Methylmercury article

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Methylmercury Warning

ScienceDaily (Oct. 30, 2008) — Recent studies hint that exposure to

the toxic chemicals, such as methylmercury can cause harm at levels

previously considered safe. A new analysis of the epidemiological

evidence in the International Journal of Environment and Health,

suggests that we should take a precautionary approach to this and

similar compounds to protect unborn children from irreversible brain

damage.

Philippe Grandjean of the Department of Environmental Health at

Harvard School of Public Health, in Boston, and the University of

Southern Denmark in Odense, explains that the causes of suboptimal

and abnormal mental development are mostly unknown. However, severe

exposure to pollutants during the development of the growing fetus

can cause problems that become apparent as brain functions develop -

and ultimately decline - in later life. Critically, much smaller

doses of chemicals, such as the neurotoxic compound methylmercury,

can harm the developing brain to a much greater extent than the

adult brain.

Methylmercury is a chemical compound formed in the environment from

released mercury. Unfortunately, the methylmercury can be

transported quickly around the body and may enter the brain. Serious

problems will ensue if important developmental processes are blocked

as there will be only one chance for the brain to develop.

The researchers point out that until recently research into the

effects of pollutants on the brain has been clouded by the lack of

information on actual exposure. Moreover, finding a direct link

between specific problems with the brain and exposure relies on

statistical, or epidemiological, analysis rather than case-by-case

understanding. The researchers say that neurodevelopmental disorders

of possible environmental origin affect between 5% and 10% of babies

born worldwide, leading to dyslexia, mental retardation, attention

deficit/hyperactivity disorder, cerebral palsy, and autism.

The toxicity of methylmercury is well known, but the researchers

believe that the medical world has underestimated the risk of brain

damage associated with exposure to this compound as well as numerous

others. Professor Grandjean emphasizes that little research has been

carried out into the effects of other neurotoxic chemicals.

" Until there is enough evidence to rule out effects of certain

chemicals on the developing nervous system, a cautious approach

would involve strict regulation of suspected developmental

neurotoxicants and prudent counseling of expectant mothers regarding

exposures to untested substances, " the researchers conclude.