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The POP Problem

By Ramneek Cheema

July 10, 2023


Haida GwaiiPictured are the remote islands of Haida Gwaii.



BiomagnificationThe above figure is demonstrating the biomagnification process seen within the marine environment. POPs are represented in red circles. The figure shows the POPs entering the marine environment and then travelling up the trophic levels, beginning with phytoplankton, then zooplankton, followed by herring, salmon and lastly orcas. As we travel up the trophic levels, we see an increase in POP concentration, denoted by the red circles becoming larger.

We can find pollutants everywhere. Even thousands of kilometers away from industrial sites we see pollutants manifest. These pesky pollutants we often see are referred to as Persistent Organic Pollutants, with the shorthand form POPs. POPs have 4 common characteristics. One, they are long-lasting, meaning they aren’t easily degraded by the environment. Two, they obtain the ability for long range transport making them borderless. Three, they cause tremendous amount of harm to human and environmental health. Four, they can not only bioaccumulate in organisms but biomagnify. Biomagnification is the process in which concentrations of contaminants are greater at higher trophic levels than at lower. Simply put, we see a greater concentration of these POPs in predators than in prey. Persistence and mobility create a troublesome combination, making these nasty chemicals a global concern. POPs have an inclination to accumulate in fat. This love affair with fat makes marine mammals prone to accumulating large amounts of these compounds. Seafood is littered with these pollutants making the primary route of exposure for humans through seafood consumption. As a result, rural coastal communities are particularly vulnerable as their primary nutrient source often comes from seafood. Due to their large seafood consumption, these communities often face a high prevalence of nutrition-related chronic diseases. The effects of climate change such as decrease in pH levels (ocean acidification) and temperature increases exacerbate the biomagnification process these POPs undergo. The question now becomes, is there a way in which we can predict the concentration levels of these POPs in the marine trophic levels in 25 years, 50 years or 100 years?

Human and ocean healthWhat if I told you there was a way to peek into the future? We can use a quantitative modelling framework in order to develop simulations to project the concentration levels of these contaminants at different trophic levels throughout the years under different climate change scenarios. These climate change scenarios could be under high mitigation tactics (low carbon emissions), and/or low mitigation tactics (high carbon emissions). Taking it one step further, we can use these climate change projections on the availability of fish stocks to simulate and develop a potential nutritionally adequate and low POP diet. The information from these diet simulations would allow rural communities to make more informed decisions on their diet but also allow them to prepare for future scenarios.

Through many years of creating synthetic harmful chemicals for our own selfish uses and with no regard for the environmental impact, we now are seeing some members of our society disproportionately being exposed resulting in adverse health consequences. These model simulations force us to consider the many ways ocean conditions affect human health and vice versa. We are one health. The concept of one health impels us to remember we must support sustainable, equitable and effective solutions to the many of today’s problems.

Links for more information:

To learn more about POPs:

Environmental Protection Agency. Persistent Organic Pollutants: A Global Issue, A Global Response. EPA.

Nadal, M., Marquès, M., Mari, M., & Domingo, J. L. (2015). Climate change and environmental concentrations of POPs: A review. Environmental Research, 143, 177–185.

To learn more about One Health:

Kenny, T.-A., Archambault, P., Ayotte, P., Batal, M., Chan, H. M., Cheung, W., Eddy, T. D., Little, M., Ota, Y., & Petrin-Desrosiers, C. (2020). Oceans and human health—Navigating changes on Canada’s coasts. Facets, 5(1), 1037–1070.

To learn more about modelling:

Ainsworth, C. H., Samhouri, J. F., Busch, D. S., Cheung, W. W. L., Dunne, J., & Okey, T. A. (2011). Potential impacts of climate change on Northeast Pacific marine foodwebs and fisheries. ICES Journal of Marine Science, 68(6), 1217–1229.

Alava, J. J., Cisneros-Montemayor, A. M., Sumaila, U. R., & Cheung, W. W. (2018). Projected amplification of food web bioaccumulation of MeHg and PCBs under climate change in the Northeastern Pacific. Scientific Reports, 8(1), 1–12.

Johnson-Down, L., Willows, N., Kenny, T.-A., Ing, A., Fediuk, K., Sadik, T., Chan, H. M., & Batal, M. (2019). Optimisation modelling to improve the diets of First Nations individuals. Journal of Nutritional Science, 8, e31.

Willows, N., Johnson-Down, L., Kenny, T.-A., Chan, H. M., & Batal, M. (2019). Modelling optimal diets for quality and cost: Examples from Inuit and First Nations communities in Canada. Applied Physiology, Nutrition, and Metabolism, 44(7), 696–703.