Everyone agrees that exposure to mercury can be toxic and even lethal at high levels. Where disagreement arises is over the level of mercury considered "safe."

For most people, the risk from mercury does not appear to pose a health concern. But, just to be safe, the Environmental Protection Agency and the Food and Drug Administration recently advised "sensitive populations"—women who may become pregnant, women who are pregnant or nursing, and young children—to avoid some types of fish and to eat fish and shellfish that are lower in mercury. That's because at very high levels, mercury can adversely affect nervous system function or the development of fetuses.

Our bodies can naturally eliminate mercury. Therefore, if we are in a "non-sensitive population" and if we follow the recommended guidelines for fish consumption, occasional exposure to relatively small amounts of mercury is believed to have no effect on our health.

While most human exposure to mercury comes from fish consumption, you also should be aware that older thermometers contain liquid elemental mercury. If broken and not cleaned up properly, the mercury can get into the air and pose a health risk. A variety of mercury-free alternatives, including digital thermometers, are available at your local pharmacy. Once you have purchased a mercury-free thermometer, it is important to dispose of your old one safely—bring your mercury thermometer to your local hazardous waste collection facility, do not throw it in the garbage.

Is exposure to mercury harmful to my health?

What mercury research is still being done?

Is exposure to mercury harmful to my health?

Exposure to mercury can be toxic and lethal at high levels. But because our bodies can naturally eliminate mercury, occasional exposure to relatively small amounts of mercury, or background levels, is believed to have no effect on human health.

There is some disagreement over the level of mercury considered "safe." At certain levels, mercury is a developmental neurotoxin—that is, it can adversely affect nervous system function and the development of fetuses. Yet, there is no consensus as to what level of exposure presents a threat to public health.

The populations most sensitive to mercury exposure are pregnant women and children. According to the National Academy of Sciences (NAS), "[T]he risk of adverse effects from current methylmercury exposures in the majority of the population is low … [t]he population at highest risk is the children of the women who consumed large amounts of fish and seafood during pregnancy."¹

Recent and comprehensive research undertaken by the Centers for Disease Control and Prevention (CDC), which measured mercury in the blood of women and children, indicates that people in the United States are not being exposed to levels of mercury considered to be harmful to fetuses, children, or adults.²

In the May 17, 2003, issue of the British medical journal, The Lancet, researchers who conducted a long-term study of children in the Seychelles Islands reported that methylmercury exposure from fish consumption during pregnancy does not have a measurable effect on cognitive skills or behavior in later childhood. "For now, there is no reason for pregnant women to reduce fish consumption below current levels, which are probably safe," wrote Dr. Constantine G. Lyketsos, Johns Hopkins University Hospital, in a commentary on the Seychelles Island child development study findings.³

What mercury research is still being done?

Though current research data and information do not establish a direct link between electric utility mercury emissions and harmful mercury levels in fish for human consumption, the industry is participating with EPA, other federal agencies, and the scientific community in new and ongoing mercury research and monitoring projects aimed at further clarifying this issue. The industry is committed to pursuing scientific research that will protect human health and the environment from the harmful effects of mercury.

Much of the mercury research in the United States is being sponsored by four organizations: DOE, EPA, the Electric Power Research Institute (EPRI), and the United States Geological Survey. These organizations, in collaboration with electric utilities, are conducting research on all aspects of mercury, including: sources, movement, and chemical transformation in the environment, as well as health effects and methods to reduce emissions.

Since there is no demonstrated technology that can control mercury emissions across the entire utility industry, several alternatives for reducing mercury are being investigated. EPA and DOE both acknowledge there is a lack of key information needed to resolve many scientific uncertainties about mercury. For example, EPA admits "Given the current scientific understanding of the environmental fate and transport of this element, it is not possible to quantify with precision how much of the methylmercury in fish consumed by the U.S. population is contributed by U.S. emissions relative to other sources of mercury."⁴

Footnotes:

1. See Toxicological Effects of Methylmercury, National Resource Council, Board on Environmental Studies and Toxicology, Commission on Life Sciences, July 2000.
2. See Third National Report on Human Exposure to Environmental Chemicals, Centers for Disease Control and Prevention, National Center for Environmental Health, Pub. No. 05-0570, July 2005.
3. See "Should pregnant women avoid eating fish? Lessons from the Seychelles," The Lancet, Vol. 361: 1667-68, May 17, 2003.
4. See Proposed National Emission Standards for Hazardous Air Pollutants; and, in the Alternative, Proposed Standards of Performance for New and Existing Stationary Sources: Electric Utility Steam Generating Units; Proposed Rule, 69 Federal Register, 4652-4752.