Workplace, household, and personal predictors of pesticide exposure for farmworkers.

In this article we identify factors potentially associated with pesticide exposure among farmworkers, grade the evidence in the peer-reviewed literature for such associations, and propose a minimum set of measures necessary to understand farm worker risk for pesticide exposure. Data sources we reviewed included Medline, Science Citation Index, Social Science Citation Index, PsycINFO, and AGRICOLA databases. Data extraction was restricted to those articles that reported primary data collection and analysis published in 1990 or later. We read and summarized evidence for pesticide exposure associations. For data synthesis, articles were graded by type of evidence for association of risk factor with pesticide exposure as follows: 1 = association demonstrated in farmworkers; 2 = association demonstrated in nonfarmworker sample; 3 = plausible association proposed for farmworkers; or 4 = association plausible but not published for farmworkers. Of more than 80 studies we identified, only a third used environmental or biomarker evidence to document farmworker exposure to pesticides. Summaries of articles were compiled by level of evidence and presented in tabular form. A minimum list of data to be collected in farmworker pesticide studies was derived from these evidence tables. Despite ongoing concern about pesticide exposure of farmworkers and their families, relatively few studies have tried to test directly the association of behavioral and environmental factors with pesticide exposure in this population. Future studies should attempt to use similar behavioral, environmental, and psychosocial measures to build a body of evidence with which to better understand the risk factors for pesticide exposure among farmworkers. Key words: agricultural workers, folk belief, personal protective equipment, psychosocial stressors, safety behavior. Environ Health Perspect 114:943-952 (2006). doi:10.1289/ehp.8529 available via http://dx.doi.org/ [Online 16 February 2006]

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Human exposure to the pesticides that exist in the home, workplace, and community is regulated by a variety of behaviors and environmental factors. While many of these factors are commonly accepted in research on farmworker health and form the basis of pesticide safety education, there has been no comprehensive review of the empirical evidence linking these factors to exposure or to the relationship of exposure and health. We focus on the measurement of behavioral and environmental factors important at the following two points in the pesticide and health relationship: a) those that predict pesticide exposure, including who is exposed and how he or she is exposed, and b) those that modify the absorbed dose of pesticides.

We based this review on the premise that such a compilation of data will allow scientists to identify factors that have been found to be associated with pesticide exposure and, perhaps more importantly, to identify the gaps in current knowledge of the pesticide and health relationship. To the extent that determinants of exposure can be assessed with comparable measures across studies, results of such studies can then be compared to provide better-grounded answers to questions on the health effects of pesticides.

In this article we present a model of the relationship between predictors of pesticide exposure among farmworkers and pesticide exposure on health outcomes. We identify comprehensively the range of factors that may be associated with pesticide exposure, and we distinguish those for which a firm relationship with farmworker exposure has been identified in the scientific literature and those for which the association can only be inferred from other data. We also suggest a minimum set of measures that are necessary to understand farmworker pesticide exposure.

Conceptual Model

This article is guided by a model (Figure 1) that contrasts the proximal and the distal determinants of pesticide exposure. Those determinants that are proximal to pesticide exposure--that is, the immediate determinants of exposure--are generally behaviors practiced either by farmworkers in the workplace or by farmworkers or their co-resident household members at home. These determinants include (in the workplace) use of personal protective equipment (PPE) and field sanitation, as well as (at home) laundry practices and child activity patterns. These proximal factors are themselves determined by predictors that are considered more distal to the exposure. These predictors include environmental conditions at work (e.g., safety training), at home (e.g., number of farmworkers in residence), and in the larger community (e.g., total farmland treated with pesticides). These environmental factors affect exposure through behavior; the association of environmental and behavioral factors is moderated by psychosocial factors, including the attitudes, values, beliefs, and knowledge held by farmworkers. For example, farmworker residences with a high residential density might be expected to store soiled work clothing that would present an exposure risk to household residents. This relationship could be positively influenced by beliefs that pesticides are harmless, or negatively influenced by knowledge of recommended laundry practices.

A portion of pesticides to which an individual is exposed is absorbed as the pesticide dose, and this dose can have health effects. According to the model, the amount absorbed is moderated by some of the workplace and household behaviors (e.g., hand washing by workers or household residents) as well as by other factors. The latter moderators include genetic factors, body size, and developmental status; these characteristics are not covered in this review.

Methods

This review focuses on the conceptual model (Figure 1) developed by the authors. Components of the model were expanded to produce a list of factors potentially related to pesticide exposure in farmworkers. These factors formed the search terms for our review of the literature that searched the PubMed, (http://www.ncbi.nlm.nih.gov/entrez/query.1fcgi?DB=pubmed); Science Citation Index and Social Science Citation Index (http://portal. isiknowledge.com/portal.cgi/wos?Init=Yes&SI D=D112jMPBmi56JK4eA1); PsycINFO (http://www.psycinfo.org/psychoinfo/); and AGRICOLA (http://agricola.nal.usda.gov/) databases. We restricted reviews to peer-reviewed publications from studies that involved primary data collection and that were published in 1990 or later. A few earlier studies were included for topics with little research coverage. Articles were graded by the type of evidence for the association of a particular risk factor with pesticide exposure, as follows: 1 = association demonstrated in farmworkers; 2 = association demonstrated in nonfarmworker sample; 3 = plausible association proposed for farmworkers; or 4 = association plausible but not published for farmworkers. To be classified as "1," the study participants had to be described as migrant or seasonal farmworkers. In most other cases the study participants were described as "growers," "farmers," or members of their families, and they were classified as nonfarmworkers. Study participants described as "applicators" were classified as nonfarmworkers. Summaries of articles were compiled by level of evidence and presented in tabular form. Because of space restrictions, only those articles graded "1" or "2" are presented here (Table 1). A minimum list of data to be collected in farmworker pesticide studies was derived from these evidence tables (Table 2).

Workplace Behaviors

Wearing PPE is one of the behaviors most widely assumed to protect workers from pesticide exposure. The label PPE can apply to everything from long-sleeve shirts to protective coveralls and respirators. Studies in the United States and abroad show that wearing PPE appropriate to the task results in lower exposure to pesticides (Table 1). Although the studies vary with regard to the types of chemicals investigated, the PPE tested (gloves, overalls), and the types of exposure measured [cholinesterase activity, skin wipes, organochlorine pesticide (OCP) serum levels], they all indicate that PPE is effective in reducing worker exposure to pesticides (Fenske et al. 1990; Gomes et al. 1999; Hernandez-Valero et al. 2001; Lander et al. 1991; Ohayo-Mitoko et al. 1999). Studies in farmers (Arbuckle et al. 2002) and applicators (Fenske et al. 2002a; Nigg et al. 1993) lend further support to the effectiveness of PPE, although they also indicate variations because of fabrics and clothing design. In general, fabric less capable of penetration and designs that cover the largest amount of skin provide the greatest protection from pesticide exposure for workers. Despite the indications of efficacy, studies (particularly of farmers and applicators) show that PPE is frequently not used (e.g., Perry et al. 2002).

Other worker behaviors have been suggested as ways to reduce pesticide exposure, and these alternatives are included as recommended practices in the U.S. Environmental Protection Agency Worker Protection Standard (WPS) training (U.S. Environmental Protection Agency 1992). These behaviors include washing hands in the field before eating and after mixing pesticides. The importance of such behavior is demonstrated by studies showing that pesticides can be transferred to the home via automobile (e.g., Curl et al. 2002; Thompson et al. 2003). Curwin et al. (2003) showed that farmworker hand levels of the OP acephate could be reduced 96% by handwashing.

