Variation across the agricultural season in organophosphorus pesticide urinary metabolite levels for Latino farmworkers in eastern North Carolina: project design and descriptive results.

BACKGROUND: Community Participatory Approach to Measuring Farmworker Pesticide Exposure, PACE3, used a longitudinal design to document pesticide biomarkers among farmworkers. This article presents an overview of PACE3 and provides a descriptive analysis of participant characteristics and one set of pesticide biomarkers, the dialkylphosphate (DAP) urinary metabolites of organophosphorus (OP) pesticides.
METHODS: Two hundred eighty seven farmworkers were recruited during 2007 from 44 farmworker camps in 11 eastern North Carolina counties. Participants provided interviews, urine samples, blood samples, and saliva samples up to four times at monthly intervals beginning in May. A total of 939 data points were collected.
RESULTS: Farmworkers were largely men (91.3%) from Mexico (94.8%) with a mean age of 33.7 years (SE 0.82); 23.3% spoke an indigenous language. Across all data points, frequencies of detection and median urinary concentrations were 41.3% and 0.96 microg/L for dimethylphosphate (DMP), 78.3% and 3.61 microg/L for dimethylthiophosphate (DMTP), 33.3% and 0.04 microg/L for dimethyldithiophosphate (DMDTP), 40.5% and 0.87 microg/L for diethylphosphate (DEP), 32.3% and 0.17 microg/L for diethylthiophosphate (DETP), and 8.09% and 0.00 microg/L for diethyldithiophosphate (DEDTP). The frequencies of detection and urinary concentrations of the DAP metabolites increased during the season.
CONCLUSIONS: More PACE3 participants were from Mexico, male, migrant workers, and spoke an indigenous language compared to national data. PACE3 participants had comparable frequencies of detection and urinary metabolite concentrations with participants in other studies. Variability in the frequencies of detection and urinary concentrations of the DAP metabolites indicates the importance of longitudinal studies of biomarkers of currently used pesticides in farmworker populations.