Noi clear link between mercury levels and adverse neurobehavioral effects

20/04/05 In a study of older adults, researchers did not find a definitive association between blood mercury levels, which can become elevated with fish consumption, and adverse neurobehavioral effects, according to a study to appear in JAMA.

Mercury can be found throughout the environment, and enters the air during fossil-fuel combustion, mining, smelting, and solid-waste incineration, according to background information in the article. It is converted to methylmercury by microorganisms, enters the food chain, and accumulates in predatory fish. Consumption of certain fish is the primary source of methylmercury exposure in the general population. Methylmercury distributes rapidly throughout the body and easily crosses the blood-brain barrier into the brain, where it may become trapped.

Megan Weil, M.H.S., of the Johns Hopkins Bloomberg School of Public Health, Baltimore and colleagues conducted a study to examine associations between mercury exposure and neurobehavioral outcomes in a representative sample of older adults in the United States. The research included 474 randomly selected participants in the Baltimore Memory Study, a longitudinal study of cognitive decline involving 1,140 Baltimore residents aged 50 to 70 years. Total mercury in whole blood samples was measured and the researchers used multiple linear regression to examine its associations with scores from 12 neurobehavioral tests. First-visit data were obtained in 2001-2002. Participants also completed a food frequency questionnaire to determine fish consumption levels

This work was supported by training grants from the National Institute of Environmental Health Sciences and from the National Institute of Occupational Safety and Health and a research grant from the National Institutes of Health.