Mercury exposure in French Guiana: levels and determinants

Mercury is used widely for gold extraction in French Guiana and throughout the entire Amazon basin. To evaluate contamination among the general population, the authors chose individuals who attended 13 health centers and maternity hospitals dispersed geographically across the territory and served Guiana's different populations. Five hundred individuals (109 pregnant women, 255 "other" adults, and 136 children) who received care at one of the centers were selected randomly for this study. Each individual answered a questionnaire and provided a hair sample. The authors determined mercury in hair with atomic absorption spectrometry. The following mean levels of mercury were observed: 1.6 microg/g (95% confidence interval [CI]=1.3, 1.9) among pregnant women; 3.4 microg/g (95% CI=3.0, 3.9) among other adults; and 2.5 microg/g (95% CI=2.1, 3.0) among children. Diet factors contributed the most to mercury levels, especially consumption of freshwater fish (mean=6.7 microg/g for individuals who ate fish more than 5 times/wk) and livers from game. Other factors, including age, dental amalgams, use of skin-lightening cosmetics, and residence near a gold-mining community, did not contribute significantly to mercury levels. Overall, 12% of the samples contained mercury levels in excess of 10 microg/g, but in some Amerindian communities up to 79% of the children had hair mercury levels that exceeded 10 microg/g. The results of this study indicated that (a) diet played a predominant role in total mercury burden, and (b) in some communities, mercury contamination exceeded safe levels.