The Price of Gold: Mercury Exposure in the Amazonian Rain Forest

Abstract

Concern has surfaced over the recent discovery of human mercury exposure throughout the tropical rain forest of South America's Amazon River Basin. The probable source of mercury has been traced to gold mines located within the interior. The mining process involves the extraction of gold from ore by burning off a mercury additive, resulting in vaporization of elemental mercury into the surrounding environment. The purpose of this case series is to document mercury levels in miners and local villagers presenting with a history of exposure, or signs and symptoms consistent with mercury toxicity. Over a five year period (1986-91), the whole blood and urine mercury levels of 55 Brazilian patients demonstrating signs and symptoms consistent with mercury exposure were collected. Thirty-three (60%) of the subjects had direct occupational exposure to mercury via gold mining and refining. Whole blood mercury levels ranged from 0.4-13.0 micrograms/dL (mean 3.05 micrograms/dL). Spot urine levels ranged 0-151 micrograms/L (mean = 32.7 micrograms/L). Occupational mercury exposure is occurring in the Amazon River Basin. Interventions aimed at altering the gold mining process while protecting the workers and surrounding villagers from the source of exposure are essential. The impact of the gold mining industry on general environmental contamination has not been investigated.

Mercury exposure and malaria prevalence among gold miners in Pará, Brazil

“…These data are consistent with reports by others on occupational exposures to mercury in artisanal gold mining in Amazônia. Branches et al (1993) 5 reported somewhat lower exposures among goldmines in Pará in 1993; a similar range of nonspecific symptoms were also reported in these subjects, as well as signs of neurological dysfunction by clinical examination. We are unaware of any cases of clinical mercury poisoning having been reported in the published literature in gold miners in Pará to date.…”

Correlation between blood mercury levels in mothers and newborns in Itaituba, Pará State, Brazil

“…The first study on clinical signs and symptoms emphasized prospectors, gold shop workers, and riverside communities in the Tapajós Basin, with the first reports of suspected cases of mercury poisoning between 1986 and 1991 10 . The study assessed Hg levels in blood and urine samples and included motor coordination tests.…”

Compostos de mercúrio. Revisão de métodos de determinação, tratamento e descarte

“…No sangue, o mercúrio é oxidado pelos eritrócitos (células vermelhas do sangue) e, uma vez oxidado, o íon Hg 2+ é rapidamente distribuído pelo corpo através do sangue, podendo se ligar também à albumina e à hemoglobina 1 . Os principais sintomas associados à toxicidade por exposição ao mercúrio incluem tremor, vertigem, entorpecimento, dor de cabeça, cãibra, fraqueza, depressão, distúrbios visuais, dispnéia, tosse, inflamações gastrointestinais, queda de cabelo, naúsea e vômitos 1,17 .…”