CHILDREN’S ENVIRONMENTAL HEALTH NETWORK
Mercury occurs in the environment in a number of forms, of which methylmercury is of greatest consequence to the health of children. Methylmercury is a potent developmental neurotoxicant. Human exposure to methylmercury, especially for infants, children and pregnant women, is a grave concern. Methylmercury interferes with brain development and more easily passes into the brains of fetuses and young children than into those of adults. Methylmercury exposure also is linked to kidney and immune system toxicity.
In July 2000, the National Academy of Sciences (NAS) published a comprehensive assessment on methylmercury that provided the best assessment to date of mercury’s risk. It estimated that each year more than 60,000 children are born at risk for neurodevelopmental problems associated with in-utero mercury exposure. The NAS recommended that every effort should be made to reduce the release of mercury into the environment.
Most environmental releases of mercury are in elemental or inorganic forms, which also are very toxic. Mercury in its pure form is a silvery liquid at room temperature that readily volatilizes and can traverse the globe long distances once it is released into the air. Once in the environment, any form of mercury can enter the food chain when microbes transform it into methylmercury, which in turn bioaccumulates up the food chain. This process is seen especially in aquatic environments. Extremely small amounts of mercury released into the environment can have devastating effects.
Methylmercury-contaminated fish are the most common and serious route of exposure. Currently, 42 states have issued consumption advisories for recreationally caught fish and 10 states have also issued advisories for commercially caught fish. Of particular concern is exposure to women who are or may become pregnant, as well as exposure to very young children. The Centers for Disease Control and Prevention has reported that blood mercury levels in young children (1-5) are within the range of safety, however, a large number of women of childbearing age have mercury levels that are above the “safe” level identified by the NAS.
The EPA estimates that the largest source of mercury found in fresh water fish is mercury emissions from coal-fired power plants.
The U.S. should establish a coordinated governmental effort that has the objective of decreasing the release of mercury into the environment, now and in the future, to the extent feasible. Such an effort will need to take a number of approaches, including:
1. Reducing inadvertent emissions of mercury due to combustion sources. Any regime for controlling mercury releases from combustion, including proposals for trading systems, needs to assure not only a substantial national reduction but also that no communities are unfairly impacted by localized mercury pollution. Any new initiatives must not weaken the mercury reductions required to comply with existing law.
Example: Mercury emissions from coal-fired power plants should be curtailed. In the 107th Congress, S. 556, the Clean Power Act of 2001, would have reduced emissions of mercury and other toxic pollutants from electric power plants.
2. Substituting mercury with safer materials in industrial processes and commercial products. Wherever possible, alternatives to mercury in business and consumer products should be used and government should encourage and support such actions.
Example 1: The chemical industry has committed to a phase out of the chloralkalai process (for producing chlorine) in the US. This process was formerly the top mercury emitter in the US.
Example 2: Numerous medical centers and hospitals have undertaken voluntary efforts to phase out mercury use and exposures. In the 107th Congress, S. 351, the Mercury Reduction Act of 2002, would have reduced the mercury released into the environment through activities such as thermometer exchange programs. The bill was unanimously adopted by the Senate.
3. Mercury must be handled, stored and disposed of properly. In this regard, it is critical the EPA develop RCRA-approved methods of disposing of mercury.
Example: Current EPA waste disposal regulations encourage the recovery and reuse of the mercury rather than its disposal; however, most uses of mercury will eventually result in additional releases to the environment.
4. Individuals, families and communities should be informed about their potential exposure to mercury. Facilities that use, store or release mercury into the environment should be required to inform the public. Public education about proper clean-up is required.
Example 1: Even small mercury spills require specialists. Improper clean-up of a mercury release, such as vacuuming up the mercury from a broken thermometer, will spread the mercury into the air. People need to know how to clean up and dispose of the existing mercury that is in households, schools, and workplaces.
Example 2: Due to the extremely deleterious effects of mercury exposure to children, the levels of mercury released by power plants should be reported to those who live near such plants.
Example 3: The sprinkling of mercury in dwellings and other places for ritualistic purposes can expose current and future occupants to mercury.
5. The nation needs to undertake systematic monitoring of mercury in fish and in people. People need to be protected from consuming mercury contaminated fish. We need to continue to follow trends of mercury exposure in the population. Additionally, we must monitor mercury exposure to the fetus by monitoring maternal levels and we need data on mercury levels in more highly exposed people (e.g., recreational fishers and their families.)
Example: Many states and the EPA have had significant efforts to monitor mercury levels in fish and to provide advice to sports fishers. These efforts need to be expanded to include all of the states and to be more comprehensive.
6. The FDA needs to strengthen its role regarding mercury in a number of respects, such as:
(a) the FDA should adopt the NAS standard for safety of methylmercury in fish with special attention to the risk to the fetus due to maternal exposure (recognizing that this could require expanding the numbers of fish species for which FDA would issue warnings to the public); and
(b) the FDA needs to clearly support the efforts of the states and EPA to provide consumers with good information about the risks of consuming fish caught in mercury-contaminated areas.
Goldman, L. R. and M. W. Shannon (2001). “Technical report: mercury in the environment: implications for pediatricians.” Pediatrics 108(1): 197-205.
National Research Council (2000). Toxicological Effects of Methylmercury. Washington, DC, National Academies Press.
Agency for Toxic Substances and Disease Registry. Mercury Fact Sheet, US Department of Health and Human Services, Public Health Service, September 1995.
Centers for Disease Control and Prevention (2003). Second National Report on Human Exposure to Environmental Chemicals. Atlanta, CDC.
American Academy of Pediatrics, Handbook of Pediatric Environmental Health, 1999, p. 152