Mercury-What are the Issues?

• Water
• Human Health
• Air
• Production, Use, and Management

• Many of California's surface water bodies contain too much mercury. The State Water Resources Control Board (SWRCB) has listed 860,000 acres of estuaries, lakes, and reservoirs and 303 miles of rivers and creeks as mercury impaired. Mercury-impaired water bodies include San Francisco Bay and Delta, Sacramento River, and Santa Monica Bay.
• Fish consumption warnings due to elevated mercury levels exist for San Francisco Bay and several lakes. Since California does not have a comprehensive fish testing program, complete data are not available. In states with comprehensive test programs (many central U.S. and New England states), widespread mercury-based fish consumption advisories have been issued. 39 states have mercury-related fish consumption warnings; in 9 of these states the warning is statewide.
• Bioaccumulation of mercury is the primary concern-mercury concentrations are higher in species that are higher in the food web. Environmental concerns include potential effects of mercury on wildlife.

Human Health

• U.S. Agency for Toxic Substances and Disease Registry (ATSDR) and U.S. EPA have issued a joint alert to the public regarding the hazards of mercury to the general public.
• Mercury can cause serious health problems. Children and fetuses are most vulnerable. Health effects can results from short-term or long-term exposure. Exposure can cause harm before symptoms arise. When symptoms do arise, health problems can include tremors, changes in vision or hearing, insomnia, weakness, difficulty with memory, headache, irritability, shyness and nervousness. In young children, exposure to metallic mercury can damage the central nervous system. Long-term mercury exposure can cause children to have trouble learning in school.
• Methylmercury compounds are the most toxic form of mercury, but other forms are also very toxic. In the environment, metallic mercury is converted to methylmercury by the action of certain types of bacteria.
• U.S. EPA considers metallic mercury to be a possible human carcinogen. Under Proposition 65, California has listed all forms of mercury as reproductive toxicants and methylmercury compounds as carcinogens.
• Exposure to metallic mercury occurs primarily from breathing contaminated air. Other forms of mercury (e.g., methyl mercury compounds) can be absorbed by eating food (like fish), drinking water, and from skin contact.
• Very small amounts of metallic mercury (e.g., a few drops) can raise air concentrations in a room to levels that may be harmful to health.
• Many serious mercury exposure incidents have occurred in homes and schools. These incidents relate to releases of metallic mercury and to religious practices involving metallic mercury ("azogue").
• Mercury releases (e.g., from breaking a thermometer or thermostat) are difficult to clean up properly. Improper cleanup can lead to ongoing, serious exposures in homes and workplaces.

Air

• Mercury is a toxic air pollutant. Air is the major pathway for local and worldwide transport of mercury. Major issue seems to be the impacts that occur upon deposition of mercury from the air onto the earth, especially into water bodies.
• The World Health Organization estimates that approximately 10,000 tons of mercury are released into air worldwide each year (from natural and manmade sources). U.S. EPA estimated U.S. releases at 160 tons per year, primarily from medical and other waste incineration, coal burning, and other incineration sources (estimate based on 1989 data).

Production, Use, and Management

• No active mercury mines exist in the U.S. Virgin mercury production is limited to byproduct production at 5 facilities where the mercury is recovered to avoid emissions to the environment.
• Mercury use is about 390 tons per year (1997 data)
• Major mercury uses include chlorine and caustic soda manufacture, switches, lighting (fluorescent lights), mercury-containing measurement and control equipment (thermometers, thermostats, manometers, etc.), laboratory uses (in reagents and equipment) and amalgam fillings.
• Mercury recycling in the U.S. (about 430 tons per year in 1997) exceeds mercury use. The remainder is stockpiled and sold overseas.
• About 200 tons per year of mercury is discharged into the municipal solid waste stream each year. Some of this mercury is released to the environment via incineration, some is placed into landfills.

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