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Tuesday, December 12, 2006

Fish DNA Damage in Lake Erie Tributaries

COLUMBUS (TDB) -- Researchers at Ohio State University have completed a scientific paper that reports genetic damage in fish exposed to polluted waters ''from three known contaminated locations," including two rivers flowing into Lake Erie. The rivers are the Cuyahoga and the Ashtabula, both used as dumping sites for industrial wastes throughout much of the 20th century.

The third site where DNA was affected is Ashumet Pond on Cape Cod in Massachusetts, where some bullhead catfish have wart-like growths called papillomas. Massachusetts officials say contamination from a chemical spill has been upwelling from the bottom sediments of the pond. So far, they report no known health risks from eating the fish. Pappillomas are often considered benign growths on the skin or mucous membranes and have been associated with viral infections.

The Ohio State researchers say the external lesions they saw are associated with DNA damage. Based at the university's school of natural resources, the five-member team said they compared levels of genetic harm in brown bullheads from the three sites to fish from three other cleaner waterways. One is the Conneaut River in Northeastern Ohio, a popular fishing spot that drains into Lake Erie and is relatively unspoiled. The scientists collected blood samples from brown bullhead (Ameiurus nebulosis) look for signs to genetic changes.

''The assay results demonstrated that fish from the three contaminated sites each suffered higher DNA damage compared with fish from their respective reference sites,'' the three member research team reported. ''The results also show that the genetic damage was associated with the occurence of external lesions and deformities in fish.''

They said a standard type of DNA assay ''is sufficiently sensitive to detect exposure of natural fish populations to environmental levels of genotoxic contaminants."

Scientists have been concerned about the appearance of tumors in fish living in industrialized waterways since the 1980s. A U.S. Army Corps of Engineers study in September 1999 said brown bullhead are''susceptible to pollutant-induced neoplasia, and have been used as a sentinel organism for pollutants in waterways." It said chemicals are probably the blame.

The Corps' researchers found damage increases because toxics exceed ''the organism's capacity to neutralize them. This includes mutations that may eventually lead to the formation of cancers. Comparing the amounts of these biomarkers in fish collected from impacted and clean areas may provide insights into the quality of the water and sediments, and the probability of adverse responses in fish exposed to them, including the probability of developing cancers."

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