PCBs and OH-PCBs in polar bear mother–cub pairs: A comparative study based on plasma levels in 1998 and 2008
2012
Bytingsvik, Jenny | Lie, Elisabeth | Aars, Jon | Derocher, Andrew E. | Wiig, Øystein | Jenssen, Bjørn M.
The aim of this study was to examine the plasma concentrations and prevalence of polychlorinated biphenyls (PCBs) and hydroxylated PCB-metabolites (OH-PCBs) in polar bear (Ursus maritimus) mothers (n=26) and their 4months old cubs-of-the-year (n=38) from Svalbard to gain insight into the mother–cub transfer, biotransformation and to evaluate the health risk associated with the exposure to these contaminants. As samplings were performed in 1997/1998 and 2008, we further investigated the differences in levels and pattern of PCBs between the two sampling years. The plasma concentrations of Σ₂₁PCBs (1997/1998: 5710±3090ng/g lipid weight [lw], 2008: 2560±1500ng/g lw) and Σ₆OH-PCBs (1997/1998: 228±60ng/g wet weight [ww], 2008: 80±38ng/g ww) in mothers were significantly lower in 2008 compared to in 1997/1998. In cubs, the plasma concentrations of Σ₂₁PCBs (1997/1998: 14680±5350ng/g lw, 2008: 6070±2590ng/g lw) and Σ₆OH-PCBs (1997/1998: 98±23ng/g ww, 2008: 49±21ng/g ww) were also significantly lower in 2008 than in 1997/1998. Σ₂₁PCBs in cubs was 2.7±0.7 times higher than in their mothers. This is due to a significant maternal transfer of these contaminants. In contrast, Σ₆OH-PCBs in cubs were approximately 0.53±0.16 times the concentration in their mothers. This indicates a lower maternal transfer of OH-PCBs compared to PCBs. The majority of the metabolite/precursor-ratios were lower in cubs compared to mothers. This may indicate that cubs have a lower endogenous capacity to biotransform PCBs to OH-PCBs than polar bear mothers. Exposure to PCBs and OH-PCBs is a potential health risk for polar bears, and the levels of PCBs and OH-PCBs in cubs from 2008 were still above levels associated with health effects in humans and wildlife.
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