A population-based mercury exposure assessment near an artisanal and small-scale gold mining site in the Peruvian Amazon.

Human exposure to mercury is a leading public health problem. Artisanal and small-scale gold mining (ASGM) is a major source of global mercury emissions. Although occupational mercury exposure to miners (via mercury vapor inhalation) is known, chronic mercury exposure to nearby residents that are not miners (via mercury-contaminated fish consumption) is poorly characterized. We conducted a population-based mercury exposure assessment in 23 communities (19 rural, 4 urban) around the Amarakaeri Communal Reserve, which is bordered on the east by heavy ASGM activity. We measured total mercury in hair (N = 2083) and blood (N = 476) from March-June 2015 and performed follow-up measurements (N = 723 hair and N = 290 blood) from February-April 2016. Mercury exposure risk was highest in communities classified as indigenous, or native, regardless of proximity to mining activity. Residence in a native community (vs. non-native) was associated with mercury levels 1.9 times higher in hair (median native 3.5 ppm vs. median non-native 1.4 ppm total mercury) and 1.6 times higher in blood (median native 7.4 ng/mL vs median non-native 3.2 ng/mL total mercury). Unexpectedly, proximity to mining was not associated with exposure risk. These findings challenge common assumptions about mercury exposure patterns and emphasize the importance of population-representative studies to identify high risk sub-populations.

Hair Mercury Level is Associated with Anemia and Micronutrient Status in Children Living Near Artisanal and Small-Scale Gold Mining in the Peruvian Amazon.

Anemia has been widely studied in global health contexts because of severe nutritional deficiency, and more recently, inflammatory status, but chemical exposures are rarely considered. Until recently, "anemia" was used synonymously with "iron deficiency anemia (IDA)" in global health settings. However, only 50% of anemia cases worldwide are IDA. Environmental toxicology studies of anemia risk have generally focused on populations in developed countries, albeit with high exposure to environmental toxicants, such as lead or cadmium. In the developing world, toxicant exposures commonly coexist with other risk factors for anemia. In particular, artisanal and small-scale gold mining (ASGM) communities are at risk for dietary methylmercury exposure through contaminated fish consumption, and for anemia due to food insecurity and infectious and chronic diseases. Here, we report analysis of total hair mercury content, hemoglobin, and serum micronutrient levels in children < 12 years of age (N = 83) near ASGM in the Peruvian Amazon. Forty-nine percent (N = 29/59) of those aged < 5 years were anemic (< 11 g/dL) and 52% (N = 12/23) of those aged 5-11 years (< 11.5 g/dL). Few children were stunted, wasted, or micronutrient deficient. Median total hair mercury was 1.18 µg/g (range: 0.06-9.70 µg/g). We found an inverse association between total mercury and hemoglobin (ß = -0.12 g/dL, P = 0.06) that persisted (ß = -0.14 g/dL, P = 0.04) after adjusting for age, sex, anthropometrics, and vitamin B12 in multivariate regression. This study provides preliminary evidence that methylmercury exposure is associated with anemia, which is especially relevant to children living near ASGM.