Accumulation and dose-response of hepatic DNA adducts in English sole ( Pleuronectes vetulus) exposed to a gradient of contaminated sediments

Abstract

Levels of hepatic DNA adducts and concentrations of fluorescent aromatic compounds (FACs) in bile were measured in English sole ( Pleuronectes vetulus) exposed for up to 5 weeks to a reference sediment amended with a sediment containing high concentrations of polycyclic aromatic compounds (PACs) from Eagle Harbor, Puget Sound, WA. Levels of hepatic DNA adducts increased linearly with both concentration of sediment polycyclic aromatic hydrocarbons (PAHs) and length of exposure, whereas concentrations of biliary FACs were dose-responsive to levels of sediment PAHs but attained steady-state concentrations after 2 weeks of exposure. The levels of DNA adducts and concentrations of biliary FACs in fish exposed to the reference sediment remained at baseline levels throughout the exposure. Formation of PAC-DNA adducts was observed in liver of English sole injected with an extract of Eagle Harbor sediment (EHSE) and in English sole hepatocytes incubated with EHSE or the neutral fraction of EHSE containing predominantly PACs. In addition, DNA adduct and biliary FAC levels measured in feral English sole captured from Eagle Harbor, when compared with levels measured in fish from the laboratory sediment exposure study, also suggested accumulation of DNA adducts in the fish captured from Eagle Harbor. These findings, in conjunction with previous studies showing PAC-DNA adducts are persistent in fish, suggest that a substantial proportion of PAC-induced DNA damage was not readily repaired in English sole, and thus, measurement of hepatic DNA adducts can be used as an indicator of cumulative exposure to genotoxic PACs.