Is EPA ignoring the Science on Mercury?

By Willie Soon & Robert Ferguson
April 18, 2003

The EPA's recently announced "Clear Skies" initiative would cut mercury emissions by 69%, resulting in the first-ever national cap on such emissions. The EPA's primary target is U.S. coal-fired power plants.

However, emerging scientific research indicates that EPA's narrow prescription for new controls on U.S. coal will mean higher energy prices, more dependence on imported natural gas and lost jobs -- all to address a public harm that has not been found.

Once emitted, naturally occurring mercury enters our atmosphere as a gas, remaining there for about a year. It may travel far before falling to the surface. This airborne mercury poses no serious threat to human health.

What has provoked concern is methylmercury, which is derived from elemental mercury deposited in the earth's waters. Methylmercury is thought to enter the human food chain only after complex bio-processing through aquatic life, ending up in some of the fish we consume. High levels of this form of mercury are thought to be particularly dangerous to fetuses and young children. However, there is significant scientific uncertainty about the nature and scope of mercury-related health risks.

The few epidemiological studies that have been conducted reached ambiguous conclusions. Recent findings by the Center for Disease Control show that the level of mercury found in humans is far below the threshold of health risk, even for sensitive populations. The EPA has admitted that it cannot determine how much, if any, of the mercury in fish comes from coal combustion, arguing that such a determination is unnecessary.

Beyond health concerns, scientific understanding of the global cycle of mercury suggests that the proposed regulation of U.S. coal power plants will do little to reduce worldwide mercury emissions and their deposition.

U.S. power plants emit only 1 percent or less of the world's total mercury emissions. About half of the world's total annual release comes from industrial activities, and the rest from natural sources - the ocean, volcanoes and wildfires. The ocean has naturally held about 100 million tons of mercury for millions of years.

U.S. power plants emitted about 50 metric tons of mercury into the atmosphere in 2000. By comparison, coal combustion in China emitted approximately 270 tons that year. Another study, limited to man-made mercury sources from fossil-fuel combustion in 1995, found that the United States is out-emitted not only by combined contributions of the top-seven European emitters, but also by China, India, Australia and Zaire individually. U.S. coal plant emissions represent about 2 months of emissions from China alone. Targeting relatively clean U.S. power plants would not achieve a meaningful reduction in annual global mercury emissions.

Mercury emissions from U.S. power plants dropped in the 1990s, plausibly as a byproduct of current scrubber technologies. The Energy Information Agency reported in October 2001 that no technology is available to make further significant cuts. EIA also noted that the very technological advances needed to lower mercury emission could be threatened by passage of technologically premature regulations.

Finally, emerging science on wildfires may point to ways to make deep cuts in worldwide mercury emissions that could yield multiple benefits. U.S. and Canadian researchers have estimated that worldwide burning of vegetation emits about 850 tons of mercury annually to the air. Independently, South African scientists found mercury emission from burning vegetation at 450 to 1200 tons annually. Reducing forest fires through better forest management may prove to be the most effective means of achieving significant reductions in mercury emissions. Annually forest fires alone completely dwarf emissions from U.S. power plants.

Reducing emissions from relatively clean U.S. power plants would not significantly lower the annual volume of mercury emissions. The EPA's "Clear Skies" initiative would undercut coal as an abundant, vital energy source at a time when the U.S. economy demands a predictable, affordable supply of domestic energy.

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Willie Soon and Bob Ferguson are the Science and Executive Directors, respectively, at The Center for Science and Public Policy, a project of Frontiers of Freedom (FOF). FOF is a non-profit organization dedicated to restoring constitutional limits on the power and extent of government.