Forms of mercury. Mercury is a naturally occurring element that is found in air, water and soil. It exists in several forms: elemental
or metallic mercury, inorganic mercury compounds, and organic mercury compounds. More information
Sources of mercury. Mercury is an element in the earth's crust. Humans cannot create or destroy mercury. Pure mercury is a liquid
metal, sometimes referred to as quicksilver that volatizes readily. It has traditionally been used to make products like thermometers,
switches, and some light bulbs.
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 50 percent of all domestic human-caused
mercury emissions (Source: 2005 National Emissions Inventory).
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.
Sources of mercury compounds. In the U.S., mercury compounds are manufactured in small amounts for specialty uses, such as chemical
and pharmaceutical applications. Larger quantities of these compounds are generated as byproducts from pollution control activities
at gold mines or in waste. Elemental mercury is processed in the U.S. from byproduct mercury compounds, and an unknown quantity of
mercury compounds is imported into the United States for conversion to elemental mercury. Learn more about mercury compounds (PDF).
(123 pp, 738K, About PDF)
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.
EPA works with the U.S. Food and Drug Administration (FDA) and with states and tribes to issue advice to women who may become
pregnant, pregnant women, nursing mothers and parents of young children about how often they should eat certain types of
commercially-caught fish and shellfish. Fish advisories are also issued for men, women, and children of all ages when appropriate.
In addition, EPA releases an annual summary of information on locally-issued fish advisories and safe-eating guidelines to the
public. Fish is a beneficial part of the diet, so EPA & FDA encourage people to continue to eat fish that are low in methylmercury. More information
Another less common exposure to mercury that can be a concern is breathing mercury vapor. These exposures can occur when elemental
mercury or products that contain elemental mercury break and release mercury to the air, particularly in warm or poorly-ventilated
indoor spaces. More information
Health effects of mercury. Mercury exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people
of all ages. Research shows that most people's fish consumption does not cause a health concern. However, it has been demonstrated
that high levels of methylmercury in the bloodstream of unborn babies and young children may harm the developing nervous system,
making the child less able to think and learn. More information
Ecological effects of mercury. Birds and mammals that eat fish are more exposed to mercury than other animals in water ecosystems.
Similarly, predators that eat fish-eating animals may be highly exposed. At high levels of exposure, methylmercury's harmful
effects on these animals include death, reduced reproduction, slower growth and development, and abnormal behavior. More information
Reducing mercury releases. EPA issues regulations that require industry to reduce mercury releases to air and water and to properly treat and dispose
of mercury wastes. In 2010, EPA is working to develop emissions standards for power plants under
Clean Air Act section 112, consistent with the D.C. Circuit’s February 2008 opinion regarding the Clean Air Mercury Rule (CAMR). On October 6, 2009,
EPA published a final rule that limits emissions, including emissions of mercury, from medical waste incinerators.
EPA works with partners in state, local and tribal governments to implement a variety of programs designed to reduce mercury pollution and impacts. Most of
EPA's environmental regulations and programs are implemented by the states. In addition, under U.S. environmental laws, the states are often permitted to
adopt local environmental laws and regulations that are more stringent than federal requirements. As of 2005, twenty- two states were implementing or
state-based mercury action plans. Many of the state plans include pollution reduction elements that exceed federal
requirements. In particular, the states in the Great Lakes basin and northeast region have led efforts to identify and pursue ways to reduce and prevent
mercury releases to the environment, both as individual states and in multi-state collaborations.
EPA also works with industry to promote voluntary reductions in mercury use and releases. In December 2008,
EPA, the ADA and the NACWA signed a Memorandum of Understanding to establish a Voluntary Dental Amalgam Discharge Reduction Program. The goal of the
program is for dentists to follow the ADA’s best management practices (BMPs) for amalgam waste.
EPA works with international organizations to prevent the release of mercury in other countries. EPA has provided expertise to the United Nations
Industrial Development Organization (UNIDO)'s Global Mercury Project's small-scale gold (artisanal) mining project, which focuses on best management
practices to reduce occupational exposures, emissions and mercury use. Learn more about
EPA's international activities.
A common mission of tribal air programs is to preserve and protect the culture, ecosystems and public health of the tribal communities.
From a tribal perspective, preservation of a tribe’s culture through improved air quality is just as vital as improved public health.
In many cases a tribe’s culture is directly linked to their environment. Therefore, poor air quality results in the potential for
tribal culture to degrade. An example of this can be found in tribes whose cultural identity is tied to subsistence fishing. Most
fresh water sources are polluted with mercury and other toxins so that it is no longer safe to consume subsistence levels of fish.
The loss of consumable fish due to bioaccumulation of mercury from air pollution is a good example of a tribe’s culture being
impacted by air quality. Nationally, 55.4% of tribal populations lives within 50 miles of major mercury sources.
Mercury is an air toxic pollutant that is of particular concern to tribes. Mercury consumption is a health concern among those tribes
whose traditional diets include large amounts of fish, waterfowl, medicinal plants, moose and other land animals. Such diets have not
been adequately considered by the USEPA in the process of addressing emissions standards for mercury. For example, in developing its
recent rule for mercury emissions from power plants, EPA considered two segments of the population to be relevant to its analysis:
recreational anglers, and "high level" consumers such as some Native American and other ethnic populations. In calculating
the risk to these groups, USEPA used maximum fish consumption levels of 25 g/day for anglers and 170 g/day for high consumers. However,
even this "high level" number may be far from adequate for some tribal populations. For example, a survey of Great Lakes
area tribes produced a range of 189.6 to 393.8 g/day, and the Minnesota Chippewa Tribe has adopted 227 g/day as its treaty protected
subsistence quantity. Many tribes are in the midst of assessments of mercury levels in their water, fish, and wildlife. In general,
however, there is marked absence of mercury deposition data in the western U.S., where the majority of the tribal land base exists.
Because dry deposition monitoring techniques are not as developed as wet deposition techniques, data is particularly lacking in the
southwest, where dry deposition predominates. Acquiring more deposition and health effects data is a priority for tribes in the years
to come. Other toxics of concern include residential wood smoke, diesel emissions, and sources that are off reservation.