Use of skin biopsies for assessing levels of organochlorines in walruses (Odobenus rosmarus)

Skin and blubber samples of ten adult male Pacific walruses (Odobenus rosma rus divergens) from Alaska were used to investigate the relationship betwee n organochlorine (OC) levels in skin and blubber of individuals. For analys es we selected 11 components that were quantified in the blubber of all ind ividuals: hexachlorocyclohexanes (alpha HCH and beta HCH), the DDT (dichlor odiphenyltrichloroethane) metabolite p,p'DDE, oxychlordane, and 7 individua l PCB congeners, 28, 99, 105, 118, 138, 153 and 180. The correlation betwee n the levels in the two types of tissues was significant and the relation w as isometric for all components. The regression coefficient between levels in blubber (dependent variable) and levels in skin (independent variable) w as different from I for only four of the components. The mean levels in the two types of tissues were significantly different for 3 of the 11 chemical components (beta HCH, oxychlordane, and PCB38). Although this analysis is based on only ten individuals, we propose that skin samples taken by biopsy darts can be used to monitor OC levels in walruses. In August 1993 skin bi opsies were collected from 25 adult male Atlantic walruses (O. r. rosmarus) at haul-out sites in southeastern Svalbard in the Norwegian Arctic and fro m 28 walruses of different sex and age at haul-out sites at Franz Josef Lan d in the Russian Arctic. The mean levels of OCs were 2-10 times higher at S valbard than at Franz Josef Land. The dominant OC component was PCB13 in bo th areas. A principal component analysis detected differences between areas in OC levels but not in patterns. Since the Franz Josef Land samples were mainly taken from females and young individuals and the Svalbard samples we re taken largely from adult males, we believe the differences in tissue OC levels observed from these areas can be explained by differences in sex and age of the walrus sampled. Comparable organochlorine levels in skin sample s from walruses from other areas are not available. However, compared to th e corresponding OC levels found in walrus blubber in other areas, the OC le vels from Svalbard and Franz Josef Land are higher. The high levels of OCs in walruses from Svalbard and Franz Josef Land may be a combined effect of high pollution level in the environment and seal-eating habits. In the pres ent study we show that it is possible to use skin biopsies taken by a non-d estructive method to assess OC levels in walruses.