolite concentrations, the individual metabolite concentrations in units of micrograms per liter or micrograms per gram creatinine were converted to their nanomolar units using the general formula (analyte concentration/molecular weight of analyte) x 1,000, giving final concentrations in units of nanomoles per liter or nanomoles per gram creatinine, respectively. SUDAAN incorporates the NHANES sampling weights and adjusts for the complex sample design of the survey. Sample weights take into account nonresponse and the unequal probabilities of selection, resulting from the cluster design and the planned oversampling of certain subgroups.

The LSGMs for each demographic group were corrected for effects of all covariates, including creatinine. Differences in LSGMs among demographic groups were considered significant when p < 0.05 and nominally or marginally significant when p > 0.05 but < 0.1.

Results

Our data included 1,949 valid concentrations for each DAP in urine samples collected during 1999 and 2000. The distribution of the DAP metabolites in the NHANES samples analyzed are presented in Table 1. These values are presented as volume-based concentrations to allow for comparisons with similar data in the literature. The creatinine-adjusted concentrations are shown in Table 2. The volume-based and creatinine-adjusted GMs for each demographic group are shown graphically in Figure 2. DEP was detected with the highest frequency in about 70% of the samples tested; however, DMTP was detected in the highest concentrations. Concentrations of DEP and DETP in individual samples were highly correlated (r = 0.66, p < 0.0001), suggesting they were derived from a common source, such as chlorpyrifos or diazinon. No other DAPs were correlated.

[FIGURE 2 OMITTED]

The LSGMs for each demographic group are shown in Table 3. For all analytes, children 6-11 years of age had higher concentrations, even after correcting for all covariates including creatinine. Children 6-11 years of age had a significantly higher LSGM concentration of DEP than did adults (p = 0.008) but only marginally significantly higher concentration than did adolescents (p = 0.07). Children had a significantly higher LSGM concentration of DMTP than did adults (p = 0.015), but the difference between values for children and adolescents was not significant.

All DAPs were detected more frequently in Mexican Americans and non-Hispanic blacks than in non-Hispanic whites, although the differences were not significant. Mexican Americans had higher concentrations of DEP and DEDTP, whereas non-Hispanic blacks had higher concentrations of DMP and DETP. Mexican Americans and non-Hispanic whites had higher concentrations of DMTP than did non-Hispanic blacks, and all groups had similar concentrations of DMDTP. The maximum concentrations observed for the DAPs were more frequently seen in Mexican Americans. None of the differences observed among the racial/ethnic groups was significant.

Because the methyl-containing metabolites are derived from O, O-dimethyl-substituted OP pesticides such as azinphos-methyl and malathion, their concentrations were converted to molar equivalents and summed to produce one composite dimethyl alkylphosphate (DMAP) concentration for each person. A similar conversion and summation was performed for the ethyl-containing metabolites [diethyl alkylphosphate (DEAP) composite]. The distributions of the composite DMAP and DEAP concentrations in the NHANES samples analyzed are presented in Table 4. These values are presented as volume-based molar concentrations to allow for comparisons with similar data in the literature. The creatinine-adjusted concentrations are shown in Table 5. The volume-based and creatinine-adjusted GMs for each demographic group are shown graphically in Figure 3. The LSGMs are given in Table 3.

[FIGURE 3 OMITTED]

Children 6-11 years of age had significantly higher concentrations of both DMAP and DEAP than did adults (both p < 0.007). Although these concentrations were also higher than for adolescents, the differences were not significant for DMAP (p = 0.26) and only marginally significant for DEAP (p = 0.06). Adolescents had higher concentrations of DMAP than did adults, but the difference was only marginally significant (p = 0.08). The total DAP concentrations in children and adolescents were also significantly greater than in adults (p < 0.0001).

Although we report only the DAP concentrations, four "selective" metabolites of OP pesticides were also measured in the same samples. These selective metabolites are derived from the organic portion of the pesticide that is unique to a specific OP pesticide or diethyl/ dimethyl congener pair. The selective metabolites we measured and their parent pesticides are listed in Table 6. Although the distribution data will be reported elsewhere (Barr et al. Unpublished data), we used a Pearson correlation analysis to examine the correlation of the concentrations of these selective pesticides with their corresponding DAP metabolites. The results of our analyses are shown in Table 6. Concentrations of 3,5,6-trichloro-2-pyridinol, a selective metabolite of chlorpyrifos and chlorpyrifos-methyl, were significantly correlated with both DEP (r = 0.22, p < 0.0001) and DETP (r = 0.29, p < 0.0001) concentrations. Likewise, concentrations of IMPY, a selective metabolite of diazinon, were significantly correlated with both DEP (r = 0.27, p < 0.0001) and DETP (r = 0.38, p < 0.0001) concentrations. Other significant, albeit weak, correlations were seen among the other metabolites tested. Similar correlations were observed among the selective metabolites and the composite DEAP and DMAP variables.

Discussion

We report concentrations of DAPs in the U.S. population using several different formats to allow these data to be more easily compared with existing data in the literature. We found that concentrations of the DAPs among the various demographic subgroups had subtle, nonsignificant differences, except for children 6-11 years of age, who had concentrations consistently significantly higher than in adults and sometimes significantly higher than in adolescents. We have reported these data both as volume-based concentrations and as creatinine-adjusted concentrations, to attempt to correct for the variability in urine dilution among the "spot" samples. However, the demographic covariates we evaluated also may affect the urinary concentrations of creatinine, thus increasing the variability of the data instead of reducing it. For example, a child 6-11 years of age is likely to have a lower concentration of creatinine than would an adult; therefore, a DAP concentration in the child may be overcorrected when adjusting for creatinine, producing a DAP concentration that is falsely elevated compared with that of an adult with a similar exposure and uptake. However, this same adjusted measurement may be more indicative of the size-related dose of the child, assuming that a urinary creatinine concentration could be used as a reasonable surrogate for body weight because it is proportional to lean muscle mass. For these reasons, the creatinine-adjusted results should be evaluated with caution. We have studied the effect of demographic covariates on creatinine in detail; these results will be published separately (Barr et al. Unpublished data). For our statistical analyses to evaluate significant differences in exposures among the subpopulations, we included creatinine as a covariate to correct for the effects of the demographic variables on creatinine. Therefore, the differences we report for children represent real differences in exposure, not false differences produced by creatinine overcorrection. These differences are likely because of increased opportunities for exposure based on their dietary and physical behaviors (Eskenazi et al. 1999; National Research Council 1993).

Although urinary DAPs have been measured for almost 30 years to evaluate both occupational and incidental exposures (Table 7), our data are the first population-based reference data reported for the United States. These data were first released in summary format in the CDC's Second National Report on Human Exposure to Environmental Chemicals in January 2003 (CDC 2003b). We observed higher frequencies of detection (Table 8) and higher GMs in 1999, the first year (CDC 2001) of the 2-year NHANES cycle than in the combined 1999-2000 data that we report. Because of the small sample size and the small number of primary sampling units included in any one year of NHANES, there is a high level of variation in annual estimates. We did not formally evaluate the statistical significance of trends in DAP metabolites over this time period, but differences are unlikely to be statistically significant. Data from additional NHANES cycles are required to determine whether exposure levels have declined.

These DAPs also were measured in urine samples collected in NHANES II (1976-1980). These data were never released publicly because of laboratory quality control issues that were not resolved (Schober S. Personal communication), but the NHANES II frequency of detection information and mean concentration of the detectable values were reported by Griffith and Duncan (1985). Those data are not directly comparable with the data we report here because the analytical technology used for those analyses was not sufficiently sensitive to detect these metabolites in more than 12% of the samples tested (Murphy et al. 1983). The mean DAP concentrations for the detectable samples in NHANES II ranged from 40 to 110 [micro]g/L, concentrations well in excess of the 95th percentiles for all of the analytes we report, except DMTP.

General population DAP data have been reported for European populations in Italy (Aprea et al. 1996, 2000) and Germany (Hardt and Angerer 2000; Heudorf and Angerer 2001; Figure 4). The Italian adult data were derived from a sample size that was only about 6% (n = 124) of the number of samples we report. They reported frequencies of detection ranging from 7% for DEDTP to 99% for DMTP (LODs ~1 [micro]g/L). Our frequencies of detection were much higher for DEDTP (55%; LOD = 0.05 [micro]g/L) and much lower for DMTP (59%; LOD = 0.18 [micro]g/L). Other DAP metabolites were detected much less frequently as well. The GMs of the Italian population ranged from 13.7 (DEDTP) to 70.7 (DMTP) nmol/g creatinine, which are equivalent to 2.5-10 [micro]g/g creatinine. Our GMs ranged from less than the LOD to 2.95 [micro]g/g creatinine in certain demographic subgroups.

In addition, one study (Aprea et al. 2000) measured concentrations of DAPs in children 6-7 years of age in a nonagricultural region of Italy. DAP metabolites were detected in 12% (DEDTP) to 96% (DMP) of the samples tested. The GMs ranged from 7.7 (DEDTP) to 117 (DMP) nmol/g creatinine, which are equivalent to 1.4-14.7 [micro]g/g creatinine. DAPs were detected much less frequently in our population of children (59-74%) for all analytes except DMDTP, DETP, and DEDTP. Aprea et al. (2000) found that the DAP concentrations of the children in their study were significantly greater than those of an adult reference population in Italy (Aprea et al. 1996). Our results are consistent with this finding.

The German population data were determined on a small population subset (n = 54; Hardt and Angerer 2000). Their frequencies of detection (LODs = 1-5 [micro]g/L) ranged from 2 to 100%, with DMTP being the most frequently detected, and the median concentrations ranged from < 1 [micro]g/L for DETP and DEDTP to 30 [micro]g/L for DMP. Our median concentrations were typically [less than or equal to] 1 [micro]g/L except for DMTP, which ranged from 1.9 to 4.2 [micro]g/L. The German median for DMTP was 22 [micro]g/L.

DAPs in urine samples from 1,146 Germans living in former U.S. Air Force housing in Germany were detected with frequency similar to that in our population, except for DMDTP and DEDTP (Heudorf and Angerer 2001). Both the GMs and the distribution percentiles were significantly higher in the German population than in ours for each age group evaluated. For example, the 95th percentile DMTP concentrations for the German population ranged from 51 to 334 [micro]g/g creatinine for the various age groups, whereas ours ranged from 47 to 66 [micro]g/g creatinine.

Other DAP data generated from reference populations in exposure studies, mostly in Washington State (Loewenherz et al. 1997; Lu et al. 2000, 2001), have been reported. Concentrations of DAPs found in reference children from these exposure studies were generally comparable with the DAP concentrations of children in our population-based data, expressed either as individual DAP metabolites or as summed DMAP and DEAP concentrations; however, our data on children were usually slightly lower.

The differences among our NHANES DAP data and other reported reference values, including the German and Italian data, may be caused by a variety of factors. First, our data were derived from samples that represent a geographically and culturally diverse population. An equal proportion of males and females were sampled, and the participants represented a wide age range. Although age, race/ethnicity, and sex were considered covariates in our analysis and were appropriately accounted for, geographic diversity was not. The geographic area in which the participants lived certainly would have some impact on the DAP concentrations. Second, our data were derived from a large enough sample population to appropriately characterize background DAP concentrations by minimizing the spikes in data associated with overt pesticide exposures. The reference data to which we have compared the NHANES data were all derived from small, likely more homogeneous, populations. Third, the analytic methodology should be considered when comparing the results. Our data were generated using analytic methodology that is highly selective, allowing us to minimize the "false positive" samples, and highly sensitive, allowing us to detect very low levels. In general, other reference data were generated using less selective methodology with LODs that were higher. Given the differences in LODs among methods where general population DAP concentrations were evaluated, we would have expected to detect DAPs more frequently in the U.S. population. However, we observed much lower detection frequencies, which can likely be explained by the factors we mention here. Fourth, the distribution of our data was generated by substituting concentrations less than the LOD with an imputed value equal to the LOD divided by the square root of 2. Other reference data were generated using censored data, zero, or unspecified methods for treatment of data less than the LOD. Finally, the differences could be due to population or subpopulation differences in OP pesticide use or seasonal variations.

DAP metabolites have also been measured to assess exposure to OP pesticides in a variety of nonoccupational exposure studies. The concentrations and primary findings from these studies are outlined in Table 7. Most nonoccupational studies took place in Washington State (Curl et al. 2002; Fenske et al. 2000; Loewenherz et al. 1997; Lu et al. 2000, 2001), California (Mills and Zahm 2001), and Arizona (O'Rourke et al. 2000) and report similar findings: Children who lived near farmland or had a parent who was a farmer had higher DAP concentrations than did both reference children in the studies and our population-based reference concentrations for children.

Many occupational exposure studies have also been reported. Shafik et al. (1973) found concentrations of DEP and DETP as high as 2,400 and 1,600 [micro]g/L, respectively, in workers formulating O, O-diethyl-substituted OP pesticides, such as phorate. Florida citrus sprayers and harvesters using both O, O-dimethyl-substituted and O, O-diethyl-substituted pesticides had urinary concentrations of DAPs ranging from 6 to 410 [micro]g/L (Griffith and Duncan 1985). Another study on a similar exposure group reported DAP concentrations as high as 3,200 [micro]g/L (Duncan and Griffith 1985). Fenske and Leffingwell (1989) reported DMTP and DMDTP concentrations approaching 700 [micro]g/L in a malathion applicator ap·pli·ca·tor (pl-k in Washington State. Sprayers and leaf thinners in Tuscany vineyards in Italy had DMP and DMTP concentrations as high as 600 and 175 [micro]g/L, respectively (Aprea et al. 1997). These studies all report concentrations well in excess of the reference concentrations we have established. However, some of the concentrations are similar to the maximum concentrations we observed, especially for DMTP, indicating some similar high-end exposures in our population.

Several incidents of nonfatal OP pesticide poisonings have been reported in which urinary DAP was measured. Davies and Peterson (1997) reported cases in which the concentrations of DEP and DETP were as high as 7,800 and 1,500 [micro]g/L, respectively, for parathion poisoning and 30,000 and 30,000 [micro]g/L, respectively, for chlorpyrifos poisoning. Bradway and Shafik (1977) reported a nonfatal malathion poisoning case in which the DMP, DMTP, and DMDTP urinary concentrations were 50,000, 96,000, and 20,000 [micro]g/L, respectively. We had a maximum concentration for DMTP in our population that was similar to these poisoning cases; health and occupation data for this individual have not yet been evaluated.

