Methylmercury can cause harm at levels previously considered safe

[Guest guest]

Methylmercury Warning

http://www.sciencedaily.com/releases/2008/10/081028103103.htm

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.

Adapted from materials provided by Inderscience Publishers, via

EurekAlert!, a service of AAAS.

..