Gov. Jennifer Granholm established the Michigan Mercury Electric Utility Workgroup two years ago to fulfill a campaign promise to phase out mercury emissions from coal-fired power plants. The workgroup was directed "to strive for recommendations based on workgroup consensus" and to produce a report in six months. Two years later, the workgroup has published its report with little consensus on what should be done.

Perhaps it is unsurprising that a committee composed of government officials, scientists, utility representatives and staff from interest groups would have trouble agreeing. But in fact, the problem is not merely political; it is fundamental, involving uncertainty on such basic issues as the scientific justification for state mercury-emission controls and the controls' likely effects. This inconclusiveness, particularly given the cost of the extreme reductions that some have recommended to the governor, explains why the state shouldn’t adopt state regulations and should instead monitor the progress of a new federal mercury-reduction program.

Mercury is a heavy metal found in rocks and in the by-products of industrial processes. Mercury created by human activities — called "anthropogenic" mercury — is estimated to account for up to two-thirds of the mercury in the environment. Coal-fired utility boilers are the single largest source of anthropogenic mercury in the United States.

The primary concern about mercury is its potential effect on human health. Mercury in aquatic ecosystems can be methylated by microorganisms into an organic form that can accumulate in fish and animal tissue. Methylated mercury, in turn, is a neurotoxicant that at elevated exposure levels can cause an increased risk to a developing fetus.

From this consideration, two questions arise: Is environmental mercury a health problem in Michigan, and if so, would the stringent regulations recommended by some in the workgroup be an effective way to address the risk?

The primary human exposure to mercury is from consuming fish. The two best-known epidemiological studies that measure the effect on fetuses and newborns of heightened exposure to mercury through maternal consumption of ocean fish are inconclusive, with one suggesting a negative effect and one suggesting no effect. There remains a great deal of controversy in the public health community about the advisability of fish consumption in the potential presence of mercury, since the risk of mercury exposure must be weighed against the positive health benefits of eating fish.

In the Great Lakes, levels of mercury continue to decline. Mercury concentrations in Great Lakes-region bald eagle feathers fell approximately 20 percent between 1985 and 2000 — a telling measure, since the eagles are at the top of the Great Lakes food chain and their primary diet is fish. Nor is the case likely to be different with humans. The panfish that Michiganians typically catch and prepare from the lakes are not the riskier types of high-food-chain fish — swordfish, tuna — that contain higher levels of bioaccumulated mercury and become the subject of scientific concern.

In addition to scientific questions about the risk posed by mercury, there are also questions about the effects of a proposal that some members of the workgroup have recommended: mandating a 90 percent reduction in mercury emissions from Michigan’s coal-fired utilities.

In theory, this sounds like a huge impact on the presence of mercury, but in practice, it is not clear how large the effect would be. Computer modeling by the U.S. Environmental Protection Agency indicates that despite the amount of mercury emitted by Michigan's coal-fired power plants, they are responsible for less than 2 percent of the mercury deposits in Northern Michigan and for less than 5 percent of the deposits in central and Southern Michigan.

One reason these percentages are so low is that much of the smokestack mercury from coal-fired power plants is believed to be oxidized before falling to earth, so that it is changed to a form that does not bioaccumulate in fish. Another reason is that the mercury emissions generated by Michigan power plants often do not land inside the state, but are blown outside the state’s boundaries. In fact, much of the mercury in Michigan’s atmosphere comes from international sources, and most anthropogenic mercury deposition in Michigan comes from sources outside the state. Thus, the proposed Michigan regulations would probably fail to address key sources of the state’s mercury.

The effectiveness of the proposed state regulations are also unclear given the federal government’s new mercury-control program. Instituted in March, the regulations establish a strict baseline emissions standard. Compliance with a second and even tougher standard may be met either by adopting new technologies, or by buying credits sold at market prices by companies that have lowered mercury emissions even further than required under the law.

Such an approach not only reduces the costs of cutting emissions, but is effective; a similar trading system has cut national sulfur dioxide emissions by 41 percent since 1980. The federal program for mercury is projected to reduce nationwide mercury deposition by approximately 20 percent by 2010, and by 70 percent by 2018.

Given the mobility of the mercury emissions across state and national borders, the federal proposal makes more sense than a state regulation. True, the projected national reductions could be uneven; the Granholm administration has in fact joined a lawsuit against the federal government arguing that because some utilities will buy emissions credits and thus avoid the strictest emission standard, reductions in Michigan would be insufficient, even if mercury emissions were decreased dramatically nationwide.

But in fact, no one knows how specific utilities will respond to the new federal system and how their actions will affect local mercury levels. Adding state regulations to the mix might even create perverse incentives in some cases to move new economic activity and power generation outside of Michigan, thereby increasing production at power plants whose mercury discharge is more likely to fall in Michigan and ultimately curtailing some of the projected effectiveness of state regulation.

And the proposed state regulations will not be cheap. An analysis found in the Mercury Electric Utility Workgroup’s own report indicates that more stringent controls in Michigan would increase homeowners’ electricity costs by $59 million annually and commercial users' costs by $153 million annually, due to the high capital cost of additional smokestack controls. Increased electricity costs in the state — which are already higher than most of the Midwest — would worsen Michigan’s already uncompetitive business climate.

Gov. Granholm should reject suggestions to add further mandatory controls on Michigan coal-fired power plants. Great Lakes mercury levels are declining, and to the extent that mercury remains a human health threat in Michigan, the federal program is a more sensible first step in improving it. It would be a big mistake indeed to implement state mercury regulations whose necessity and effectiveness would be uncertain, but whose costs to Michigan's economy would be high.

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Russ Harding is senior environmental analyst for the Mackinac Center for Public Policy, a research and educational institute headquartered in Midland, Mich. Permission to reprint in whole or in part is hereby granted, provided that the author and the Center are properly cited.