Sources of metal(loid) exposures in a cohort study of workers in El Salvador

Exposure to elements such as arsenic, cadmium, lead, and mercury, which are associated with cancer, cardiovascular disease, and kidney disease, are not well-studied in Central American populations. We evaluated differences in urine metal(loid) concentrations by dietary/behavioral, occupational, and geographic factors within a cohort of adult male workers in El Salvador. We measured spot urinary concentrations of 14 metal(loid)s and speciated arsenic in 194 participants in 2021. We compared concentrations in our study to the US National Health and Nutrition Examination Survey (NHANES) data. We used multiple linear regression to examine known metal(loid) exposure sources (e.g. smoking and seafood consumption) and the role of occupational and geographic-related predictors (e.g. industry and region) in association with urinary metal(loid) concentrations. We detected 13 of 14 metal(loid)s and all targeted biomarkers of arsenic species in participants’ urine samples, with detection frequencies ranging from 4-100%. Compared to NHANES data, MANOS participants had significantly higher (p<0.05) median concentrations (µg/L) of all arsenic species (sum of inorganic arsenic species 10 vs. 54), cobalt (0.39 vs. 0.030), and thallium (0.27 vs. 0.20), while molybdenum and uranium were significantly lower in MANOS (35 vs. 49 and 0.0035 vs. 0.75, respectively). Arsenobetaine concentrations were 140% higher (95% CI: 58, 260%) in recent seafood consumers. Among smokers, cadmium and lead were 57% (95% CI: 21, 102) and 38% higher (95% CI: 3, 85), respectively. The sum of inorganic arsenic species was 48% higher (95% CI: 24, 77), while mercury and lead were -30% (95% CI: -48, -6.4) and -43% (95% CI: -59, -22) lower in sugarcane workers compared to corn workers. Compared to participants with normal kidney function, indicated by estimated glomerular filtration rate (eGFR) >90 ml/min/1.73m 2 , participants with higher Ba, Cs, Pb, and Tl concentrations had lower kidney function, while those with higher Mn and U had higher kidney function. Findings suggest dietary, renal, and workplace factors influence some metal(loid) exposures in El Salvador. Understanding sources of metal(loid) concentrations may help identify strategies to reduce exposures and accompanying health risks.