Scientists have established that an alarming amount of microplastic is present in soils, the atmosphere, drinking water and more. But the effect on human health largely remains a mystery, they say.
It’s a mystery that will start to be unravelled with Ottawa’s $2.1 million in research grants to McGill University, Memorial University of Newfoundland and the University of Toronto for research into how microplastics affect humans.
The funding will help researchers determine whether Canadians have been exposed to microplastics in key areas such as food, food packaging, drinking water, indoor and outdoor air and dust.
“A lot of the initial studies have been to figure out where microplastics are. And we finally understand the stuff is pretty well everywhere,” said Dr. Jesse Vermaire, an associate professor of environmental science at Carleton University.
“So now the question is, what impact is it having?”
Going forward, research on the topic needs to be done with policy changes in mind, says Dr. Jennifer Provencher, a research scientist focused on plastic pollution with the federal department Environment and Climate Change Canada.
“We can keep stamp collecting by finding plastics in all the places that we look, but that’s not actually helping our policymaker colleagues. We need to tailor our research questions for the policy questions,” she said.
Provencher says she tells her academic friends they need to get to know at least three policymakers so they can share what they learn in their research with them and influence policy.
Sharply impacted
Microplastics are extremely small particles of plastic that are generally considered to be between five millimetres and one micrometre, which is one thousand times smaller than a millimetre. Even smaller than that are nanoplastics, measured in nanometres, which are a thousand times smaller than a micrometre.
“The number of people interested in microplastic pollution research and the number of people who have the expertise to answer these questions has greatly increased over the last 10 years,” said Provencher.
For many years, Provencher has been studying the effects of microplastic ingestion in seabirds, which she says are particularly vulnerable to ingesting marine plastic pollution.
“Most seabird species feed at or near the ocean surface, the same zone in which marine plastics occur at a high density,” Provencher and her colleagues wrote in a 2019 study. That study recommended best practices for studies into plastic and litter ingestion in marine birds.
In another study, Provencher and her colleagues suggested further research into the chemical behaviour of plastic additives in the arctic. It is those additives — not the plastic particles themselves — that are having detrimental effects on the health of seabirds, Provencher says.
“Some of those chemicals have endocrine and hormone disruption attributes. All those things could also be true for humans. But it’s really hard to study that in humans because we’re exposed to so many other things as well.”
In 2023, Provencher and her colleagues conducted a study looking at the presence of microplastics in biosolids, which is treated sewage waste that is used to fertilize agricultural soil.
They picked biosolid samples from nine Canadian provinces and found microplastic particles present in all 24 anaylzed samples, with concentrations ranging from 228 to 1353 particles per gram — much higher than the researchers had anticipated.
“Now that we know there are some areas like agricultural soils and marine sediments that are sharply impacted by microplastics, we need to start moving our toxicological models to study the human health and animal health effects,” Provencher said.
Plastic waste comes from many different sources, but a big volume of it is polyethylene and polypropylene, which are the kinds of plastics typically found in packaging materials, says Dr. Cathy Chin, a professor of chemical engineering at the University of Toronto.
She agrees that not much is understood about the health effects yet.
“Perhaps we need to step back and understand how to prevent the disintegration of the plastic. Or maybe we need to be able to figure out how to collect it, so that it doesn’t enter our ecosystem.”
Last fall, researchers at the University of Hawaii discovered an alarming rise of microplastics present in the placentas of Hawaiian mothers.
The researchers collected 10 placentas each year in 2006, 2013 and 2021.
In 2006, six of the 10 placentas contained microplastics. In 2013, they were present in nine of 10 placentas. In 2021, they were present in all.
“We believe that the plastics may be floating around in food or being inhaled. It’s coming through our digestive fluids or lungs, and the particles are getting absorbed through the gut and travelling through the bloodstream, and then somehow collecting in the placenta during pregnancy,” wrote Dr. Men-Jean Lee, one of the study’s researchers.
Dr. Chin is excited about the new funding from Health Canada.
“As you can see, this research involves multiple different disciplines: from material science engineers to health experts. I think this is a really good time for the government to fund these projects that will bring all the research together.”
