Killer Whale Population Collapse - PCB Pollution


#PCB #POPs #Stockholm Convention #chemicals & waste #pollution #biodiversity

Polychlorinated biphenyls (PCBs) were once used widely until they were recognized as highly toxic and carcinogenic. Their production was banned in the United States in 1978. And they are one of the original twelve POPs covered by the Stockholm Convention on Persistent Organic Pollutants (POPs) which was signed in 2001 and became effective from May 2004. And one of the intrinsic properties of POPs is that they could magnify across trophic levels, dominantly in fat.

No wonder that in a recent publication on Science, Desforges et al. found high concentrations of PCBs within the tissues of one of the largest marine predators, the killer whale (Orcinus orca), among the most highly PCB-contaminated mammals in the world. Despite a near-global ban of PCBs about 15 years ago, the world's killer whales illustrate the troubling persistence of this chemical class. The health consequences? The authors modeled and showed that PCB-mediated effects on reproduction and immune function threaten the long-term viability of >50% of the world's killer whale populations. PCB-mediated effects over the coming 100 years predicted that killer whale populations near industrialized regions, and those feeding at high trophic levels regardless of location, are at high risk of population collapse.

There are many other stressors on the population of killer whale e.g. noise, habitat change, changes in the availability of prey which could and should be addressed. But emphasis on the actions of preventing more PCBs releasing into the environment should not be ignored. As once they enter the environment, it's hard to reclaim them back.

The parties to the Stockholm Convention can no longer produce PCBs and are obliged to stop using this chemical. However, existing equipment that contains or is contaminated with PCBs may continue to be used until 2025. To ensure that all PCB uses are ceased by 2025, parties, especially those that are developing countries or countries with economies in transition, will need support:

- To complete national inventories of all PCBs and related contaminated equipment;

- To improve the capacity and increase the knowledge of PCB equipment owners on proper maintenance of equipment to avoid further contamination;

- To establish proper storage of discontinued equipment and to ensure disposal of all the PCB oils and contaminated equipment in an environmentally sound manner.

Association 3 Herissons support the spirit of and lots of work under Stockholm Convention, and would also like to see more countries to be parties. Global problem requires Global Action.

For more details, please refer to the original Science publication and Stockholm Convention website.

(Desforges et al. (2018) Predicting global killer whale population collapse from PCB pollution. Science 361 (6409) 1373-1376. DOI: 10.1126/science.aat1953)