Exposure to organic mercury (methylmercury) occurs almost universally due to ingestion via
contaminated fish and shellfish tissue. Ultimate sources of mercury consist of air release by domestic
industrial combustion, mining, and international mercury emissions transported via a global cycle.
Deposition of mercury from air to surface waters results in methylation to organic methylmercury and
bioaccumulation in the aquatic food web.
Health effects from methylmercury exposure consist mainly of neurological and
neurodevelopmental effects, with fetuses particularly sensitive. Thus regulation of methylmercury
exposure has concentrated on acceptable exposure levels and reference doses aimed toward protecting
developing fetuses.
The risk of methylmercury exposure in humans is regulated largely by the federal government,
especially by the Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA). The EPA imposes limits on mercury emissions and seeks to research methylmercury levels in fish and humans. The EPA sets a reference dose for methylmercury exposure. The FDA conducts uses date on methylmercury levels in fish to advise consumers on how to make informed decisions regarding fish consumption.
There are numerous shortcoming to government regulation of this issue. Further scientific
research, improved implementation of available data and scientific conclusions, and improved public
communication of risk would all lead to more effective treatment of the risk of methylmercury
exposure via ingestion of fish and shellfish. This could include more effective monitoring systems of
human and fish methylmercury levels, research into the process of bioaccumulation, and
implementation of stricter fish labeling standards, as well as research into higher-risk subpopulations
allowing for targeted standards and recommendations.
Cognitive deficits and changes in gene expression of NMDA receptors after prenatal methylmercury exposure.