Additional practices have been suggested to reduce exposure. These practices include wearing grower-provided uniforms and showering at the worksite before returning home. There have been no tests to determine if such workplace behaviors would reduce exposure of the farmworker or the farmworker family.

Farmworker children are sometimes taken to the fields either to work or because adequate child care is lacking (Cooper et al. 2001). Such practices are likely to be predictors of pesticide exposure. Hernandez-Valero et al. (2003) investigated the possible pathways of OCP exposure among 36 migrant farmworker children whose home base was Baytown, Texas. One-third of the children had previously conducted farmwork, and the farmwork duration significantly increased their exposure levels. Mandel et al. (2005) found that children of Minnesota growers often helped apply chemicals and, therefore, had levels of pesticide exposure closer to those of the parent who applied chemicals than to the other parent.

Household Behaviors

The application of residential pesticides in the home and yard has been investigated as a source of pesticide exposure among farmworkers and nonfarmworkers (Table 1). The collection of wipe (Quandt et al. 2004) or vacuum samples (Bradman et al. 1997), which allow direct identification of the type of pesticide found, has been used to link pesticides applied to worker dwellings to those pesticides detected. However, not all studies have had positive results (McCauley et al. 2001). Urinary metabolites of OP pesticides have also supported the link between residential pesticide application and worker exposure (Arcury et al. 2005).

Similar results have been found in nonfarmworker populations. Yard and garden pesticides were found to be transferred into homes by residents and by dogs (Lewis et al. 2001, Morgan et al. 2001; Nishioka et al. 2001). Use of OP pesticides in gardens is associated with metabolite levels in children (Fenske 2002b; Lu et al. 2001).

Several household sanitation behaviors are associated with farmworker pesticide exposure. Bradman et al. (1997) found that more frequent mopping and vacuuming was associated with lower pesticide recoveries in dust wipes. Arcury et al. (2005) suggested that having a vacuum cleaner was associated with lower levels of urinary OP metabolites.

A number of studies have documented the high potential for personal exposure to pesticides caused by waiting for extended periods before showering after work, not changing clothes immediately after work, and failure to separate work from household laundry (Alavanja et al. 1999; Curwin et al. 2002; Goldman et al. 2004). However, with the exception of McCauley et al. (2003), there is little direct evidence to support this association.

Work Environment

The organization of work is a subfield of occupational health that is concerned with the way that work processes are structured and managed. Organization of work investigators attend to such factors as the nature of the employment relationship (e.g., permanent versus contingent labor), job design (e.g., complexity of tasks and level of worker control), interpersonal elements of jobs (e.g., worker-supervisor relations), as well as such things as work schedules, job security, and communication with an employing organization. Although it has not been explicitly used in farmworker research, evidence suggests that several aspects of the way farm work is organized contribute to pesticide exposure (Marquart et al. 2003).

Several interrelated processes underlying the nature of the employment relationship suggest that pesticide exposure is likely to be greater among farmworkers in seasonal (e.g., workers with H2A visas) or day labor relationships in contrast to those in more "permanent" positions. Farmworkers in employment relationships that are more permanent may receive more effective safety training and more consistent reinforcement of safety behaviors than seasonal farmworkers or day-laborers. Researchers contend that workers in nonstandard employment relationships, such as seasonal workers or day-laborers, may be given tasks that place them at greater risk of becoming exposed to pesticides compared to permanent workers (Quinlan et al. 2001). Moreover, farmworkers in seasonal and day-labor arrangements may be less likely to request safety equipment or to report potential hazards to owners/operators out of fear that it may jeopardize future opportunities for work (Aronsson 1999; Aronsson et al. 2002; Quinlan et al. 2001). Despite the plausibility of several of these linkages, differences in pesticide exposure among farmworkers in different types of employment relationships have not been studied explicitly.

Different aspects of job design, or the tasks performed on a job and how they are performed, have been linked to pesticide exposure (Table 1). Tasks that are not regulated by the WPS can result in elevated pesticide exposure (Coronado et al. 2004). A great number of tasks or duties that put individuals in contact with pesticides or pesticide residues, such as self-service and repair of application equipment among applicators and a greater number of field activities among workers, are associated with more exposure (Alavanja et al. 1999; Hernandez-Valero et al. 2001). Environments that provide farmworkers with little control over how pesticides are applied (e.g., highexposure application methods), when pesticides are applied (e.g., avoiding windy days), and frequency of application are all associated with increased pesticide exposure among farmworkers (Mage et al. 2000; Martin et al. 2002; Mekonnen and Agonafir 2002). Similarly, environments that provide little personal control over protective behaviors, such as absence of well-maintained PPE or inability to wash or change clothes during the workday, contribute to elevated pesticide exposure (Alavanja et al. 1999; Arcury et al. 2002; Austin et al. 2001; Mekonnen and Agonafir 2002; Parrott et al. 1999).

Although there have been no explicit comparison studies, it is likely that different crops are associated with different levels of pesticide exposure because of the differences in tasks associated with crops. For example, some will involve greater hand labor for cultivation and harvest than others. It is likely that those requiring more hand labor will result in greater exposure.

Interpersonal elements of farm work also contribute to pesticide exposure. Better-quality relationships between workers and farmers/growers are important for identifying potential sources of pesticide exposure as well as for designing and implementing effective strategies for minimizing exposure (Grieshop et al. 1996). Communication difficulties caused by language differences between workers and farmers/growers contribute to greater pesticide exposure through less effective training (McCauley et al. 2002; Rao et al. 2004). Similarly, differences in belief systems about the risks of pesticide exposure and appropriate behaviors for minimizing risk can contribute to elevated exposure by undermining the effectiveness of training and safety programs (Arcury et al. 2001; Quandt et al. 1998; Rao et al. 2004). The psychological demands of the work environment can also contribute to lower adherence to safety regulations (Kidd et al. 1996; Thu 1998; Walter et al. 2002). Despite the strong suggested connection of these work environmental factors to pesticides, no studies have examined pesticide exposure and the organization of work, either in farmworkers or in other populations.

One of the major aspects of the work environment directly related to pesticide exposure is safety training for workers. Minimum content and standards for pesticide safety training are part of the WPS, which mandates training for field workers as well as for applicators. A number of studies have examined safety training in farmworkers, but none of these have examined the association of safety training with pesticide exposure. This work shows that many farmworkers fail to receive training as mandated (Arcury et al. 1999; Elmore and Arcury 2001; U.S. General Accounting Office 2000) but that the rates vary over time (Arcury et al. 2001). Salazar et al. (2004) found that even when safety training is presented, it is sometimes understood poorly because of language barriers. Research with applicators (Martinez et al. 2004) and farmers (Perry and Layde 2003) shows that safety training produces increased knowledge, but it does not necessarily result in appropriate safety behaviors.

