Neurotoxic effects of low-level methylmercury contamination in the Amazonian basin

Journal Article · Thu Oct 01 04:00:00 EDT 1998 · Environmental Research

DOI:https://doi.org/10.1006/enrs.1998.3846· OSTI ID:653166

Lebel, J; Mergler, D; Lucotte, M; Larribe, F; Dolbec, J ^[1]; Branches, F ^[2]; Amorim, M ^[3]

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1. Univ. du Quebec, Montreal, Quebec (Canada)
2. Santarem, Para (Brazil)
3. Univ. Federal do Para (Brazil). Cytogenetic Lab.

Many studies have demonstrated mercury contamination in the Amazonian ecosystem, particularly in fish, a dietary mainstay of populations in this region. The present study focused on potential health effects of this low-level methylmercury exposure. The study was carried out in a village on the Tapajos River, a tributary of the Amazon, on 91 adults inhabitants whose hair mercury levels were inferior to 50 {micro}/g. Performance on a neurofunctional test battery and clinical manifestations of nervous system dysfunction were examined in relation to hair mercury concentrations. Near visual contrast sensitivity and manual dexterity, adjusted for age, decreased significantly with hair mercury levels (P < 0.05), while there was a tendency for muscular fatigue to increase and muscular strength to decrease in women. For the most part, clinical examinations were normal, however, hair mercury levels were significantly higher (P < 0.05) for persons who presented disorganized movements on an alternating movement task and for persons with restricted visual fields. These results suggest dose-dependent nervous system alterations at hair mercury levels below 50 {micro}g/g, previously considered a threshold for clinical effects. The profile of dysfunction in this adult population is consistent with the current knowledge on methylmercury poisoning. The long-term implications of these findings are unknown and need to be addressed.

• OSTI ID: 653166
• Journal Information: Environmental Research, Journal Name: Environmental Research Journal Issue: 1 Vol. 79; ISSN ENVRAL; ISSN 0013-9351
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
AMAZON RIVER
BRAZIL
FISHES
FOOD CHAINS
METHYLMERCURY
NERVOUS SYSTEM DISEASES
TOXICITY
WATER POLLUTION