MERCURY

Mercury is found in many rocks including coal. When coal is burned, mercury is released into the environment. Coal-burning power plants are the largest human-caused source of mercury emissions to the air in the United States, accounting for over 40 percent of all domestic human-caused mercury emissions. EPA has estimated that about one quarter of U.S. emissions from coal-burning power plants are deposited within the contiguous U.S. and the remainder enters the global cycle. Burning hazardous wastes, producing chlorine, breaking mercury products, and spilling mercury, as well as the improper treatment and disposal of products or wastes containing mercury, can also release it into the environment. Current estimates are that less than half of all mercury deposition within the U.S. comes from U.S. sources.

Exposure to mercury. Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methylmercury exposure to humans. Methylmercury builds up more in some types of fish and shellfish than others.The levels of methylmercury in fish and shellfish depend on what they eat, how long they live and how high they are in the food chain.

Environmental Effects

Mercury in the air may settle into water bodies and affect water quality. This airborne mercury can fall to the ground in raindrops, in dust, or simply due to gravity (known as ¡°air deposition¡±). After the mercury falls, it can end up in streams, lakes, or estuaries, where it can be transferred to methylmercury through microbial activity. Methylmercury accumulates in fish at levels that may harm the fish and the other animals that eat them. Mercury deposition in a given area depends on mercury emitted from local, regional, national, and international sources. The amount of methylmercury in fish in different waterbodies is a function of a number of factors, including the amount of mercury deposited from the atmosphere, local non-air releases of mercury, naturally occurring mercury in soils, the physical, biological, and chemical properties of different waterbodies and the age, size and types of food the fish eats. This explains why fish from lakes with similar local sources of methylmercury can have significantly different methylmercury concentrations.

Recycling and Disposal Options

Many states and local agencies have developed collection/exchange programs for mercury-containing devices, such as thermometers, manometers, and thermostats, and recycling programs for fluorescent light bulbs. Some counties and cities also have household hazardous waste collection programs. For information about these programs, contact your local officials to find out when and where a collection will be held in your area. Earth911.com also provides information about local collection programs. For compact fluorescent lights (CFLs) only, The Home Depot launched an in-store CFL recycling program (PDF) (2 pp., 32K, About PDF) at all of its store locations in June 2008.

Households are generally exempt from Resource Conservation and Recovery Act (RCRA) regulations that govern the transportation, storage and disposal of hazardous wastes that contain mercury, but small and large businesses and industries are not exempt. Their mercury wastes are governed under EPA¡¯s Land Disposal Restrictions (LDR) Program. EPA has designated some widely generated hazardous wastes, including certain spent batteries, pesticides, mercury-containing equipment and light bulbs, as "universal wastes". The regulations that govern universal wastes include special management provisions intended to facilitate the recycling of such materials. Find more information about how households and businesses can manage, recycle and dispose of fluorescents and other mercury-containing bulbs.