Gold-mining activities and mercury contamination of native Amerindian communities in French Guiana: Key role of fish in dietary uptake

In 1994, the French National Public Health Network reported significant mer cury exposure of native Amerindians in French Guiana. In 1997, a study was conducted in the Wayana community to quantify the dietary intake and to ide ntify the fish species contributing the most to the contamination. The stud y was completed by an impregnation analysis based on Hg determination in ha ir samples. The methodology used was a detailed familial dietary study asso ciated with Hg measurements in fish and some game. The study was conducted over 7 days in two different seasons in the four most populated Wayana vill ages on the upper part of the Maroni River (521 people; 70% of the Wayana p opulation in French Guiana). Analysis was based on data on consumption obta ined from 165 people in a 1-14 day period (i.e., 940 persons x days) and in volved 270 fish samples from 48 species. Total Hg and monomethylmercury (MM Hg) were also determined in hair samples (235 samples for total Hg). The re sults confirm mercury exposure of the Wayana population related to a diet r ich in fish, which are relatively highly contaminated for certain species ( up to 1.62 mg/kg fresh weight or 8.1 mg/kg dry weight in skeletal muscle). Results from hair samples showed that 57% of the Amerindians had Hg levels above the World Health Organization (WHO) safety limit (10 mug/g); all thos e over 1 year of age had a Hg intake greater than the WHO safety limit (200 mug MMHg/week for a 60-kg male). Hg concentrations in fish muscle were clo sely linked to the feeding regime and position of fish in the food webs. Ov erall, 14.5% of the fish collected exceeded the 0.5 mg/kg (fresh weight) sa fety limit. Four carnivorous species accounted for no less than 72% of the metal ingested by the Wayana families, although these represented only 28% of the consumed fish biomass. In conclusion, this study revealed excessive exposure to mercury in the Wayana population in French Guiana related to th e consumption of contaminated fish.