"Mercury threat to children rising," blared a front-page Wall Street Journal article this week.

"A report warning that emissions of mercury by coal-fired power plants and other industrial sources pose an increasing danger to young children has been delayed nine months, while the Bush administration struggles with how to handle an increasingly contentious environmental problem," the Journal reported.

Regardless of whatever "struggle" is occurring in the White House over the report from the Environmental Protection Agency, the facts about mercury aren't likely to support the scary story the EPA is apparently set to tell.

What's really going on is an effort by eco-activist staffers at the EPA to force backbreaking regulations on coal-fired electric power plants.

The EPA apparently will claim in the report, America's Children and the Environment, that there is mounting evidence that mercury is collecting in the blood of women of child-bearing age and that high doses of mercury can cause mental retardation and other neurological disorders in infants.

Mercury occurs naturally in the environment and it can be released into the air through industrial emissions. It can get into both fresh and salt water and then accumulate up the food chain through fish and birds.

There is no question mercury can cause toxic effects -- just like every substance including water, sugar and salt. It's a matter of dose, though.

Harm to the nervous systems of unborn children is the primary concern. Two episodes of mass mercury poisoning bear this out. A number of Japanese children living near Minamata Bay in the 1950s were mentally retarded and had other neurological problems after pregnant mothers ate fish contaminated with high levels of methyl mercury.

No one knows exactly how much mercury was consumed by the mothers. But mercury levels in samples of the mothers’ hair averaged 41 parts per million (ppm).

A second episode of mass mercury poisoning occurred in Iraq in the 1970s when seed grain treated with a mercury-containing fungicide was consumed. The effects on the Iraqi children mirrored those reported among the Japanese children. Although maternal hair levels of methyl mercury ranged from one to 674 ppm, many children of Iraqi mothers with hair concentrations exceeding 100 ppm had normal development.

Despite the association between mercury and the neurological problems among the Japanese and Iraqi children, these episodes are of little relevance to fish consumption in the U.S.

The average level of mercury in hair associated with seafood consumption in the U.S. is 0.12 ppm, according to a 1997 study. This level of mercury exposure is not associated with harm to children's nervous systems.

A July 2000 report from the National Academy of Sciences noted that a 66-month study of 711 children in the Seychelles Islands assessed the effects of prenatal mercury in tests of global intelligence and developmental milestones. No adverse effects were attributable to mercury. Maternal hair samples collected at birth contained mercury concentrations that ranged from 0.5 to 27 ppm.

A smaller study of Faroe Islands children reported only "subtle" (invisible?) effects at corresponding exposure levels.

The NAS concluded "the functional importance of the apparent effects is uncertain," and the studies "provide little evidence" that children are affected appreciably by low-dose prenatal exposure to mercury.

This body of evidence linking low-level mercury exposure with harm to children is so weak that U.S. regulations are based on extrapolation from the Iraqi poisoning data. The EPA's current "safe" level of mercury exposure is based on a maternal hair level of about 11 ppm -- way above U.S. exposures to mercury from fish consumption.

Even the intake of mercury among women of child-bearing age who consume the most fish is about three times below the level at which risks are thought to begin.

So what's all the fuss about?

Congress barred the EPA from regulating mercury emissions from electric power plants until the NAS reported on the matter, which it did in July 2000.

With the EPA unchained, coal-hating environmentalists clamor for stringent regulation of mercury emissions to make it more difficult for coal-fired power plants to operate.

Hoping to steal the environmentalists' thunder and pre-empt EPA over-regulation, the Bush administration has proposed the Clear Skies Act that, among other things, would require industries to reduce mercury emissions by 50 percent by 2010 and by 70 percent by 2018.

Caught between a rock and hard place, the electric power industry says that it can meet the 2018 goal, but that the 2010 goal is "unrealistic."

What's really unrealistic -- given our indisputably low-levels of mercury exposure -- is the notion that mercury poses an imminent public health threat and that burdensome regulation is needed.

Steven Milloy is the publisher of JunkScience.com, an adjunct scholar at the Cato Institute and the author of Junk Science Judo: Self-defense Against Health Scares and Scams (Cato Institute, 2001).

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