PARENT SESSION

(06-10) Reduced infection resistance in polar bears (Ursus maritimus) with high polychlorinated biphenyl (PCB) exposure?

Lie, Elisabeth^*,1, Larsen, Hans Jørgen S.², Derocher, Andrew E.³, Lunn, Nick⁴, Norstrom, Ross⁵, Wiig, Øystein⁶, Skaare, Janneche Utne^1,2, ¹ National Veterinary Institute, Oslo, Norway² The Norwegian School of Veterinary Science, Oslo, Norway³ Norwegian Polar Institute, Tromsø, Norway⁴ Canadian Wildlife Service, Edmonton, Canada⁵ Canadian Wildlife Service, Hull, Canada⁶ Zoological Museum, Oslo, Norway

ABSTRACT- The present study investigates possible immune suppressive effects of high PCB exposure in polar bears (Ursus maritimus) from Svalbard/Barents Sea and Canada in 1995-1999. Specific immune function tests and induction of protective antibodies were used. PCBs were determined in 380 bears, immune globulin (IgG) in 494 bears, and lymphocyte response after in vitro stimulation with different mitogens in 130 bears. Furthermore, specific immune responses in bears (n=56) having high (Svalbard) and low (Canada) PCB exposure were determined in a vaccination model where bears were recaptured 6 weeks after immunisation. Significantly higher PCB levels were found in polar bears at Svalbard compared to Canada. Preliminary results have demonstrated that high PCB exposure of polar bears impairs IgG concentration (significant inverse correlation between IgG and PCBs, both sum PCB and specific congeners PCB99, 118 and 194), lymphocyte function (significant lower lymphocyte responses to lipopolysaccharide from E.coli and mycobacteria with high PCB blood levels) and the ability to produce antibodies following immunization of the bears with certain microbes (significantly higher antibody titres to influenza virus in Canada as opposed to Svalbard together with significantly higher PCB levels in the Svalbard bears). From the present preliminary results on effects of PCBs on the immune system of the polar bears it is reasonable to assume that PCBs are associated with decreased resistance to infections. Some results of the project will be presented and discussed.

Key words: PCBs, polar bears, effects, immune toxicity