Catfish in Md. River Have High Cancer Rates
Wednesday, January 25, 2006
Catfish from Maryland's South River have a skin cancer rate as high as any found in the nation and the second-highest liver cancer rate in the Chesapeake Bay watershed, and both are probably caused by polluted runoff, a study released yesterday says.
In the U.S. Fish and Wildlife Service study, more than half the brown bullheads -- a type of catfish -- sampled from the South River had skin tumors, the highest incidence in 14 years of bay watershed testing. The rate matches that found in Great Lakes bullheads, which had the nation's highest.
One-fifth of the South River bullheads tested had liver cancer, a rate second only to that of the Anacostia River, where studies in 2001 showed nearly 70 percent of bullheads had liver tumors.
"The fish are clearly exposed to cancer-causing agents, and at this point, we really don't know what chemicals are responsible," said Fred Pinkney, the Fish and Wildlife Service biologist who conducted the study. "We suspect it's from [polluted] runoff."
The agency hopes to pinpoint the carcinogen by next year if it finds money for additional work. The initial study was partly paid for by the South River Federation, a nonprofit group that monitors the 12-mile river, which flows through Anne Arundel County into the bay just south of Annapolis.
Bullheads are used in river studies because they live and feed on the bottom, where toxins accumulate; they don't migrate far; and they metabolize certain carcinogens just as humans do.
Despite the alarming findings, Richard McIntire, a Maryland Department of the Environment spokesman, said the state is not likely to issue a catfish consumption advisory for the South River. "This has been a known problem for quite some time," McIntire said.
"If you catch any fish that looks strange," he added, "throw it back."
The state also has no plans for advisories on swimming and other recreational use, based on cancer findings, he said.
Drew Koslow, the federation-appointed riverkeeper, said anglers eat the South River's catfish, perch and pickerel. The river has a water-skiing course and several community beaches.
"A lot of kids and adults swim in the river, [and] we don't have the authority to close it to swimming" or fishing, Koslow said.
Route 50 and other roads cross the river, so "maybe it's coming from the runoff off the highway -- or ski boats," he said of the pollution. "We don't have a lot of industry on the river, so we're pushing hard to figure out what's going on and deal with it."
The South River Federation contributed $3,200 to the initial study. Pinpointing the source of the disease would cost about $5,500, Koslow said. "We're hoping we can get some grant dollars to cover it."
In the Anacostia, Fish and Wildlife scientists linked liver tumors in bullheads to polynuclear aromatic hydrocarbons (PAHs), found in urban runoff laden with car exhaust residue, pavement sealants and asphalt particles.
But so far researchers are puzzled about what is causing the tumors in South River fish. There, PAHs in river bottom samples are far lower than in the Anacostia. Further, many more South River bullheads show signs of skin cancer than do Anacostia bullheads.