Concentration of Mercury in Hair of Indigenous Mothers and Infants from the Amazon Basin

Abstract

Hair mercury concentration, as an indicator of mercury body load, was studied in 251 samples of indigenous women and children living in selected areas of the Amazonian region. The mothers or women of child-bearing age, either non-Indians or Indians, and their children were sampled along the Madeira River and in the Kayapó reservation (Fresco River), respectively. Among the sampled individuals there were mothers with infants less than 2 years old. Total mercury in hair was determined by cold vapor atomic absorption spectrometry after alkaline digestion. The distribution of hair mercury concentration greater than 10 microg/g occurred in 67.4% of non-Indian women and 25% of Indian women; overall only 1% of non-Indian women had concentrations of hair mercury above 50 microg/g. In women of child-bearing age, the median and range of hair mercury concentration was 14.08 microg/g, and 0.8-94.7 microg/g for non-Indians, and 8.30 microg/g, and 0.8-13.3 microg/g for Indians. The correlation between maternal hair mercury and mercury in hair of infants (less than 2 years of age) still breast-feeding, was statistically significant only for non-Indians (r = 0.555 p < 0. 001). The correlation between length of breast-feeding and mercury concentration in infant's hair was significant for Indian children (r = 0.512; p = 0.029) but not for non-Indian children (r = 0.025; p = 0.832). A subsampling of 30 mothers had segmented hair analysis that showed a mean decrease of 20% in body burden during pregnancy, thus indicating the extent of placental transference of mercury to fetuses.

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

“…Fish at the top of a food chain have the greatest accumulation of methylmercury (Barbosa et al, 1995;Shoeny, 1996;Ashner, 2002). In the Brazilian Amazon, many studies have already been carried out on riverine and Amerindian populations to investigate the health impacts of mercury exposure in different communities (Akagi et al, 1995;Barbosa et al, 1998;Boischio and Henshel, 2000;Santos et al, 2000;Dolbec et al, 2001;Dorea, 2003).…”

Losses of immunoreactive parvalbumin amacrine and immunoreactive alphaprotein kinase C bipolar cells caused by methylmercury chloride intoxication in the retina of the tropical fish Hoplias malabaricus

“…In the Amazon, gold-mining activities have caused water basin contamination with mercury, with serious consequences for the health of riverine populations, whose potential intoxication has been recently demonstrated (5)(6)(7)(8). Fish differ in the amount of methylmercury they accumulate according to their foraging characteristics.…”

Major aspects of the mercury cycle in the Negro River Basin, Amazon

“…1 After this episode, several research groups, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] have investigated this topic in different areas in the Amazon, in order to understand the sources and fate of mercury. In the Negro river basin high mercury concentrations were found in soils (average value of 170 mg kg -1 ) [3][4][5][6][7][8] and in other matrices, although the median concentration in the atmosphere was relatively low, on the order of 1.3 ng m -3 .…”

“…In the Negro River region, as a result of this process, fish and the riparian population show high mercury levels when compared to populations living close to white water rivers. 8,9,16 A broad project on the mercury cycle in the Negro river basin has been undertaken by our laboratories over a period of ten years in order to evaluate mercury concentrations in different compartments (air, water, soil, sediments, fish and humans) and from different mercury sources, trying to assess the soil function in the mercury cycle and to understand the factors that govern invasive and evasive fluxes in the air/water and air/soil interfaces. Our major contribution is to present the mercury budget in this area, based upon data collected during these last ten years, together with some new experiments, and to discuss factors affecting the mercury cycle in the Negro River basin, with emphasis on the organic matter, solar radiation, hydrogen peroxide formation, seasonality and soil function.…”