Deeper insights into PCBs in orcas

• Main Authors: Dietz, Rune, Eulaers, Igor, Desforges, Jean-Pierre, Sonne, Christian
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Killer Whale; North Atlantic; Killer whale
• Online Access: https://pure.au.dk/portal/da/publications/deeper-insights-into-pcbs-in-orcas(5853c912-9067-4670-bf9c-5b963eb7a320).html

Having read the recent article by Jepson and Law (DOI:10.1126/science.aaf9075) we want to emphasise the worrying nature of the fact that at present many marine apex predators, including killer whales, remain highly polluted with PCBs despite world-wide initiatives over past decades to restrict the production and use of these compounds. Our research shows that, among a cocktail of industrial pollutants, PCBs are the primary driver of reproductive, immunotoxic and carcinogenic effects. While environmental PCB concentrations were indeed observed declining after legal mitigation, large body burdens remain in many top predators, especially in the North Atlantic. Moreover, both intentional and unintentional production of PCBs, as well the use and recycling of PCB-containing equipment, are contemporary primary and secondary sources. The Stockholm Convention therefore urges its ratifying parties to cease using PCB-containing equipment by 2025 and perform environmentally sound waste management by 2028. This means nonetheless that PCBs will continue to leach into the environment over the next decade. Given present-day observed reproductive failure in several killer whale populations we must urgently reduce the ultimate industrial PCB phase-out deadline before conservation of this species surpasses a tipping point. The IUCN Red List of Threatened Species does not state concern for killer whales as data are deficient. This urgently asks for international risk assessment, requiring in vivo and in vitro approaches to determine physiological effect thresholds of PCB exposure that allow identifying meaningful population impacts using state-of-the–art modelling. Worldwide collaborative efforts are crucial to identify populations at risk of extinction and those that could maintain this iconic species. Killer whales are excellent marine sentinel species, indicating that not one nation can address the persistent threat that is environmental PCB pollution. We believe the choice for international PCB mitigation is timely in order to not lose this canary in the coalmine.