Microplastics in Our Waters: From Pollution to Human Consumption
By Mary Mahon
Microplastics have been impacting our ecosystems globally with growing awareness to the public, further studies conducted and adopting initiatives to address the growing problem. The reduction of single-use plastic has been important in reducing the levels of plastic waste entering our marine and freshwater environments. However, as the problem grows and persists, the impacts that have already been caused, along with efforts to develop a sustainable future, still require a larger push. The full impact of plastics and microplastics in marine and freshwater ecosystems continues to be studied, with a recent study showing that microplastics have entered the human food chain.
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What are Microplastics?
Microplastics are small pieces of plastic that are less than five millimetres (mm) in size and are absorbed and end up in marine and freshwater ecosystems. Microplastics are typically categorized in two ways: 1) Primary microplastics are purposely created products, including microbeads in commercial products for personal use, e.g. exfoliating scrubs and fibres broken down from textiles and fishing equipment. 2) Secondary microplastics are larger plastics broken down, including bottles, bags, and fishing equipment. Microplastics contain chemicals, including BPA (bisphenol A), phthalates and Perfluoroalkyl and Polyfluoroalkyl substances (PFAS), that can cause several health impacts, including disrupting hormones, cause cardiovascular issues and immune issues.
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While microplastics have been shown to be more dense accumulation in higher populated areas, microplastics can be found across the globe. They are spread through natural forces such as ocean currents and wind. As a result of natural forces, some areas have shown to have a dense microplastic accumulation, such as the Great Garbage Patch. The Great Garbage Patch is the largest accumulation of plastics that can be found in the North Pacific Ocean, accumulating in one location because of natural ocean movement. The Great Garbage Patch is a prime example of the plastic crisis.
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A study from 2016 noted that microplastics in Canada enter freshwater ecosystems through wastewater treatment plants, wastewater effluent overflow, and agricultural runoff. While microplastics typically enter marine ecosystems through terrestrial runoff, shipping waste, fishing and aquaculture discarding. Fibers from clothing and discarded fishing gear have shown to be amongst the higher levels of microplastics found in water. Fibers can enter the water streams through the breakdown of clothes through washing, wastewater treatment plants run off and breakdown of fishing gear. Freshwater and marine ecosystems connecting show that microplastics are widespread and impacting throughout water ecosystems.
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Microplastics entering the human food chain
Fish, shellfish, and other seafood are exposed to and consume microplastics directly and indirectly. Microplastics can be ingested through contaminated water or through prey. Predators are then susceptible to higher concentration levels of microplastics while moving up the food chain. This is a process called biomagnification. Additionally, this leads to higher levels of chemicals higher up the food chain. This is called bioaccumulation. For example, filter-feeding shellfish consume microplastics mixed in the water column, and phytoplankton-eating fish consume microplastics through consuming their prey.
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In recent years, studies have been carried out globally showing that humans consuming fish, shellfish and other seafood result in the microplastics entering the human food chain, which can lead to health impacts. A recent article showed that 180 out of 182 fish samples showed levels of microplastics. While most studies do not sample the whole fish but, predominantly, the fillet was tested, typically the part of the fish consumed by humans. Further studies could be carried out to assess the full impact of microplastics in fish consumed.
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Similarly, the health concerns of humans consuming microplastics include disruption to digestion, changes in the gastrointestinal tract and ingestion of harmful chemicals to the human body. Long term build up of toxins consumed could lead to further health risks. Currently, further studies, particularly over the long term, would need to be carried out to assess the full impacts of microplastics entering the human food chain. Additionally, harmful pathogens and bacteria can be found in microplastics, leading to the potential of foodborne illness in humans that consume contaminated fish, shellfish or other seafood.
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Efforts to address Microplastic Pollution
Many organizations and countries have attempted to address and take steps to combat microplastic pollution in the environment. Including banning single-use plastics, banning microbeads in personal care products, developing technology and processes to remove microplastics, campaigning, and managing waste disposal. Organizations, including The Ocean Cleanup and 4Ocean, have been making efforts to clean up the debris and plastics in the ocean and rivers through technology, campaigning and community efforts. The Ocean Cleanup uses technology to scale the marine debris and by cutting the flow of pollution in rivers, and cleaning the plastics that have built up in the ocean, with the goal of cleaning up 90% of floating plastic by 2040. While this goal is ambitious and would make significant positive impacts to the plastic pollution caused to date, the core of the problem remains. The plastic pollution issue is vast and will continue until the core of the issue is addressed through stopping plastic use and production, countries and individuals responsibly managing waste disposal, and enforcing effective policies and legislations.
Canada could have the opportunity to lead by example in addressing the plastic issue as it has the largest coastline in the world, joining the Arctic, Pacific and Atlantic Oceans. In 2018, Canada championed the Oceans Plastic Charter, focusing on the production, usage and managing plastics. Through this charter, Canada developed the Canada-wide Strategy on Zero Plastic Waste and Action Plan and a series of initiatives, providing funding investments in these initiatives to work towards a more sustainable future. However, Canadians produce an average of 3.3 million tonnes of plastic waste per year. While taking steps in combatting plastic waste is crucial as the problem grows, stronger efforts and enforcement of policies would be needed to show substantial results, and how to effectively address the problem. Additionally, there is a lack of studies in Canada on the full effects of the plastics and microplastics in freshwater and marine ecosystems. Leading to a lack of understanding of the true extent and scale of the issue in our ecosystems and impacts on human health.
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