Household Environment: Physical and Social

Proximity of dwellings to agricultural fields treated with pesticides has been suggested as a dwelling characteristic associated with exposure (Fenske et al. 2000). Studies of dust samples from farmworker residences support this suggestion, both in terms of concentrations of pesticides (McCauley et al. 2001) and in numbers of pesticides found in the home (Quandt et al. 2002, 2004). Curl et al. (2003) found no association between distance to field and levels of metabolites found in children's urine. However, these metabolite levels were associated with house dust concentrations, which, in turn, were associated with the dust in cars of farmworkers, thereby indicating a pathway from worksite to home. Among nonfarmworkers, distance from dwelling to fields was associated with concentrations in house dust (Fenske et al. 2002b; Lu et al. 2000). This linkage was reflected in higher urine concentrations of metabolites in some (Loewenherz et al. 1997) but not all (Fenske et al. 2002b) studies measuring urinary metabolites.

Various housing quality indicators have been linked to greater pesticide exposure for farmworker families. Older dwelling age (Bradman et al. 1997) and renting rather than owning (Arcury et al. 2005) have been examined. These studies were based on the belief that the greater age of a house as well as a history of different tenants might lead to the accumulation of larger amounts of pesticides, both simply as a matter of time and because there might be more opportunity for pest infestations to which pesticides are applied. Both of these measures have been linked to exposure. Quandt et al. (2004) used an interviewer's judgment of how difficult or easy a house was to clean, reasoning that houses more difficult to clean would have a less thorough elimination of pesticides. Cleaning difficulty was associated with greater pesticide exposure.

Several aspects of the household social environment related to household composition have been suggested as major influences on pesticide exposure at home. The logic is that more persons in the household, particularly more farmworkers, will increase the volume of take-home pesticides, and this situation might be most extreme in cases of crowding. The simplest measure, total household size, has been linked to pesticides in two studies of farmworkers (Arcury et al. 2005; McCauley et al. 2001). These findings are supported by the study of Goldman et al. (2004) of pesticide-related behaviors. They found that larger household size was associated with fewer in-home safety behaviors. McCauley et al. (2003), in a study of nonfarmworker agricultural households, found weak and nonsignificant associations between household size and OP residues. More specific measures of household social environment (number of adults and number of agricultural workers in the household) have been suggested. However, this association generally has been tested by comparing agricultural and nonagricultural households (Bradman et al. 1997; Lu et al. 2000; Simcox et al. 1995), not by looking at the variation in number of adults within farmworker homes. Exceptions are the work of Arcury et al. (2005) and Quandt et al. (2004), which compared nuclear family households with those that comprised other adult relatives or nonrelatives and appeared to find more pesticides in the latter. This finding may be caused by greater track-in of pesticides with more adults, or by culture-specific issues. The investigators found that women residing in farmworker homes reported difficulty in enforcing standards of household cleanliness when male in-laws lived with the family because gender roles limit the authority of women over the behavior of fathers-in-law and other relatives. Only two studies have used density or crowding (e.g., persons/room and persons/square foot) as measures of the household social environment. McCauley et al. (2001) found no association in homes of farmworkers, and only a slight association in homes of other agricultural workers (McCauley et al. 2003).

Community Environment

Several different measures have been used to associate overall use of pesticides in a community with exposure. None has focused specifically on farmworkers. Fenske et al. (2000) found that a majority of children in an agricultural region from both agricultural and nonagricultural families had urinary metabolites for OPs. Similar results were reported by Koch et al. (2002), who found no differences because of parental occupation or residential proximity to fields. Lee et al. (2002) measured airborne agricultural pesticides at monitoring stations in California communities. They found that the level of exposure exceeded reference values for noncancer health effects for half of the population.

In agricultural communities, historical use of some persistent pesticides may have led to long-term contamination of the soil. In areas where lead arsenate was used extensively, soil samples have demonstrated the persistence of arsenic (Wolz et al. 2003). DDT, an OCP, is still found in soil samples despite its having been removed from use decades ago (Miersma et al. 2003).

Factors Moderating Behavior and Environment

Psychosocial stressors. Two pathways have been proposed by which psychosocial stressors might lead to pesticide exposure of farmworkers or of growers (Figure 1). None of the studies of these stressors have actually measured pesticides, so no data have been gathered with which to validate these pathways. The first pathway is through stressors on the farmworkers, primarily the result of their social position as immigrants and the process of acculturation that they undergo. Vega et al. (1985) found that Mexican American farmworkers experience high levels of psychiatric symptoms. These symptoms are associated with limited social mobility, transience, poverty, discrimination, and a high rate of traumatic life events. These findings were supported by Hovey et al. (2002a, 2002b), who found that farmworkers suffer from high rates of anxiety. This anxiety, in turn, is associated with elevated acculturative stress, low self-esteem, ineffective social support, and lack of control over the migrant lifestyle. Looking specifically at female farmworkers, Carruth and Logan (2002) documented high levels of depressive symptoms, which were predicted by poor health, perceived hazards of farm work, having experienced recent farmwork-related injuries, and engaging in farm work over long periods of time. These documented stressors and associated mental health deficits may lead farmworkers to take more risks and to neglect to practice safety behaviors protective against pesticide exposure.

The second pathway is through stressors on growers and workers that result from the organization of farm work. Thu (1998) proposed that the narrow temporal window for growing and harvesting, long work hours in isolated work conditions, and the psychological stress associated with farming can push farmers to minimize safety standards. Others have argued that the psychological and physical demands of the job confronted by day-laborers, including farmworkers, directly promote accidents and injuries through fatigue and distraction (Kidd et al. 1996; Salazar et al. 2004; Thu 1998; Walter et al. 2002). They also argue that other difficulties faced by farmworkers, including economic hardship and job insecurity, further elevate the risk of exposure and exacerbate health effects of exposure because farmworkers who have few other employment options may fear requesting PPE or may work through dangerous situations.

Pesticide knowledge and beliefs. Farmworkers' knowledge about pesticides has generally been measured relative to prevailing scientific data, while beliefs come from more exploratory, ethnographic investigations. However, conceptually, both provide workers with information upon which they base their actions, so the distinction is somewhat artificial. Farmworker beliefs and knowledge have been collected in a number of studies that do not relate these data to pesticide exposure or to behaviors that might predict exposure. Quandt et al. (1998, 2001) identified several key beliefs held by farmworkers that might increase behaviors that would promote pesticide exposure. These beliefs include the ideas that pesticides must be felt, seen, tasted, or smelled to be present; the skin blocks absorption and body openings facilitate it; exposure occurs only when a pesticide is wet; susceptibility is individualized; and acute, not low-level chronic, exposure is the primary danger inherent in pesticide exposure. Elmore and Arcury (2001) found similar beliefs among Christmas tree workers. Salazar et al. (2004) found that workers expected to get sick as part of the job. They believed it was all right to work in unsafe conditions if the benefits were high enough. Hunt et al. (1999) found similar beliefs in southern Mexico.

In research with pesticide applicators, Martinez et al. (2004) found that applicators believe, in contrast to farmworkers, that dermal exposure is linked to long-term adverse health consequences, but not to acute illness. The knowledge and beliefs held by applicators reflect their participation in required training (Martinez et al. 2004; Perry et al. 2000). Much of it appears to have been learned by rote with less than optimal understanding of the health consequences of exposure.

Some studies have tried to measure the association of pesticide knowledge and beliefs with pesticide-related behavior. These studies (Arcury et al. 2002; Grieshop et al. 1996; McCauley et al. 2002; Vaughan 1993) show that greater knowledge of pesticide risks increases workers' sense of control and willingness to practice safety behaviors that should reduce exposure. Among farm operators, the belief that one had previously experienced adverse events of exposure was linked to taking greater precautions when working with pesticides (Lichtenberg et al. 1999).

