Low level methylmercury exposure affects neuropsychological function in adultsReport as inadecuate

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Environmental Health

, 2:8

First Online: 04 June 2003Received: 20 February 2003Accepted: 04 June 2003DOI: 10.1186-1476-069X-2-8

Cite this article as: Yokoo, E.M., Valente, J.G., Grattan, L. et al. Environ Health 2003 2: 8. doi:10.1186-1476-069X-2-8


BackgroundThe neurotoxic effects of methylmercury MeHg have been demonstrated in both human and animal studies. Both adult and fetal brains are susceptible to the effects of MeHg toxicity. However, the specific effects of adult exposures have been less well-documented than those of children with prenatal exposures. This is largely because few studies of MeHg exposures in adults have used sensitive neurological endpoints. The present study reports on the results of neuropsychological testing and hair mercury concentrations in adults >17 yrs living in fishing communities of Baixada Cuiabana Mato Grosso in the Pantanal region of Brazil.

MethodsA cross-sectional study was conducted in six villages on the Cuiaba River. Participants included 129 men and women older than 17 years of age. They were randomly selected in proportion to the age range and number of inhabitants in each village. Questionnaire information was collected on demographic variables, including education, occupation, and residence history. Mercury exposure was determined by analysis of hair using flameless atomic absorption spectrophotometry. The neurocognitive screening battery included tests from the Wechsler Memory Scale and the Wechsler Adult Intelligence Scale, Concentrated Attention Test of the Toulouse-Pierron Factorial Battery, the Manual Ability Subtests of the Tests of Mechanical Ability, and the Profile of Mood States.

ResultsMercury exposures in this population were associated with fish consumption. The hair mercury concentration in the 129 subjects ranged from 0.56 to 13.6 μg-g; the mean concentration was 4.2 ± 2.4 micrograms-g and the median was 3.7 μg-g. Hair mercury levels were associated with detectable alterations in performance on tests of fine motor speed and dexterity, and concentration. Some aspects of verbal learning and memory were also disrupted by mercury exposure. The magnitude of the effects increased with hair mercury concentration, consistent with a dose-dependent effect.

ConclusionsThis study suggests that adults exposed to MeHg may be at risk for deficits in neurocognitive function. The functions disrupted in adults, namely attention, fine-motor function and verbal memory, are similar to some of those previously reported in children with prenatal exposures.



WHOWorld Health Organization

ORodds ratio

TAMTests of Mechanical Ability

POMSProfile of Mood States

CEPACentro de Psicologica Aplicada

Electronic supplementary materialThe online version of this article doi:10.1186-1476-069X-2-8 contains supplementary material, which is available to authorized users.

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Author: Edna M Yokoo - Joaquim G Valente - Lynn Grattan - Sérgio Luís Schmidt - Illeane Platt - Ellen K Silbergeld

Source: https://link.springer.com/

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