The mercury problem and diets in the Brazilian Amazon: planning a solution

Abstract

SummaryIn order to determine whether mercury from distant goldmining affected health in the districts of lranduba and Barreirinha, Amazonas State, Brazil, mercury in the scalp hair of 101 peasants (39 males and 62 females) was determined by cold vapour atomic absorption. In both areas fish is the major source of dietary protein. The average hair mercury content was 38.6 ppm (1SD = 14.1) in Barreirinha, where the diet contains a high proportion of carnivorous fish, and 5.6 ppm (1SD = 3.1) in Iranduba, where the diet contains more herbivorous fish. The levels found in women's hair in Barreirinha are particularly critical in view of the evidence that peak maternal hair mercury levels above 70 ppm are associated with 30% of risk of neurological disorder in the offspring, and that 5% risk may be associated with a peak mercury level of 10–20 ppm in the maternal hair (WHO 1990).The health of many people, and thus forest preservation, are threatened. An environmental monitoring and health programme is urgently needed for the Brazilian Amazon. Dietary assessment could be a useful indicator of the risk of mercury poisoning, if taken together with periodic analysis of mercury contents of commonly eaten fishes and of scalp hair, particularly that of young and pregnant women. Environmental monitoring is pointless if not directed at effective action; and a planning approach to this is suggested which includes a major educational component.

Human mercury exposure and adverse health effects in the Amazon: a review

“…While the authors point to gold mining in the Upper Negro River (Colombian Amazon) as the probable source, recent biogeochemical studies have shown the important impact of naturally occurring Hg in this basin 14,61,62 , concluding that Hg leaching from soils constitutes the largest regional reservoir of this metal 14 . These findings are supported by studies analyzing environmental determinants of Hg levels in fish as well as dietary human exposure, all of which indicate that fish and human Hg levels in the Negro River Basin are strongly influenced by naturally high background Hg levels 37,63,64 . However, it is difficult to ascertain the true source of exposure (which may not be unique) for each community, and the variation in results from communities in the Negro River basin might depend upon where sampling was performed.…”

“…No matter what the environmental source, fish-eating practices are the most important predictor of Hg exposure in most areas of the Amazon, explaining a substantial proportion of the variation of total and methyl-Hg concentrations in both blood and hair. Based on these bioindicators, as well as Hg measurements in fish tissue, many studies in the Amazon have associated Hg exposure with fish consumption 4,26,27,32,33,37,39,45,46,65,66,67,68,69,70,71,72,73,74 , especially for members of fishing families 75,76,77 . These studies support the universal observation that fish consumption constitutes the most important source of Hg exposure worldwide 22,25 .…”

“…Despite general recognition of the antioxidant properties of many nutrients contained in fruits 123 , including Amazonian fruits 124,125,126,127 , this food has received little attention as a dietary factor with potential to counteract Hg exposure and/or toxicity. And yet, fruit gathering and consumption are repeatedly reported by many studies addressing Hg issues in traditional communities of the Amazon 26,33,37,128,129,130 . Fruit is a particularly important component of riparian and indigenous diets, contrary to the diet of communities occupationally exposed in the mining areas 131 .…”

Analysis of genetic susceptibility to mercury contamination evaluated through molecular biomarkers in at-risk Amazon Amerindian populations

“…In the Brazilian Amazon, mercury contamination of fish can occur as a result of both natural biogeochemical processes and gold-mining activities (Pfeiffer and Lacerda, 1988;Eve et al, 1996;Lechler et al, 2000). Human mercury contamination results primarily from fish consumption because fish not only absorb methylmercury (MeHg) from the water throughout their life but also convert inorganic Hg +2 to methylmercury through biomethylation occurring in their body.…”

Mercury and methylmercury concentration assessment in children's hair from Manaus, Amazonas state, Brazil

“…The median values for total Hg and MeHg interval (in % of total Hg) in hair samples for the Mercury and methylmercury concentration assessment in children's hair from Manaus, Amazonas State, Brazil be assumed that low income communities such as Indian and riverine populations have as their primary protein source, fish. cited that among fish consumers, riparian communities present the highest degree of exposure, with mean hair-Hg as high as 38.6 ± 14.4 mg kg -1 (Eve et al, 1996) and 65 ± 58 mg kg -1 (Leino et al, 1996). Overall, urban fish-consumers are the least exposed, presenting mean hair-Hg levels of 2.4 mg kg -1 , 2 mg kg -1 (Passos et al 2003), and 1.9 mg kg -1 (Webb et al 2004).…”