Policy Paper — MERCURY: To Protect the Public's Health

Part I: Mercury Hazards, Sources and Forms

The United States Environmental Protection Agency (USEPA), the National Academy of Sciences, and other government authorities have identified mercury as a significant public health and environmental concern. While scientists have not identified thresholds of unsafe mercury exposure because of substantial differences in toxicity of various mercury compounds, enough is known about mercury toxicity to warrant strong mercury emissions reduction standards for coal-fired power plants.

Approximately 5,500 tons of elemental mercury are released into the global environment each year. Once released, mercury remains in the environment for years. Approximately 70 percent comes from man-made sources, primarily emissions from coal-fired power generation plants, municipal incinerators, and waste dumps. Natural sources such as volcanoes and forest fires, and disrupted natural areas including mines, also add or recycle mercury. Mercury released in the U.S. accounts for about 60 percent of the deposition within our borders, with the remaining 40 percent coming from other global sources. Increases in power plant emissions and industrial uses of mercury during the past 100 years have resulted in a three-fold increase in environmentally available mercury.

Mercury is used in a variety of industrial applications and manufacturing processes (including chlorine gas production), in some medical devices, in amalgam dental fillings, and in some electrical switches, gauges and meters. Many of these are historic uses, and while current technologies no longer require mercury, recycling of older devices remains a problem.
Approximately 75 tons of mercury are contained in the coal burned annually in U.S. power plants. Burning the coal vaporizes the mercury, about two-thirds of which is released to the atmosphere as microscopic droplets if facilities do not have scrubbers to remove this material. Mercury can travel long distances in the air, and is ultimately deposited by rain and snow into rivers, lakes, oceans, and onto the ground, where a portion enters groundwater. Natural recycling of mercury at the earth’s surface, especially in the oceans, extends its biological influence and active lifetime as an environmental contaminant before it becomes sequestered in forms that do not readily recycle. If all man-made emissions were stopped today, it would take at least 15 years for the mercury levels in oceans and the atmosphere to return to pre-industrial conditions.

While mercury vapor in the atmosphere disperses widely, deposition is generally higher in areas close to emission sources and in areas with greater annual precipitation. The Great Lakes states account for 29 percent of the U.S. population, but 36 percent of estimated mercury emissions from electric utilities. EPA has estimated that about 40 percent of mercury deposited in the upper Midwest is attributable to U.S. man-made sources, with the remainder divided between natural emissions and global man-made sources.

Methylmercury is an organic form of mercury. Methylmercury is highly toxic, and has resulted in documented harm to people and to wildlife. The principal source of human exposure to methylmercury is fish consumption. Consumption of fish from mercury-polluted waters can constitute a substantial health hazard, especially to infants, children, and pregnant women. Current EPA guidelines set the maximum methylmercury intake for an average woman at 45.5 micrograms per week. Assuming the average methylmercury concentration in fish is 0.5 micrograms per gram of fish, a woman could consume less than a quarter pound of fish per week before reaching the maximum. It is clear that much of the population is exposed beyond this guideline.

Elemental metallic mercury can be transformed by bacteria into methylmercury, which is both more mobile and more toxic. Methylmercury may bioaccumulate in fish and shellfish to levels up to 10 million times greater than those in surface waters. While consumption of a diet high in fish has been shown to result in benefits to cardiovascular health, consumption of a high-fish diet that is also high in methylmercury has resulted in mercury poisoning. Symptoms include abnormal tingling or burning sensations of the mouth and face, numbness in extremities, difficult or slurred speech, headache, constriction of the visual fields, hearing loss, memory loss, ataxia (loss of muscle coordination) that results in problems with walking and balance, psychiatric disturbances, visual loss, or neuropathy (numbness, tingling, pain).

Part II: The Primary At-Risk Population

The Food and Drug Administration (FDA) issued an advisory in March 2001 to women who are pregnant or of childbearing age, and to young children, to avoid consumption of large predatory ocean fish, including tuna, swordfish, and king mackerel, in which high accumulations of mercury have been shown. Forty-five states have issued mercury advisories warning pregnant women and young children to limit or avoid native freshwater fish in their diets, and 13 states have issued mercury-based fish consumption advisories for all surface waters. Fish consumption advisories have been issued for the Great Lakes and their connecting waters, and for 52,000 lakes and 238,000 miles of rivers and streams across the United States.

Evidence relating to methylmercury toxicity in human infants has come from outbreaks in Japan and Iraq in the 1950s following consumption by pregnant women of methylmercury (Japan) and of fungicide-treated grain containing ethylmercury (Iraq). Exposure in utero to such high organic mercury levels as were found in Minimata Bay in Japan and in Iraq has been determined to result in severe birth defects such as micrognathia (small, malformed teeth and jaws) and neuroencephalopathy (small head circumference, mental retardation, blindness), abnormal neuromuscular development and control, and chronic severe pain. Chronic, low-dose prenatal methylmercury exposure from maternal consumption of fish has been associated with more subtle effects of neurotoxicity in children: poor performance on neurobehavioral tests, particularly on tests of attention, fine-motor function, language, visual-spatial abilities (e.g., drawing), and verbal memory.

