The Government of Canada undertook a thorough scientific review of the potential impacts of plastic pollution on human health and the environment.
Plastic pollution is considered to be plastic that is discarded, disposed of, or abandoned in the environment outside of a waste management system (such as a recycling facility or a landfill).
Plastic pollution is often classified by size, with macroplastics being larger than 5 millimetres (mm) and microplastics being less than or equal to 5 mm.
The improper management of plastic waste has led to plastics becoming pervasive in all parts of the environment.
Plastic pollution has been found on shorelines and in surface waters, sediment, soil, groundwater, indoor and outdoor air, drinking water and food. It has also been found in wildlife.
There is increasing global concern that plastic pollution may negatively impact human health and negatively impacts the environment.
The purpose of the draft science assessment is to summarize the current state of the science regarding the potential impacts of plastic pollution on human health and the environment, as well as to guide future research and inform decision-making on plastic pollution in Canada.
Release to the environment
Plastics from land and water-based activities can be released into the environment:
in their initial manufactured form, for example, as discarded single-use or short-lived products, such as plastic bags and straws, or through spills, such as plastic pellets lost during transport;
as large pieces of plastics, for example, fragments of plastic products or damaged fishing gear; or
as microplastics, for example, microfibres released from washing clothes.
Plastics enter the environment intentionally or unintentionally, such as through litter, environmental emergencies, or inadequate waste management.
Microplastics can also come from the breakdown of larger plastic items in the environment.
The presence of microplastics in outdoor air is largely thought to be attributable to tire wear and tear, while microplastics in indoor air result from the shedding of fibres from clothing, furniture, carpeting and household goods.
Human and environmental exposure
Humans may be exposed to microplastics by eating food and drinking bottled water and tap water, as well as from breathing indoor and outdoor air.
Single-use plastics are found in freshwater environments, while microplastic particles are found in fresh and marine surface waters. These particles have been found in aquatic organisms, specifically fish and shellfish. In addition, microplastic particles may eventually sink in aquatic environments, leading to their accumulation in the bottom sediment. They are also found in soil, where they may travel into groundwater. Additionally, microplastics have been detected in both indoor and outdoor air.
Science assessment findings
The Government of Canada summarized scientific information on plastic pollution in a draft science assessment. Information included in this assessment indicates that plastic pollution, in both macroplastic and microplastic form, is everywhere in the environment.
Macroplastics have been shown to cause physical harm to individual animals and to have the potential to negatively affect the habitat of animals.
The evidence for potential effects of microplastics on individual animals, the environment, and human health is less clear and requires more research.
The draft assessment finds that there are many sources that contribute to plastic pollution. It recommends pursuing action to reduce the presence of plastic pollution in the environment.
The assessment also recommends that more research is needed to address the knowledge gaps identified:
developing standardized methods for sampling, quantifying, characterizing, and evaluating the effects of macroplastics and microplastics;
furthering the understanding of the ecotoxicological effects of microplastics;
furthering the understanding of human exposure to microplastics;
furthering the understanding of the effects of microplastics on human health; and,
expanding and developing consistent monitoring efforts to include parts of the environment which are less studied, such as soil.