Values and folk beliefs. Familism (an orientation to the welfare of one's immediate and extended family) has been noted as a strong value among Mexican and Central American immigrants (Romero et al. 2004; Sabogal et al. 1987; Salazar et al. 2004). Among adolescent farmworkers, this value is so strong that researchers (e.g., Salazar et al. 2004) have suggested that these workers are likely to neglect themselves (e.g., not adhere to safety practices) in their agricultural work with pesticides. Other authors (e.g., Romero et al. 2004; Sabogal et al. 1987) have suggested that familism should be associated with more positive health outcomes. Thus, of farmworkers who have been exposed to pesticides, those with greater familism may experience lower rates of pesticide-related illness.

Two folk illness concepts that are characteristic of Mexico have been identified among farmworkers. "Susto," an illness associated with having experienced a fright (Rubel 1984), was reported by a significant number of Mexican farmworkers in Florida who had experienced pesticide exposure (Baer et al. 1993). Arcury et al. (2001) reported that farmworkers expressed reluctance to use cold water for washing in the field and to shower immediately after returning home from work. They attributed this reluctance to a concern (indicative of a belief in humoral medicine) (Rubel 1960; Weller 1983) that their bodies were metaphorically hot from work and that the contact with water that, despite variation in temperature, is metaphorically cold, would result in rheumatism and other adverse health outcomes. These studies suggest that folk beliefs about the causes of illness can promote greater pesticide exposure by undermining protective behaviors such as hand washing and using PPE.

Summary of the Evidence

While many diverse factors have been proposed to have direct, indirect, or modifying effects on whether or not farmworkers are exposed to pesticides (Table 1; Figure 1), the research connecting characteristics of workers' environments and behaviors with actual measures of pesticide exposure is meager. Behavioral factors for which the best evidence of a direct relationship with pesticide exposure exists are use of PPE, use of pesticide products in and around the home, and personal hygiene behaviors such as hand washing at work and showering upon returning home from work.

Evidence of environmental factors associated with exposure is lacking for the occupational setting. Aside from clear evidence that job tasks that bring workers into contact with pesticides produce greater exposure, there has been little attempt actually to measure the effect of workplace safety training or the organization of work on exposure. Far more attention has been paid to the effects of the household environment of farmworkers and applicators on the exposure of workers and family members because we have better access to homes than to work sites. With some exceptions, research supports the link between proximity to fields and exposure. While studies use different measures, older houses of poorer quality appear to be linked to exposure. Similarly, different measures of household composition have been used. Most suggest that a greater number of adults and farmworkers in a house leads to greater amounts of pesticide in the dwelling and more pesticide exposure of the residents.

None of the psychosocial or cultural factors proposed as moderators in the association of environment or behavior with exposure has been examined with actual pesticide exposure data. Thus, the role of such factors in farmworker exposure is unknown.

The review of the evidence also highlights the fact that many of the existing studies that identify predictors of pesticide exposure in farmworkers, as well as in nonfarmworkers, have relied on self-reported behaviors rather than on true exposure measures. Among those studies that have included measures of exposure, some have employed environmental samples rather than biological measures. This history suggests that further studies of the association between predictors of exposure and actual biomarkers are warranted.

Recommendations for Data Collection and for Future Research

The evidence provided by this review, encompassing both factors with demonstrable links to exposure and those plausible but not well studied, indicates that a minimum set of concepts should be included in studies of farmworker pesticide exposure. The exact measures for each concept are not entirely clear because of the dearth of research that has actually sought to measure the association of predictors and exposure outcomes. Therefore, the recommendation is to obtain a broad enough group of measures to test for likely pathways of exposure.

This minimum set differs depending on whether the research focus is limited to occupational pesticide exposure of workers or if the focus includes the paraoccupational and environmental pesticide exposure of adults and children who reside with farmworkers. For the latter, some additional measures are included (e.g., child play areas). Measures are presented from proximal to distal determinants (Table 2). Although this review has included a variety of moderators that are likely to be important in the exposure pathway, there is currently insufficient research to recommend any particular set of such measures.

Future Research

This review suggests that a productive line of research would be to focus on the role of the organization of work with regard to pesticide exposure. This area of research can help identify aspects of the workplace that can be modified to protect workers from pesticide exposure. It is consistent with the approach of much of occupational safety and health, in that it relies less on changing human behavior directly than on "engineering" changes in work and the workplace environment. While the organization of work is a well developed area of research, it has not had widespread application to farmworker pesticide safety research.

The most obvious dearth of data found in this review is in the area of cultural and psychosocial factors that may moderate the effect of household and workplace environments on safety behaviors. Although such factors are clearly not direct influences on exposure, they condition the extent to which behavior or environmental change to protect workers and their families will be accepted, and they are, therefore, necessary components of behavioral interventions. It is premature to list specific data to be collected because such factors do not lend themselves to measurement through simple questions.

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Sara A. Quandt, (1) Maria A. Hernandez-Valero, (2) Joseph G. Grzywacz, (1) Joseph D. Hovey, (3) Melissa Gonzales, (4) and Thomas A. Arcury (1)

(1) Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA; (2) University of Texas, M.D. Anderson Cancer Center, Houston, Texas, USA; (3) University of Toledo, Toledo, Ohio, USA; (4) University of New Mexico, Albuquerque, New Mexico, USA

This article is part of the mini-monograph "Farmworker Exposure to Pesticides: Methodological Issues for the Collection of Comparable Data."

Address correspondence to S.A. Quandt, Division of Public Health Sciences, Dept. of Epidemiology and Prevention, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1063 USA. Telephone: [phone]. Fax: [phone]. E-mail: [e-mail]

This article was produced as part of the Farmworker Environmental Health Research Comparable Data Conference held in Winston-Salem, NC, on 30 September-1 October 2004.

Financial support was provided by the Pesticide Environmental Trust Fund, N.C. Department of Agriculture and Consumer Services; the National Institute of Environmental Health Sciences (NIEHS) and the National Institute for Occupational Safety and Health (R13 ES/OH013378); and CropLife America, Inc. This work was supported in part by the intramural research program of the NIEHS, National Institutes of Health.

The authors declare they have no competing financial interests.

Received 11 July 2005; accepted 3 November 2005.

Table 1. Review of literature on predictors of pesticide exposure among
migrant and seasonal farmworkers.