The fetal brain is especially susceptible to damage from exposure to organic mercury, although the data are less certain regarding exposure to inorganic mercury. First, methylmercury readily crosses the placenta and achieves a higher level in the umbilical cord blood than in the maternal circulation. Second, animal studies indicate that excretion of methylmercury in milk corresponds to at least 5 percent of the dose administered to the mother. There are extensive data on neurodevelopmental effects of methylmercury in humans and animals. Methylmercury inhibits brain cell division and migration, causing abnormal brain development. Evidence from animal studies indicates that there is delayed neurotoxicity from methylmercury exposure to juveniles. Animal data also indicate that methylmercury exposure can affect immune function. All of these effects are likely to result in higher medical costs for individuals exposed as infants.

Research suggests that prenatal effects occur at intake levels 5-10 times lower than effects in adults. A recent report from Mt. Sinai Hospital in New York suggests that effects of mercury linked to decreased IQ levels alone cost $8.7 billion annually in lost earnings potential. An epidemiologic study of children in the Faroe Islands (a population with high fish consumption) indicates that children exposed to high levels methylmercury in utero were prone to abnormal heart rates, a risk factor for development of heart disease, which kills nearly a million people each year in the U.S., and carries health care costs of $209 billion annually.

Part III: Proposals for Reducing Mercury Pollution

The electric power industry has estimated that it will cost $50 billion over the next decade to implement the new EPA rules regarding SOx, NOx, and mercury emissions. However, the healthcare costs attributable to environmental mercury pollution may well exceed this.

President Bush has talked extensively about a “culture of life,” especially in regards to fetuses and newborn infants. Reducing environmental sources of mercury that are demonstrably harmful, especially to infants and children, should be part of this culture. The toxic effects of both organic and inorganic mercury have been documented. Children, infants, and fetuses are at highest risk of toxicity. There is no doubt that environmental mercury should be reduced to protect human health.

The Clean Air Act requires that emission of mercury from coal-fired utilities be regulated as a hazardous air pollutant, and that effective, technology-based controls (MACT, or Maximum Achievable Control Technology) be used at the pollutant source to do so. Under the provisions of the Clean Air Act, mercury emissions from municipal waste incineration were reduced from 41.7 tons in 1990 to 29.6 tons in 1995, and will fall to an estimated 4 tons by 2006. Mercury emissions from medical waste incineration will have been reduced from 50.2 tons in 1990 to just 1 ton in 2006. Whereas MACT would reduce mercury emissions 90 percent by 2007 (to 4.8 tons per year), the cap-and-trade rule adopted by EPA on March 15, 2005, would cut mercury emissions of coal-fired power plants just 70 percent by 2018, from 48 tons per year to 15 tons.

Further, cap-and-trade may produce hot spots, especially in the upper Midwest. At best, it is estimated that emissions allowed under the cap-and-trade rule would be two- to 10-fold greater in this geographical area than if they were controlled by MACT. Under the cap-and-trade rules, emissions are actually projected to be higher in 2020 in the upper Great Lakes states than they are currently. Mercury emissions in this area are of particular concern, as the surface of this region is 23 percent water bodies, compared to a national average of 7 percent, and mercury deposition on water has a relatively rapid impact on fish, compared to mercury deposition on land.

Part IV: Conclusions

A balance must be found between America’s need for electrical energy and protecting public health, especially for the nation’s most vulnerable populations.

As a fuel, coal is plentiful and relatively inexpensive. Because of its economic advantages, coal is likely to serve as a power plant fuel for many years to come, but the health and climate hazards of coal combustion must be held to a practical minimum.

EPA’s mercury cap-and-trade rule does not go far enough to protect public health and wildlife. A combination of MACT standards and limited cap-and-trade, with earlier compliance deadlines than provided in the EPA rule, would provide a better balance. MACT standards should be imposed on all new coal-fired power plants and on all power plants “grandfathered” under the Clean Air Act’s “New Source Review” provisions. Once “grandfathered” power plants reach a certain age, all should be required to install the full suite of pollution controls required by New Source Review.
For other power plants, a regional cap-and-trade policy, with safeguards against “hot spots,” may be appropriate, with allowances allocated on an “output” basis (pounds per MWh of electricity generated). Implementation of a regional cap-and-trade policy should be conditioned on long-term mercury monitoring in the vicinity of participating power plants. If monitoring shows unsafe mercury accumulations in local bodies of water, and/or fish and wildlife populations, MACT should be automatically imposed on nearby power plants without exception.

REP members realize that there is an increasing demand for power, that coal is plentiful in the United States, and that retrofitting old power plants with MACT will be costly. We believe that a combination of MACT, for the worst plants and for new plants, combined with a modified regional cap-and-trade policy, will benefit both public health and power production, and may well decrease healthcare expenditures. Putting mercury and other pollution control devices in place on all power plants will allow more coal to be burned for power without decreasing air quality. As efficient mercury and other pollution control devices are developed by U.S. companies, these technologies can be sold to other countries with power plant emission problems. Recovery of industrially useful commodities such as mercury and sulfur that can be sold will help offset the cost of installing scrubbers and other pollution control devices. We encourage our legislators to consider a win-win policy combining cap and trade with MACT.