The Hidden Side of Plastic Pollution: Tracking Chemical Additives in Ontario Waters

Keywords: Plastic Additives, Passive Sampling, Persistent, Mobile, and Toxic, Water Pollution

My interest in environmental chemistry began during my undergraduate thesis, where I studied how different types of microplastics weather in the environment. Watching these plastics slowly break down and transform in different environments sparked a lasting curiosity about what they release and how those changes affect our ecosystems. That curiosity led me to pursue graduate studies in environmental chemistry, first as a master’s student focused on developing new ways to monitor plastic-associated contaminants, and later as a PhD candidate at Toronto Metropolitan University. As my research has evolved, so too has my commitment to tackling plastic pollution more broadly. Outside of my research, I volunteer with the University of Toronto Trash Team and Girls SySTEM Toronto, where I advocate for sustainable practices and mentor young women pursuing careers in science.

Plastics have become essential in modern life, used in everything from clothing and electronics to food packaging.¹ These products are known to contain thousands of chemical additives that give them, for example, their flexibility, durability, and colour.^2,3 As plastics break down in the environment, these additives can leach into surrounding waters, entering aquatic systems.^2,3 Some of these additives are persistent, mobile, and toxic (PMT), meaning they resist natural breakdown, move readily through water, and can have harmful effects on ecosystems and potentially on human health.^1,3 Because of these properties, PMT plastic additives can often bypass conventional wastewater treatment systems, allowing them to flow directly into rivers and lakes.² Once released, these invisible pollutants can travel far from their sources, contaminating surface waters and even entering drinking water supplies.^1-3 While plastic pollution is often thought of as visible litter, these chemical additives represent an invisible but ever-growing contamination issue.³

My research focuses on identifying where these pollutants come from, how they move through our water systems, and which ones may pose the greatest risks. To investigate this, I use passive sampling methods; small devices that act like “chemical sponges,” slowly collecting contaminants from the water over time.⁴ This approach provides a more accurate picture of long-term pollution than traditional grab samples.⁴ Over the past two years, I have deployed these samplers at multiple sites across Ontario, including rivers, creeks, wastewater treatment plants, and nearshore areas of Lake Ontario. Early findings suggest that wastewater effluent may be a major pathway through which PMT plastic additives enter the lake, highlighting the need to better understand and manage pollution from urban sources.

By identifying and prioritizing the most concerning additives, my research aims to help bridge the gap between scientific evidence and policy action. The goal is to provide data that can support future regulations and more sustainable chemical management in Canada.

Plastic pollution doesn’t disappear when the visible waste fades, it continues through the release of chemical additives that can persist, move through waterways, and accumulate in ecosystems.^1-3 These substances can have lasting impacts on both environmental and human health.^1-3 Understanding how these additives travel, where they come from, and the risks they pose is essential for protecting our water resources and building a cleaner, more sustainable future.

References: 

1. Reemtsma, T.; Berger, U.; Arp, H. P. H.; Gallard, H.; Knepper, T. P.; Neumann, M.; Quintana, J. B.; Voogt, P. De. Mind the Gap: Persistent and Mobile Organic Compounds – Water Contaminants That Slip Through. Environ Sci Technol 2016, 50 (19), 10308–10315. 

2. Fries, E.; Grewal, T.; Sühring, R. Persistent, Mobile, and Toxic Plastic Additives in Canada: Properties and Prioritization. Environ Sci Process Impacts 2022, 24 (10), 1945–1956. 

3. Hale, S. E.; Arp, H. P. H.; Schliebner, I.; Neumann, M. What’s in a Name: Persistent, Mobile, and Toxic (PMT) and Very Persistent and Very Mobile (VPvM) Substances. Environ Sci Technol 2020, 54 (23), 14790–14792. 

4. Gong, X.; Li, K.; Wu, C.; Wang, L.; Sun, H. Passive Sampling for Monitoring Polar Organic Pollutants in Water by Three Typical Samplers. Trends in Environmental Analytical Chemistry2018, 17, 23–33.

About Author: Ericka De Oliveira