DNA adduct formation and DNA strand breaks in green-lipped mussels (Perna viridis) exposed to benzo[a]pyrene: Dose- and time-dependent relationships

Green-lipped mussels, Perna viridis, were exposed to 0, 0.3, 3 and 30 mug l (-1) (nominal concentrations) B[a]P under laboratory conditions over a peri od of 24 days. Mussels were collected on day 0, 1, 3, 6, 12, 18 and 24, and the levels of DNA adducts and DNA strand breaks in their hepatopancreas ti ssues monitored. Mussels exposed to 0.3 and 3 mug l(-1) B[a]P showed marked increases in strand breaks after 1 day of exposure. DNA strand break level s in these mussels remained high and significantly different from the contr ol values until day 3 for the 0.3 mug l(-1) treatment group, and day 6 for the 3 mug l(-1) treatment group. This was followed by a gradual reduction i n strand breaks. After 12 days, the levels of both groups had returned to t he same level as that of the control. No increase in DNA strand breaks was observable in mussels exposed to 30 mug l(-1) B[a]P in the first 12 days of exposure, but a significant increase was observed from day 12 to day 24. I ncreasing B[a]P concentrations resulted in elevated DNA adduct levels after 3-6 days of exposure, but this pattern of dose-related increase disappeare d after 12 days. These results indicate that a better understanding of the complex interactions between exposure levels and durations is crucially imp ortant before DNA adduct levels and DNA strand breaks in P. viridis can be used as effective biomarkers for monitoring genotoxicants in marine waters. (C) 2001 Elsevier Science Ltd. All rights reserved.