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Environ Health Perspect. 1999 July; 107(7): 587–591.
PMCID: PMC1566671
Research Article

Methylmercury neurotoxicity in Amazonian children downstream from gold mining.


In widespread informal gold mining in the Amazon Basin, mercury is used to capture the gold particles as amalgam. Releases of mercury to the environment have resulted in the contamination of freshwater fish with methylmercury. In four comparable Amazonian communities, we examined 351 of 420 eligible children between 7 and 12 years of age. In three Tapajós villages with the highest exposures, more than 80% of 246 children had hair-mercury concentrations above 10 microg/g, a limit above which adverse effects on brain development are likely to occur. Neuropsychological tests of motor function, attention, and visuospatial performance showed decrements associated with the hair-mercury concentrations. Especially on the Santa Ana form board and the Stanford-Binet copying tests, similar associations were also apparent in the 105 children from the village with the lowest exposures, where all but two children had hair-mercury concentrations below 10 microg/g. Although average exposure levels may not have changed during recent years, prenatal exposure levels are unknown, and exact dose relationships cannot be generated from this cross-sectional study. However, the current mercury pollution seems sufficiently severe to cause adverse effects on brain development.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Malm O. Gold mining as a source of mercury exposure in the Brazilian Amazon. Environ Res. 1998 May;77(2):73–78. [PubMed]
  • Malm O, Branches FJ, Akagi H, Castro MB, Pfeiffer WC, Harada M, Bastos WR, Kato H. Mercury and methylmercury in fish and human hair from the Tapajós river basin, Brazil. Sci Total Environ. 1995 Dec 11;175(2):141–150. [PubMed]
  • Bidone ED, Castilhos ZC, Cid de Souza TM, Lacerda LD. Fish contamination and human exposure to mercury in the Tapajós River Basin, Pará State, Amazon, Brazil: a screening approach. Bull Environ Contam Toxicol. 1997 Aug;59(2):194–201. [PubMed]
  • Grandjean P, Weihe P, White RF, Debes F, Araki S, Yokoyama K, Murata K, Sørensen N, Dahl R, Jørgensen PJ. Cognitive deficit in 7-year-old children with prenatal exposure to methylmercury. Neurotoxicol Teratol. 1997 Nov-Dec;19(6):417–428. [PubMed]
  • Grandjean P, Weihe P, Nielsen JB. Methylmercury: significance of intrauterine and postnatal exposures. Clin Chem. 1994 Jul;40(7 Pt 2):1395–1400. [PubMed]
  • Pineau A, Piron M, Boiteau HL, Etourneau MJ, Guillard O. Determination of total mercury in human hair samples by cold vapor atomic absorption spectrometry. J Anal Toxicol. 1990 Jul-Aug;14(4):235–238. [PubMed]
  • Davidson PW, Myers GJ, Cox C, Axtell C, Shamlaye C, Sloane-Reeves J, Cernichiari E, Needham L, Choi A, Wang Y, et al. Effects of prenatal and postnatal methylmercury exposure from fish consumption on neurodevelopment: outcomes at 66 months of age in the Seychelles Child Development Study. JAMA. 1998 Aug 26;280(8):701–707. [PubMed]
  • From the Centers for Disease Control and Prevention. Human rabies--Virginia, 1998. JAMA. 1999 Mar 10;281(10):891–892. [PubMed]
  • Smith JC, Farris FF. Methyl mercury pharmacokinetics in man: a reevaluation. Toxicol Appl Pharmacol. 1996 Apr;137(2):245–252. [PubMed]
  • Boischio AA, Cernichiari E. Longitudinal hair mercury concentration in riverside mothers along the Upper Madeira river (Brazil). Environ Res. 1998 May;77(2):79–83. [PubMed]

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