Mercury released from products contributes nearly one-third of total mercury emissions to the air in the United States. The study shows that in 2000, mercury-containing products accounted for an estimated 32 percent of mercury releases to air, two percent of mercury releases to land, and four percent of mercury releases to water.
Mercury is also released by coal-burning power plants and factories, from transport and storage of waste because of broken mercury equipment, from cremations because of the mercury contained in dental amalgam used for tooth fillings, and from burn barrels used for trash disposal in rural areas.
'Mercury-containing products such as thermometers, switches and dental products release mercury throughout the product life-cycle, including during production, use and disposal,' says Alexis Cain, lead author of the study and an environmental scientist with the EPA Region 5 based in Chicago.
Mercury, at high levels, may damage the brain, kidneys, and developing fetus, according to the federal Agency for Toxic Substances.
When mercury falls on water or land, contact with bacteria results in the formation of methylmercury. This form of mercury accumulates in fish populations, jeopardizing the health of children and women of childbearing age who eat the fish.
Mercury's harmful effects that may be passed from the mother to the fetus include brain damage, mental retardation, incoordination, blindness, seizures, and inability to speak. Children poisoned by mercury may develop problems of their nervous and digestive systems, and kidney damage.
A number of highly-used products release mercury throughout their lifecycles, often in ways that are difficult to measure directly, says Cain. As a result, there has been uncertainty about the magnitude of mercury release into the environment that is associated with these products.
Cain's study, published in 'Journal of Industrial Ecology,' uses a method called substance flow analysis to develop improved estimates of the environmental releases caused by mercury-containing products.
'Substance flow analysis can be used to estimate the mercury releases to air, land and water at different stages of a product lifecycle,' Cain says. 'It can also help identify actions that would be effective in minimizing mercury releases.'
The model can be used as a predictive tool to evaluate the potential impact of measures to reduce the use of mercury, to improve the management of mercury wastes or to reduce mercury releases through the installation of mercury control technologies.
Cain says, 'Reductions in the mercury content of some products, along with mercury emissions limitations imposed on municipal and medical incinerators, have resulted in significant reductions in mercury releases.'
Campaigns are underway to eliminate mercury in thermometers and dental amalgam, and to discontinue mercury use in energy-saving compact fluorescent light bulbs.
In August 2006, the U.S. EPA announced a national program to remove mercury-containing light switches from scrap vehicles before the vehicles are flattened, shredded, and melted to make new steel.
Together with existing state mercury switch recovery efforts, the National Vehicle Mercury Switch Recovery Program is intended to reduce mercury air emissions from the fourth leading source in the United States - the furnaces used in steel making.