                     Relationship to pesticide exposure
Characteristic       Rating (a)  Reference           Population

Workplace behaviors
  Availability and   1           Fenske et al.       12 farmworkers
  use of personal                  1990
  protective
  equipment          1           Gomes et al.        532 farmworkers in
                                   1999                United Arab
                                                       Emirates
                     1           Lander et al.       100 greenhouse
                                   1991                workers and 43
                                                       fruit growers;
                                                       113 slaughtermen
                                                       served as
                                                       controls
                     1           Ohayo-Mitoko        539 agricultural
                                   et al. 1999         workers in 4
                                                       areas of Kenya
                     1           Spencer et al.      28 peach
                                   1995                harvesters,
                                                       California
                     1           Hernandez-Valero    26 Mexican
                                   et al. 2001         American migrant
                                                       farmworkers in
                                                       Baytown, Texas
                     2           Arbuckle et al.     126 pesticide
                                   2002                applicators in
                                                       Ontario
                     2           Fenske et al.       6 pesticide
                                   2002a               applicators in
                                                       central Florida
                                                       citrus groves
                     2           Nigg et al. 1993    3 greenhouse
                                                       pesticide
                                                       applicators in
                                                       Florida
Field sanitation     1           Curwin et al.       12 Hispanic male
                                   2003                tobacco
                                                       harvesters near
                                                       Kinston, North
                                                       Carolina
Household behaviors
  Residental         1           Arcury et al.       9 Latino
  pesticide use                    2005                farmworker
                                                       family
                                                       households in
                                                       western North
                                                       Carolina and
                                                       Virginia
                     1           Bradman et al.      5 farmworker and
                                   1997                6 nonfarmworker
                                                       dwellings in
                                                       California's
                                                       Central Valley
                     1           McCauley et al.     96 farmworker
                                   2001                homes and 24
                                                       grower homes in
                                                       two agricultural
                                                       communities in
                                                       Oregon
                     1           Quandt et al.       41 farmworker  in
                                   2002, 2004          family homes
                                                       North Carolina
                                                       and Virginia
                     2           Fenske et al.       12 farmworker
                                   2002b               homes in Central
                                                       Washington
                                                       State; 14
                                                       non-agricultural
                                                       reference homes
                     2           Lewis et al. 2001   Single household
                     2           Lu et al. 2001      110 children, ages
                                                       2-5 years, from
                                                       96 households in
                                                       the Seattle
                                                       metropolitan area
                     2           McCauley et al.     24 agricultural
                                   2003                families in
                                                       northwestern US
                     2           Morgan et al.       Single family
                                   2001                dwelling in
                                                       Chatham County,
                                                       North Carolina
                     2           Nishioka et al.     11 occupied and 2
                                   2001                unoccupied homes
Cleaning             1           Arcury et al.       9 Latino
                                   2005                farmworker
                                                       family
                                                       households in
                                                       western North
                                                       Carolina and
                                                       Virginia
                     1           Bradman et al.      5 farmworker and
                                   1997                6 nonfarm-
                                                       workers
                                                       dwellings in
                                                       California's
                                                       Central Valley
Laundry              1           Arcury et al.       9 Latino
                                   2005                farmworker
                                                       family
                                                       households in
                                                       western North
                                                       Carolina and
                                                       Virginia
Delay changing       1           Arcury et al.       9 Latino
clothes and                        2005                farmworker
bathing                                                family
                                                       households in
                                                       western North
                                                       Carolina and
                                                       Virginia
                     2           McCauley et al.     24 agricultural
                                   2003                families in
                                                       northwestern US
Household pets       2           Lu et al. 2001      110 children, ages
                                                       2-5 years, from
                                                       96 households in
                                                       the Seattle
                                                       metropolitan area
                     2           McCauley et al.     24 agricultural
                                   2003                families in
                                                       northwestern US
                     2           Morgan et al.       Single-family
                                   2001                dwelling in
                                                       Chatham County,
                                                       North Carolina
                     2           Nishioka et al.     11 occupied and 2
                                   2001                unoccupied homes
Child activity       2           Morgan et al.       Single-family
patterns                           2001                dwelling in
                                                       Chatham County,
                                                       North Carolina
                     2           Mandel et al.       95 farm families
                                   2005                (grower, spouse,
                                                       and child) in
                                                       Minnesota and
                                                       South Carolina
Diet                 2           Curl et al. 2003    39 preschool age
                                                       children (18
                                                       children with
                                                       organic diets
                                                       and 21 children
                                                       with
                                                       conventional
                                                       diets) in
                                                       Seattle,
                                                       Washington
                     2           Stehr-Green et al.  85 rural-dwelling
                                   1988                persons
Transportation       1           Curl et al. 2002    218 farmworker
                                                       households in
                                                       Washington State
                     1           Thompson et al.     571 farmworkers in
                                   2003                the Lower Yakima
                                                       Valley in
                                                       Washington State
Workplace environment
Task variety         1           Hernandez-Valero    26 Mexican
                                   et al. 2001         American migrant
                                                       farmworkers in
                                                       Baytown, Texas
Job design           1           Coronado et al.     213 farmworkers in
                                   2004                24 communities
                                                       and labor camps
                                                       in eastern
                                                       Washington State
Household environment: dwelling characteristics
Dwelling             1           McCauley et al.     96 farmworker
(location                          2001                homes and 24
relative to                                            grower homes in
exposure                                               two agricultural
sources)                                               communities in
                                                       Oregon
                     1           Curl et al. 2002    218 farmworker
                                                       households in
                                                       Washington State
                     1           Quandt et al.       41 farmworker
                                   2002, 2004          family
                                                       residences in
                                                       North Carolina
                                                       and Virginia
                     2           Fenske et al.       12 farmworker
                                   2002b               homes in Central
                                                       Washington State
                                                       and 14
                                                       non-agricultural
                                                       reference homes
                     2           Loewenherz et al.   88 children under
                                   1997                6 years in 48
                                                       pesticide
                                                       applicator and
                                                       14 reference
                                                       families
                     2           Lu et al. 2000      109 children, 9
                                                       months to 6
                                                       years, in an
                                                       agricultural
                                                       community in
                                                       central
                                                       Washington State
Dwelling type        1           McCauley et al.     96 farmworker
                                   2001                homes and 24
                                                       grower homes in
                                                       two agricultural
                                                       communities in
                                                       Oregon
Dwelling tenure      1           Arcury et al.       9 Latino
                                   2005                farmworker
                                                       family
                                                       households in
                                                       western North
                                                       Carolina and
                                                       Virginia
Housing              1           Bradman et al.      5 farmworker and
quality/state                      1997                6 nonfarmworker
of repair dwellings                                    dwelling in
                                                       California's
                                                       Central Valley
                     1           Quandt et al.       41 farmworker
                                   2002, 2004          family
                                                       residences in
                                                       North Carolina
                                                       and Virginia
Household environment: household characteristics
Total household      1           Arcury et al.       9 Latino
size (total                        2005                farmworker
number of                                              family
residents)                                             households in
                                                       western North
                                                       Carolina and
                                                       Virginia
                     1           McCauley et al.     96 farmworker
                                   2001                homes and 24
                                                       grower homes in
                                                       two agricultural
                                                       communities in
                                                       Oregon
                     2           McCauley et al.     24 agricultural
                                   2003                families in
                                                       northwestern
                                                       United States
                     1           Arcury et al.       9 Latino
                                   2005                farmworker
                                                       family
                                                       households in
                                                       western North
                                                       Carolina and
                                                        Virginia
Number of            1           McCauley et al.     96 farmworker
farmworkers in                     2001                homes and 24
household                                              grower homes in
                                                       two agricultural
                                                       communities in
                                                       Oregon
                     1           Bradman et al.      5 farmworker and
                                   1997                6 nonfarm-
                                                       workers
                                                       dwellings in
                                                       California's
                                                       Central Valley
                     2           Lu et al. 2000      109 children, 9
                                                       months to 6 years
                                                       of age, in an
                                                       agricultural
                                                       community in
                                                       central
                                                       Washington State
                     2           Simcox et al.       26 farming, 22
                                   1995                farmworker, and
                                                       11 nonfarming
                                                       residences in
                                                       eastern
                                                       Washington State
Household            1           Arcury et al.       9 Latino
composition                        2005                farmworker
                                                       family
                                                       households in
                                                       western North
                                                       Carolina and
                                                       Virginia
                     1           Quandt et al.       41 farmworker
                                   2004                family
                                                       residences in
                                                       North Carolina
                                                       and Virginia
Household            1           McCauley et al.     96 farmworker
density or                         2001                homes and 24
crowding                                               grower homes in
                                                       two agricultural
                                                       communities in
                                                       Oregon
                     2           McCauley et al.     24 agricultural
                                   2003                families in
                                                       northwestern
                                                       United States
Community environment
  Overall level of   1-2         Fenske et al.       109 children in
  agricultural                     2000                agricultural
  use                                                  community in
                                                       eastern
                                                       Washington State
                                                       (91 had parents
                                                       working
                                                       agriculture)
                     2           Koch et al. 2002    44 children living
                                                       in an
                                                       agricultural
                                                       community in
                                                       central
                                                       Washington State
                     2           Lee et al. 2002     California
                                                       communities
Historical           2           Wolz et al. 2003    58 homes in
agricultural                                           agricultural
pesticide use                                          community in
                                                       Washington State
                     2           Miersma et al.      Elementary school
                                   2003                yards in 8 cities
                                                       near the Texas-
                                                       Mexico border

