Does Methylmercury Have a Role in Developmental Disabilities in Children?

The Scientific Paper:

Does Methylmercury Have a Role in Developmental Disabilities in Children? G. J. Myers and P. W. Davidson. Environmental Health Perspectives Supplements Vol. 108, No. S3. pp. 413-420. 2000.

Review This Scientific Paper’s Abstract:
http://ehp.niehs.nih.gov/docs/2000/suppl-3/413-420myers/abstract.html

The Purpose of this Study:
These scientists review the data available in 2000 that associates methylmercury exposure with bad effects on human development. They also list some of the unanswered questions in methylmercury research

Some Background, Methods, Results, Caveats, and Other Select Points:

• This peer-reviewed, scientific paper was published in 2000.
  
• Methylmercury is present in all fresh and saltwater fish and in other seafoods.
  
• This scientific paper is based on a presentation at the 20th Rochester Conference on Environmental Toxicity titled “The Role of Environmental Neurotoxicants in Developmental Disabilities” held 23-25 September 1998 in Rochester, New York.
  
• Various public health agencies have tried to determine the risk to the general population of methylmercury exposure by eating contaminated foods.
  
• In 1972, the World Health Organization established a tolerable weekly intake (TWI) of methylmercury in the diet. This tolerable weekly intake (TWI) is based on scientific data from the very large, accidental methylmercury poisoning that happened many years ago in Minamata Japan.
  
• Our Environmental Protection Agency subsequently reevaluated the available data and proposed that their methylmercury reference dose be lowered. This lowering was based primarily on data from a large accidental methylmercury poisoning of people several years ago in Iraq.
  
• The Agency for Toxic Substances and Disease Registry (ATSDR, a part of the Department of Health and Human Services or DHHS) reevaluated its methylmercury chemical data profile of methylmercury exposure after reviewing data from studies in the Faroe Island and in the Seychelles Islands. Based primarily on the Seychelles islands study data, the Agency for Toxic Substances and Disease Registry (ATSDR) investigators recommended that a methylmercury minimal risk level.
  
• These various and different federal government regulatory limits of the levels of methylmercury that are believed (by various, credible, learned scientists) to be safe for people to eat appear to result from the different scientific studies on which these various and different federal government regulatory limits of the levels of methylmercury are based, the uncertainty or safety factor(s) that each federal regulatory agency believes is most appropriate to use, and the differences in various scientific definitions: 1) the methylmercury reference dose; 2) the methylmercury; 3) the methylmercury minimal risk level; and 4) the methylmercury tolerable weekly intake.
  
• Certain scientific studies of human populations who regularly eat large amounts of certain types of fish are very difficult to properly perform. It is difficult to compare one of these scientific studies with another of these scientific studies. This is because at least in part because of differences in the people participating in these studies, what results are actually measured in these studies, the type of statistics used to analyze these studies, and other factors.
  

A Bottom Line:
These two scientists believe in 2000 that methylmercury exposure does not have a role in developmental disabilities in children.

Important issues that these two scientist believe need resolving:

• How should methylmercury levels be measured?
• Do short periods of exposure to high methylmercury levels (peak methylmercury exposures) or does the average exposure to methylmercury levels (over time) more accurately indicate human brain methylmercury exposure?
• Should the thing that scientists look for in recent high-level and chronic methylmercury exposures be different?
• Do dietary exposure top-of-the-low doses of methylmercury differ from high methylmercury dose exposure?
• What is the importance of methylmercury exposures at different ages?
• How should scientific studies deal with simultaneous methylmercury exposures?
• Are animal and human methylmercury exposures comparable?
• How important is effect modification?
• How should child development be evaluated?
• What are the problems in conducting statistical analyses?

Find This Scientific Paper for Your Review:
Does Methylmercury Have a Role in Developmental Disabilities in Children? Environmental Health Perspectives Supplements Vol. 108, No. S3. pp. 413-420. 2000.