Historical monitoring of biomarkers of PAH exposure of brown bullhead in the remediated Black River and the Cuyahoga River, Ohio

Biomarkers of exposure to chemical contamination, benzo[a]pyrene (BAP)- and naphtha lene (NAPH)-type metabolites, were measured in brown bullhead from a heavily polycyclic aromatic hydrocarbons (PAHs) contaminated section of the Black River, Ohio, during and immediately after remedial sediment dredg ing in 1990-1991, and in follow-up revisits in 1993 and 1998. Biomarker lev els of bullhead from the historically polluted Cuyahoga River and the prote cted Old Woman Creek National Estuarine Sanctuary in Ohio were also measure d over the same rime periods. PAM-bile metabolite concentrations of bullhea ds from the Black River were still elevated in the year following dredging, but were significantly lower in the later resampling years. Metabolite con centrations of Cuyahoga River bullhead decreased significantly between 1991 and 1993, possibly in response to the shutdown of coking opera tions on th e river. Fish from Old Woman Creek showed some variation in metabolite conc entrations among periods, bur were consistently lower than the other two ri vers at each rime. Measurement of bile metabolites proved an effective tool for estimating changes in exposure over rime and among sampling sites. Tre nds in biomarkers indicated lowered exposures in the Black and Cuyahoga Riv ers. These findings are likely a result of remediation activities in the Bl ack River and source reduction and incidental sediment displacement in the Cuyahoga River.