Conclusions

We report the first U.S. population-based reference data for DAP metabolites of OP pesticides; these data are stratified by age, sex, and race/ethnicity. We found that concentrations of the DAPs among the various demographic subgroups had subtle, nonsignificant differences, except for children 6-11 years of age, who had concentrations consistently significantly higher than did adults and sometimes significantly higher than did adolescents. Sex and race/ethnicity did not significantly affect DAP concentrations. Our data indicate that most of the U.S. population have some exposure to OP pesticides; however, the concentrations we report are much lower than those of other reference populations in the literature.

These data will serve many purposes in environmental public health primarily to help minimize or prevent any adverse health outcome that may result from exposure to these pesticides. To help accomplish this, these data will have many specific uses. They will be used as reference range values by physicians and public health officials for comparing urinary levels of these metabolites to potentially exposed persons or populations to assess their relative exposure status. They will be used by risk assessors for modeling to estimate the intake (e.g., daily) and compare with regulated doses, such as the U.S. EPA's reference dose and the Food and Drug Administration's acceptable daily intake. These data will be used in many disciplines in environmental public health to track trends in exposure over time and to determine the effectiveness of public health efforts, including legislation such as the FQPA, to reduce exposures for all Americans, but particularly for certain vulnerable or sensitive subgroups, such as children. These data also will help prioritize research gaps and needs for relating human exposures and adverse health outcomes; they will be used for comparing human urinary levels with urinary levels found in dosed animals that have exhibited adverse health outcomes. In summary, these data serve as U.S. landmark data that will be used in many ways, including those mentioned above.
Table 1. Weighted quantiles of urinary DAP concentrations
([micro]g/L) in the NHANES 1999-2000 study population.

Analyte/                          Detection
demographic category     No.    frequency (%)       GM

DMP
  All (a)               1,949        53             NC
  6-11 years of age       471        63             NC
  12-19 years of age      664        50             NC
  20-59 years of age      814        52             NC
  Males                   952        53             NC
  Females                 997        54             NC
  Non-Hispanic whites     594        49             NC
  Non-Hispanic blacks     509        62             NC
  Mexican Americans       672        59             NC
DMTP
  All (a)               1,949        64            1.82
                                                (1.43-2.32)
  6-11 years of age       471        69            2.72
                                                (1.85-4.01)
  12-19 years of age      664        67            2.53
                                                (1.72-3.63)
  20-59 years of age      814        63            1.59
                                                (1.25-2.03)
  Males                   952        66            2.10
                                                (1.58-2.78)
  Females                 997        62            1.59
                                                (1.2-2.11)
  Non-Hispanic whites     594        64            1.77
                                                (1.30-2.39)
  Non-Hispanic blacks     509        68            2.13
                                                (1.38-3.28)
  Mexican Americans       672        63            1.79
                                                (1.11-2.90)
DMDTP
  All (a)               1,949        53             NC
  6-11 years of age       471        63             NC
  12-19 years of age      664        51             NC
  20-59 years of age      814        48             NC
  Males                   952        53             NC
  Females                 997        53             NC
  Non-Hispanic whites     594        50             NC
  Non-Hispanic blacks     509        56             NC
  Mexican Americans       672        53             NC
DEP
  All (a)               1,949        71            1.03
                                                (0.76-1.40)
  6-11 years of age       471        74            1.32
                                                (0.85-2.05)
  12-19 years of age      664        73            1.21
                                                (0.85-1.72)
  20-59 years of age      814        69            0.955
                                                (0.70-1.30)
  Males                   952        72            1.11
                                                (0.81-1.54)
  Females                 997        69            0.954
                                                (0.69-1.32)
  Non-Hispanic whites     594        68            0.98
                                                (0.67-1.44)
  Non-Hispanic blacks     509        82            1.56
                                                (1.23-1.98)
  Mexican Americans       672        74            1.22
                                                (0.87-1.71)
DETP
  All (a)               1,949        53             NC
  6-11 years of age       471        59             NC
  12-19 years of age      664        46             NC
  20-59 years of age      814        54             NC
  Males                   952        57             NC
  Females                 997        50             NC
  Non-Hispanic whites     594        51             NC
  Non-Hispanic blacks     509        64             NC
  Mexican Americans       672        58             NC
DEDTP
  All (a)               1,949        56             NC
  6-11 years of age       471        60             NC
  12-19 years of age      664        50             NC
  20-59 years of age      814        56             NC
  Males                   952        57             NC
  Females                 997        54             NC
  Non-Hispanic whites     594        53             NC
  Non-Hispanic blacks     509        61             NC
  Mexican Americans       672        66             NC

                             Percentile of distribution

Analyte/
demographic category    25th        50th           75th

DMP
  All (a)               < LOD       0.74           2.80
                                (< LOD-1.30)    (2.10-3.90)
  6-11 years of age     < LOD       1.00           4.40
                                (0.59-2.00)     (2.90-6.80)
  12-19 years of age    < LOD       0.65           3.80
                                (< LOD-1.50)    (2.40-5.50)
  20-59 years of age    < LOD       0.68           2.60
                                (< LOD-1.20)    (1.80-3.60)
  Males                 < LOD       0.65           2.80
                                (< LOD-1.20)    (2.10-4.10)
  Females               < LOD       0.78           2.80
                                (< LOD-1.40)    (2.00-4.00)
  Non-Hispanic whites   < LOD      < LOD           2.90
                                (1.80-4.20)     (5.50-9.60)
  Non-Hispanic blacks   < LOD       0.98           3.60
                                (0.65-1.30)     (2.40-5.50)
  Mexican Americans     < LOD       1.00           3.80
                                (< LOD-1.60)    (2.70-4.70)
DMTP
  All (a)               < LOD       2.70           10.0
                                (1.50-3.80)     (8.00-16.0)
  6-11 years of age     < LOD       4.10           20.0
                                (2.30-7.60)     (13.0-30.0)
  12-19 years of age    < LOD       3.60           16.0
                                (1.70-6.00)     (8.80-24.0)
  20-59 years of age    < LOD       2.20           9.10
                                (1.10-3.40)     (7.10-13.0)
  Males                 < LOD       3.40           13.0
                                (2.40-4.50)     (8.50-20.0)
  Females               < LOD       2.00           9.70
                                (0.72-3.30)     (6.70-16.0)
  Non-Hispanic whites   < LOD       2.60           10.0
                                (1.10-4.00)     (7.00-17.0)
  Non-Hispanic blacks   < LOD       3.60           11.0
                                (1.60-5.60)     (8.30-18.0)
  Mexican Americans     < LOD       2.00           10.0
                                (0.60-4.30)     (6.60-16.0)
DMDTP
  All (a)               < LOD      < LOD           2.30
                                                (1.40-3.60)
  6-11 years of age     < LOD      < LOD           4.30
                                                (2.50-6.90)
  12-19 years of age    < LOD      < LOD           2.20
                                                (1.30-4.50)
  20-59 years of age    < LOD      < LOD           2.10
                                                (1.10-3.10)
  Males                 < LOD      < LOD           2.30
                                                (1.30-4.30)
  Females               < LOD      < LOD           2.10
                                                (1.30-3.20)
  Non-Hispanic whites   < LOD      < LOD           2.00
                                                (0.850-370)
  Non-Hispanic blacks   < LOD      < LOD           3.20
                                                (1.70-6.50)
  Mexican Americans     < LOD      < LOD           1.80
                                                (1.20-2.30)
DEP
  All (a)               < LOD       1.20           3.10
                                (0.80-1.50)     (2.40-4.60)
  6-11 years of age     < LOD       1.40           4.50
                                (0.99-2.10)     (2.30-0.50)
  12-19 years of age    < LOD       1.30           3.70
                                (1.00-1.90)     (2.40-5.40)
  20-59 years of age    < LOD       1.00           3.00
                                (0.73-1.40)     (2.10-4.40)
  Males                 < LOD       1.10           3.80
                                (0.85-1.40)     (2.50-4.90)
  Females               < LOD       1.10           2.90
                                (0.73-1.50)     (2.10-4.40)
  Non-Hispanic whites   < LOD       1.10           3.30
                                (0.58-1.50)     (2.30-4.90)
  Non-Hispanic blacks   < LOD       1.60           4.20
                                (1.30-1.80)     (2.90-5.80)
  Mexican Americans     < LOD       1.10           4.10
                                (0.84-1.50)     (2.60-6.40)
DETP
  All (a)               < LOD       0.49           0.76
                                (< LOD-0.62)    (0.66-0.91)
  6-11 years of age     < LOD       0.59           0.90
                                (< LOD-0.72)    (0.73-1.20)
  12-19 years of age    < LOD       0.21           0.78
                                (< LOD-0.64)    (0.63-1.20)
  20-59 years of age    < LOD      0.480           0.74
                                (< LOD-0.59)    (0.63-0.91)
  Males                 < LOD       0.50           0.79
                                (< LOD-0.630)   (0.70-1.00)
  Females               < LOD      < LOD           0.72
                                               (0.600-0.910)
  Non-Hispanic whites   < LOD       0.16           0.73
                                (< LOD-0.63)    (0.60-1.00)
  Non-Hispanic blacks   < LOD       0.56           0.81
                                (< LOD-0.670)   (0.69-1.20)
  Mexican Americans     < LOD       0.56           0.84
                                (< LOD-0.70)    (0.74-0.98)
DEDTP
  All (a)               < LOD       0.08           0.20
                                (< LOD-0.11)    (0.15-0.29)
  6-11 years of age     < LOD       0.08           0.19
                                (< LOD-0.11)    (0.15-0.24)
  12-19 years of age    < LOD       0.08           0.26
                                (< LOD-0.11)    (0.12-0.35)
  20-59 years of age    < LOD       0.08           0.21
                                (< LOD-0.11)    (0.13-0.29)
  Males                 < LOD       0.09           0.22
                                (< LOD-0.10)    (0.16-0.29)
  Females               < LOD       0.08           0.19
                                (< LOD-0.10)    (0.11-0.30)
  Non-Hispanic whites   < LOD       0.08           0.19
                                (< LOD-0.12)    (0.12-0.28)
  Non-Hispanic blacks   < LOD       0.09           0.27
                                (< LOD-0.11)    (0.18-0.33)
  Mexican Americans     < LOD       0.10           0.31
                                (0.07-0.15)     (0.23-0.39)

                              Percentile of
                              distribution

Analyte/
demographic category        90th          95th

DMP
  All (a)                   7.90          13.0
                        (5.90-9.50)    (9.50-21.0)
  6-11 years of age         10.0          21.0
                        (6.60-18.0)    (10.0-41.0)
  12-19 years of age        9.90          22.0
                        (6.10-18.0)    (12.0-29.0)
  20-59 years of age        6.50          9.70
                         (5.2-8.8)     (8.50-16.0)
  Males                     7.90          18.0
                        (5.90-10.0)    (9.00-25.0)
  Females                   7.60          10.0
                        (5.40-9.50)    (8.50-15.0)
  Non-Hispanic whites       7.90          10.0
                        (8.90-21.0)
  Non-Hispanic blacks       8.90          21.0
                        (6.50-15.0)    (12.0-24.0)
  Mexican Americans         9.50          15.0
                        (6.80-13.0)    (10.0-23.0)
DMTP
  All (a)                   38.0          46.0
                        (21.0-38.0)    (38.0-60.0)
  6-11 years of age         40.0          62.0
                        (38.0-54.0)    (38.0-110)
  12-19 years of age        37.0          69.0
                        (21.0-38.0)    (39.0-190)
  20-59 years of age        38.0          38.0
                        (18.0-38.0)    (38.0-48.0)
  Males                     38.0          41.0
                        (17.0-38.0)    (38.0-62.0)
  Females                   38.0          52.0
                        (19.0-38.0)    (38.0-120)
  Non-Hispanic whites       37.0          45.0
                        (15.0-38.0)    (38.0-62.0)
  Non-Hispanic blacks       37.0          39.0
                        (25.0-38.0)    (38.0-88.0)
  Mexican Americans         38.0          130.0
                        (26.0-79.0)    (41.0-230)
DMDTP
  All (a)                   12.0          19.0
                        (5.40-17.0)    (17.0-37.0)
  6-11 years of age         16.0          32.0
                        (5.90-18.0)    (18.0-38.0)
  12-19 years of age        12.0          19.0
                        (6.20-17.0)    (12.0-52.0)
  20-59 years of age        10.0          16.0
                        (4.20-17.0)    (6.30-19.0)
  Males                     16.0          18.0
                        (5.80-17.0)    (17.0-32.0)
  Females                   10.0          20.0
                        (4.50-17.0)    (13.0-40.0)
  Non-Hispanic whites       13.0          18.0
                        (4.20-17.0)    (16.0-40.0)
  Non-Hispanic blacks       14.0          18.0
                         (7.0-18.0)    (17.0-39.0)
  Mexican Americans         5.70          12.0
                        (4.00-9.70)    (6.80-17.0)
DEP
  All (a)                   7.50          13.0
                        (5.20-11.0)    (8.00-21.0)
  6-11 years of age         10.0          15.0
                        (4.80-16.0)    (11.0-27.0)
  12-19 years of age        7.90          20.0
                        (4.20-23.0)    (8.00-27.0)
  20-59 years of age        7.20          10.0
                        (4.90-10.0)    (6.90-19.0)
  Males                     8.00          18.0
                        (5.00-19.00)   (7.40-27.0)
  Females                   7.50          11.0
                        (4.90-10.0)    (7.70-14.0)
  Non-Hispanic whites       7.60          14.0
                        (4.80-14.0)    (7.90-23.0)
  Non-Hispanic blacks       10.0          18.0
                        (6.20-16.0)    (10.0-26-0)
  Mexican Americans        11.00          17.0
                        (6.90-13.0)    (12.0-23.0)
DETP
  All (a)                   1.30          2.20
                        (1.20-1.60)    (1.70-2.80)
  6-11 years of age         1.70          3.13
                        (1.30-2.40)    (1.70-5.00)
  12-19 years of age        1.40          2.20
                        (1.20-1.90)    (1.60-3.10)
  20-59 years of age        1.30          2.00
                        (0.99-1.50)    (1.50-2.80)
  Males                     1.40          2.70
                        (1.20-1.90)    (1.90-4.10)
  Females                   1.24          1.70
                        (0.950-1.50)   (1.30-2.70)
  Non-Hispanic whites       1.30          1.80
                        (0.980-1.50)   (1.50-2.80)
  Non-Hispanic blacks       1.80          3.50
                        (1.24-3.30)    (1.80-4.80)
  Mexican Americans         1.40          2.20
                        (1.10-1.90)    (1.90-2.90)
DEDTP
  All (a)                   0.47          0.87
                        (0.39-0.63)    (0.65-1.00)
  6-11 years of age         0.43          0.85
                        (0.30-0.55)    (0.49-1.00)
  12-19 years of age        0.64          0.90
                        (0.36-0.86)    (0.68-1.30)
  20-59 years of age        0.45          0.90
                        (0.36-0.62)    (0.61-1.10)
  Males                     0.47          0.87
                        (0.36-0.66)    (0.65-1.10)
  Females                   0.45          0.85
                        (0.35-0.69)    (0.46-1.40)
  Non-Hispanic whites       0.42          0.87
                        (0.32-0.68)    (0.51-1.10)
  Non-Hispanic blacks       0.56          0.85
                        (0.42-0.82)    (0.65-1.20)
  Mexican Americans         0.65           1.1
                        (0.49-1.00)    (0.63-1.70)

Abbreviations: GM, geometric mean; LOD, limit of detection; NC,
not calculated because proportion of results below the LOD was
too high to provide reliable result; NE, could not be reliably
estimated. Upper and lower 95th confidence intervals of each
quantile are shown in parentheses; these data are shown as
total population data and divided into demographic subgroups
based on race/ethnicity, sex, and age.

