Increase of the background human exposure to mercury through fish consumption due to gold mining at the Tapajós River Region, Pará State, Amazon

Abstract

Methylmercury (MeHg) is a well know human neurotoxic substance (Clarkson 1994; Watanabe and Satoh 1996). It is listed by the International Program of Chemical Safety (IPCS) as one of the six most dangerous chemicals in the world’s environment. The general population is primarily exposed to MeHg through fish consumption. Over 90% of Hg present in fish from the Tapajós river basin is MeHg (Akagi et al. 1994) although the source is usually inorganic Hg. In Brazilian gold mining (“garimpos”), elemental Hg0 (metallic) is used to amalgamate the fine particles of gold. About 3,000t of Hg has been released by “garimpos” between 1987 and 1994 into the Brazilian Amazon (Lacerda 1997). Approximately half of this total came from “garimpos” in the Tapajós river basin (Cid de Souza and Bidone 1994). [...]