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"Since 1992, we have surveyed 10 other locations in the Chesapeake
watershed. These catfish from the South River have the highest skin tumor
rate and second highest liver tumor rate," Pinkney said. Fish from the
Anacostia River have a higher incidence of liver tumors.
"I am very concerned we are seeing unusually high cancer rates among these
fish. We are determined to continue investigating this issue until we
establish what is giving these fish cancer," said Drew Koslow, riverkeeper
for the South River Federation.
"We collected 30 fish from the South River near Annapolis last year," Pinkney said.
"Sixteen fish had raised, pinkish red lesions around the
mouth."
Dr. John Harshbarger, a tumor pathologist with George Washington University
Medical Center, identified the lesions as tumors. He diagnosed 13 of the 16
fish with invasive carcinomas; the remaining three fish had non-invasive
skin tumors. In addition to the skin tumors, six of the 30 fish had liver
tumors.
In studies conducted over the past 10 years, the Service linked the types
of tumors found in bullheads with a class of chemicals known as polynuclear
aromatic hydrocarbons. Petroleum, coal and other fossil fuels contain PAHs.
They enter rivers through water runoff and build up in sediments where
bullheads live. Service biologists found high concentrations of these
compounds in areas of the Chesapeake watershed that also had a high
incidence of tumors in bullheads.
"In the South River, however, we have not established a link between the
tumors and PAH exposure," Pinkney said.
This study was a partnership between the Service and the South River
Federation, a local watershed group. Together, they are pursuing follow-up
studies to identify classes of chemicals that may be responsible for the
high tumor incidence.
A fact sheet is at http://www.fws.gov/northeast/pdf/southriv.pdf . A full
report on the study is available from the Service's Chesapeake Bay Field
Office or from http://www.fws.gov/chesapeakebay/envcont.htm
The Maryland Department of the Environment has a restricted consumption
advisory for some fish species in the South River based on the presence of
PCBs and pesticides.
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Laboratory studies confirm suspicions that lip growths on catfish from a
Maryland river are a form of skin cancer, according to Fred Pinkney,
environmental contaminants biologist with the U.S. Fish and Wildlife
Service?s Chesapeake Bay Field Office in Annapolis.
Scientists have linked this type of tumor in brown bullheads, a species of
catfish, with exposure to cancer-causing chemicals. 