Longitudinal Nephrotoxic Metal Exposure in a Cohort of Farm Workers in Sonora, Mexico

Metal exposure among farmworkers along the US-Mexico border is understudied, despite links between certain metals and kidney injury or disease. We assessed seasonal metal exposure in agricultural workers in Sonora, Mexico, compared to office workers and other populations. Adult male agricultural and office workers provided urine samples and demographic data at the start and end of the work season. Urine was analyzed for specific gravity, creatinine, and metal(loid) concentrations. Agricultural workers had significantly higher urinary arsenic, lead, nickel, and uranium than office workers. Uranium increased over time, while arsenic, lead, and nickel declined. Urinary metal levels exceeded those in NHANES Mexican Americans, with cadmium levels similar to other farmworker populations but higher arsenic and uranium. Findings enhance understanding of regional exposure, support global farmworker comparisons, and inform exposure modeling, mitigation strategies, and policy.