POSTED 6 MAY 2004

1. Mercury morass

2. Danger signs

3. Mercury mystery

4. Safety: In eye of beholder?

Coal-fired electric utilities are the largest single source of mercury in the atmosphere. Photo: USGS

Burning makes 86 percent of total U.S. mercury emissions. Coal-fired utility boilers account for 34 percent; other big sources include coal-fired industrial boilers, burning of municipal, medical, and hazardous waste, and manufacturing. Graph: Environmental Protection Agency

Mercury from power plants and other pollution sources is converted by bacteria into methylmercury, which gets bio-accumulated in the food chain. Top predators have far higher concentrations of methylmercury than the animals they eat. Image: USGS

Mother's mercury
Just before leaving office, the Clinton Administration wrote regulations to reduce mercury air pollution. Nobody argues that high levels of mercury contamination can cause birth defects and brain damage.

Although cases of obvious mercury poisoning are rare, levels in rain and surface waters have risen over the decades, and coal-burning power plants are the largest single source of mercury in the air. Pres. Clinton's Environmental Protection Agency (EPA) proposed a 90 percent reduction in electric-utility emissions by the end of 2007.

Industry objected. Too expensive, it said. "...there is no existing technology that can control mercury emissions across the entire utility industry," it wrote.

The new administration deep-sixed the Clinton cuts and called for a regulatory system to reduce utility mercury by 70 percent -- in 2018.

Like the Administration's earlier proposal to ease regulation on arsenic in drinking water, the back-tracking alarmed physicians, public-health types and environmental activists. The EPA itself had said that each year, mothers' mercury threatened 300,000 American children with brain defects (see "Blood Organic Mercury..." in the bibliography).

"The fundamental question is, does this protect children as soon as technologically possible? Everything indicates that it doesn't," says Susan West Marmagas, director of environment and health programs at the non-profit Physicians for Social Responsibility. Charging that two EPA reviews had already agreed that power plant controls were feasible, she adds, "We have the technology to produce the 90 percent reduction by 2007, and this proposal does not do it soon enough."

The revised mercury rule also sparked protests from eastern-state senators. The March of Dimes, an organization that fights birth defects, asked the EPA to "withdraw its current proposal on mercury emissions from coal-powered utility units and replace it with a more stringent set of guidelines to be implemented as soon as possible." Industrial mercury, the normally non-political group said, "seriously threatens the health of America's mothers and babies."

The mercury rule and other changes caused upheaval at the EPA, and some air-pollution staffers quit in disgust (see "Changing All the Rules..." in the bibliography).

Quicksilver message
Over a decade, mercury pollution has ballooned from an obscure concern into a pressing environmental problem. Almost every list of dangerous air pollutants now mentions the silvery, liquid metal that, like uranium, plutonium and neptunium, shares its name with a planet.

Mercury has been used in patent medicine, thermometers, vaccines, paints, light switches, and is still used in fluorescent light bulbs. Once released into the atmosphere, usually by burning, some mercury compounds can be converted by bacteria into methylmercury, which is taken up in plants and the animals that eat them.

Biological accumulation sounds like a nightmare invented by radical greenies, but it's a reality with decay-resistant chemicals like PCBs and mercury. In water that contains 1 to 10 parts of mercury per trillion parts of water, methylmercury can bio-accumulate to 1 part per million, a level found in some top predators like tuna, swordfish and shark.

That's a million-fold increase.

Don't drink the water. Don't breathe the air. And DON'T eat the fish!
One result of bio-accumulation is a profusion of warning signs at America's waterways. Indeed, mercury pollution is "extraordinarily widespread," says Charles Driscoll, a professor of civil and environmental engineering at Syracuse University, who studies mercury levels in the environment. "There are 45 states with fish advisories, 19 with blanket advisories [covering all surface waters], 12 million acres of lakes and 473,000 river miles where there are advisories. It's a large proportion of our aquatic resources."

Nonetheless, the Edison Electric Institute, a utility-industry group that failed to respond to our request for comment, answered "Is it safe for me to eat fish" with a bold-faced, one-word sentence: "Yes" in its publication, "Straight Answers about Mercury".)

Industrial dumping of mercury in Japan during the 1950s caused horrific birth defects and proved the danger of high-level mercury poisoning.

The health worries about mercury date to the mid-1950s, when villagers in Minamata, Japan, began complaining of numbness, dizziness, and other nerve symptoms. Cats were said to be "committing suicide," and birds were falling from the sky.

It turned out that a local chemical factory had dumped about 27 tons of mercury into nearby waters over the decades, and the mercury was concentrated -- bio-accumulated -- in fish eaten by all the injured parties. "Minamata disease" proved that high concentrations of mercury could kill and cause grievous injury.

Just how much of a health threat is low-level mercury contamination?

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Terry Devitt, editor; Sarah Goforth, project assistant; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive

©2004, University of Wisconsin, Board of Regents.