                     Relationship to pesticide exposure
Characteristic       Reference           Exposure measurement

Workplace behaviors
  Availability and   Fenske et al.       Dermal exposure to lindane
  use of personal      1990
  protective
  equipment          Gomes et al.        Blood sample:
                       1999                Acetylcholinesterase (AChE)
                                           activity
                     Lander et al.       Blood sample: AChE activity
                       1991
                     Ohayo-Mitoko        Blood sample: AChE activity
                       et al. 1999
                     Spencer et al.      Dislodgeable foliar residue of
                       1995                azinphos-methyl (AM)
                                           pesticides measured on skin
                                           and clothing
                     Hernandez-Valero    Blood samples: 21
                       et al. 2001         organochlorine pesticides
                                           (OCPs)
                     Arbuckle et al.     Urine samples: Phenoxy-
                       2002                herbicides 2,4-
                                           dichlorophenoxyacetic acid
                                           (2,4-D) or 4-chloro-2-
                                           methylphenoxyacetic acid
                                           (MCPA)
                     Fenske et al.       Exposure to organophosphorus
                       2002a               (OP) insecticide ethion
                                           during airblast application
                                           by fluorescent tracer
                                           deposition on skin surfaces
                                           beneath garments, video
                                           imaging analysis instrument
                                           (VITAE system), and alpha-
                                           cellulose patches placed
                                           outside and beneath the
                                           garments
                     Nigg et al. 1993    Pads placed inside and outside
                                           three types of protective
                                           coveralls measured exposure
                                           to chlorpyrifos, fluvalinate,
                                           and ethazol
Field sanitation     Curwin et al.       Handwipes: acephate residues
                       2003
Household behaviors
  Residental         Arcury et al.       Urine samples: OP metabolites
  pesticide use        2005
                     Bradman et al.      House dust and handwipe sample:
                       1997                33 pesticides
                     McCauley et al.     House dust samples: residues of
                       2001                major OPs used in area crops
                     Quandt et al.       Wipe samples from floor, toys,
                       2002, 2004          and children's hands: 8
                                           locally reported agricultural
                                           pesticides and 13 pesticides
                                           commonly found in U.S. houses
                     Fenske et al.       House dust samples and
                       2002b               children's urine samples: 2
                                           diethyl OP pesticides--
                                           chlorpyrifos and parathion
                     Lewis et al. 2001   Samples of indoor air;
                                           vacuumable carpet dust;
                                           carpet dislodgeable residues;
                                           deposits on bare floors,
                                           table tops, and dinnerware;
                                           surrogate food; and residues
                                           on children's hands and toys:
                                           diazinon and chlorpyrifos
                     Lu et al. 2001      Urine samples: 6
                                           dialkylphosphate (DAP)
                                           compounds
                     McCauley et al.     House dust samples: OP
                       2003                pesticides
                     Morgan et al.       Soil, turf, and carpet
                       2001                samples; 24-hr air samples;
                                           handwipes; and samples taken
                                           from dog fur and paws
                     Nishioka et al.     Indoor air samples; surface
                       2001                wipes from floors, table
                                           tops, and window sills; and
                                           floor dust samples before and
                                           after lawn application of the
                                           herbicide 2,4-D
Cleaning             Arcury et al.       Urine samples: OP metabolites
                       2005
                     Bradman et al.      House dust and handwipe
                       1997                samples: 33 pesticides
Laundry              Arcury et al.       Urine samples: OP metabolites
                       2005
Delay changing       Arcury et al.       Urine samples: OP metabolites
clothes and            2005
bathing
                     McCauley et al.     House dust samples: OP
                       2003                pesticides
Household pets       Lu et al. 2001      Spot urine samples: six
                                           dialkylphosphate (DAP)
                                           compounds
                     McCauley et al.     House dust samples: OP
                       2003                pesticides
                     Morgan et al.       Soil, turf, and carpet
                       2001                samples; 24-hr air samples;
                                           handwipes; and samples taken
                                           from dog fur and paws:
                                           pesticides
                     Nishioka et al.     Indoor air samples; surface
                       2001                wipes from floors, table
                                           tops, and window sills; and
                                           floor dust samples: before
                                           and after lawn application of
                                           herbicide 2,4-D
Child activity       Morgan et al.       Soil, turf, and carpet samples;
patterns               2001                24-hr air samples; handwipes,
                                           and samples taken from dog
                                           fur and paws: pesticides
                     Mandel et al.       24-hr urine samples: 2,4-D;
                       2005                glyphosphate; and metabolite
                                           of chlorpyrifos
Diet                 Curl et al. 2003    24-hr urine samples: 5 OP
                                           pesticide metabolites
                     Stehr-Green et al.  Blood samples: 11 pesticide
                       1988                residues and metabolites
Transportation       Curl et al. 2002    House and vehicle dust samples:
                                           6 pesticides
                                         Urine samples: 5-
                                           dialkylphosphate (DAP)
                                           metabolites
                     Thompson et al.     Urine samples of farmworkers
                       2003                and children, house and
                                           vehicle dust samples:
                                           pesticides
Workplace environment
Task variety         Hernandez-Valero    Blood samples measured 21
                       et al. 2001         organochlorine pesticides
                                           (OCPs)
Job design           Coronado et al.     Urine samples: OP metabolites;
                       2004                House and vehicle dust
                                           samples: OP pesticides
Household environment: dwelling characteristics
Dwelling             McCauley et al.     Home dust samples: OP residues
(location              2001
relative to
exposure             Curl et al. 2002    House and vehicle dust samples:
sources)                                   6 pesticides Urine samples: 5
                                           OP metabolites
                     Quandt et al.       Wipe samples from floor, toys,
                       2002, 2004          and children's hands: 8 eight
                                           locally reported agricultural
                                           pesticides and 13 pesticides
                                           commonly found in U.S. houses
                     Fenske et al.       House dust samples and
                       2002b               children's urine samples:
                                           chlorpyrifos and parathion
                     Loewenherz et al.   Urine samples: OP metabolites
                       1997
                     Lu et al. 2000      Urine and hand wipe samples: OP
                                           pesticides
                                         House dust samples and wipe
                                           samples: OP pesticides
Dwelling type        McCauley et al.     Home dust samples: residues of
                       2001                major OPs used in area crops
Dwelling tenure      Arcury et al.       Urine samples: OP metabolites
                       2005
Housing              Bradman et al.      House dust and handwipe sample:
quality/state          1997                33 pesticides
of repair
                     Quandt et al.       Wipe samples from floor, toys,
                       2002, 2004          and children's hands: 8
                                           locally reported agricultural
                                           pesticides and 13 pesticides
                                           commonly found in U.S. houses
Household environment: household characteristics
Total household      Arcury et al.       Urine samples: OP metabolites
size (total            2005
number of
residents)           McCauley et al.     Home dust samples: OP residues
                       2001
                     McCauley et al.     House dust samples: OP
                       2003                pesticides
                     Arcury et al.       Urine samples: OP metabolites
                       2005
Number of            McCauley et al.     Home dust samples: OP residues
farmworkers in         2001
household
                     Bradman et al.      House dust and handwipe sample:
                       1997                33 pesticides
                     Lu et al. 2000      Urine and hand wipe samples: OP
                                           pesticides. House dust
                                           samples and wipe samples from
                                           various surfaces: OP
                                           pesticides
                     Simcox et al.       House dust and soil samples: 4
                       1995                OP insecticides
Household            Arcury et al.       Urine samples: OP metabolites
composition            2005
                     Quandt et al.       Wipe samples from floor, toys,
                       2004                and children's hands: 8
                                           locally reported agricultural
                                           pesticides and 13 pesticides
                                           commonly found in U.S. houses
Household            McCauley et al.     Home dust samples: OP residues
density or             2001
crowding
                     McCauley et al.     House dust samples: OP residues
                       2003
Community environment
Overall level of     Fenske et al.       Urine samples: OP metabolites
agricultural           2000
use
                     Koch et al. 2002    Urine samples: dialkylphosphate
                                           (DAP) metabolites
                     Lee et al. 2002     Ambient air sampling of
                                           multiple classes of
                                           airborne pesticides
Historical           Wolz et al. 2003    Soil and house dust samples:
agricultural                               lead arsenate
pesticide use
                     Miersma et al.      Soil samples: OCPs
                       2003

