Study finds high rate of tumors in catfish caught in Anacostia
Some catfish in the Anacostia River have high rates of liver and skin tumors that appear to result from cancer-causing contaminants in the sediment, according to a newly released survey by the U.S. Fish and Wildlife Service.
While contamination in the Anacostia, which flows through Washington, D.C., is not new — it is one of three toxic “hot spots” identified by the Bay Program — the survey found that the prevalence of tumors in the fish rivaled that in some of the most polluted sections of the Great Lakes.
“The numbers are quite high,” said Fred Pinkney, environmental contaminants biologist with the USF&WS Chesapeake Bay Field Office. “There had been a lot of anecdotal information that the fish in the Anacostia don’t look good, but this study is really the first quantitative survey.”
The District of Columbia already has a consumption advisory for fish from both the Anacostia and the Potomac.
The USF&WS undertook the study after brown bullheads, a type of catfish, with tumors were noticed in Neabsco Creek, which borders the Featherstone National Wildlife Refuge along the Potomac about 25 miles downstream of Washington.
Brown bullheads are considered a good indicator of toxic problems because it is believed they have a relatively small home range, feed on the bottom where contaminants can accumulate and bury themselves in the mud over the winter.
In summer and fall of 1996, Pinkney sampled 30 fish each from the Neabsco. The results showed that 50 percent of the brown bullheads from the Anacostia had liver tumors in the spring and 60 percent had them in the fall. Also, 37 percent of the spring sample and 10 percent of the fall sample had skin tumors.
Rates were also high on the Neabsco, where 17 percent had liver tumors and 3 percent had skin tumors.
Work in the Great Lakes indicates that liver tumor rates above 9 percent and skin tumor rates above 20 percent are nearly always found in contaminated sites. Pinkney said levels found in the Anacostia were similar to the highest reported liver tumor rates in the Great Lakes, which has several severely contaminated sites.
“The liver is the first place we check for cancer because it is the seat of chemical metabolism in the body,” said John Harshbarger of the George Washington University Medical Center, a fish pathologist who did the lab work on the bullheads. “Catfish metabolize carcinogens in much the same way humans do.”
Chemical tests at the sample sites suggest that exposure to polynuclear aromatic hydrocarbons in the sediment may be causing the tumors, according to Pinkney. PAHs are found in petroleum, coal and other fossil fuels. When burned, fossil fuels release an even more toxic form of PAHs. They can enter the water as a result of runoff from roads and parking lots, leaks or spills, or as a result of deposition from air pollution.
Reducing tumors in the Anacostia could be a problem. Work at a Lake Erie tributary found tumor rates declined after an industry releasing PAHs closed. But the Anacostia has no “smoking gun” as a PAH source, Pinkney said. Rather, it appears the contamination results from widespread runoff from streets, rail yards, parking lots and other sources.
Likewise, Pinkney said, no obvious pollution sources for PAHs exist in the Neabsco. The watershed, he said, has experienced a lot of development associated with the Interstate 95 corridor.
Because of the difficulty in controlling pollution in runoff, the Bay Program’s draft toxics strategy does not call for a “zero-release” goal from stormwater. But it does call for reducing toxics from runoff by 10 percent for each of its “regions of concern” — which includes the Anacostia River — by 2010.
A summary of the report is available on the USF&WS Chesapeake Bay Field Office’s web site at www.fws.r5cbfo/BULLHEAD.PDF
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