(a) All population data, including those individuals not grouped
into one of the three composite race/ethnicity categories, are
presented.

Table 2. Weighted quantiles of creatinine-adjusted urinary DAP
concentrations ([micro]g/g creatinine) in the NHANES 1999-2000
study population.

Analyte/                          Detection
demographic category     No.    frequency (%)        GM

DMP
  All (a)               1,949        53              NC
  6-11 years of age       471        63              NC
  12-19 years of age      664        50              NC
  20-59 years of age      814        52              NC
  Males                   952        53              NC
  Females                 997        54              NC
  Non-Hispanic whites     594        49              NC
  Non-Hispanic blacks     509        62              NC
  Mexican Americans       672        59              NC
DMTP
  All (a)               1,949        64             1.64
                                                (1.27-2.10)
  6-11 years of age       471        69             2.95
                                                (2.00-4.34)
  12-19 years of age      664        67             1.71
                                                (1.13-2.59)
  20-59 years of age      814        63             1.47
                                                (1.14-1.90)
  Males                   952        66             1.61
                                                (1.19-2.18)
  Females                 997        62             1.66
                                                (1.24-2.21)
  Non-Hispanic whites     594        64             1.68
                                                (1.21-2.32)
  Non-Hispanic blacks     509        68             1.45
                                                (0.95-2.23)
  Mexican Americans       672        63             1.60
                                                (0.962-2.67)
DMDTP
  All (a)               1,949        53              NC
  6-11 years of age       471        63              NC
  12-19 years of age      664        51              NC
  20-59 years of age      814        48              NC
  Males                   952        53              NC
  Females                 997        53              NC
  Non-Hispanic whites     594        50              NC
  Non-Hispanic blacks     509        56              NC
  Mexican Americans       672        53              NC
DEP
  All (a)               1,949        71             0.93
                                                (0.69-1.25)
  6-11 years of age       471        74             1.43
                                                (0.94-2.17)
  12-19 years of age      664        73             0.76
                                                (0.55-1.05)
  20-59 years of age      814        69             0.90
                                                (0.67-1.23)
  Males                   952        72             0.86
                                                (0.63-1.17)
  Females                 997        69             1.00
                                                (0.73-1.37)
  Non-Hispanic whites     594        68             0.94
                                                (0.65-1.37)
  Non-Hispanic blacks     509        82             1.06
                                                (0.84-1.35)
  Mexican Americans       672        74             1.08
                                                (0.74-1.58)
DETP
  All (a)               1,949        53              NC
  6-11 years of age       471        59              NC
  12-19 years of age      664        46              NC
  20-59 years of age      814        54              NC
  Males                   952        57              NC
  Females                 997        50              NC
  Non-Hispanic whites     594        51              NC
  Non-Hispanic blacks     509        64              NC
  Mexican Americans       672        58              NC
DEDTP
  All (a)               1,949        56              NC
  6-11 years of age       471        60              NC
  12-19 years of age      664        51              NC
  20-59 years of age      814        56              NC
  Males                   952        57              NC
  Females                 997        54              NC
  Non-Hispanic whites     594        53              NC
  Non-Hispanic blacks     509        61              NC
  Mexican Americans       672        66              NC

                             Percentile of distribution

Analyte/
demographic category    25th       50th          75th

DMP
  All (a)               < LOD      0.81          2.93
                                (0.59-1.11)   (2.12-3.86)
  6-11 years of age     < LOD      1.38          4.48
                                (0.89-2.38)   (2.63-8.20)
  12-19 years of age    < LOD      0.59          2.27
                                (0.45-0.95)   (1.67-2.91)
  20-59 years of age    < LOD      0.76          2.87
                                (0.56-1.11)   (1.91-3.92)
  Males                 < LOD      0.62          2.38
                                (0.45-0.89)   (1.78-3.23)
  Females               < LOD      1.00          3.53
                                (0.68-1.50)   (2.35-5.00)
  Non-Hispanic whites   < LOD      < LOD         3.15
                                              (2.03-4.26)
  Non-Hispanic blacks   < LOD      0.69          2.67
                                (0.53-1.06)   (1.78-3.87)
  Mexican Americans     < LOD      1.06          3.68
                                (0.72-1.47)   (2.77-4.67)
DMTP
  All (a)               < LOD      2.12          9.57
                                (1.38-3.11)   (6.67-15.1)
  6-11 years of age     < LOD      5.25          18.7
                                (2.50-7.03)   (11.6-31.5)
  12-19 years of age    < LOD      2.14          13.4
                                (1.22-4.13)   (7.01-21.0)
  20-59 years of age    < LOD      1.90          8.09
                                (1.00-2.83)   (5.58-12.4)
  Males                 < LOD      2.28          9.27
                                (1.42-3.35)   (6.43-15.4)
  Females               < LOD      2.01          10.0
                                (0.92-3.11)   (6.20-17.5)
  Non-Hispanic whites   < LOD      2.20          9.27
                                (1.17-3.42)   (5.96-16.9)
  Non-Hispanic blacks   < LOD      1.75          8.21
                                (1.01-3.38)   (4.65-12.4)
  Mexican Americans     < LOD      1.83          10.4
                                (0.74-3.75)   (5.93-17.1)
DMDTP
  All (a)               < LOD      < L0D         1.86
                                              (1.04-3.25)
  6-11 years of age     < LOD      < LOD         4.07
                                              (2.34-7.00)
  12-19 years of age    < LOD      < LOD         1.52
                                              (0.64-3.37)
  20-59 years of age    < LOD      < LOD         1.71
                                              (0.92-2.82)
  Males                 < LOD      < LOD         1.64
                                              (0.87-3.45)
  Females               < LOD      < LOD         1.99
                                              (1.00-3.67)
  Non-Hispanic whites   < LOD      < LOD         1.75
                                              (0.85-4.00)
  Non-Hispanic blacks   < LOD      < LOD         2.39
                                              (1.18-4.53)
  Mexican Americans     < LOD      < LOD         1.35
                                              (0.97-1.99)
DEP
  All (a)               < LOD      0.92          2.73
                                (0.63-1.28)   (1.89-4.29)
  6-11 years of age     < LOD      1.47          3.94
                                (1.02-2.41)   (2.39-8.15)
  12-19 years of age    < LOD      0.79          2.29
                                (0.62-1.13)   (1.40-3.42)
  20-59 years of age    < LOD      0.86          2.63
                                (0.58-1.18)   (1.71-4.38)
  Males                 < LOD      0.81          2.61
                                (0.59-1.19)   (1.76-4.13)
  Females               < LOD      0.96          2.80
                                (0.64-1.45)   (1.89-4.72)
  Non-Hispanic whites   < LOD      0.90          2.82
                                (0.51-1.48)   (1.75-5.33)
  Non-Hispanic blacks   < LOD      1.17          2.55
                                (0.83-1.53)   (2.13-3.24)
  Mexican Americans     < LOD      1.05          3.78
                                (0.74-1.57)   (2.29-5.79)
DETP
  All (a)               < LOD      0.25          0.71
                                (0.10-0.42)   (0.51-0.96)
  6-11 years of age     < LOD      0.47          1.08
                                (0.15-0.83)   (0.83-1.30)
  12-19 years of age    < LOD      0.18          0.51
                                (0.06-0.33)   (0.34-0.76)
  20-59 years of age    < LOD      0.25          0.69
                                (0.10-0.41)   (0.47-0.96)
  Males                 < LOD      0.27          0.67
                                (0.10-0.42)   (0.52-0.81)
  Females               < LOD      < LOD         0.79
                                              (0.45-1.20)
  Non-Hispanic whites   < LOD      0.23          0.71
                                (0.08-0.46)   (0.46-1.05)
  Non-Hispanic blacks   < LOD      0.30          0.72
                                (0.15-0.46)   (0.54-0.84)
  Mexican Americans     < LOD      0.34          0.83
                                (0.10-0.57)   (0.57-1.13)
DEDTP
  All (a)               < LOD      0.07          0.20
                                (0.06-0.11)   (0.15-0.26)
  6-11 years of age     < LOD      0.10          0.19
                                (0.07-0.13)   (0.15-0.25)
  12-19 years of age    < LOD      0.05          0.17
                                (0.04-0.07)   (0.10-0.22)
  20-59 years of age    < LOD      0.08          0.21
                                (0.06-0.11)   (0.15-0.29)
  Males                 < LOD      0.07          0.19
                                (0.05-0.10)   (0.14-0.22)
  Females               <LOD       0.09          0.22
                                (0.06-0.12)   (0.16-0.32)
  Non-Hispanic whites   < LOD      0.07          0.20
                                (0.05-0.11)   (0.14-0.29)
  Non-Hispanic blacks   < LOD      0.07          0.18
                                (0.05-0.10)   (0.13-0.22)
  Mexican Americans     < LOD      0.09          0.30
                                (0.07-0.15)   (0.19-0.41)

                              Percentile of
                              distribution

Analyte/
demographic category       90th           95th

DMP
  All (a)                  8.46           16.1
                        (6.74-11.2)   (12.1-19.5)
  6-11 years of age        15.9           21.7
                        (7.65-21.7)   (16.7-45.1)
  12-19 years of age       7.70           14.5
                        (4.16-13.8)   (7.78-35.3)
  20-59 years of age       8.11           14.6
                        (5.45-10.6)   (10.1-17.6)
  Males                    7.58           15.2
                        (4.64-11.6)   (9.74-19.5)
  Females                  9.12           16.4
                        (7.59-12.2)   (10.4-21.4)
  Non-Hispanic whites      8.73           15.8
                        (6.12-12.8)   (10.2-19.7)
  Non-Hispanic blacks      7.07           13.9
                        (4.77-11.5)   (9.61-19.5)
  Mexican Americans        9.41           15.9
                        (7.24-12.2)   (12.7-23.2)
DMTP
  All (a)                  32.0           51.0
                        (23.9-40.4)   (39.0-71.1)
  6-11 years of age        45.2           65.9
                        (32.1-60.3)    (50.7-100)
  12-19 years of age       36.0           61.5
                        (25.1-51.4)    (37.1-179)
  20-59 years of age       27.0           47.4
                        (20.6-37.1)   (34.2-70.1)
  Males                    28.9           41.1
                        (20.5-37.6)   (32.0-57.1)
  Females                  34.5           69.5
                        (25.4-47.4)    (41.7-118)
  Non-Hispanic whites      32.5           54.4
                        (21.3-49.4)   (39.2-74.7)
  Non-Hispanic blacks      25.5           52.1
                        (17.9-38.8)   (25.55-97.6)
  Mexican Americans        37.0           112
                        (22.8-63.1)    (39.2-207)
DMDTP
  All (a)                  10.1           21.7
                        (5.63-16.6)   (13.8-30.8)
  6-11 years of age        16.2           30.8
                        (9.25-27.0)   (20.2-38.9)
  12-19 years of age       9.42           18.5
                        (4.02-16.8)   (8.76-44.8)
  20-59 years of age       8.46           19.2
                        (4.96-16.6)   (9.82-35.2)
  Males                    11.0           17.8
                        (5.32-16.6)   (10.1-34.2)
  Females                  9.30           27.0
                        (5.41-21.5)   (9.82-47.5)
  Non-Hispanic whites      11.3           21.5
                        (4.79-20.2)   (12.8-30.8)
  Non-Hispanic blacks      9.41           17.8
                        (5.11-16.6)   (11.6-36.0)
  Mexican Americans        6.55           16.7
                        (4.10-11.6)   (6.94-34.2)
DEP
  All (a)                  7.94           12.1
                        (4.90-11.7)   (8.75-17.5)
  6-11 years of age        10.3           16.2
                        (4.55-20.6)   (10.5-32.7)
  12-19 years of age       5.38           12.3
                        (2.89-12.3)   (4.87-23.8)
  20-59 years of age       7.37           12.1
                        (4.60-11.3)   (8.57-15.7)
  Males                    7.69           12.2
                        (4.55-11.7)   (8.00-21.6)
  Females                  8.00           12.1
                        (4.90-11.7)   (8.10-17.5)
  Non-Hispanic whites      8.46           12.6
                        (4.95-13.3)   (8.89-19.6)
  Non-Hispanic blacks      5.98           11.7
                        (4.22-8.93)   (6.62-19.4)
  Mexican Americans        9.84           15.6
                        (6.57-14.4)   (10.3-19.3)
DETP
  All (a)                  1.70           2.64
                        (1.21-2.17)   (2.12-2.96)
  6-11 years of age        1.73           2.45
                        (1.44-2.36)   (1.88-5.42)
  12-19 years of age       1.07           1.97
                        (0.78-1.53)   (1.07-3.92)
  20-59 years of age       1.79           2.75
                        (1.18-2.32)   (2.12-3.06)
  Males                    1.34           2.66
                        (1.08-2.18)   (1.56-3.23)
  Females                  1.89           2.52
                        (1.22-2.33)   (2.08-2.96)
  Non-Hispanic whites      1.88           2.58
                        (1.20-2.36)   (2.12-2.96)
  Non-Hispanic blacks      1.35           2.89
                        (0.90-2.89)   (1.35-5.13)
  Mexican Americans        1.69           2.71
                        (1.30-2.16)   (1.86-3.55)
DEDTP
  All (a)                  0.55           0.86
                        (0.41-0.69)   (0.69-1.13)
  6-11 years of age        0.57           1.03
                        (0.39-0.77)   (0.60-1.57)
  12-19 years of age       0.44           0.73
                        (0.23-0.73)   (0.39-0.95)
  20-59 years of age       0.55           0.86
                        (0.38-0.71)   (0.67-1.16)
  Males                    0.42           0.72
                        (0.32-0.52)   (0.49-0.94)
  Females                  0.67           0.89
                        (0.41-0.86)   (0.71-1.38)
  Non-Hispanic whites      0.55           0.88
                        (0.39-0.73)   (0.65-1.16)
  Non-Hispanic blacks      0.45           0.69
                        (0.28-0.68)   (0.48-1.07)
  Mexican Americans        0.81           1.16
                        (0.52-1.00)   (0.86-2.66)

Abbreviations: GM, geometric mean; LOD, limit of detection; NC,
not calculated because proportion of results below the LOD was
too high to provide reliable result; NE, could not be reliably
estimated. Upper and lower 95th confidence intervals of each
quantile are shown in parentheses; these data are shown as
total population data and divided into demographic subgroups
based on race/ethnicity, sex, and age.

