Genotoxic Effects in relation to Polycyclic Aromatic Hydrocarbons in Blood from Female Common Eiders (Somateria mollissima) in Arctic Environments
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- Institutt for biologi 
Increasing intensity of shipping, off-shore oil exploitation and cruise ship tourism are expected to enhance the background levels of polycyclic aromatic hydrocarbons (PAHs) in Arctic areas. Studies on possible relationships between this group of genotoxicants and genotoxic damage on the biota living in these areas are thus important. Most previous studies on genotoxic effects of PAHs have focused on the 16 parent compounds listed by United States Environmental Protection Agency (US-EPA). However, research has found alkylated PAHs to induce toxic effects in the biota. The common eider population at Svalbard has been suggested to be threatened by this contamination. Common eiders are low trophic level birds, and thus they are expected to have low biomagnification of PAHs. The breeding habits of these birds also make them prone to increasing levels of PAHs during the fasting period.In the present study, whole blood from incubating common eider females was analysed for correlation between genotoxic damage and concentrations of parent PAHs and alkylated PAHs in Tromsø and remote Arctic areas. The genotoxic damage was measured as frequency of DNA double-strand breaks (DSB) and mean molecular length (MML) of the resulting fragments. Sampling was done at three locations in Kongsfjorden (Mietheholmen, Storholmen and Breholmen) and one near Tromsø (Grindøya). The results showed similar blood levels of PAHs at all four locations. The levels of PAHs were generally low, below detection limit for all types of PAHs for 64 % of the birds. The birds at Grindøya had significantly higher frequency of DNA-DSBs compared to the birds at Breholmen in Kongsfjorden. No significant differences in DNA-FTM were found between the other locations.A significant positive relationship between DNA-FTM and PAH in blood collected from individuals at Grindøya was found, even in the low concentrations in the present study. The alkylated PAHs were found to be the major contributor to this relationship, with a significant correlation to DNA-FTM. Parent PAHs, however, showed no correlation with DNA damage. This highlights the importance of studies of all types of PAHs when investigating possible genotoxic effects. In Kongsfjorden, no significant correlation between DNA-FTM and types or sum PAH in blood was found. The low significance levels indicate that individual variation may be important in the Kongsfjorden location. The individuals were suggested to be influenced by differences in sampling time during the incubation period, exposure to other contaminants, external conditions or biological factors, such as feeding habits. There may also be a closer coupling between the common eiders and their environment at Grindøya than in Kongsfjorden. Thus, a positive correlation between genotoxicity measured as frequency of DNA-DSB and different types and concentrations of PAHs cannot be dismissed in Kongsfjorden. Further studies are recommended to include knowledge and observations on the start of incubation, for more deliberate choices of sampling times. Additionally, further studies on genotoxicity of PAH should also include PAH metabolites to review the full genotoxic damage induced by PAHs.