Health Effects of Exposures to Mercury
- The form of mercury (for example, methylmercury or elemental (metallic) mercury);
- The amount of mercury in the exposure;
- The age of the person exposed (unborn infants are the most vulnerable);
- How long the exposure lasts;
- How the person is exposed -- breathing, eating, skin contact, etc.; and
- The health of the person exposed.
Note on Mercury and Cancer: No human data currently ties mercury exposure to cancer, but the data available are limited. In very high doses, some forms of mercury have caused increases in several types of tumors in rats and mice. When EPA published its Cancer Guidelines in 2005, the Agency concluded that environmental exposures to inorganic mercury and methylmercury are not likely to cause cancer in humans. Technical information about mercury and cancer is available in:
- Volume V of the 1997 Mercury Study Report to Congress; and
- IRIS Chemical Assessment Summaries for elemental mercury (PDF) and methylmercury (PDF).
Methylmercury
Effects on People of All Ages
Exposure to methylmercury most commonly occurs when people eat kinds of fish and shellfish that have high levels of methylmercury in their tissues. Almost all people have at least small amounts of methylmercury in their bodies, reflecting the widespread presence of methylmercury in the environment. U.S. Centers for Disease Control and Prevention (CDC) data show that most people have blood mercury levels below levels associated with possible health effects. Methylmercury, however, is a powerful neurotoxin, and people exposed to high levels may experience adverse health effects. If you are concerned about your exposure to methylmercury, you should consult your physician.
- Loss of peripheral vision;
- "Pins and needles" feelings, usually in the hands, feet, and around the mouth;
- Lack of coordination of movements;
- Impairment of speech, hearing, walking; and/or
- Muscle weakness
Effects on Infants and Children
Additional Resources
- Guidelines for eating fish that contain mercury
- How people are most commonly exposed to methylmercury
- Technical summary of risk assessment for methylmercury in EPA's IRIS database
Elemental (Metallic) Mercury
Exposures to metallic mercury most often occur when metallic mercury is spilled, or when products that contain metallic mercury break, so that mercury is exposed to the air. If you are concerned about your exposure to metallic mercury, you should consult your physician.
- Tremors;
- Emotional changes (such as mood swings, irritability, nervousness, excessive shyness);
- Insomnia;
- Neuromuscular changes (such as weakness, muscle atrophy, twitching);
- Headaches;
- Disturbances in sensations;
- Changes in nerve responses; and/or
- Poor performance on tests of mental function.
Higher exposures may also cause kidney effects, respiratory failure and death.
Note that metallic mercury vapor is not the same as methylmercury.
Additional Resources
- How people are most commonly exposed to elemental (metallic) mercury
- Technical summary of risk assessment for elemental mercury in EPA's IRIS database
Other Mercury Compounds
- Skin rashes and dermatitis;
- Mood swings;
- Memory loss;
- Mental disturbances; and/or
- Muscle weakness.
Some people who drink water containing inorganic mercury substantially in excess of the maximum contaminant level (MCL)The highest level of a contaminant that EPA allows in drinking water. MCLs ensure that drinking water does not pose either a short-term or long-term health risk. EPA sets MCLs at levels that are economically and technologically feasible. Some states set MCLs which are more strict than EPA's. for many years could experience kidney damage. If you are concerned about an exposure to inorganic mercury, you should consult your physician.