(a) All population data, including those individuals not grouped
into one of the three composite race/ethnicity categories, are
presented.

Table 3. LSGMs (95% CIs) of urinary DAP metabolites among
demographic groups.

                                           DMTP           DEP
Category         Demographic group     ([micro]g/L)   ([micro]g/L)

Age              6-11 years of age        3.08 *         1.73 *
                   (children)          (1.90-4.97)    (1.06-2.83)
                 12-19 years of age        2.07           1.06
                   (adolescents)       (1.35-3.17)    (0.73-1.55)
                 20-59 years of age        1.59           1.00
                   (adults)            (1.16-2.16)    (0.74-1.37)
Sex              Males                     2.00           1.08
                                       (1.44-2.78)    (0.79-1.49)
                 Females                   1.57           1.07
                                       (1.11-2.22)    (0.77-1.48)
Race/ethnicity   Non-Hispanic whites       1.78           1.03
                                       (1.25-2.53)    (0.73-1.47)
                 Non-Hispanic blacks       1.79           1.25
                                       (1.155-2.79)   (0.98-1.60)
                 Mexican Americans         1.69           1.16
                                       (1.02-2.80)    (0.80-1.70)

Category         Demographic group     DMAP (nmol/L)   REAP (nmol/L)

Age              6-11 years of age        72.8 *          17.4 *
                   (children)           (54.3-97.5)     (11.1-27.3)
                 12-19 years of age        56.9            11.0
                   (adolescents)        (40.2-80.7)     (7.6-15.9)
                 20-59 years of age        42.1            10.0
                   (adults)             (33.6-52.8)     (7.5-13.2)
Sex              Males                     50.6            10.8
                                        (40.0-64.2)     (8.0-14.5)
                 Females                   42.9            10.7
                                        (33.8-54.3)     (8.0-14.3)
Race/ethnicity   Non-Hispanic whites       45.2            10.4
                                        (35.3-57.8)     (7.5-14.3)
                 Non-Hispanic blacks       53.0            12.0
                                        (38.8-72.6)     (9.3-15.5)
                 Mexican Americans         50.1            12.2
                                        (36.8-68.3)     (8.6-17.2)

Category         Demographic group     DAP (nmol/L)

Age              6-11 years of age       109.6 *
                   (children)          (83.3-144.3)
                 12-19 years of age       89.3 *
                   (adolescents)       (65.2-122.2)
                 20-59 years of age        66.9
                   (adults)            (54.3-82.5)
Sex              Males                     79.1
                                       (62.6-9.99)
                 Females                   68.2
                                       (55.9-83.3)
Race/ethnicity   Non-Hispanic whites       70.9
                                       (56.4-89.1)
                 Non-Hispanic blacks       83.0
                                       (65.6-105.0)
                 Mexican Americans         82.7
                                       (62.1-110.2)

LSGMs were adjusted for age, sex, race/ethnicity, and concentrations
of serum cotinine and urinary creatinine. LSGMs were calculated for
metabolites with detection frequencies of [greater than or equal to]
60%.

* Significantly different from adults at 0.05.

Table 4. Weighted quantiles of composite DMAP and DEAP concentrations
(nmol/L) in the NHANES 1999-2000 study population.

Analyte/                         Detection
demographic category     No.    frequency(%)        GM

DAP
  All (a)               1,949        94            76.3
                                               (65.0-89.6)
  6-11 years of age       471        96            101
                                                (80.7-126)
  12-19 years of age      664        94            96.5
                                                (73.6-127)
  20-59 years of age      814        92            69.4
                                               (58.5-82.4)
  Males                   952        94            82.9
                                               (67.5-101.8)
  Females                 997        93            70.4
                                               (60.0-82.6)
  Non-Hispanic whites     594        92            72.8
                                               (59.0-90.0)
  Non-Hispanic blacks     509        96            96.3
                                                (79.1-117)
  Mexican Americans       672        93            84.1
                                                (65.0-109)
DMAP
  All (a)               1,949        84            49.4
                                               (41.7-58.5)
  6-11 years of age       471        87            70.3
                                               (55.6-88.8)
  12-19 years of age      664        84            63.0
                                               (46.8-84.7)
  20-59 years of age      814        82            44.3
                                               (36.9-53.1)
  Males                   952        84            53.1
                                               (43.2-65.2)
  Females                 997        84            46.0
                                               (38.2-55.5)
  Non-Hispanic whites     594        82            47.3
                                               (37.9-59.0)
  Non-Hispanic blacks     509        86            59.6
                                               (44.9-79.0)
  Mexican Americans       672        84            52.1
                                               (39.1-69.4)
DEAP
  All (a)               1,949        77            10.5
                                               (7.93-13.9)
  6-11 years of age       471        80            13.2
                                               (8.80-19.8)
  12-19 years of age      664        82            11.8
                                                (8.4-16.6)
  20-59 years of age      814        76            9.85
                                               (7.46-13.0)
  Males                   952        80            11.5
                                               (8.60-15.4)
  Females                 997        77            9.56
                                                (710-12.8)
  Non-Hispanic whites     594        76            9.96
                                               (7.03-14.1)
  Non-Hispanic blacks     509        83            15.2
                                               (12.1-19.2)
  Mexican Americans       672        81            12.5
                                               (9.10-17.1)

                              Percentile of distribution

Analyte/
demographic category       10th          25th          50th

DAP
  All (a)                  8.65          31.1          81.7
                        (6.00-15.2)   (24.0-40.0)   (65.5-98.9)
  6-11 years of age        10.6          40.3           113
                        (6.00-22.0)   (26.5-61.0)   (78.2-152)
  12-19 years of age       12.9          36.0          93.2
                        (6.50-21.9)   (28.0-50.2)   (64.3-135)
  20-59 years of age       7.36          26.6          75.3
                        (6.00-12.8)   (20.0-39.6)   (60.3-92.5)
  Males                    11.2          35.7          87.1
                        (6.40-19.4)   (26.4-47.0)   (65.4-110)
  Females                  6.46          25.0          76.2
                        (6.00-12.5)   (19.6-36.0)   (61.6-92.3)
  Non-Hispanic whites      6.51          27.5          76.2
                        (6.00-12.4)   (19.4-41.0)   (60.7-107)
  Non-Hispanic blacks      18.1          43.4           105
                        (12.0-26.8)   (32.0-56.8)   (78.1-123)
  Mexican Americans        10.5          32.2          81.7
                        (6.00-20.7)   (24.4-43.0)   (59.7-114)
DMAP
  All (a)                  4.47          13.2          54.5
                        (4.20-4.55)   (7.60-19.5)   (42.2-68.8)
  6-11 years of age        4.47          23.4          90.6
                        (4.20-4.55)   (11.8-39.0)   (64.9-112)
  12-19 years of age       4.55          18.1          62.2
                        (4.20-4.55)   (11.6-28.0)   (41.2-103)
  20-59 years of age       4.55          11.8          48.3
                        (4.20-4.55)   (6.10-18.4)   (37.4-62.4)
  Males                    4.55          17.2          59.1
                        (4.20-4.55)   (11.6-24.0)   (45.1-74.5)
  Females                  4.55          11.0          46.8
                        (4.20-4.55)   (4.80-18.0)   (37.7-68.7)
  Non-Hispanic whites      4.15          11.6          54.0
                        (4.20-4.55)   (5.4-21.9)    (38.4-70.2)
  Non-Hispanic blacks      4.55          22.3          71.9
                        (4.20-4.55)    (10.0-37)    (50.3-96.3)
  Mexican Americans        4.15          15.6          48.0
                        (4.20-4.55)   (7.10-24.6)   (38.6-72.0)
DEAP
  All (a)                  < LOD         2.30          12.3
                                      (1.50-7.20)   (9.9-15.6)
  6-11 years of age        < LOD         4.70          15.6
                                      (1.50-11.7)   (12.3-21.4)
  12-19 years of age       < LOD         3.23          12.9
                                      (1.48-8.34)   (10.3-16.8)
  20-59 years of age       < LOD         1.80          11.6
                                      (1.48-6.10)   (9.12-14.4)
  Males                    < LOD         2.96          12.4
                                      (1.48-7.70)   (10.0-16.6)
  Females                  < LOD         < LOD         11.9
                                                    (9.00-15.5)
  Non-Hispanic whites      < LOD         < LOD         12.0
                                                    (7.80-16.5)
  Non-Hispanic blacks      < LOD          9.0          15.7
                                      (3.23-11.2)   (12.5-19.0)
  Mexican Americans        < LOD         3.82          13.9
                                      (1.48-9.18)   (10.9-17.3)

                               Percentile of distribution

Analyte/
demographic category       75th          90th          95th

DAP
  All (a)                   202           399           651
                         (168-270)     (357-475)     (516-911)
  6-11 years of age         287           507           832
                         (218-350)     (410-623)    (599-1,230)
  12-19 years of age        268           541          1,130
                         (175-320)    (362-1,000)   (563-2,180)
  20-59 years of age        188           380           552
                         (144-233)     (294-416)     (411-798)
  Males                     239           400           648
                         (164-288)     (332-520)     (486-930)
  Females                  190.0          387           692
                         (152-227)     (300-454)     (428-971)
  Non-Hispanic whites       202           386           651
                         (151-273)     (314-494)     (471-932)
  Non-Hispanic blacks       233           417           692
                         (171-278)     (330-623)     (481-911)
  Mexican Americans         215           479          1,250
                         (172-264)     (347-798)    (532-1,930)
DMAP
  All (a)                   159           377           583
                         (123-216)     (290-403)     (441-725)
  6-11 years of age         270           460           679
                         (174-308)     (338-515)    (493-1,080)
  12-19 years of age        224           472          1,120
                         (139-271)     (320-911)    (498-2,140)
  20-59 years of age        137           331           426
                         (102-181)     (271-378)     (379-623)
  Males                     179           377           552
                         (117-271)     (288-419)     (378-725)
  Females                   149           375           638
                         (116-179)     (274-414)     (401-937)
  Non-Hispanic whites       153           366           568
                         (112-237)     (273-409)     (394-783)
  Non-Hispanic blacks       195           379           623
                         (121-268)     (292-469)     (421-812)
  Mexican Americans         155           403          1,230
                         (124-189)     (271-748)    (455-1,920)
DEAP
  All (a)                  28.3          64.7           108
                        (22.0-36.6)   (42.9-84.7)   (73.4-147)
  6-11 years of age        35.9          87.5           136
                        (21.2-60.3)   (51.3-121)    (87.2-200)
  12-19 years of age       30.5          84.4           161
                        (19.1-45.1)   (39.5-164)    (64.4-185)
  20-59 years of age       27.0          59.0          88.0
                        (20.5-34.1)   (41.8-78.5)   (65.9-137)
  Males                    31.9          68.9           147
                        (22.0-39.7)   (46.4-137)    (73.4-186)
  Females                  25.5          58.4          80.1
                        (19.1-34.0)   (41.7-77.1)   (70.6-104)
  Non-Hispanic whites      28.0          65.1           109
                        (19.2-39.9)   (41.7-105)    (70.6-161)
  Non-Hispanic blacks      36.6          77.8           126
                        (29.2-44.1)   (50.5-113)    (78.5-186)
  Mexican Americans        33.5          83.9           126
                        (23.1-48.6)   (58.4-102)    (95.8-178)

NE, could not be reliably estimated. To determine the composite
concentrations, the dialkylphosphate concentrations were converted
to their molar equivalents and then summed. Upper and lower 95th
confidence intervals of each quantile are shown in parentheses;
these data are shown as total population data and divided into
demographic subgroups based on race/ethnicity, sex, and age.

(a) All population data, including those individuals not grouped
into one of the three composite race/ethnicity categories, are
presented.

Table 5. Weighted quantiles of creatinine-adjusted composite DMAP
and DEAP concentrations (nmol/L) in the NHANES 1999-2000 study
population.

