Conscious Choice: Mercury Alert!

May 2006

Mercury Alert!

A recent study reveals unsafe levels of mercury contamination are widespread in Illinois sport fish

By Max Muller

One in six women of childbearing age in the U.S. are estimated to have a sufficiently high mercury blood level. That means 630,000 of the 4 million American babies born each year are at risk of neurological damage, according to data compiled by U.S. Environmental Protection Agency (epa) scientists in an April 2004 study.

The primary route of human exposure to mercury is eating contaminated fish. Coal-fired power plants are by far the largest source of human-created mercury emissions.

Mercury released during coal combustion is deposited from the atmosphere into our waters, where it is converted by bacteria into methyl- mercury, a potent toxin that accumulates in fish that eventually end up on our dinner tables. Studies of the tissues of popular sport fish discovered that unsafe levels of mercury have contaminated fish throughout Illinois.

Why is Mercury Dangerous?

Exposure to all forms of mercury is harmful to the health of humans and animals. Mercury is well-known to be toxic to humans in incidents of acute high-dose exposure, but such events are rare in the U.S. Rather, it is the widespread, chronic, low-dose exposure to methylmercury that poses the greatest threat to public heath.

Developing fetuses and children are especially at risk from mercury contamination. When pregnant women eat contaminated fish, methylmercury easily crosses the placenta and blood-brain barrier and can cause irreversible damage to the fetus’s developing central nervous system.

Even very low-dose in utero exposure can cause developmental delays, decreased IQ, and memory and attention problems.

Since the human brain continues to develop after birth, this heightened sensitivity lasts, to a lesser extent, through childhood.

Researchers at the Center for Children’s Health and the Environment at the Mount Sinai School of Medicine recently estimated the dollar value of diminished productivity attributable to IQ loss from power-plant mercury emissions at $1.3 billion dollars per year.

In another study still under peer review, those same researchers estimated that in 1,566 American children each year, mercury caused large enough loss in IQ to result in mental retardation, with a monetary cost to the U.S. of approximately $2 billion per year.

Although the developing brain is thought to be the most sensitive to methylmercury, mercury can also harm the human heart, nervous system, and immune system.

Adults exposed to methylmercury may experience neurocognitive deficits similar to those seen in prenatally exposed children, as well as effects on blood pressure and fertility. Studies also associate mercury exposure with an increased risk of heart attacks.

Taken together, these findings indicate that consumption of mercury-contaminated fish can be harmful to men and women of all ages.

The Role of Coal-Fired Power Plants

Mercury is a naturally occurring element present in the Earth’s rocks and soils, where it remains sequestered and generally biologically unavailable until disturbances cause it to be “emitted,” or released to cycle in the environment. One study estimated that in 1990 about 30 percent of mercury emissions were caused by natural processes, such as the weathering of rock containing mercury.

The other 70 percent were caused by human activities, such as burning mercury-containing coal. Other studies have indicated that since the beginning of the industrial era, human activities have typically increased bio-available mercury concentrations by a factor of three to ten.

Power plants remain the largest source of manmade mercury emissions both in Illinois and in the nation. Although mercury emissions from power plants are not currently systematically monitored, emissions have been estimated using several different methodologies.

Illinois Mercury Levels

In Illinois, 21 coal-fired power plants are the source of an estimated 71 percent of manmade mercury emissions in the state. That’s based on information from U.S. EPA’s 2002 National Emissions Inventory, which collects data from a variety of sources on emissions of nearly 200 different pollutants.

In-state coal-fired power plants were estimated to emit 7,022 pounds of mercury in 2002, based on U.S. EPA’s 1999 Information Collection Request, which was another, more rigorous survey that focused exclusively on power-plant mercury emissions.

In Illinois, mercury contamination of fish is already so widespread that the Illinois Department of Public Health warns people to limit their consumption of Illinois predator species at the top of the food chain — species such as largemouth bass, flathead catfish, walleye and sauger.

A study that looked at 804 fish samples from the Illinois Fish Contaminant Monitoring Program and 24 fish samples from the U.S. EPA’s National Lake Fish Tissue Study found the mean mercury concentration in Illinois fish samples was about 0.16 parts per million (ppm). That’s about 20 percent higher than U.S. EPA’s 0.13 ppm safe limit for women of average weight who eat fish twice per week.

In addition, the studies revealed that 59 percent of the fish samples exceeded the safe mercury limit for children of average weight under age three who eat fish twice a week; 50 percent exceeded the safe limit for children ages three to five years; and 34 percent exceeded the safe limit for children ages six to eight years.

Other key findings:

• In nearly half (36) of the 77 counties included in the studies, the average fish sample mercury concentration exceeded U.S. EPA’s safe limit for women. These counties are geographically distributed throughout the state. In eight counties (Boone, DeKalb, Edwards, Effingham, Kane, Pope, Pulaski, and Schuyler), 100 percent of fish samples were contaminated above the safe limit.

• In half (16) of 32 species included in the studies, the average fish-sample mercury concentration exceeded U.S. EPA’s safe limit for women. These species were, in descending order of average mercury concentration, bigmouth buffalo, freshwater drum, striped bass, lake trout, spotted bass, sauger, smallmouth buffalo, spotted sucker, flathead catfish, largemouth bass, brown trout, Chinook salmon, white bass, channel catfish, carp, and white sucker.

• In 66 of the 145 lakes and streams included in the studies, the average fish-sample mercury concentrations exceeded U.S. EPA’s safe limit for women.

• The 10 lakes with highest average fish-sample mercury concentrations were, in descending order: Lusk Creek in Pope County, Monee Reservoir in Will County, Devil’s Kitchen Lake in Williamson County, an unnamed lake in Tazewell County, Piscasaw Creek in Boone County, McKinley Park Lagoon in Cook County, Steven A. Forbes Lake in Marion County, Big Muddy Creek in Clay County, Kinkaid Lake in Jackson County, and Cedar Lake in Jackson County.

Mercury Regulation

Under the Bush Administration, the U.S EPA is currently implementing a mercury reduction rule that will allow power companies to buy, trade, and bank emissions credits instead of reducing pollution. Under this rule plants can avoid installing mercury controls for a decade; may not achieve their meager reduction targets for another quarter-century; and won’t remedy local hot spots of mercury pollution.

In response, many states are pursuing more stringent mercury reductions of their own. Three states already have laws in effect that will reduce their mercury emissions by 90 percent, an achievable and affordable standard using modern emissions control technology.

At the direction of Gov. Rod Blagojevich, the Illinois EPA on March 14 finalized a proposed administrative rule to adopt a similar standard in Illinois. To protect public health by reducing mercury deposition that accumulates in fish, Illinois should adopt the proposed mercury rule.

Excerpted and adapted with permission from “Risky Fishing: Power Plant Mercury Pollution and Illinois Sport Fish,” a 2006 study released by Illinois Public Interest Research Group, a non-partisan, non-profit environmental and consumer advocacy group. Download the story at illinoispirg.org.

Max Muller is an environmental advocate for Illinois PIRG Education Fund.

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