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Abstract
In two experiments the responses of the antioxidant enzymes catalase and superoxide dismutase (SOD) were measured in liver of flounder with exposure to PAH and other pollutants as an indicator of contaminant-enhanced oxyradical generation. In a short-term experiment flounder were injected i.p. with 10 mg benzo[a]pyrene (BaP) per kg body weight, and samples taken after 0, 1, 2, 3, 4 and 7 days. In a mesocosm experiment flounder were exposed for 6 months to heavily contaminated harbor sludge containing PAH. Hepatic catalase and SOD activities were indicated to increase slightly with exposure to harbor sludge, but the differences were not statistically significant (P>0.05). No changes were detected in either activity with i.p. injection of BaP. As a comparison, induction of cytochrome P4501A, by means of hepatic 7-ethoxyresorufin O-deethylase (EROD) activity, and excretion of PAH metabolites in the bile were also measured as well-established biomarkers for PAH exposure. In the short-term experiment a marked increase occurred in EROD activity and enhanced 3-OH-BaP levels were detected in the bile after injection. In the mesocosm experiment high levels of 1-OH-pyrene were detected in the bile after exposure. The results of both experiments suggest that long-term rather than short-term exposure, plus possibly the presence of a mixture of contaminants, is necessary to invoke a response in antioxidant enzymes. This combined with the fact that oxyradical generation can also be increased by factors other than pollution alone e.g. oxygen tension, indicates a limited application for such measurements as a biomarker for PAH contamination per se.