Analyte/                          Detection
demographic category     No.    frequency (%)        GM

DAP
  All (a)               1,949        94             68.5
                                                (57.98-80.92)
  6-11 years of age       471        96              109
                                                (88.7-134.1)
  12-19 years of age      664        94             65.1
                                                (48.96-86.67)
  20-59 years of age      814        92             64.1
                                                (53.33-77.06)
  Males                   952        94             63.7
                                                 (51.1-79.3)
  Females                 997        93             73.6
                                                 (62.2-87.0)
  Non-Hispanic whites     594        92             69.2
                                                 (55.4-86.5)
  Non-Hispanic blacks     509        96             65.9
                                                 (54.2-80.1)
  Mexican Americans       672        93             75.3
                                                 (56.4-100)
DMAP
  All (a)               1,949        84             44.3
                                                 (37.2-52.8)
  6-11 years of age       471        87             76.1
                                                 (61.0-94.9)
  12-19 years of age      664        84             42.5
                                                 (30.9-58.5)
  20-59 years of age      814        82             40.9
                                                 (33.9-49.4)
  Males                   952        84             40.8
                                                 (32.7-50.9)
  Females                 997        84             48.1
                                                 (39.7-58.3)
  Non-Hispanic whites     594        82             44.9
                                                 (35.5-56.8)
  Non-Hispanic blacks     509        86             40.75
                                                 (31.3-53.1)
  Mexican Americans       672        84             46.6
                                                 (34.1-63.6)
DEAP
  All (a)               1,949        77             14.7
                                                 (11.0-19.6)
  6-11 years of age       471        80             21.5
                                                 (15.9-29.0)
  12-19 years of age      664        82             10.7
                                                 (8.16-14.1)
  20-59 years of age      814        76             14.0
                                                 (11.0-17.7)
  Males                   952        80             12.8
                                                 (9.98-16.4)
  Females                 997        77             15.7
                                                 (12.3-20.1)
  Non-Hispanic whites     594        76             14.7
                                                 (11.0-19.6)
  Non-Hispanic blacks     509        83             13.9
                                                 (11.5-16.8)
  Mexican Americans       672        81             15.5
                                                 (11.6-20.6)

                              Percentile of distribution

Analyte/
demographic category       10th          25th          50th

DAP
  All (a)                  10.0          25.9          70.9
                        (8.10-12.5)   (19.0-34.6)   (55.5-84.6)
  6-11 years of age        14.9          41.3           116
                        (10.8-24.2)   (28.4-63.2)   (95.1-159)
  12-19 years of age       9.42          22.0          57.1
                        (7.90-13.5)   (15.0-33.0)   (40.0-87.0)
  20-59 years of age       9.42          23.9          67.8
                        (7.5-11.9)    (17.5-34.2)   (51.3-81.0)
  Males                    10.2          23.8          64.1
                        (8.20-12.6)   (17.0-35.0)   (51.0-82.2)
  Females                  9.99          27.3          78.3
                        (7.80-12.6)   (18.8-35.9)   (59.7-92.8)
  Non-Hispanic whites      9.67          25.3          74.2
                        (7.50-12.3)   (16.7-38.2)   (54.8-94.2)
  Non-Hispanic blacks      13.7          23.8          62.5
                        (10.5-17.3)   (19.1-31.0)   (49.2-76.3)
  Mexican Americans        10.0          29.5          75.1
                        (6.33-18.2)   (22.1-39.7)   (57.1-97.8)
DMAP
  All (a)                  4.14          13.5          43.4
                        (3.30-5.50)   (9.50-19.8)   (36.4-56.3)
  6-11 years of age        5.60          26.5          91.0
                        (4.40-11.1)   (16.4-46.6)   (67.4-109)
  12-19 years of age       3.92          10.4          36.7
                        (2.80-6.40)   (7.10-19.0)   (27.8-58.9)
  20-59 years of age       3.64          12.9          41.1
                        (3.20-5.50)   (8.40-19.6)   (33.8-50.3)
  Males                    3.73          13.3          40.4
                        (3.30-5.10)   (9.10-18.9)   (34.7-63.0)
  Females                  4.24          14.4          47.3
                        (3.50-6.10)   (9.30-22.7)   (36.3-61.1)
  Non-Hispanic whites      3.79          13.8          44.2
                        (3.20-5.50)   (8.60-23.3)   (35.8-60.4)
  Non-Hispanic blacks      5.00          13.6          42.5
                        (3.20-7.50)   (9.00-22.3)   (30.9-57.3)
  Mexican Americans        4.14          16.1          41.9
                        (2.50-7.00)   (8.90-23.3)   (35.6-57.5)
DEAP
  All (a)                  1.33          3.44          8.82
                        (1.20-1.80)   (2.30-4.91)   (6.81-11.9)
  6-11 years of age        1.65          5.92          14.9
                        (1.21-3.66)   (2.52-10.7)   (10.7-22.4)
  12-19 years of age       1.28          3.20          7.55
                        (1.06-1.81)   (1.83-4.35)   (6.01-10.2)
  20-59 years of age       1.30          3.28          8.42
                        (1.16-1.82)   (2.22-4.78)   (6.41-11.5)
  Males                    1.26          3.12          8.42
                        (1.10-1.46)   (1.91-4.62)   (6.78-11.7)
  Females                  1.63          3.68          9.15
                        (1.26-2.21)   (2.62-5.28)   (6.72-13.4)
  Non-Hispanic whites      1.30          3.20          8.60
                        (1.11-1.82)   (2.20-4.88)   (5.90-13.6)
  Non-Hispanic blacks      1.59          4.48          10.8
                        (1.16-3.02)   (3.72-6.44)   (8.05-13.7)
  Mexican Americans        1.32          3.89          10.6
                        (1.05-2.12)   (2.28-6.78)   (7.81-15.8)

                             Percentile of distribution

Analyte/
demographic category       75th          90th          95th

DAP
  All (a)                   189           405           748
                         (152-223)     (310-493)    (536-1,000)
  6-11 years of age         283           574           979
                         (205-351)     (364-905)    (609-1,240)
  12-19 years of age        170           432          1,120
                         (115-227)     (252-880)    (500-1,470)
  20-59 years of age        176           352           611
                         (139-217)     (281-471)    (412-1,000)
  Males                     177           352           611
                         (135-222)     (269-452)     (409-981)
  Females                   204           438           912
                         (157-240)     (342-566)    (538-1,120)
  Non-Hispanic whites       197           405           713
                         (146-246)     (288-566)    (475-1,030)
  Non-Hispanic blacks       148           336           656
                         (115-217)     (259-540)     (423-854)
  Mexican Americans         180           453          1,130
                         (137-261)     (290-912)    (512-1,460)
DMAP
  All (a)                   153           337           601
                         (118-184)     (272-408)     (414-923)
  6-11 years of age         243           494           753
                         (169-316)     (326-683)    (499-1,060)
  12-19 years of age        139           418           961
                         (103-191)     (226-762)    (425-1,430)
  20-59 years of age        143           312           522
                        (95.7-173)     (238-403)     (352-822)
  Males                     144           295           472
                         (103-182)     (237-403)     (362-692)
  Females                   163           393           768
                         (114-206)     (312-534)    (494-1,110)
  Non-Hispanic whites       159           337           581
                         (105-196)     (249-454)     (402-964)
  Non-Hispanic blacks       122           318           536
                        (86.6-193)     (232-472)     (328-713)
  Mexican Americans         140           410          1,120
                         (100-187)     (241-758)    (446-1,460)
DEAP
  All (a)                  24.0          66.9          97.7
                        (16.3-35.3)   (43.4-85.5)   (80.7-120)
  6-11 years of age        34.4          85.4           128
                        (21.1-54.6)   (56.0-113)    (91.8-213)
  12-19 years of age       19.6          47.1           112
                        (11.9-27.4)   (26.1-110)    (44.2-194)
  20-59 years of age       23.0          65.5          94.3
                        (15.4-36.3)   (43.1-85.3)   (77.4-120)
  Males                    23.0          68.0           104
                        (16.3-34.0)   (40.9-86.3)   (80.0-129)
  Females                  24.5          65.6          96.4
                        (15.8-38.0)   (43.1-88.4)   (69.8-139)
  Non-Hispanic whites      26.1          73.9           108
                        (15.4-43.1)   (43.1-97.2)   (85.3-139)
  Non-Hispanic blacks      22.8          48.6          84.5
                        (17.8-28.1)   (35.4-70.2)   (57.0-153)
  Mexican Americans        31.9          75.5           110
                        (20.9-47.9)   (58.5-100)    (75.5-145)

NE, could not be reliably estimated. To determine the composite
concentrations, the DAP concentrations were converted to their
molar equivalents and then summed. Upper and lower 95th confidence
intervals of each quantile are shown in parentheses; these data
are shown as total population data and divided into demographic
subgroups based on race/ethnicity, sex, and age.

(a) All population data, including those individuals not grouped
into one of the three composite race/ethnicity categories, are
presented.

Table 6. Pearson correlation coefficients of DAP metabolites of OP
pesticides with selective OP metabolites.

                    TCPY
               (chlorpyrifos,
                chlorpyrifos-
                   methyl)          IMPY (diazinon)

Metabolite   r-Value   p-Value    r-Value   p-Value

DMP           0.11       0.007      ND         ND
DMTP          0.12       0.0101     ND         ND
DEP           0.22     < 0.0001    0.27     < 0.0001
DETP          0.29     < 0.0001    0.38     < 0.0001
DEAP          0.25     < 0.0001    0.29     < 0.0001
DMAP          0.114      0.009      ND         ND

                                       PNP (a)
                                     (parathion,
               MAL (malathion)     methyl parathion)

Metabolite   r-Value   p-Value    r-Value   p-Value

DMP           0.10      0.0138     0.16       0.014
DMTP          0.16     < 0.0001    0.09       0.015
DEP            ND         ND       0.27     < 0.0001
DETP           ND         ND       0.27       0.0003
DEAP           ND         ND       0.27     < 0.0001
DMAP          0.14      0.0004     0.064      0.114

Abbreviations: MAL, malathion dicarboxylic acid; ND, not determined;
PNP, para-nitrophenol; TCPY, 3,5,6-trichloropyridinol. The parent
pesticides for each selective metabolite are listed below the
metabolite. All analyses were weighted and used log-transformed data.

(a) PNP can also be derived from exposure to pesticides such as EPN
(0-ethyl-4- 0-nitro phenyl phenylphasphonothioate) and other
nonpesticide sources such as 4-aminophenol.

Table 7. DAP concentrations in reported studies. Concentrations
shown are mean values unless otherwise indicated; median values
shown in parentheses.

Study                           Study population         No.

Incidental or community-based measures
  Griffith and Duncan        General U.S.               6,894
    1985 (a)                   (NHANES II:
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults               124
  Loewenherz et al. 1997     Reference children            33
                               (0-6 years, WA
                               State)
                             Applicator children          127
                             Children living               51
                               < 200 ft of orchard
  Azaroff 1999 (d)           Nonfieldworkers in           110
                               farm families
  Aprea et al. 2000 (b)      Italian children             195
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period                  28
                             Control period                 6
  Hardt and Angerer 2000     German adults                 54
    Lu et al. 2000 (e)       Reference children            14
                               (central WA)
                             Applicator children           49
                             Farm children                 13
  0'Rourke et al. 2000 (d)   U.S.-Mexico border           121
  CDC 2001 (b)               General U.S-                 703
                               (NHANES 1999)
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age             309
                             6-13 years of age            294
                             14-19 years of age            59
                             [greater than or equal       484
                               to] 20 years of age
  Lu et al. 2001             Children (2-5 years          110
                               of age, Seattle, WA)
  Mills and Zahm 2001        Adult farmworkers             18
                             Farm children                  9
  Curl et al. 2002 (b)       Agricultural workers         213
                             Workers' children            211
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months                44
                                                      (26/child)
                               Nonspray months             44
                                                      (26/child)
  Royster et al. 2002        Toddlers in                   15
                               agricultural
                               region of CA
                             2nd visit                     17
  Castorina et al. 2003      Pregnant women             1,365
                               (Salinas, CA)
  Curl et al. 2003b (b)      Organic diet (2-6             18
                               years of age;
                               WA State)
                             Regular diet (2-6             21
                               years of age;
                               WA State)
  Shalat et al. 2003 (c,f)   Children at U.S.-             41
                               Mexico border
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide                   6
                               formulators
                             Nonexposed                     6
  Duncan and Griffith        Citrus sprayers              332
    1985 (h)                 Citrus harvesters            265
  Griffith and Duncan 1985   Citrus sprayers              332
                             Citrus harvesters            264
  Franklin et al. 1986 (i)   Canadian applicators          23
                             Guthion-dosed                 10
                               volunteers (dermal
                               500-6,000 [micro]g)
  Fenske and Leffingwell     Malathion applicator           1
    1989 (j)
  Drevenkar et al.           Orchard sprayers              97
    1991 (c)
  Aprea et al. 1994          Controls                      99
    (b,c,k)
                             Applicator women              19
                               with rubber gloves
                               and masks
                             Applicator women              28
                               with waterproof
                               cotton gloves and
                               masks
                             Applicator women              28
                               with cotton gloves
                               and masks
                             Applicator women              54
                               with cotton gloves
                             Men with no                   13
                               protective wear
  Takamiya 1994              Pest control               2 DMP
                               operators                4 DEP
  Aprea et al. 1997 (b,c)    Vineyard sprayers              9
                             Vineyard leaf thinners         2
                             Controls                      46
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                        5
                               Reentry day 2                5
                               Reentry day 4                5
                               Reentry day 6                5
                               Controls                    21
  Cocker et al. 2002 (c,l)   Controls                     463
                             Occupational                 917
                               exposures
  Lin et al. 2002 (m)        Farmers                        4
                               preexposure
                             Farmers                        4
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion             1
                               poisoning
  Richter et al. 1992        Residents of                   4
                               diazinon-
                               contaminated home
                             After cleanup                  4
  Davies and Peterson 1997   Parathion poisoning            1
                             Chlorovrifos ooisonino         1

Study                           Study population             DMP

Incidental or community-based measures
  Griffith and Duncan        General U.S.               50 [micro]g/L
    1985 (a)                   (NHANES II:
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults             12 [micro]g/g
  Loewenherz et al. 1997     Reference children              NA
                               (0-6 years, WA
                               State)
                             Applicator children             NA

