Integrating NHANES and Toxicity Forecaster Data to Compare Pesticide Exposure and Bioactivity by Farmwork History and US Citizenship.

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= 2.01×10 ) 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 -hexachlorocyclohexane (BHC) (OR= 8.50, p= 1.23×10 ), p,p-DDE (OR= 2.98, p= 3.11×10 ), and p,p'-DDT (OR= 10.78, p= 8.70×10 ).

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.