No effect of mercury exposure on kidney function during ongoing artisanal gold mining activities in Colombia: A cross-sectional study

This cross-sectional study examined whether people who are exposed to mercury (Hg) vapours in ongoing artisanal gold mining activities have alteration in kidney function monitoring parameters. The study enrolled 164 miners and 127 participant controls. The Hg concentrations for miners and control participants were measured in blood (B-Hg; median 7.0 vs. 2.5 μg/L), urine (U-Hg; median 3.9 vs. 1.5 μg/g creatinine) and hair (H-Hg; median 0.8 vs. 0.4 μg/g hair). The biomarkers of renal function were creatinine, albumin and excretion of β-2 microglobulin. Glomerular filtration rate (eGFR) was calculated using the chronic kidney disease epidemiology collaboration equation. Significant statistical differences were found in Hg concentrations and eGFR levels between the two study groups (p < 0.01) but not with the other biomarkers of renal function. A multiple regression model was applied to explore the relationship of eGFR levels and Hg concentrations. However, no association was found between the prevalence of reduced eGFR (<71.96 mL/min/1.73 m²) and the B-Hg or U-Hg levels after adjustment for covariates. Nevertheless, it was observed that having B-Hg levels above 10 μg Hg/L decreased the eGFR by 1.7 mL/min/1.73 m² (confidence interval 95% -'5.1 to 1.7) compared to having levels below 2.0 μg Hg/L. Our results found no support for kidney damage associated with Hg vapour exposure in ongoing artisanal gold mining, whose population has a level of Hg exposure from low to moderate (B-Hg from 3.4 to 11.0 μg/L and U-Hg from 1.3 to 9.6 μg/g creatinine).