                             Children living                 NA
                               < 200 ft of orchard
  Azaroff 1999 (d)           Nonfieldworkers in              NA
                               farm families
  Aprea et al. 2000 (b)      Italian children           15 [micro]g/g
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period              250 [micro]g/L
                             Control period            250 [micro]g/L
  Hardt and Angerer 2000     German adults             (30 [micro]g/L)
    Lu et al. 2000 (e)       Reference children              NA
                               (central WA)
                             Applicator children             NA
                             Farm children                   NA
  0'Rourke et al. 2000 (d)   U.S.-Mexico border              25%
                                                       > 25 [micro]g/L
  CDC 2001 (b)               General U.S-              1.84 [micro]g/L
                               (NHANES 1999)               (1.67)
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age           63 [micro]g/g
                                                            (27)
                             6-13 years of age          35 [micro]g/g
                                                            (16)
                             14-19 years of age         24 [micro]g/g
                                                            (17)
                             [greater than or equal     28 [micro]g/g
                               to] 20 years of age          (16)
  Lu et al. 2001             Children (2-5 years             NA
                               of age, Seattle, WA)
  Mills and Zahm 2001        Adult farmworkers          8 [micro]g/L
                             Farm children              8 [micro]g/L
  Curl et al. 2002 (b)       Agricultural workers            NA
                             Workers' children               NA
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months                  NA
                               Nonspray months               NA
  Royster et al. 2002        Toddlers in               26.6 [micro]g/L
                               agricultural                (6.63)
                               region of CA
                             2nd visit                 30.1 [micro]g/L
                                                           (8.13)
                                                           (8.14)
  Castorina et al. 2003      Pregnant women           (1.7 [micro]g/L)
                               (Salinas, CA)
  Curl et al. 2003b (b)      Organic diet (2-6         1.1 [micro]g/L
                               years of age;                (0.6)
                               WA State)
                             Regular diet (2-6         1.9 [micro]g/L
                               years of age;                (0.6)
                               WA State)
  Shalat et al. 2003 (c,f)   Children at U.S.-          22 [micro]g/g
                               Mexico border                (10)
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide               20 [micro]g/L
                               formulators
                             Nonexposed                 30 [micro]g/L
  Duncan and Griffith        Citrus sprayers           170 [micro]g/L
    1985 (h)                 Citrus harvesters        1,650 [micro]g/L
  Griffith and Duncan 1985   Citrus sprayers           160 [micro]g/L
                             Citrus harvesters         390 [micro]g/L
  Franklin et al. 1986 (i)   Canadian applicators            NA
                             Guthion-dosed                   NA
                               volunteers (dermal
                               500-6,000 [micro]g)
  Fenske and Leffingwell     Malathion applicator            NA
    1989 (j)
  Drevenkar et al.           Orchard sprayers                NA
    1991 (c)
  Aprea et al. 1994          Controls                        NA
    (b,c,k)
                             Applicator women                NA
                               with rubber gloves
                               and masks
                             Applicator women                NA
                               with waterproof
                               cotton gloves and
                               masks
                             Applicator women                NA
                               with cotton gloves
                               and masks
                             Applicator women                NA
                               with cotton gloves
                             Men with no                     NA
                               protective wear
  Takamiya 1994              Pest control             99,000 [micro]g/g
                               operators
  Aprea et al. 1997 (b,c)    Vineyard sprayers          23 [micro]g/g
                             Vineyard leaf thinners     13 [micro]g/g
                             Controls                   5 [micro]g/g
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                         NA
                               Reentry day 2                 NA
                               Reentry day 4                 NA
                               Reentry day 6                 NA
                               Controls                      NA
  Cocker et al. 2002 (c,l)   Controls                        NA
                             Occupational                    NA
                               exposures
  Lin et al. 2002 (m)        Farmers                         NA
                               preexposure
                             Farmers                         NA
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion       50,000 [micro]g/L
                               poisoning
  Richter et al. 1992        Residents of                    NA
                               diazinon-
                               contaminated home
                             After cleanup                   NA
  Davies and Peterson 1997   Parathion poisoning             NA
                             Chlorovrifos ooisonino          NA

Study                           Study population            DMTP

Incidental or community-based measures
  Griffith and Duncan        General U.S.               60 [micro]g/L
    1985 (a)                   (NHANES II:
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults             16 [micro]g/g
  Loewenherz et al. 1997     Reference children         18 [micro]g/L
                               (0-6 years, WA         (< 15 [micro]g/L)
                               State)
                             Applicator children        39 [micro]g/L
                                                       (15 [micro]g/L)
                             Children living            28 [micro]g/L
                               < 200 ft of orchard      53 [micro]g/L
  Azaroff 1999 (d)           Nonfieldworkers in              NA
                               farm families
  Aprea et al. 2000 (b)      Italian children           15 [micro]g/g
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period              430 [micro]g/L
                             Control period             50 [micro]g/L
  Hardt and Angerer 2000     German adults             (22 [micro]g/L)
    Lu et al. 2000 (e)       Reference children         20 [micro]g/L
                               (central WA)            (5 [micro]g/L)
                             Applicator children        40 [micro]g/L
                             Farm children              30 [micro]g/L
  0'Rourke et al. 2000 (d)   U.S.-Mexico border              26%
                                                       > 25 [micro]g/L
  CDC 2001 (b)               General U.S-              2.61 [micro]g/L
                               (NHANES 1999)               (3.80)
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age           77 [micro]g/g
                                                            (29)
                             6-13 years of age          37 [micro]g/g
                                                            (15)
                             14-19 years of age         18 [micro]g/g
                                                            (14)
                             [greater than or equal     37 [micro]g/g
                               to] 20 years of age          (14)
  Lu et al. 2001             Children (2-5 years             NA
                               of age, Seattle, WA)
  Mills and Zahm 2001        Adult farmworkers          13 [micro]g/L
                             Farm children              14 [micro]g/L
  Curl et al. 2002 (b)       Agricultural workers            NA
                             Workers' children               NA
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months                  NA
                               Nonspray months               NA
  Royster et al. 2002        Toddlers in                     NA
                               agricultural
                               region of CA
                             2nd visit                       NA
                                                            (3.2)
  Castorina et al. 2003      Pregnant women           (6.2 [micro]g/L)
                               (Salinas, CA)
  Curl et al. 2003b (b)      Organic diet (2-6         4.3 [micro]g/L
                               years of age;                (2.8)
                               WA State)
                             Regular diet (2-6          41 [micro]g/L
                               years of age;                (14)
                               WA State)
  Shalat et al. 2003 (c,f)   Children at U.S.-          6 [micro]g/g
                               Mexico border                 (0)
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide               60 [micro]g/L
                               formulators
                             Nonexposed                120 [micro]g/L
  Duncan and Griffith        Citrus sprayers           100 [micro]g/L
    1985 (h)                 Citrus harvesters         500 [micro]g/L
  Griffith and Duncan 1985   Citrus sprayers            80 [micro]g/L
                             Citrus harvesters         150 [micro]g/L
  Franklin et al. 1986 (i)   Canadian applicators      146 [micro]g/L
                             Guthion-dosed              72 [micro]g/L
                               volunteers (dermal
                               500-6,000 [micro]g)
  Fenske and Leffingwell     Malathion applicator      550 [micro]g/L
    1989 (j)
  Drevenkar et al.           Orchard sprayers         (111 [micro]g/g)
    1991 (c)
  Aprea et al. 1994          Controls                        NA
    (b,c,k)
                             Applicator women                NA
                               with rubber gloves
                               and masks
                             Applicator women                NA
                               with waterproof
                               cotton gloves and
                               masks
                             Applicator women                NA
                               with cotton gloves
                               and masks
                             Applicator women                NA
                               with cotton gloves
                             Men with no                     NA
                               protective wear
  Takamiya 1994              Pest control                    NA
                               operators
  Aprea et al. 1997 (b,c)    Vineyard sprayers          32 [micro]g/g
                             Vineyard leaf thinners     59 [micro]g/g
                             Controls                   14 [micro]g/g
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                         NA
                               Reentry day 2                 NA
                               Reentry day 4                 NA
                               Reentry day 6                 NA
                               Controls                      NA
  Cocker et al. 2002 (c,l)   Controls                        NA
                             Occupational                    NA
                               exposures
  Lin et al. 2002 (m)        Farmers                    32 [micro]g/L
                               preexposure
                             Farmers                    77 [micro]g/L
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion       96,000 [micro]g/L
                               poisoning
  Richter et al. 1992        Residents of                    NA
                               diazinon-
                               contaminated home
                             After cleanup                   NA
  Davies and Peterson 1997   Parathion poisoning             NA
                             Chlorovrifos ooisonino          NA

Study                           Study population            DMDTP

Incidental or community-based measures
  Griffith and Duncan        General U.S.               50 [micro]g/L
    1985 (a)                   (NHANES II:
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults             5 [micro]g/g
  Loewenherz et al. 1997     Reference children              NA
                               (0-6 years, WA
                               State)
                             Applicator children             NA
                             Children living                 NA
                               < 200 ft of orchard
  Azaroff 1999 (d)           Nonfieldworkers in              NA
                               farm families
  Aprea et al. 2000 (b)      Italian children           2 [micro]g/g
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period               60 [micro]g/L
                             Control period                  NA
  Hardt and Angerer 2000     German adults             (1 [micro]g/L)
    Lu et al. 2000 (e)       Reference children         3 [micro]g/L
                               (central WA)            (0 [micro]g/L)
                             Applicator children        5 [micro]g/L
                             Farm children              2 [micro]g/L
  0'Rourke et al. 2000 (d)   U.S.-Mexico border        3% > [micro]g/L
                                                       > 25 [micro]g/L
  CDC 2001 (b)               General U.S-              0.51 [micro]g/L
                               (NHANES 1999)               (0.60)
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age           5 [micro]g/g
                             6-13 years of age          3 [micro]g/g
                             14-19 years of age        0.7 [micro]g/g
                                                             (3)
                             [greater than or equal     2 [micro]g/g
                               to] 20 years of age
  Lu et al. 2001             Children (2-5 years             NA
                               of age, Seattle, WA)
  Mills and Zahm 2001        Adult farmworkers         < 8 [micro]g/L
                             Farm children             < 8 [micro]g/L
  Curl et al. 2002 (b)       Agricultural workers            NA
                             Workers' children               NA
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months                  NA
                               Nonspray months               NA
  Royster et al. 2002        Toddlers in                     NA
                               agricultural
                               region of CA
                             2nd visit                       NA
  Castorina et al. 2003      Pregnant women           (0.5 [micro]g/L)
                               (Salinas, CA)
  Curl et al. 2003b (b)      Organic diet (2-6         0.8 [micro]g/L
                               years of age;                (0.7)
                               WA State)
                             Regular diet (2-6         4.8 [micro]g/L
                               years of age;                (2.1)
                               WA State)
  Shalat et al. 2003 (c,f)   Children at U.S.-         0.05 [micro]g/g
                               Mexico border                 (0)
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide              < 20 [micro]g/L
                               formulators
                             Nonexposed                < 20 [micro]g/L
  Duncan and Griffith        Citrus sprayers           150 [micro]g/L
    1985 (h)                 Citrus harvesters         600 [micro]g/L
  Griffith and Duncan 1985   Citrus sprayers           110 [micro]g/L
                             Citrus harvesters         250 [micro]g/L
  Franklin et al. 1986 (i)   Canadian applicators            NA
                             Guthion-dosed                   NA
                               volunteers (dermal
                               500-6,000 [micro]g)
  Fenske and Leffingwell     Malathion applicator      630 [micro]g/L
    1989 (j)
  Drevenkar et al.           Orchard sprayers         (145 [micro]g/g)
    1991 (c)
  Aprea et al. 1994          Controls                        NA
    (b,c,k)
                             Applicator women                NA
                               with rubber gloves
                               and masks
                             Applicator women                NA
                               with waterproof
                               cotton gloves and
                               masks
                             Applicator women                NA
                               with cotton gloves
                               and masks
                             Applicator women                NA
                               with cotton gloves
                             Men with no                     NA
                               protective wear
  Takamiya 1994              Pest control                    NA
                               operators
  Aprea et al. 1997 (b,c)    Vineyard sprayers               NA
                             Vineyard leaf thinners          NA
                             Controls                        NA
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                         NA
                               Reentry day 2                 NA
                               Reentry day 4                 NA
                               Reentry day 6                 NA
                               Controls                      NA
  Cocker et al. 2002 (c,l)   Controls                        NA
                             Occupational                    NA
                               exposures
  Lin et al. 2002 (m)        Farmers                    27 [micro]g/L
                               preexposure
                             Farmers                   164 [micro]g/L
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion       20,000 [micro]g/L
                               poisoning
  Richter et al. 1992        Residents of                    NA
                               diazinon-
                               contaminated home
                             After cleanup                   NA
  Davies and Peterson 1997   Parathion poisoning             NA
                             Chlorovrifos ooisonino          NA

