Occupational pesticide exposure, hematological parameters, and cholinesterase and paraoxonase-1 activities among avocado farmworkers in Michoacán, Mexico

Avocado farmworkers are potentially exposed to multiple pesticides, which may influence hematological parameters and detoxification enzyme activities. This study enrolled 105 avocado farmworkers from Michoacán, Mexico, during May-August 2021. We quantified 12 pesticide metabolites in urine samples collected at two visits (12-13 weeks apart) and estimated annual exposure intensity scores (EIS) using a questionnaire-based algorithm. Blood samples were analyzed for hemoglobin (Hb), hematocrit, platelet count, white blood cell (WBC) count, and enzymatic activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and paraoxonase 1 (PON1). We assessed single-metabolite associations using multivariable linear regression with false discovery rate (FDR) correction, and mixture effects using Bayesian weighted quantile sum (BWQS) regression. In single-metabolite models, higher hydroxy-thiabendazole was associated with higher WBC count (β per 2-fold increase = 0.21; 95% CI: 0.07, 0.35), higher hydroxy-pyrimethanil was associated with lower WBC count (β per 2-fold increase = -0.14; 95% CI: -0.26, -0.02), and higher trans-DCCA (a pyrethroid metabolite) was associated with lower Hb (β per 2-fold increase = -0.24; 95% CI: -0.46, -0.01). These associations were attenuated after FDR correction. Annual EIS was not significantly associated with hematological parameters or AChE, BChE, or PON1 activities. BWQS analyses detected no significant mixture effects. Although no associations were robust to multiple-comparison correction, suggestive patterns for fungicide and pyrethroid metabolites warrant confirmation in larger studies with repeated exposure measurement and outcome monitoring.