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Pesticides Pose Threat to Children of Farrnworkers.

WASHINGTON -- Children of migrant farmworkers are at high risk for pesticide exposure and associated health problems, according to preliminary data that Maria A. Hernandez-Valero, Dr.P.H., presented at a meeting on cancer and the environment sponsored by the National Institute of Environmental Health Sciences.

Children and adolescents make up 20%-25% of the total U.S. migrant farmworker population of 3-6 million. Even those who never set foot in the fields are at high risk for pesticide exposure in utero or through breast feeding, aerial spraying beyond fields, application drift, and carry-home contamination from their parents.

"This population is chronically exposed to pesticides," said Dr. Hernandez-Valero of the Center for Research on Minority Health at the University of Texas M.D. Anderson Cancer Center, Houston.

The preliminary findings suggest that physicians should consider exposure to toxic chemicals as a possible cause of health problems in children or adults with a history of agricultural work or other exposures to dangerous chemicals, she said in a later interview.

"Nobody asks about that. These are the things that physicians need to be thinking about," Dr. Hernandez-Valero said.

In a pilot study, the investigators, studied 62 Mexican Americans--26 adults (8 men, 18 women) and 36 children (16 boys, 20 girls), ages 3-19--from migrant farmworker communities outside Houston. The study population consisted of seasonal workers who spend only 3 months a year working in the fields, as opposed to other migrant worker populations that do such work year-round.

The researchers measured a panel of 21 organochlorine pesticides (OCPs), including DDE (dichlorodiphenyldichloroethylene, a metabolite of DDT), mirex, and trans-nonachlor. Serum OCP levels were correlated with data on occupational history and pesticide exposure, obtained using the Migrant Farmworker Questionnaire that was developed by the National Cancer Institute and the Farmworker Epidemiology Research Group.

The mean total serum OCP concentration was 17.0 parts per billion (ppb) in the adults and 2.6 ppb in the children. The children had measurable levels of DDE and mirex. Only one. child in the study did not have measurable OCP levels, Dr. Hernandez-Valero reported.

There are no data on OCP levels in the general population, she noted. The farm workers in the pilot study had OCP levels that were higher than those previously measured in a comparison group of 1,200 individuals who were tested due to suspected pesticide exposure. That group had measurable levels of DDE (3.2 .ppb) and nondetectable levels of mirex ([greater than] 0.3 ppb).

In the study group, the 31% of the children who had worked in the fields had higher OCP levels than the 69% who had not worked in the fields. Higher OCP levels were seen in children who had spent more time working in the fields, according to Dr. Herrnandez-Valero. (See chart below.)

Children who were breast-fed for at least 6 months also had relatively high OCP levels. Women with a history of breast-feeding had OCP levels that were almost 50% lower than those of women who never breast-fed, suggesting that "lactation may be a direct route of pesticide exposure for migrant farmworker children and of pesticide excretion for migrant farmworker women," Dr. Hernandez-Valero said.

Of the 18 women in the study, 13 reported working in the fields during pregnancy. Those who reported a history of spontaneous abortion had higher OCP levels than those who didn't report such' a history.

High OCP levels were associated with childhood health problems. The three most common health conditions in the children were gastrointestinal problems (21%), infections (ear, respiratory, and kidney--19%), and asthma (11%). In contrast, the leading health problems in the adults were asthma (33%), CNS/orthopedic (28%), and diabetes (22%).

"The adults developed more chronic health problems," possibly due to lifetime exposure to pesticides, she said.

OCPs are slow to be eliminated from the body and highly lipophilic. They become mobilized when fat tissues are metabolized.

They have been shown to be tumor promoters, immunotoxicants, and endocrine disruptors and have been linked to breast, reproductive, and other cancers in humans, Dr. Hernandez-Valero said.

"Since OCPs remain in the environment for many years and migrant farmworker children are constantly exposed through many pathways, there is the need to monitor this high-risk population," she said.

Prospective cohort studies of migrant farmworker children are needed to determine whether chronic pesticide exposure early in life leads to poorer health outcomes, Dr. Hernandez-Valero said.

Other recommended steps include blood testing (particularly in children) to identify those who are at high risk; evaluating the benefit of breast-feeding vs. the use of infant formula in U.S. populations that are at high risk; and restricting children from working in the fields, she added.
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Comment:Pesticides Pose Threat to Children of Farrnworkers.
Publication:Family Practice News
Article Type:Brief Article
Geographic Code:1USA
Date:Jul 1, 2001
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