Mercury (Hg) use in artisanal gold mining in the Colombian Amazon is widespread, and little is known about the exposure on local indigenous people. The aim of this study was to assess the levels of total Hg (T-Hg) in human hair on the Yaigojé Apaporis National Natural Park, Colombia, at the Colombian Amazon, specifically at the communities of Bocas de Taraira, Ñumi, Vista Hermosa, and Bocas de Uga. Total-Hg levels were measured using a direct mercury analyzer. The mean ± SD (min-max) of the T-Hg level in human hair volunteers was 23.0 ± 1.2 μg/g (2.6-63.7 μg/g). T-Hg concentrations increase from upstream to downstream localities, with the highest average observed at Bocas de Taraira (34.9 ± 2.4 μg/g); to the best of our knowledge, the highest value reported for an indigenous community in Latin America. Ninety-three percent of all examined individuals had T-Hg concentrations greater than the WHO "threshold" level (5 μg/g) and 86% displayed levels higher than 10 μg/g in hair. Mercury levels correlated with fish consumption frequency (r = 0.27, p = 0.008). Risk assessment analysis showed that 85.5% of the analyzed participants have a 60% chance of developing adverse neurological effects and 50% of women at reproductive age are at risk of having children with intelligence quotient reduced by up to four points. Since the consumption of carnivorous fish is the main factor for Hg exposure, it is necessary to implement strategies to reduce their presence in the diet, without undermining cultural traditions. The Colombian government must assume control of this devastating situation and immediately halt mining activities in this natural park of global importance.
Keywords: Amazon; Heavy metal; Human health; Pollution; Toxicity.