A look at the impact of plastics on human health
TORONTO — A proposed ban on some single-use plastics should serve as a wake-up call to Canadians concerned about the potential harms everyday items may pose, say experts who expect the move will spur research into settling ongoing questions about whether and how microplastic affects human health.
Ottawa's plan to add "plastic manufactured items" to the toxic substances list under the Canadian Environmental Protection Act (1999) cites evidence that microplastic pollution has found its way into shorelines and surface waters, sediment, soil, groundwater, indoor and outdoor air, drinking water and food.
But experts say challenges remain in definitively linking plastic or plastic particles to disease, cancer or other human health problems, outlining a nascent field of study where scientists have yet to reach consensus on methodology and sampling techniques, let alone definitive cause-and-effects.
Dalhousie University environmental studies professor Tony Walker, who has advised the federal government on this issue, says there's no question plastic pollution has harmed the environment, wildlife and their habitats.
It's not a huge leap to suspect it holds consequences for humans, too, he says, and that should be enough to start scaling back everyday use.
"Humans are part of the environment, so if it's impacting the environment — either directly or indirectly — it's going to be impacting us," says Walker.
"Maybe we don't have overwhelming evidence to quantify it yet, but we know we're ingesting it. We know we're breathing it in. But just because we don't have the evidence that yes, you know, a certain dose of plastic will give you this disease, or that disease ... I still think it's very prudent to take the precautionary approach."
By the end of 2021, plastic grocery bags, straws, stir sticks, six-pack rings, cutlery and food containers made from hard-to-recycle plastics would be phased from use by the proposal, which is seeking public input until Dec. 9.
Walker suggests people may want to consider ditching these everyday items now, as well as other common plastic items Ottawa considered banning, such as beverage bottles and caps, and hot and cold drink cups and lids.
While government research found "exposure to macroplastic pollution is not expected to be of concern for human health," it does note that plastic waste does breakdown in the environment — albeit very slowly — to produce microplastic waste.
Otherwise, these tiny particles, defined as less than five millimetres in size, also emerge in the form of microfibres that are released while washing laundry; as part of fibres that shed from clothing, furniture, and carpets; and can even be found in outdoor air thanks to vehicle tire wear-and-tear.
What all of that does to our bodies is under increasing scrutiny and attracting more interest from the medical sphere, says University of Toronto ecologist Chelsea Rochman, a scientific advisor to the Ocean Conservancy and a National Geographic Explorer.
She notes plastic pollution research began with public alarm over an obvious garbage problem emerging in oceans, gradually leading environmentalists and ecologists to examine the impact on shorelines, freshwater and land.
"People have measured it in stool so we know we eat it and excrete it. The next question is: How does it impact humans? And so people are starting to study that," says Rochman, pointing to about 10 investigations involving human cell lines or mice.