Introduction: Farmworkers in the United States, especially migrant workers, face unique barriers to healthcare and have documented disparities in health outcomes. Exposure to pesticides, especially those persistent in the environment, may contribute to these health disparities. Methods: We queried the National Health and Nutrition Examination Study (NHANES) from 1999-2014 for pesticide exposure biomarker concentrations among farmworkers and non-farmworkers by citizenship status. We combined this with toxicity assay data from the US Environmental Protection Agency's (EPA's) Toxicity Forecast Dashboard (ToxCast). We estimated adverse biological effects that occur across a range of human population-relevant pesticide doses. Results: In total, there were 1,137 people with any farmwork history and 20,205 non-farmworkers. Of the 14 commonly detectable pesticide biomarkers in NHANES, 2,4-dichlorophenol (OR= 4.32, p= 2.01x10-7) was significantly higher in farmworkers than non-farmworkers. Farmworkers were 1.37 times more likely to have a bioactive pesticide biomarker measurement in comparison to non-farmworkers (adjusted OR=1.37, 95% CI: 1.10, 1.71). Within farmworkers only, those without U.S. citizenships were 1.31 times more likely to have bioactive pesticide biomarker concentrations compared those with U.S. citizenship (adjusted OR 1.31, 95% CI: 0.75, 2.30). Additionally, non-citizen farmworkers were significantly more exposed to bioactive levels of beta-hexachlorocyclohexane (BHC) (OR= 8.50, p= 1.23x10-9), p,p-DDE (OR= 2.98, p= 3.11x10-3), and p,p'-DDT (OR= 10.78, p= 8.70x10-4). Discussion: These results highlight pesticide exposure disparities in farmworkers, particularly those without U.S. citizenship. Many of these exposures are occurring at doses which are bioactive in toxicological assays.

The authors have declared no competing interest.

The researchers included on this study were supported by the National Institute of Occupational Safety and Health Education Research Center (Grant# T42 OH 008455), the National Institute of Environmental Health Sciences Environmental Toxicology and Epidemiology Program (Grant# T32 ES007062), the National Science Foundation Graduate Research Program (Grant # DGE-1256260), and the National Institutes of Health (R01 ES028802, P30 ES017885, R01AG072396).

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The study used (or will use) ONLY openly available human data that were originally located at: the CDC, https://wwwn.cdc.gov/nchs/nhanes/; and the EPA, https://www.epa.gov/chemical-research/exploring-toxcast-data

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