Environmental metal exposures and kidney function of Guatemalan sugarcane workers

Background Exposure to environmental metals can cause nephrotoxicity. There is an international epidemic of chronic kidney disease of unknown cause (CKDu). Whether metal exposures contribute to kidney dysfunction in populations at risk for CKDu remains unresolved. Objective Urinary metals (arsenic, cadmium, nickel, and uranium) were examined in 222 sugarcane cutters in Guatemala at three time points over 1 year. Methods We explored the relationships between metal concentrations and markers of kidney function using multivariable linear mixed-effect models. Results Arsenic, cadmium, and nickel were detected in the majority of the 340 urine samples and were generally within limits previously considered to be nonnephrotoxic. Nevertheless, higher urine cadmium was inversely associated with estimated glomerular filtration rate (eGFR) (β: −4.23, 95% confidence interval [CI]: −6.92, −1.54) and positively associated with neutrophil gelatinase-associated lipocalin (NGAL) (β: 2.92, 95% CI: 1.20, 4.64). Higher urine arsenic was also inversely associated with eGFR (β: −4.36, 95% CI: −7.07, −1.64). Significance Our findings suggest that exposures to metals, including cadmium and arsenic, might contribute to kidney toxicity seen in workers at risk for CKDu. These findings are consistent with the potential for metal nephrotoxicity at lower than expected levels in the setting of manual work in a very hot environment.