                     Relationship to pesticide exposure
Characteristic       Reference           Findings

Workplace behaviors
  Availability and   Fenske et al.       Demonstrated penetration of
  use of personal      1990                lindane through workshirt and
  protective                               pants. Recommended adding
  equipment                                coveralls and gauntlet-type
                                           gloves
                     Gomes et al.        Higher AChE was associated with
                       1999                changing work clothes and use
                                           of work coveralls, gloves,
                                           and face scarf
                     Lander et al.       Wearing gloves was protective
                       1991                of AChE activity in
                                           greenhouse workers
                     Ohayo-Mitoko        Use of coverall resulted in
                       et al. 1999         less AChE inhibition than not
                                           wearing coverall or just
                                           wearing boots
                     Spencer et al.      More pesticides were found on
                       1995                outer of two shirts,
                                           indicating the protective
                                           effect of clothing from
                                           dislodgeable residues
                     Hernandez-Valero    Wearing gloves and hats
                       et al. 2001         resulted in less OCP exposure
                                           in farmworkers than wearing
                                           only hats
                     Arbuckle et al.     Reduced pesticide in urine
                       2002                following application was
                                           associated with use of rubber
                                           gloves for mixing/loading,
                                           and wearing rubber boots for
                                           cleanup
                     Fenske et al.       Among applicators, compared
                       2002a               dermal exposure to pesticides
                                           for cotton work shirts/pants,
                                           woven coveralls, nonwoven
                                           garments. All garments
                                           allowed fabric penetration.
                                           Exposure was highest with
                                           nonwoven garments, mostly
                                           because of large sleeve and
                                           neck openings
                     Nigg et al. 1993    Less penetration of synthetic
                                           disposable coverall than of
                                           reusable treated twill
                                           coverall
Field sanitation     Curwin et al.       Farmworkers removed 96% of
                       2003                acephate on hands by washing
Household behaviors
  Residental         Arcury et al.       Residential pesticide use was
  pesticide use        2005                associated with higher levels
                                           of OP metabolites in samples
                                           from children and adults
                                           living in farmworker
                                           dwellings
                     Bradman et al.      Residential application of
                       1997                agricultural and residential
                                           pesticides was related to
                                           presence of pesticides in
                                           dust samples
                     McCauley et al.     Found no relationship between
                       2001                pesticides in wipe samples
                                           and "family use of pest
                                           control products"
                     Quandt et al.       Found a greater number and
                       2002, 2004          weight of residential
                                           pesticides than agricultural
                                           pesticides in dust samples
                                           collected in farmworker
                                           dwellings
                     Fenske et al.       OP pesticide use in garden was
                       2002b               associated with increased
                                           metabolite concentrations in
                                           children's urine
                     Lewis et al. 2001   Demonstrated that indoor and
                                           outdoor residential pesticide
                                           application resulted in
                                           pesticides on surfaces in
                                           homes accessible to human
                                           contact
                     Lu et al. 2001      Children's OP pesticide
                                           concentrations were higher if
                                           parents reported garden
                                           pesticide use but were not
                                           based on indoor residential
                                           pesticide use
                     McCauley et al.     Pesticide use in the home was
                       2003                not related to levels of
                                           total OP residues
                     Morgan et al.       Children and adults were
                       2001                exposed to pesticides that
                                           were applied to yards and
                                           then were transferred into
                                           the house by pets (dogs),
                                           adults, and children
                     Nishioka et al.     Children and adults were
                       2001                exposed to pesticides that
                                           were applied to yards and
                                           then were transferred into
                                           the house by pets (dogs) and
                                           adults
Cleaning             Arcury et al.       Living in a dwelling that is
                       2005                easier to clean and that has
                                           a vacuum cleaner was
                                           associated with lower levels
                                           of OP metabolites among
                                           children and adults
                     Bradman et al.      Frequency and type of cleaning
                       1997                (mopping, vacuuming) was
                                           related to presence of
                                           pesticides in dust samples
Laundry              Arcury et al.       Higher levels of OP metabolites
                       2005                for adults and children were
                                           associated with improper
                                           handling of laundry,
                                           including storage of work
                                           clothes in house and
                                           laundering of work clothes
                                           with family clothes
Delay changing       Arcury et al.       Higher levels of OP metabolites
clothes and            2005                for adults and children were
bathing                                    associated with farmworkers
                                           who delay changing from work
                                           clothes and bathing
                     McCauley et al.     Level of total OPs and of
                       2003                azinphos-methyl was higher
                                           in homes where workers waited
                                           > 2 hr before changing out of
                                           work clothes
Household pets       Lu et al. 2001      OP pesticide concentrations in
                                           children were not different
                                           based on reported pet
                                           treatment
                     McCauley et al.     Total number of pets in the
                       2003                home was not related to
                                           levels of total OP residues
                     Morgan et al.       Pet dog was a vehicle for the
                       2001                transfer of pesticide
                                           residues from lawn to house
                     Nishioka et al.     Pet dog was a vehicle for the
                       2001                transfer of pesticide
                                           residues from lawn to house
Child activity       Morgan et al.       Children were a vehicle for the
patterns               2001                transfer of pesticide
                                           residues from lawn to house
                     Mandel et al.       Children's urine pesticide
                       2005                concentrations were lower
                                           than those of growers, but
                                           higher than those of growers'
                                           spouses, thus reflecting
                                           children's activity patterns
Diet                 Curl et al. 2003    Urine of children who ate an
                                           organic diet contained
                                           significantly lower levels of
                                           OP metabolites than urine of
                                           those who ate a conventional
                                           diet
                     Stehr-Green et al.  In "rural-dwelling persons,"
                       1988                consumption of home-produced
                                           eggs and root vegetables was
                                           associated with increased
                                           serum concentrations of
                                           pesticides
Transportation       Curl et al. 2002    Found pesticides in dust
                                           samples collected in
                                           farmworker vehicles
                     Thompson et al.     Found pesticides in dust
                       2003                samples collected in
                                           farmworker vehcles
Workplace environment
Task variety         Hernandez-Valero    Number of tasks that brought
                       et al. 2001         farmworkers into contact with
                                           pesticides was associated
                                           with elevated serum levels
