by James J. Galligan, Ph.D., Associate Chair,
Department of Pharmacology and Toxicology

Anyone who has fished for walleye and beached their boat on a lakeshore to pan fry the freshly caught fish for lunch, knows – that if there is a heaven – this is it.

However, disturbing news has been provided by the results of a recent United States Geological Survey study revealing a very high incidence of mercury in fish caught in streams and lakes throughout the United States (http://www.doi.gov/news/09_News_Releases/081909.html).  Mercury is a neurotoxin.  More specifically, methylmercury is a neurotoxin.  Mercury gets into lakes and streams from a number of sources but emissions from coal-fired power plants is a major source.  Once mercury is deposited in lakes and streams, it is converted into methylmercury by bacteria living in the water and sediments.  Methylmercury is then passed up the food chain where it can accumulate in predatory fish, like walleye.  This bioaccumulation is potentially hazardous to anything or anyone that consumes predators at the top of the food chain.

Why do we care?  Well, methylmercury has numerous effects on the developing and mature nervous system of mammals, including humans.  Methylmercury disrupts signals between nerve cells in the brain leading to movement disorders, memory loss and perhaps permanent nerve cell damage.  Methylmercury also disrupts the normal development of the nervous system in young animals and children.  Methylmercury is also very fat soluble so it can accumulate in tissues and stay there for a very long time.

The Department of Pharmacology and Toxicology at Michigan State University is home to two of the world’s experts on the effects of methylmercury on the mature and developing nervous system.  Dr. Yukun Yuan has been studying the consequences of early methylmercury exposure on the developing nervous system, while Dr. Bill Atchison has identified many of the major targets for methylmercury poisoning in the adult nervous system.

I am one of those who think that pan fried walleye on the lakeshore is as good as it gets.  However, I may have to begin to revise my ideas of what heaven might look like.

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