Abstract
Polychlorinated biphenyls (PCBs) can provide crucial information into the bioaccumulation and biomagnification of POPs in marine mammals. Muscle tissue samples were obtained for detailed PCB congener specific analysis of all 209 PCBs in 11 species of marine mammals stranded across the coast of the UK between 2010 and 2013. At least 145 PCB congeners were found in each individual. The highest concentrations of PCBs were recorded in a killer whale (318 mg/kg lipid) and the highest toxic equivalent in a Risso's dolphin (1687 pg/g TEQ2005 wet). Concentrations of PCBs in the majority of samples exceeded toxic thresholds (9 mg/kg lipid) for marine mammals, highlighting the health risk they face from PCB exposure. Many PCB profiles did not fit typical ‘Aroclor’ signatures, but instead indicated patterns of congeners that are resistant to biotransformation and elimination. However, this study identified a novel PCB signature in a sei whale that has not yet been previously observed in marine mammals. The whale had a PCB profile that included lighter and inadvertent PCB congeners such as PCB 11, suggesting that the main source of exposure was through atmospheric deposition, rather than terrestrial discharges. Seven subsamples were chosen for chiral analysis of PCB 95, 136 and 149. The enantiomer fractions (EFs) of C-PCBs 95 and 149 were non racemic suggesting there may be enantiomer selective metabolism in marine mammals. Although there has been a shift in the literature towards emerging pollutants, this study acts as a stark reminder that PCBs continue to pose a significant risk to wildlife.
Highlights
Persistent organic pollutants (POPs) are a subset of chemicals that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effects to human health and the envi ronment
On average 150 different Polychlorinated biphenyls (PCBs) congeners were detected in the samples analysed, with at least 145 PCBs being detected in each sample
The greatest number of congeners were detected in the white beaked dolphin and Risso’s Dolphin (155 different PCBs), which is amongst the greatest number of different PCBs ever detected in one environmental sample
Summary
Persistent organic pollutants (POPs) are a subset of chemicals that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effects to human health and the envi ronment. Polychlorinated biphenyls (PCBs) are some of the most widely studied POPs, they are ubiquitous in the environment, and as a result are routinely detected in marine environmental samples (Domingo and Bocio, 2007; Letcher et al, 2010). Long range atmospheric transport of POPs has been widely docu mented and results in the accumulation of POPs in the Arctic with major source regions identified as North America and Western Europe (O’Sullivan and Sandau, 2013). The North Atlantic Ocean presents an excellent study area for the presence of POPs as it boarders two major PCB source regions The high lipophilicity and biomagnification of POPs results in the accumulation of high concen trations of these compounds in top predators, especially marine mam mals with high blubber contents in Arctic and sub-Arctic areas (Tanabe et al, 1983, 1987; Aguilar et al, 1999; Arnot and Gobas, 2004; Kelly et al, 2007)
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