Pollutants in Wild Freshwater Fish Pose Public Health Risks

The same team presented a separate study showing that wild-caught fish sold commercially contained higher levels of mercury, arsenic and selenium than fish caught near former industrial areas of Lake Erie. Mercury, arsenic and selenium are markers for coal-burning pollution.

The Conemaugh coal-burning power plant in Pennsylvania is operated by Reliant Energy, but it is not the one in the University of Pittsburgh study. (Photo by Stefan Schlöhmer)

And in a third study, the same researchers showed that exposing estrogen-sensitive breast cancer cells to extracts of channel catfish caught in areas with heavy sewer and industrial waste causes the cells to multiply.

The three studies were presented at a special session on contaminants in freshwater fish.

The first study found high levels of mercury and selenium in channel catfish caught in a rural area upstream of Pittsburgh and downwind of a coal-fired power plant. Both mercury and selenium are well-known contaminants that result from burning coal for power generation.

Researchers asked local anglers to catch channel catfish from the three rivers area of Pittsburgh, where the Allegheny, Monongahela and Ohio rivers meet.

The anglers also caught catfish from the Allegheny River at Kittanning, 40 miles upstream from Pittsburgh and downwind of Reliant Energy's Cheswick Power Station in Springdale, 26 miles away.

Tests showed 19 times more mercury and three times more selenium in the Kittanning-caught fish than in the three rivers area fish.

The risk of developing neurological disorders from eating catfish with such high levels of mercury as those caught near Kittanning is eight times higher than the U.S. Environmental Protection Agency's acceptable risk for children under six years of age, six times higher for women of childbearing age, and five times higher for the general population.

Channel catfish are found in the St. Lawrence-Great Lakes, Hudson Bay, and Missouri-Mississippi River basins from southern Quebec to southern Manitoba and Montana south to theGulf of Mexico. (Photo NJ DEP )

Volz is co-director for exposure assessment in the Department of Environmental and Occupational Health. "These types of power plants may be significant sources of mercury and selenium in fish contamination," he said.

Pat Hammond, communications director for Reliant Energy based in Houston, Texas, said company officials have not seen the study, but the plant is in compliance with its air and water permits.

Reliant announced last year it will spend $250 million to install a flue gas desulfurization scrubber at Cheswick.

Volz said, "We believe it is important for fish consumption advisories to take into account industries such as power plants that may be important sources of water pollution, and warn people in these areas about the dangers of consuming local fish."

Dr. Conrad Volz (Photo courtesy CRESP)

In a second study Volz showed that white bass wild-caught in the Canadian part of Lake Erie and sold commercially contained higher levels of mercury, arsenic and selenium than fish caught near former iron and steel mills on the Allegheny and Monongahela rivers in Pittsburgh.

"We were surprised by our results since we had hypothesized that levels of contaminants in fish would be higher in specimens caught near once heavily polluted sites," said Volz.

"These results indicate to us that purchasing fish from a local market cannot guarantee food safety," he said. "We recommend a more rigorous testing program for commercial freshwater fish with particular attention to fish entering the U.S. from other countries."

Volz said the results may indicate that sediments in Lake Erie remain contaminated because reductions in industrial pollution are recent, while coal-fired power plants and wastewater treatment plants around Lake Erie and to the southwest continue to emit pollutants.

Volz presented a third study showing that exposing estrogen-sensitive breast cancer cells to extracts of channel catfish caught in areas of the Allegheny and Monongahela rivers near Pittsburgh with heavy sewer and industrial waste causes the cells to multiply.

The study suggests that the fish contain substances that mimic the actions of estrogen, the female hormone.

"We believe there are vast quantities of pharmaceutical and xeno-estrogenic waste in outflows from sewage treatment plants and from sewer overflows, and that these chemicals end up concentrated and magnified in channel catfish from contaminated areas," said Volz.

"These findings have significant public health implications, since we drink water from the rivers where the fish were caught," he said. "Additionally, the consumption of river-caught fish, especially by semi-subsistence anglers, may increase their risks for endocrine-related health issues and developmental problems."

The three studies were funded by grants from the Highmark Foundation, the DSF Charitable Trust and the Heinz Endowments.

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