Study                           Study population             DEP

Incidental or community-based measures
  Griffith and Duncan        General U.S.               40 [micro]g/L
    1985 (a)                   (NHANES II:
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults             6 [micro]g/g
  Loewenherz et al. 1997     Reference children              NA
                               (0-6 years, WA
                               State)
                             Applicator children             NA
                             Children living                 NA
                               < 200 ft of orchard
  Azaroff 1999 (d)           Nonfieldworkers in              NA
                               farm families
  Aprea et al. 2000 (b)      Italian children           5 [micro]g/g
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period                    NA
                             Control period                  NA
  Hardt and Angerer 2000     German adults             (4 [micro]g/L)
    Lu et al. 2000 (e)       Reference children              NA
                               (central WA)
                             Applicator children             NA
                             Farm children                   NA
  0'Rourke et al. 2000 (d)   U.S.-Mexico border              5%
                                                       > 25 [micro]g/L
  CDC 2001 (b)               General U.S-              2.6 [micro]g/L
                               (NHANES 1999)               (1.85)
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age           8 [micro]g/g
                                                             (5)
                             6-13 years of age          5 [micro]g/g
                                                             (3)
                             14-19 years of age         4 [micro]g/g
                             [greater than or equal     4 [micro]g/g
                               to] 20 years of age           (2)
  Lu et al. 2001             Children (2-5 years             NA
                               of age, Seattle, WA)
  Mills and Zahm 2001        Adult farmworkers         < 8 [micro]g/L
                             Farm children             < 8 [micro]g/L
  Curl et al. 2002 (b)       Agricultural workers            NA
                             Workers' children               NA
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months                  NA
                               Nonspray months               NA
  Royster et al. 2002        Toddlers in               4.9 [micro]g/L
                               agricultural                (2.69)
                               region of CA
                             2nd visit                 3.8 [micro]g/L
  Castorina et al. 2003      Pregnant women            (1 [micro]g/L)
                               (Salinas, CA)
  Curl et al. 2003b (b)      Organic diet (2-6         1.0 [micro]g/L
                               years of age;                (0.7)
                               WA State)
                             Regular diet (2-6         0.8 [micro]g/L
                               years of age;                (0.7)
                               WA State)
  Shalat et al. 2003 (c,f)   Children at U.S.-          14 [micro]g/g
                               Mexico border                 (3)
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide               50 [micro]g/L
                               formulators
                             Nonexposed               1,200 [micro]g/L
  Duncan and Griffith        Citrus sprayers           350 [micro]g/L
    1985 (h)                 Citrus harvesters         650 [micro]g/L
  Griffith and Duncan 1985   Citrus sprayers           410 [micro]g/L
                             Citrus harvesters          90 [micro]g/L
  Franklin et al. 1986 (i)   Canadian applicators            NA
                             Guthion-dosed                   NA
                               volunteers (dermal
                               500-6,000 [micro]g)
  Fenske and Leffingwell     Malathion applicator            NA
    1989 (j)
  Drevenkar et al.           Orchard sprayers                NA
    1991 (c)
  Aprea et al. 1994          Controls                        NA
    (b,c,k)
                             Applicator women                NA
                               with rubber gloves
                               and masks
                             Applicator women                NA
                               with waterproof
                               cotton gloves and
                               masks
                             Applicator women                NA
                               with cotton gloves
                               and masks
                             Applicator women                NA
                               with cotton gloves
                             Men with no                     NA
                               protective wear
  Takamiya 1994              Pest control             97,000 [micro]g/g
                               operators
  Aprea et al. 1997 (b,c)    Vineyard sprayers               NA
                             Vineyard leaf thinners          NA
                             Controls                        NA
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                         NA
                               Reentry day 2                 NA
                               Reentry day 4                 NA
                               Reentry day 6                 NA
                               Controls                      NA
  Cocker et al. 2002 (c,l)   Controls                        NA
                             Occupational                    NA
                               exposures
  Lin et al. 2002 (m)        Farmers                         NA
                               preexposure
                             Farmers                         NA
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion              NA
                               poisoning
  Richter et al. 1992        Residents of               31, 000 pg/L
                               diazinon-
                               contaminated home
                             After cleanup             < 10 [micro]g/L
  Davies and Peterson 1997   Parathion poisoning      7,800 [micro]g/L
                             Chlorovrifos ooisonino   30,000 [micro]g/L

Study                           Study population            DETP

Incidental or community-based measures
  Griffith and Duncan        General U.S.               40 [micro]g/L
    1985 (a)                   (NHANES II:
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults             5 [micro]g/g
  Loewenherz et al. 1997     Reference children              NA
                               (0-6 years, WA
                               State)
                             Applicator children             NA
                             Children living                 NA
                               < 200 ft of orchard
  Azaroff 1999 (d)           Nonfieldworkers in              NA
                               farm families
  Aprea et al. 2000 (b)      Italian children           3 [micro]g/g
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period               90 [micro]g/L
                             Control period             30 [micro]g/L
  Hardt and Angerer 2000     German adults            (< 3 [micro]g/L)
    Lu et al. 2000 (e)       Reference children              NA
                               (central WA)
                             Applicator children             NA
                             Farm children                   NA
  0'Rourke et al. 2000 (d)   U.S.-Mexico border        < 25 [micro]g/L
  CDC 2001 (b)               General U.S-              0.8 [micro]g/L
                               (NHANES 1999)               (0.70)
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age           4 [micro]g/g
                             6-13 years of age          2 [micro]g/g
                             14-19 years of age         1 [micro]g/g
                             [greater than or equal     1 [micro]g/g
                               to] 20 years of age
  Lu et al. 2001             Children (2-5 years             NA
                               of age, Seattle, WA)
  Mills and Zahm 2001        Adult farmworkers          8 [micro]g/L
                             Farm children              6 [micro]g/L
  Curl et al. 2002 (b)       Agricultural workers            NA
                             Workers' children               NA
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months                  NA
                               Nonspray months               NA
  Royster et al. 2002        Toddlers in                     NA
                               agricultural
                               region of CA
                             2nd visit                       NA
  Castorina et al. 2003      Pregnant women           (0.9 [micro]g/L)
                               (Salinas, CA)
  Curl et al. 2003b (b)      Organic diet (2-6         2.7 [micro]g/L
                               years of age;                (2.0)
                               WA State)
                             Regular diet (2-6         4.0 [micro]g/L
                               years of age;                (3.0)
                               WA State)
  Shalat et al. 2003 (c,f)   Children at U.S.-          12 [micro]g/g
                               Mexico border                 (8)
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide               5 [micro]g/L
                               formulators
                             Nonexposed                900 [micro]g/L
  Duncan and Griffith        Citrus sprayers           250 [micro]g/L
    1985 (h)                 Citrus harvesters          75 [micro]g/L
  Griffith and Duncan 1985   Citrus sprayers           370 [micro]g/L
                             Citrus harvesters          70 [micro]g/L
  Franklin et al. 1986 (i)   Canadian applicators            NA
                             Guthion-dosed                   NA
                               volunteers (dermal
                               500-6,000 [micro]g)
  Fenske and Leffingwell     Malathion applicator            NA
    1989 (j)
  Drevenkar et al.           Orchard sprayers                NA
    1991 (c)
  Aprea et al. 1994          Controls                        NA
    (b,c,k)
                             Applicator women                NA
                               with rubber gloves
                               and masks
                             Applicator women                NA
                               with waterproof
                               cotton gloves and
                               masks
                             Applicator women                NA
                               with cotton gloves
                               and masks
                             Applicator women                NA
                               with cotton gloves
                             Men with no                     NA
                               protective wear
  Takamiya 1994              Pest control                    NA
                               operators
  Aprea et al. 1997 (b,c)    Vineyard sprayers               NA
                             Vineyard leaf thinners          NA
                             Controls                        NA
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                         NA
                               Reentry day 2                 NA
                               Reentry day 4                 NA
                               Reentry day 6                 NA
                               Controls                      NA
  Cocker et al. 2002 (c,l)   Controls                        NA
                             Occupational                    NA
                               exposures
  Lin et al. 2002 (m)        Farmers                    52 [micro]g/L
                               preexposure
                             Farmers                    54 [micro]g/L
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion              NA
                               poisoning
  Richter et al. 1992        Residents of                    NA
                               diazinon-
                               contaminated home
                             After cleanup                   NA
  Davies and Peterson 1997   Parathion poisoning      1,500 [micro]g/L
                             Chlorovrifos ooisonino   30,000 [micro]g/L

Study                           Study population           DEDTP

Incidental or community-based measures
  Griffith and Duncan        General U.S.              110 [micro]g/L
    1985 (a)                   (NHANES II:
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults             3 [micro]g/g
  Loewenherz et al. 1997     Reference children              NA
                               (0-6 years, WA
                               State)
                             Applicator children             NA
                             Children living                 NA
                               < 200 ft of orchard
  Azaroff 1999 (d)           Nonfieldworkers in              NA
                               farm families
  Aprea et al. 2000 (b)      Italian children           1 [micro]g/g
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period              110 [micro]g/L
                             Control period            50 [micro]g/L
  Hardt and Angerer 2000     German adults            (< 3 [micro]g/L)
    Lu et al. 2000 (e)       Reference children              NA
                               (central WA)
                             Applicator children             NA
                             Farm children                   NA
  0'Rourke et al. 2000 (d)   U.S.-Mexico border       < 25 [micro]g/L
  CDC 2001 (b)               General U.S-             0.19 [micro]g/L
                               (NHANES 1999)               (0.14)
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age          < 1 [micro]g/g
                             6-13 years of age         < 1 [micro]g/g
                             14-19 years of age         1 [micro]g/g
                             [greater than or equal     1 [micro]g/g
                               to] 20 years of age
  Lu et al. 2001             Children (2-5 years             NA
                               of age, Seattle, WA)
  Mills and Zahm 2001        Adult farmworkers         < 8 [micro]g/L
                             Farm children             < 8 [micro]g/L
  Curl et al. 2002 (b)       Agricultural workers            NA
                             Workers' children               NA
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months                  NA
                               Nonspray months               NA
  Royster et al. 2002        Toddlers in                     NA
                               agricultural
                               region of CA
                             2nd visit                       NA
  Castorina et al. 2003      Pregnant women            (0 [micro]g/L)
                               (Salinas, CA)
  Curl et al. 2003b (b)      Organic diet (2-6               NA
                               years of age;
                               WA State)
                             Regular diet (2-6               NA
                               years of age;
                               WA State)
  Shalat et al. 2003 (c,f)   Children at U.S.-          1 [micro]g/g
                               Mexico border                (0)
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide             < 20 [micro]g/L
                               formulators
                             Nonexposed               < 20 [micro]g/L
  Duncan and Griffith        Citrus sprayers           250 [micro]g/L
    1985 (h)                 Citrus harvesters         60 [micro]g/L
  Griffith and Duncan 1985   Citrus sprayers           240 [micro]g/L
                             Citrus harvesters         60 [micro]g/L
  Franklin et al. 1986 (i)   Canadian applicators            NA
                             Guthion-dosed                   NA
                               volunteers (dermal
                               500-6,000 [micro]g)
  Fenske and Leffingwell     Malathion applicator            NA
    1989 (j)
  Drevenkar et al.           Orchard sprayers                NA
    1991 (c)
  Aprea et al. 1994          Controls                        NA
    (b,c,k)
                             Applicator women                NA
                               with rubber gloves
                               and masks
                             Applicator women                NA
                               with waterproof
                               cotton gloves and
                               masks
                             Applicator women                NA
                               with cotton gloves
                               and masks
                             Applicator women                NA
                               with cotton gloves
                             Men with no                     NA
                               protective wear
  Takamiya 1994              Pest control                    NA
                               operators
  Aprea et al. 1997 (b,c)    Vineyard sprayers               NA
                             Vineyard leaf thinners          NA
                             Controls                        NA
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                         NA
                               Reentry day 2                 NA
                               Reentry day 4                 NA
                               Reentry day 6                 NA
                               Controls                      NA
  Cocker et al. 2002 (c,l)   Controls                        NA
                             Occupational                    NA
                               exposures
  Lin et al. 2002 (m)        Farmers                         NA
                               preexposure
                             Farmers                         NA
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion              NA
                               poisoning
  Richter et al. 1992        Residents of                    NA
                               diazinon-
                               contaminated home
                             After cleanup                   NA
  Davies and Peterson 1997   Parathion poisoning             NA
                             Chlorovrifos ooisonino          NA

Study                           Study population           DMAP

Incidental or community-based measures
  Griffith and Duncan        General U.S.                   NA
    1985 (a)                   (NHANES II:
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults                 NA
  Loewenherz et al. 1997     Reference children             NA
                               (0-6 years, WA
                               State)
                             Applicator children            NA
                             Children living                NA
                               < 200 ft of orchard
  Azaroff 1999 (d)           Nonfieldworkers in             27%
                               farm families          > 25 [micro]g/L
  Aprea et al. 2000 (b)      Italian children               NA
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period                   NA
                             Control period                 NA
  Hardt and Angerer 2000     German adults                  NA
    Lu et al. 2000 (e)       Reference children           60 mg/L
                               (central WA)              (10 mg/L)
                             Applicator children            NA
                             Farm children                70 mg/L
                                                         (50 mg/L)
  0'Rourke et al. 2000 (d)   U.S.-Mexico border             NA
  CDC 2001 (b)               General U.S-                   NA
                               (NHANES 1999)
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age               NA
                             6-13 years of age              NA
                             14-19 years of age             NA
                             [greater than or equal         NA
                               to] 20 years of age
  Lu et al. 2001             Children (2-5 years            190
                               of age, Seattle, WA)       nmol/L
                                                           (110)
  Mills and Zahm 2001        Adult farmworkers              NA
                             Farm children                  NA
  Curl et al. 2002 (b)       Agricultural workers           130
                                                          nmol/L
                             Workers' children              90
                                                          nmol/L
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months                 96
                                                          nmol/L
                                                           (70)
                               Nonspray months              72
                                                          nmol/L
                                                           (60)
                                                           (61)
  Royster et al. 2002        Toddlers in                    NA
                               agricultural
                               region of CA
                             2nd visit                      NA
  Castorina et al. 2003      Pregnant women                 NA
                               (Salinas, CA)
  Curl et al. 2003b (b)      Organic diet (2-6              40
                               years of age;              nmol/L
                               WA State)
                             Regular diet (2-6              340
                               years of age;              nmol/L
                               WA State)                   (170)
  Shalat et al. 2003 (c,f)   Children at U.S.-              NA
                               Mexico border
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide                   NA
                               formulators
                             Nonexposed                     NA
  Duncan and Griffith        Citrus sprayers                NA
    1985 (h)                 Citrus harvesters              NA
  Griffith and Duncan 1985   Citrus sprayers                NA
                             Citrus harvesters              NA
  Franklin et al. 1986 (i)   Canadian applicators           NA
                             Guthion-dosed                  NA
                               volunteers (dermal
                               500-6,000 [micro]g)
  Fenske and Leffingwell     Malathion applicator           NA
    1989 (j)
  Drevenkar et al.           Orchard sprayers               NA
    1991 (c)
  Aprea et al. 1994          Controls                      145.4
    (b,c,k)                                               nmol/g
                                                          (143.1)
                             Applicator women              555.6
                               with rubber gloves         nmol/g
                               and masks                   (768)
                             Applicator women              654.4
                               with waterproof            nmol/g
                               cotton gloves and          (611.5)
                               masks
                             Applicator women              326.3
                               with cotton gloves         nmol/g
                               and masks                  (385.5)
                             Applicator women              614.0
                               with cotton gloves         nmol/g
                                                          (657.5)
                             Men with no                  3568.4
                               protective wear            nmol/g
                                                          (3,227)
  Takamiya 1994              Pest control                   NA
                               operators
  Aprea et al. 1997 (b,c)    Vineyard sprayers              NA
                             Vineyard leaf thinners         NA
                             Controls                       NA
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                        183
                                                          nmol/g
                               Reentry day 2                245
                                                          nmol/g
                               Reentry day 4                174
                                                          nmol/g
                               Reentry day 6                354
                                                          nmol/g
                               Controls                     103
                                                          nmol/g
  Cocker et al. 2002 (c,l)   Controls                   195 nmol/g
                                                           (141)
                             Occupational               292 nmol/g
                               exposures                   (132)
  Lin et al. 2002 (m)        Farmers                        NA
                               preexposure
                             Farmers                        NA
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion             NA
                               poisoning
  Richter et al. 1992        Residents of                   NA
                               diazinon-
                               contaminated home
                             After cleanup                  NA
  Davies and Peterson 1997   Parathion poisoning            NA
                             Chlorovrifos ooisonino         NA

