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Regulating Persistent Organic Pollutants (POPs) and Their Impact on Humans and Marine Mammals

By: Amy Jordan

Media from Wix

Some may be familiar with the notorious “dirty dozen,” a list of twelve Persistent Organic Pollutants (POPs) requiring immediate action by the Stockholm Convention, a global treaty designed to protect us and the earth from their detrimental effects. Not only do these pollutants disastrously affect human health and the environment, but there is a third party particularly harmed by these chemicals: marine mammals, particularly cetaceans such as killer whales. Contamination from these chemicals has been found even in the Arctic and Antarctic oceans, showing that even though POPs are controlled by various regulations, the harm they inflict on the environment and living beings is far from over.

POPs are carcinogenic and persistent chemicals that bioaccumulate up the food chain, meaning that they become magnified and more toxic in higher trophic level animals, such as whales, dolphins, pinnipeds, and more. The most common POPs are organochlorine pesticides, such as DDT, industrial chemicals, and polychlorinated biphenyls (PCBs), which are particularly harmful to marine mammals. Organochlorine pesticides were used for public health purposes and in agriculture for decades and are still used by some countries, while there are still significant amounts of PCBs in stockpiles or contaminated materials since the current management strategy for many nations is purely containment. Not only are they toxic, but POPs also don’t break down easily, and are easily transported around the atmosphere and the environment, including the oceans. Regarding human health, exposure to POPs causes cancer and neurological effects, and damage to vital biological systems such as our productive and immune systems.

Studies have shown that marine polar environments are “sinks” for these chemicals, even though they are not used in those areas, demonstrating just how easily POPs can disperse and spread all over the globe. The high concentrations of POPs, particularly PCBs in marine mammals, clearly show that current regulations and legislation are insufficient to combat the problem. This means that the conservation of marine mammals as well as the safeguarding of human health depends on new initiatives to manage and alleviate the damage caused by these industrial chemicals.

Marine mammals are specifically harmed due to their higher trophic level status due to the bioaccumulating nature of POPs, specifically PCBs. Additionally, the increased vulnerability of marine mammals can be attributed to their physiology since the enzymes found in their bodies cannot break down or degrade the toxins, which can result in sterility, stillbirths, shortened lifespan, and other serious consequences. The killer whale is the most PCB-contaminated mammal species on the planet because of their high trophic level, long lifespans, and how they can transfer the toxin to their young through feeding. Studies have shown that populations of killer whales and other cetaceans have been reduced due to PCBs. Moreover, there is also added risk for humans if people eat POP-contaminated fish.

Signed by numerous countries including the US, the Stockholm Convention is an international treaty specifically for the management and regulation of POPs, yet it has not been ratified by the US. The Stockholm Convention is a useful global framework for POPs, but there needs to be more prioritization and urgency regarding the regulation and mitigation of them. Currently regulating 29 POPs, the Convention created a scientific review process, restricts trade of POPs, and requires both national action plans and the adoption of control measures to reduce and eliminate (whenever possible) the release of POPs. According to the US Department of State: “the United States signed the Stockholm Convention in 2001 but has yet to ratify because we currently lack the authority to implement all of its provisions.” Other political reasons include the fear of treaties infringing on national sovereignty. In the US, ratification requires changes to two federal laws: the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) which regulates pesticides, and the Toxic Substances Control Act (TSCA) which regulates industrial chemicals. These statutes are in need of an update, and since the science regarding the dangers of toxic chemicals can change frequently, this would only benefit current legislation in the US.

Solutions to the problem of toxic environmental contaminants lie in the fact that the marine and environmental pollution caused by these chemicals was preventable, and now action must be taken to ensure that the damage is mitigated and living beings are protected. Regarding regulatory framework, greater environmental monitoring and stricter controls or eliminations on activities that produce POPs can be established. There are many possible ways to help, and one bill offered a solution (H.R.4800 - POPs, LRTAP POPs, and PIC Implementation Act of 2006), but it did not receive a vote when it was introduced to Congress in 2006. The United States would benefit from either ratifying the Stockholm Convention or passing similar legislation because the health of humans and ecosystems is of utmost importance. To conserve marine mammals, global efforts need to be mobilized and nations need to prioritize eliminating POPs, not just reducing their use or solely containing the hazard. Lastly, adopting a health-based standard using a precautionary approach to industrial chemicals and pesticides would benefit not only human health but marine mammals as well.


Works Cited

H.R.4800 - 109th Congress (2005-2006): Pops, LRTAP Pops, and pic ... (n.d.). Retrieved April 19, 2023, from

Megson, D., Brown, T., Jones, G. R., & Robson, M. (2021, October 20). Polychlorinated biphenyl (PCB) concentrations and profiles in marine mammals from the North Atlantic Ocean. Chemosphere. Retrieved April 19, 2023, from

Tanabe, S. (2002, June 4). Contamination and toxic effects of persistent endocrine disrupters in marine mammals and birds. Marine Pollution Bulletin. Retrieved April 19, 2023, from

Tanabe, S., & Iwata, H. (2003, July 1). Global contamination by persistent organochlorines and their ecotoxicological impact on marine mammals. Science of The Total Environment. Retrieved April 19, 2023, from

U.S. Department of State. (2021, January 5). Stockholm Convention on Persistent Organic Pollutants - United States Department of State. U.S. Department of State. Retrieved April 19, 2023, from,and%20in%20technical%20working%20groups.

U.S. ratification of the Stockholm Convention: Analysis of Pending Pops Legislation (February 2006). Center for International Environmental Law. (2015, March 24). Retrieved April 19, 2023, from

World Health Organization. (n.d.). Food safety: Persistent organic pollutants (pops). World Health Organization. Retrieved April 19, 2023, from,human%20health%20and%20the%20environment.

Zhou, Y., Roberts, D. A., Jartun, M., & Eggleton, J. (2017, July 8). Persistent threats need persistent counteraction: Responding to PCB pollution in marine mammals. Marine Policy. Retrieved April 19, 2023, from


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