                                           of mirex, DDT, and
                                           trans-nonachlor
Job design           Coronado et al.     Workers performing tasks not
                       2004                regulated by WPS (e.g.,
                                           thinning) were more likely
                                           to have detectable levels of
                                           azinphos-methyl in house and
                                           vehicle dust
Household environment: dwelling characteristics
Dwelling             McCauley et al.     Found that azinphos-methyl
(location              2001                concentration decreased with
relative to                                increased distance from
exposure                                   fields
sources)             Curl et al. 2002    Strong correlation between
                                           pesticides in cars and in
                                           house dust. Weaker
                                           correlation between house
                                           dust and child urine. No
                                           association between distance
                                           to fields and child's urine,
                                           thus suggesting that
                                           behavior, not proximity to
                                           fields, was responsible for
                                           exposure
                     Quandt et al.       Proximity to agricultural
                       2002, 2004          fields was related to the
                                           number of agricultural
                                           pesticides detected in dust
                                           samples collected in
                                           dwellings
                     Fenske et al.       Homes in close proximity (200
                       2002b               ft/60 m) to pesticide-treated
                                           farmland had higher
                                           chlorpyrifos and parathion
                                           house dust concentrations
                                           than did homes farther away,
                                           but this effect was not
                                           reflected in the urinary
                                           metabolite data
                     Loewenherz et al.   Higher DMTP levels were found
                       1997                in applicator children living
                                           < 200 ft from an orchard than
                                           in nonproximal applicator
                                           children
                     Lu et al. 2000      Higher levels of pesticides
                                           were found in dust samples
                                           from dwellings closer to
                                           orchards
Dwelling type        McCauley et al.     Housing type (labor camp,
                       2001                trailer, apartment) was not
                                           related to pesticide residues
Dwelling tenure      Arcury et al.       Renting rather than owning was
                       2005                associated with higher levels
                                           of OP metabolites found in
                                           samples from persons living
                                           in farmworker dwellings
Housing              Bradman et al.      Dwelling age is related to
quality/state          1997                presence of pesticides
of repair
                     Quandt et al.       More residential pesticides
                       2002, 2004          were found in dust samples
                                           collected in dwellings judged
                                           to be difficult to clean
Household environment: household characteristics
Total household      Arcury et al.       Larger household size was
size (total            2005                associated with higher
number of                                  levels of OP metabolites for
residents)                                 adults and children
                     McCauley et al.     More persons in household was
                       2001                related to greater
                                           azinphos-methyl in dust
                     McCauley et al.     Weak, nonsignificant
                       2003                correlation was found
                                           between number of household
                                           residents and levels of total
                                           OP residues. Number of adults
                                           in household
                     Arcury et al.       More adults in the household
                       2005                was associated with higher
                                           levels of OP metabolites for
                                           adults and children
Number of            McCauley et al.     More farmworkers in household
farmworkers in         2001                was related to greater
household                                  azinphos-methyl in dust
                     Bradman et al.      Higher amounts of pesticides in
                       1997                dust in farm worker than
                                           nonfarmworker homes.
                                           Pesticides found on hands of
                                           children in farmworker, but
                                           not nonfarmworker homes,
                                           suggest take home pesticides
                     Lu et al. 2000      Households with agricultural
                                           workers had higher levels of
                                           OP pesticides in dust wipe
                                           samples and on children's
                                           hands, and higher levels of
                                           metabolites in children's
                                           urine samples, than reference
                                           homes
                     Simcox et al.       OP pesticide residues were
                       1995                found more often in homes of
                                           agricultural workers than in
                                           reference homes
Household            Arcury et al.       Higher levels of OP metabolites
composition            2005                for adults and children were
                                           associated with nonnuclear
                                           family household composition
                     Quandt et al.       Nonnuclear family household
                       2004                composition was weakly
                                           associated with agricultural
                                           but not with residential
                                           pesticides
Household            McCauley et al.     Found no relationship between
density or             2001                pesticides and area of home
crowding
                     McCauley et al.     Weak correlation was found
                       2003                between total area of home
                                           and levels of total OPs
                                           residues
Community environment
Overall level of     Fenske et al.       Most children living in an
agricultural           2000                agricultural region during
use                                        the spray season had
                                           measureable
                                           dialkyphosphates, and a
                                           substantial fraction
                                           had doses > reference
                                           values for azinphos-methyl
                     Koch et al. 2002    DAP metabolites were elevated
                                           when OP pesticides were
                                           sprayed in the region. No
                                           differences were found to be
                                           related to parental
                                           occupation or residential
                                           proximity to fields
                     Lee et al. 2002     Exposure estimates
                                           [greater than or equal to]
                                           risk of noncancer health
                                           effects reference values
                                           occurred for 50% of exposed
                                           population for several
                                           pesticides
Historical           Wolz et al. 2003    Dwellings near land used for
agricultural                               orchard production during
pesticide use                              1905-1947 had significantly
                                           higher soil and household
                                           lead, and also higher soil
                                           arsenic than other homes
                     Miersma et al.      Attributed OCPs found in school
                       2003                yards to historical
                                           agricultural activity

(a) 1 = Association with pesticide exposure was demonstrated in
farmworkers. 2 = Association with pesticide exposure was demonstrated in
nonfarmworker samples.

Table 2. Recommended measures of predictors of pesticide exposure among
migrant and seasonal farmworkers.

Workplace    Wear clean clothes to work (frequency)
behaviors    Wash hands at work (frequency)
             Use of personal protective equipment (type, frequency)
Household    Residential use of pesticides (type, frequency), including
behaviors      pet products
             Wear work clothes into dwelling
             Wear work shoes into dwelling
             Time to changing from work clothes after work
             Time to bathing after work
             Contact with others before changing clothes after work
             Contact with others before bathing after work
             Storage of soiled work clothes
             Laundry method (machine, hand)
             Separation of work and family clothes in laundry
             Child play areas (inside, outside)
Work         Safety training (contents, quality)
environment  Work task (fieldwork, mix and load, apply)
             Access to hygiene facilities
             Availability of personal protective equipment
             Ability to communicate with supervisor
Residential  Location relative to pesticide application
environment  Housing structure type
             Housing overall repair
             Housing size (area, rooms)
             Bathing facilities per resident
             Laundry facilities per resident
             Total number residents
             Total number of farmworkers
             Crowding; adult/room; workers/room; workers/sleeping room
Community    Agricultural acreage
environment  Volume pesticides applied/year