Effect of remedial dredging on bullhead tumor frequency in a recovering river
- National Biological Service, Columbus, OH (United States)
In 1980 and 1981 high tumor frequencies in brown bullhead from the Black River, Ohio were correlated with high concentrations of polynuclear aromatic hydrocarbons (PAH) in sediment. Surficial sediment levels of PAH dropped after a decline in the steel industry in 1982 followed by closure of the USX coke plant in 1983. By 1987 PAH concentrations had declined to less than one-hundredth of those found in 1980. During this same period liver cancer in age 3+ brown bullhead (Ameiurus nebulosus) underwent a significant decline to about one quarter of the 1982 frequency (38.5%) by 1987 (10%). Then in mid to late 1990, in a delayed reaction to a US EPA consent decree, PAH contaminated sediments were dredged from the river. Surveys in 1992 and 1993 revealed that the cancer frequency in age 3+ brown bullhead had increased to more than 45%. Preliminary 1994 data indicates a decline in grossly observable liver tumors (usually diagnosed as biliary cancers), along with declines in external tumors and eye pathology. The data fit the following hypothesis: Contaminated sediments become less bioavailable with time after a point source is removed, possibly due to deposition of cleaner sediment. Dredging temporarily restores bioavailability (and consequent effects). These data support the position that in some locations controlling contaminants in situ may be preferable to dredging on a cost-benefit basis.
- OSTI ID:
- 211994
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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