Organophosphate Pesticide Exposure in Farmworker Family Members in Western North Carolina and Virginia: Case Comparisons

Human Organization, Spring 2005 by Arcury, Thomas A, Quandt, Sara A, Rao, Pamela, Doran, Alicia M, Et al

Farmworkers and their family members are exposed to pesticides in their homes as well as at work. Using a sample of nine farmworker households in western North Carolina and Virginia, this analysis describes the organophosphate (OP) pesticide urinary metabolite levels of adults and children in these households, and compares these farmworker household OP metabolite levels to the national reference data. Data from survey and in-depth interviews are analyzed to find dwelling, household, and work characteristics related to OP metabolite levels. All participants had measurable OP metabolites. Every household had a high level of OP metabolites when compared to national reference data. There were common factors among the households that could cause the high household OP exposure, including farm employment and living adjacent to agricultural fields. Factors associated with household variability in OP exposure included having a non-nuclear family structure, and, therefore, having more adult males who were employed doing farm work, living in rental housing, not owning a vacuum cleaner, residing in a dwelling that is difficult to clean, and the season (spring versus summer) in which urine samples were collected. These results indicate that regulatory changes that improve low income housing, improve industrial hygiene standards, and provide farmworkers information about their pesticide exposure are needed to protect farmworkers and their families.

Key words: migrant and seasonal farmworkers, farmworker families, pesticides, organophosphate pesticide metabolites

The risk of pesticide exposure among farmworkers is well established. This risk is not limited to those who labor directly in the fields. Those who live with farmworkers-their spouses and children-are exposed to pesticides through a variety of routes (Fenske, Lu, Simcox, Loewenherz, Touchstone, Moate, Alien and Kissel 2000), including drift from applications in nearby fields, entering fields to which pesticides have been applied, residues on workers' skin, clothing, boots and tools, remnants in pesticide containers, and food brought from work. While the dose from each of these exposures may be small, their combined effects can have serious repercussions for every family member's health, particularly that of children (Eskenazi, Bradman and Castronia 1999).

This paper presents evidence of exposure to organophosphate (OP) pesticides by examining the OP metabolite levels measured in urine from the members of nine Latino farmworker families in rural western North Carolina and Virginia. The goal of this analysis is to determine whether the members of farmworker families are exposed to OPs at levels greater than the general US population, and to document factors related to greater exposure. This would document an issue of environmental justice and a possible cause of health disparities. Policy and regulation that can reduce OP exposure based on these results can then be developed.

OP pesticides are among the most widely applied and toxic agricultural pesticides (Reigart and Roberts 1999). They are applied to crops ranging from tobacco and Christmas trees to vegetables and orchard fruit. OPs can be absorbed by inhalation, by ingestion or through the skin. OPs affect the nervous system in reducing the amount of acetycholinesterase (AChE) enzyme at nerve endings. If they do not inactivate AChE, they are quickly metabolized and excreted, with the majority excreted within 24 to 48 hours. Recovery from OP poisoning depends on the generation of new enzyme in affected tissue or the regeneration of OP-inactivated enzyme. The amount needed to cause immediate symptoms or delayed health effects depends on dose. The immediate health effects of OP exposure can include rashes, nausea and vomiting, dizziness and headache, muscle ache, fatigue, loss of consciousness, shock, coma, and death. The delayed health effects can include impotence, birth defects, impaired neurological development and status, and cancer (US-EPA 1999). In addition to their effects on physical health, OPs are suspected to cause depression (Stallones and Beseler 2002).

There are no reliable data on the number of agricultural workers who annually are exposed to OPs, nor are there data on the number whose exposure is sufficiently severe to result in illness. Only a few states have mandated reporting of occupational pesticide exposure (Maizlish, Rudolph and Dervin 1995). Most research on farmworker pesticide exposure focuses on occupational exposure. However, there is growing literature that shows that family members, especially children, of farmworkers are also exposed to pesticides due to: (1) farmworker housing location that exposes them to drift or over-spraying of pesticides; (2) pesticides taken home by farmworkers on skin, clothes, boots, containers, produce, and in vehicles; and (3) direct application of agricultural and residential pesticides to farmworker dwellings to control household pests (Fenske et al. 2000). Several investigators have shown that pesticides can be detected in the dwellings of farmworkers, in the farmworkers themselves, and in those who live with farmworkers (Curl, Fenske, Kissel, Shirai, Moate, Griffith, Coronado and Thompson 2002; Fenske, Lu, Barr and Needham 2002; Lu, Fenske, Simcox and Kalman 2000; Shalat, Donnelly, Freeman, Calvin, Ramesh, Jimenez, Black, Coutinho, Needham, Barr and Ramirez 2003).