Something Fishy in Pittsburgh: Studies Suggest Water Pollution Still Pervasive

Issue Date: 
November 26, 2007

New research at the University of Pittsburgh suggests that pollution in the region’s rivers continues to present a health threat to residents who use the local water supply and eat fish caught here.

What’s more, buying fish at the supermarket might not be any safer. One study found that fish caught in Lake Erie and sold commercially in Pittsburgh contained levels of arsenic and selenium almost twice as high as those from the Allegheny and Monongahela rivers, and levels of mercury two-to-four times higher.

Three separate Pitt studies were presented to the American Public Health Association during its annual meeting Nov. 7 in Washington, D.C.

The principal investigator of all three was Conrad Volz, assistant professor of environmental and occupational health in Pitt’s Graduate School of Public Health.

Experts consider the studies significant because fish are thought to be reliable indicators of unsafe water. Fish consume fat-soluble chemicals from the water in which they swim and concentrate the toxins within their own bodies.

In the first study, researchers reported that extracts taken from channel catfish caught in the Allegheny and Monongahela caused breast cancer cells to multiply. The fish were caught in areas where sanitary sewers often overflow during rainstorms, releasing raw, untreated sewage directly into rivers.

The study suggests the fish are absorbing chemicals that mimic the actions of the female hormone estrogen, and that those chemicals are making their way into the local water supply, Volz said.

Researchers think the chemicals are accumulating in the fish because “vast quantities” of human waste containing pharmaceutical byproducts are running into local rivers from untreated sewage, Volz said.

About 16 billion gallons of raw sewage reach Pittsburgh rivers each year, he said, “with major implications for public health.”

In the study, Volz and colleagues found that exposing extracts of catfish to human breast cancer cells caused them to multiply, if those cells were rated as receptive to estrogen. Cells that were rated nonresponsive to estrogen did not change.

Extracts of fish caught in areas heavily polluted by industrial and municipal wastes resulted in the greatest amount of cell growth, Volz said.

The next step in the research is to identify the specific chemicals and their sources in both local water and fish, he said. “These findings have significant public health implications, since we drink water from the rivers where the fish were caught,” Volz said.

Coauthors of the study include Pitt researchers Yan Liu, Christopher Price, Mary Elm, Devra Davis, Maryann Donovan, and Patricia Eagon.

In the second study, Volz and his colleagues reported that white bass caught on the Canadian side of Lake Erie contained significantly higher levels of mercury, arsenic, and selenium than fish caught near active and former steel mills in Pittsburgh.

Researchers asked local anglers to catch 45 white bass at two locations near Pittsburgh; the researchers then compared them to 10 white bass purchased at local markets.

According to study results, mercury levels in store-bought fish were 2.2 to 4.8 times higher, while arsenic levels were 1.7 times higher and selenium levels were 1.9 times higher.

“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,” Volz said. “These results indicate to us that purchasing fish from a local market cannot guarantee food safety.”

According to Volz, the results may indicate that sediments in Lake Erie are still being contaminated by coal-fired power plants.

Burning coal in power plants produces toxic byproducts such as mercury, arsenic, and selenium that can contaminate rivers both directly and indirectly through air pollution and water runoff.

In their report, Volz and his colleagues recommend a more rigorous testing program for commercial freshwater fish, “with particular attention to fish entering the U.S. from other countries,” he said.

Coauthors of this study include Nancy Sussman, Devra Davis, Maryann Donovan, Jeanne Zborowski, and Yan Liu, all of the University of Pittsburgh.

Additional support came from Sean Brady of Venture Outdoors and fishing instructor Karen Gainey.
In the third study, researchers concluded that emissions from coal-fired power plants travel far upstream, contaminating water supplies many miles away. The study found higher levels of mercury than the Environmental Protection Agency (EPA) recommends, along with elevated levels of selenium in channel catfish caught both around Pittsburgh and near Kittanning, Armstrong County.

Fish caught near Pittsburgh had 3.1 times more mercury than recommended. Surprisingly, fish caught near Kittanning were significantly worse, containing 19 times more mercury than recommended by the EPA.

Fish caught near Kittanning also had higher levels of selenium than those caught in Pittsburgh.
The risk of developing neurological disorders from eating catfish with the levels of mercury found near Kittanning are five- to-eight times higher than those considered “acceptable” by the EPA, Volz said.

He said anglers should be “concerned” about eating fish caught in areas close to coal-fired power plants, and that the general public should be told about the risks.

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

Coauthors of the third study include Yan Liu, Nancy Sussman, Tiffany Green, Jim Peterson, Charles Christen, Maryann Donovan, Devra Davis, Patricia Eagon, Kelly McMahon, and Ravi Sharma, all of the University of Pittsburgh; along with Sean Brady of Venture Outdoors; local angler Paul Caruso; and Myron Arnowitt of Clean Water Action.