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Philippe Grandjean,^1,2 Roberta F. White,^1,2 Anne Nielsen,¹ David Cleary,³ and Elisabeth C. de Oliveira Santos⁴

¹Department of Environmental Medicine, Odense University, Odense, Denmark; ²Departments of Environmental Health and Neurology, Boston University Schools of Medicine and Public Health, Boston, Massachusetts, USA; ³IC Consultants Ltd., Imperial College, London, United Kingdom; ⁴Instituto Evandro Chagas, Universidad Federal do Pará, Belém, Brazil

Abstract

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 µg/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 µg/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. Key words: environmental pollution, exposure assessment, food contamination, hair analysis, mercury poisoning, neuropsychological tests, prenatal exposure delayed effects. Environ Health Perspect 107:587-591 (1999) . [Online 14 June 1999]

http://ehpnet1.niehs.nih.gov/docs/1999/107p587-591grandjean/ abstract.html

Address correspondence to P. Grandjean, Institute of Public Health, Winslowparken 17, 5000 Odense, Denmark. Telephone: 45 65 57 37 69. Fax: 45 65 91 14 58. E-mail: p.grandjean@winsloew.ou.dk

This study was supported by the DG-1 Tropical Forest Programme (B7-6201) of the European Commission, by Imperial College Consultants, London, and by the Danish Medical Research Council.

Received 9 November 1998 ; accepted 22 March 1999.