Study                           Study population           DEAP

Incidental or community-based measures
  Griffith and Duncan        General U.S.                   NA
    1985 (a)                   (NHANES II:
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults                 NA
  Loewenherz et al. 1997     Reference children             NA
                               (0-6 years, WA
                               State)
                             Applicator children            NA
                             Children living                NA
                               < 200 ft of orchard
  Azaroff 1999 (d)           Nonfieldworkers in             10%
                               farm families          > 25 [micro]g/L
  Aprea et al. 2000 (b)      Italian children               NA
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period                   NA
                             Control period                 NA
  Hardt and Angerer 2000     German adults                  NA
    Lu et al. 2000 (e)       Reference children             NA
                               (central WA)
                             Applicator children            NA
                             Farm children                  NA
  0'Rourke et al. 2000 (d)   U.S.-Mexico border             NA
  CDC 2001 (b)               General U.S.-                  NA
                               (NHANES 1999)
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age               NA
                             6-13 years of age              NA
                             14-19 years of age             NA
                             [greater than or equal         NA
                               to] 20 years of age
  Lu et al. 2001             Children (2-5 years            50
                               of age, Seattle, WA)       nmol/L
                                                           (40)
  Mills and Zahm 2001        Adult farmworkers              NA
                             Farm children                  NA
  Curl et al. 2002 (b)       Agricultural workers           60
                                                          nmol/L
                             Workers' children              60
                                                          nmol/L
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months                 49
                                                          nmol/L
                                                           (40)
                               Nonspray months              35
                                                          nmol/L
                                                           (40)
  Royster et al. 2002        Toddlers in                    NA
                               agricultural
                               region of CA
                             2nd visit                      NA
  Castorina et al. 2003      Pregnant women                 NA
                               (Salinas, CA)
  Curl et al. 2003b (b)      Organic diet (2-6              20
                               years of age;              nmol/L
                               WA State)
                             Regular diet (2-6              30
                               years of age;              nmol/L
                               WA State)                   (20)
  Shalat et al. 2003 (c,f)   Children at U.S.-              NA
                               Mexico border
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide                   NA
                               formulators
                             Nonexposed                     NA
  Duncan and Griffith        Citrus sprayers                NA
    1985 (h)                 Citrus harvesters              NA
  Griffith and Duncan 1985   Citrus sprayers                NA
                             Citrus harvesters              NA
  Franklin et al. 1986 (i)   Canadian applicators           NA
                             Guthion-dosed                  NA
                               volunteers (dermal
                               500-6,000 [micro]g)
  Fenske and Leffingwell     Malathion applicator           NA
    1989 (j)
  Drevenkar et al.           Orchard sprayers               NA
    1991 (c)
  Aprea et al. 1994          Controls                       NA
    (b,c,k)
                             Applicator women               NA
                               with rubber gloves
                               and masks
                             Applicator women               NA
                               with waterproof
                               cotton gloves and
                               masks
                             Applicator women               NA
                               with cotton gloves
                               and masks
                             Applicator women               NA
                               with cotton gloves
                             Men with no                    NA
                               protective wear
  Takamiya 1994              Pest control                   NA
                               operators
  Aprea et al. 1997 (b,c)    Vineyard sprayers              NA
                             Vineyard leaf thinners         NA
                             Controls                       NA
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                        NA
                               Reentry day 2                NA
                               Reentry day 4                NA
                               Reentry day 6                NA
                               Controls                     NA
  Cocker et al. 2002 (c,l)   Controls
                             Occupational
                               exposures
  Lin et al. 2002 (m)        Farmers                        NA
                               preexposure
                             Farmers                        NA
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion             NA
                               poisoning
  Richter et al. 1992        Residents of                   NA
                               diazinon-
                               contaminated home
                             After cleanup                  NA
  Davies and Peterson 1997   Parathion poisoning            NA
                             Chlorovrifos ooisonino         NA

Study                           Study population          Findings

Incidental or community-based measures
  Griffith and Duncan        General U.S.             Low frequency
    1985 (a)                   (NHANES II:              of detection
                               1976-1980)
  Aprea et al. 1996 (b,c)    Italian adults           Frequent
                                                        detection
  Loewenherz et al. 1997     Reference children       Higher levels in
                               (0-6 years, WA           applicator
                               State)                   children
                             Applicator children        and children
                                                        living close
                             Children living            to orchards
                               < 200 ft of orchard
  Azaroff 1999 (d)           Nonfieldworkers in       Adult exposures
                               farm families            associated
                                                        with child
                                                        exposures
  Aprea et al. 2000 (b)      Italian children         Higher levels in
                                                        children
  Garcia et al. 2000 (a)     Adults and teenagers in rice-growing
                               region
                             Spray period             No appreciable
                             Control period             increase in
                                                        DAPS after
                                                        spraying; no
                                                        association of
                                                        DAPS with
                                                        symptoms
  Hardt and Angerer 2000     German adults            Frequent
                                                        detection
    Lu et al. 2000 (e)       Reference children       Higher levels in
                               (central WA)             applicator
                             Applicator children        children
                             Farm children
  0'Rourke et al. 2000 (d)   U.S.-Mexico border       Levels above a
                                                        reference
                                                        population
  CDC 2001 (b)               General U.S.-            Frequent
                               (NHANES 1999)            detection
  Heudorf and Angerer 2001   Germans in former U.S. military
                               housing
                             0-5 years of age         Higher levels in
                                                        children
                             6-13 years of age
                             14-19 years of age
                             [greater than or equal
                               to] 20 years of age
  Lu et al. 2001             Children (2-5 years      Residential
                               of age, Seattle, WA)     pesticide use
                                                        associated
                                                        with DAPS
  Mills and Zahm 2001        Adult farmworkers        Infrequent
                             Farm children              detection
  Curl et al. 2002 (b)       Agricultural workers     Children of
                                                        farmers have
                                                        measureable
                             Workers' children          DAP levels;
                                                        dust azinphos-
                                                        methyl levels
                                                        predictive of
                                                        urinary DAP
  Koch et al. 2002 (b)       Agricultural children 2-5 years of age
                               Spray months           Increased DAP
                                                        levels during
                                                        spraying
                                                        months
                               Nonspray months
  Royster et al. 2002        Toddlers in              Proximity to
                               agricultural             field not
                               region of CA             associated
                                                        with DAPS
                             2nd visit
  Castorina et al. 2003      Pregnant women           Some calculated
                               (Salinas, CA)            doses above
                                                        U.S. EPA
                                                        benchmark
                                                        dose/100
  Curl et al. 2003b (b)      Organic diet (2-6        Lower DMAP
                               years of age;            levels with
                               WA State)                organic diets
                             Regular diet (2-6
                               years of age;
                               WA State)
  Shalat et al. 2003 (c,f)   Children at U.S.-        Higher levels
                               Mexico border
Occupational exposure measures
  Shafik et al. 1973 (g)     FL pesticide             Differences in
                               formulators              DAPS between
                             Nonexposed                 exposed and
                                                        nonexposed
  Duncan and Griffith        Citrus sprayers          Measurable
    1985 (h)                 Citrus harvesters          levels
  Griffith and Duncan 1985   Citrus sprayers          More frequent
                             Citrus harvesters          detection
                                                        among
                                                        sprayers,
                                                        higher levels
                                                        among
                                                        harvesters
  Franklin et al. 1986 (i)   Canadian applicators     Metabolite
                             Guthion-dosed              measurements
                               volunteers (dermal       more reliable
                               500-6,000 [micro]g)      and accurate
                                                        than dermal
                                                        patch
  Fenske and Leffingwell     Malathion applicator     Measureable
    1989 (j)                                            levels
  Drevenkar et al.           Orchard sprayers         DAP levels are
    1991 (c)                                            sensitive
                                                        indicators
                                                        of exposure
  Aprea et al. 1994          Controls                 Applicators had
    (b,c,k)                                             increased DAP
                                                        levels; using
                             Applicator women           no protective
                               with rubber gloves       equipment
                               and masks                increased
                             Applicator women           levels
                               with waterproof
                               cotton gloves and
                               masks
                             Applicator women
                               with cotton gloves
                               and masks
                             Applicator women
                               with cotton gloves
                             Men with no
                               protective wear
  Takamiya 1994              Pest control             Daily
                               operators                fluctuations
                                                        in levels
  Aprea et al. 1997 (b,c)    Vineyard sprayers        Higher levels in
                             Vineyard leaf thinners     vineyard
                             Controls                   sprayers and
                                                        thinners
  Aprea et al. 1999 (b)      Greenhouse workers
                               Basal                  No significant
                                                        difference in
                               Reentry day 2            DAPS among
                                                        workers in
                               Reentry day 4            days following
                                                        application or
                               Reentry day 6            between
                               Controls                 workers and
                                                        controls
  Cocker et al. 2002 (c,l)   Controls                 Nonoccupatio-
                                                        nally exposed
                             Occupational               have
                               exposures                measurable
                                                        levels,
                                                        differences
                                                        only in
                                                        distribution
                                                        tails
  Lin et al. 2002 (m)        Farmers                  Measurable
                               preexposure              differences
                             Farmers                    after exposure
                               postexposure
Poisoning or contamination measures
  Bradway and Shafik 1977    Nonfatal malathion       High levels, no
                               poisoning                death
  Richter et al. 1992        Residents of             Decontamination
                               diazinon-                of home
                               contaminated home        dramatically
                             After cleanup              reduced DEP
                                                        levels
  Davies and Peterson 1997   Parathion poisoning      High levels
                             Chlorovrifos ooisonino

NA, not applicable. Concentrations shown are mean values unless
otherwise indicated; median concentrations are shown in parentheses,
when available. Units are either [micro]g/L or [micro]g/g creatinine
for individual metabolites and nmol/L or [micro]mol/g creatinine for
summed metabolites. Where noted, conversions to common units were
made.

(a) Mean value of detectable values. (b) GM. (c) Values presented in
citation converted to common units. (d) Only values given in citation
were percentages of values above analytic LODs. LODs are given in the
table as the value following the "<" sign. (e) Values expressed as
azinphos-methyl equivalents. (f) Values calculated from raw data.
(g) Values estimated from ranges given in citation. (h) Values
estimated from charts and/or graphs. (i) Values calculated from
total amounts excreted over 2 or 3 days assuming 1,000 mL urine
excreted per day. (j) Maximum value observed. (k) n represents
number of serial urine samples. Number of control subjects was 99,
and number of subjects for each exposure group was 2, 2, 2, 5, and
1, respectively. (l) Value given is a composite value summing all
DAP metabolites together. (m) Metabolite concentrations not
reported for all subjects.

Table 8. Frequencies of detection (%) of each DAP metabolite among
general population-based studies.

Study                              LOD            Participants

Murphy et al. 1983            20 [micro]g/L       NHANES II
                                                    (1976-1980)
                                                    5,976 adults
                                                    and children
Aprea et al. 1996             ~1 [micro]g/L       124 adults
                              (< 10 nmol/L)
Aprea et al. 2000             2-3 [micro]g/L      195 children
Hardt and Angerer 2000         1 [micro]g/L       54 adults
                            (5 [micro]g/L DMP)
Heudorf and Angerer 2001       1 [micro]g/L       1,146 adults,
                            (5 [micro]g/L DMP)      adolescents,
                                                    and children
CDC 2001 (a)               0.01-0.58 [micro]g/L   703 adults,
                                                    adolescents,
                                                    and children
NHANES 1999-2000           0.01-0.58 [micro]g/L   1,949 adults,
                                                    adolescents,
                                                    and children

Study                      Country   DMP   DMTP   DMDTP

Murphy et al. 1983           USA     12      6     < 1
Aprea et al. 1996           Italy    87     99     48
Aprea et al. 2000           Italy    96     94     34
Hardt and Angerer 2000     Germany   96    100     89
Heudorf and Angerer 2001   Germany   79     87     32
CDC 2001 (a)                 USA     83     84     72
NHANES 1999-2000             USA     53     64     53

Study                      DEP   DETP   DEDTP

Murphy et al. 1983          7      6     < 1
Aprea et al. 1996          82     73      7
Aprea et al. 2000          75     48     12
Hardt and Angerer 2000     94     46      2
Heudorf and Angerer 2001   78     45      2
CDC 2001 (a)               99     99     99
NHANES 1999-2000           71     53     56

(a) Nonweighted frequencies of detection.


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Dana B. Barr, (1) Roberto Bravo, (1) Gayanga Weerasekera, (1) Lisa M. Caltabiano, (1) Ralph D. Whitehead, Jr., (1) Anders O. Olsson, (1) Samuel P. Caudill, (1) Susan E. Schober, (2) James L. Pirkle, (1) Eric J. Sampson, (1) Richard J. Jackson, (1) and Larry L. Needham (1)

(1) National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA; (2) National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Maryland, USA

Address correspondence to D.B. Barr, Centers for Disease Control and Prevention, 4770 Buford Highway NE, Mailstop F-17, Atlanta, GA 30341 USA. Telephone: (770) 488-7886. Fax: (770) 488-0142. E-mail: dbarr@cdc.gov

We thank the people at the National Center for Health Statistics (NCHS) and Westat who were responsible for planning and conducting the National Health and Nutrition Examination Study (NHANES), especially B. Lewis, C. Johnson, B. Lindstrom, A. Jeffries, and C. Humbertson. We thank E. Gunter and C. Pfeiffer for managing the National Center for Environmental Health's involvement in NHANES and for serving as liaisons with NCHS, and C. Fernandez for technical assistance. We also thank the Fairview University Medical Center for providing creatinine measurements.

The authors declare they have no competing financial interests.

Received 6 June 2003; accepted 4 November 2003.
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