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It’s raining plastic in Canada, scientists say. But no one knows the source or toxicity
According to a U.S. study, geologists studying the effects of nitrogen pollution have unwittingly found tiny plastic fibres, beads and shards within rainwater samples collected from the remote slopes of the Rocky Mountain National Park in Denver, Colorado, located 1,763 km away from Canada.
By: Devika Desai
It’s been raining plastic in Canada, researchers have found in the last two years.
And no one knows where it’s coming from. Or what it can do.
A U.S. survey published in May, made headlines around the world last week due to its eye-catching title, “It is raining plastic.” According to the survey, geologists researching the effects of nitrogen pollution, unwittingly found tiny plastic fibres, beads and shards within rainwater samples collected from the remote slopes of the Rocky Mountain National Park in Denver, Colorado, located 1,763 km away from Canada.
“It wasn’t entirely surprising to find them in an urban environment,” said Gregory Wetherbee, the study’s lead researcher, “but when we saw them in the remote areas of the mountain, we started to become a little more surprised at those results.”
Although the topic of microplastics — plastic particles smaller than five millimetres long, the size of a breadcrumb — is one in its infancy, research into the topic has proven the extent to which plastic pollution has pervaded the planet’s most remote corners.
Liisa Jantunen, who has been researching microplastics in the Canadian Arctic and Great Lakes since 2017, says the survey’s discovery is more common than one might think. “We’ve been collecting snow in places like Whitehorse, Alert and Eureka as well as in Southern Ontario and we’ve found microplastics in all our snow samples, often in microfibre form,” she said.
The presence of microplastics isn’t confined to snow samples. “We’ve also found them deep in the ocean sediment and in plankton,” she said. “Everywhere we look, we find it.”
The level of microplastic concentration is much higher in urban environments such as Toronto than in more remote regions simply due to the wide variety of sources that create/consume plastic. Dryers and vaccum cleaners for example, produce microfibres such as lint and dust, according to Jantunen. The pollutant concentration decreases the further one moves away from urban centres.
“We’re finding a good amount especially in the Arctic sediment, since the sedimentation rate (rate by which particles settle down) is quite low versus the lakes,” explained Jantunen, estimating that for every gram of sediment, there could be up to hundreds of microplastic particles and for every litre, hundreds to thousands of particles.
Earlier this year, European researchers found tiny plastic fibres in the French Pyrenees mountain regions, which they said were carried by the wind. They estimated that France is “blanketed by 2,000 tons of plastic particles” every year.
Swiss researchers also discovered alarmingly high concentrations of microplastics, as high as 14,000 particles per litre of snow samples in the Arctic snowfields, according to a report published this month.
The minuscule size of microplastics, often due to the degradation of larger plastics, makes them particularly buoyant and easily transportable through the atmosphere and water systems.
“It’s not a constant source in the Canadian Arctic,” said Jantunen. “There are winds that come from over an urban city, where they pick (microplastics) up and transport it to the Arctic. And then in the winter, there is that Arctic haze where you have almost a vortex around that keeps it in.”
Waste-water treatment plants also produce huge quantities of microplastics, despite removing close to 99 percent of pollutants in water, according to Jantunen.“The remaining one percent is still a huge mass of microfibre going into that environment.”
The size of microplastics also presents a new challenge to the global pollution problem — no one knows where it’s coming from. Evidence found in the Canadian Arctic could originate in Toronto, but could just as well be coming from Europe, said Jantunen. “While we can say that urban centres are sources, we can’t pinpoint.”
“The atmosphere doesn’t obey national boundaries, it just goes where it wants.”
Part of why it’s difficult to identify where microplastics originate is because of the lack of technology to analyze the evidence, according to Chelsea Rochman, who researches plastic pollutants in freshwater and marine ecosystems at the University of Toronto.“In my lab, we might spend about 40 percent of the time doing method development, which I would love to not have to do.”
As her research progresses, Rochman said she has started to see microplastic pollution as different from big plastic pollution, namely in its ability to self-transport in ways big plastics can’t. “It’s similar to the way we talk about persistent organic chemical pollutants in that it seems as if they’re everywhere because they have this ability to transport everywhere,” she said. “They have chemicals on them that can bioaccumulate and are toxic.”
But just as with its source, very little is known about the potential toxicity of microplastic pollution. Unlike big plastics, which cause larger issues of entanglement, microplastics are able to enter biochemical pathways within the body and have been used as “carriers of medication” in mainstream medicine. Little is known about whether they have any effect or are simply excreted.