They're in the air, soil and Arctic ice. There's even a massive soupy patch three times the size of France strewn across the Pacific Ocean.

Microplastics have been found in almost every environment on the planet, and according to a Marketplace investigation, they are also in Canada's leading bottled water brands.

Researchers at McGill University tested a sampling of Aquafina, Dasani, Eska, Naya and Nestle Pure Life brands, which, according to Euromonitor International, had combined Canadian sales of more than $1 billion in water last year.

The companies market their products with labels and promotions that suggest purity, but microplastics were found in each brand, even in glass bottles of Eska water — albeit at lower levels than its plastic counterpart.

"The fact that we have plastic in a bottle of water that is glass suggests that the plastic is not just coming from ... the bottle itself or the [bottle] cap," said Nathalie Tufenkji, who led the research at McGill's Biocolloids and Surfaces Laboratory.

"It could be coming from the environment where you're having the bottling process take place."

Tufenkji's team tested bottled water purchased in Vancouver, Calgary, Toronto and Montreal. Thirty of the 50 bottles tested had microplastics.

Microplastics — tiny shards of plastic less than five millimetres (5,000 microns) in length — can come from a variety of sources: daily wear and tear of tires, washing clothes that have plastic fibres or the breakdown of plastic bottles and bags.

Washing into waterways

As the plastic breaks into microscopic pieces, it often washes into rivers, lakes and waterways. It's not known how the microplastics got into the bottled water.

In total, 12 types of plastics, including the types in bottle caps and water bottles — polyethylene and polyethylene terephthalate (PET) — were found in the water tested. Other types found include polyvinyl acetate, nylon, rayon, polystyrene and polytetrafluoroethylene.

A majority of the particles above 100 microns — about the width of a hair — were identified as plastic. Some of the particles smaller than that were also identified as plastic, using a different method. Tufenkji isn't sure what the other particles are but suggests they could be organic matter such as dust.

A sample of the particles found after bottled water is dyed and filtered. (McGill University)

The team at McGill found that on average there were 5.08 particles per 500 millilitres of water for particles more than 100 microns, while the average for particles less than 100 microns jumped to 725.12 per 500 millilitres.

Particle counts varied from bottle to bottle. One had 96 particles while another had 2,268.

"We can't hyper-extend on the meaning of these results," said Tufenkji. "But we do know that … it's something worth looking into more closely."

When informed of the tests results, all five brands told Marketplace they take food safety, quality control and filtration seriously — while maintaining bottled water is safe. Nestle said it had found microplastics in its bottled water at trace levels.

' Living in this big experiment'

The effects, if any, of microplastics on humans aren't known, but there have been lab studies looking at their impact on animals.

Chelsea Rochman, an ecologist at the University of Toronto and a leading microplastics pollution expert, has seen the effects microplastics can have when fed to animals like fish. They include liver toxicity, initial stages of tumour formation and endocrine system disruption.

University of Toronto ecologist Chelsea Rochman holds a jar of seawater from San Francisco Bay. Embedded in the top layer of seawater are bunches of confetti-like specks, many of which are likely microplastics, she says. (Dave MacIntosh/CBC)

Rochman said there is evidence that these particles are translocating into other parts of animals such as the livers of fish and mice. Even smaller nanoplastic particles have been found in the brains of fish.

"Should we be concerned? Yes, we should be concerned that there's a material that we're using so prevalently in our society that's become so ubiquitous," she said. "Should we be concerned for [human] health? We still need to do some work on that."

While it's believed most microplastics will be excreted by the human body, there is concern, according to a United Nations Food and Agriculture Organization report, that particles of less than 150 microns can pass through the intestinal wall and end up in the bloodstream and organs.

"This idea that they can transfer is certainly something that we're interested in. We are studying this in our lab with fish," said Rochman.

It's been shown that toxic chemicals — like flame retardants or polychlorinated biphenyl (PCB) — can be absorbed and released by plastic, harming fish health.

"The dose makes the poison," said Rochman. "For plastics, it's really important that we know the dose…. We're exposed to things all the time, we humans are living in this big experiment right now of all the chemicals and contaminants we're exposed to."

Bernard Robaire, a reproductive toxicologist at McGill University, says if the concentration of a chemical is barely detectable, it likely won't have any effect.

"When you talk about risk, it's a combination of exposure and harm. So if the exposure [to a chemical] is very, very low and the harm is high, then it is irrelevant. Because if you're not exposed to it, it doesn't matter," said Robaire. "Similar to asbestos in the building in a wall. It's not toxic until you break the building and the wall down."

Fluorescent tagging

The team at McGill conducted its tests independently of Orb Media, a non-profit journalism organization in Washington, D.C., which recently conducted its own global bottled water study at State University of New York (SUNY) in Fredonia and found a majority of bottles of water tested had microplastics.

Following the release of the Orb report in March, the World Health Organization announced it would be launching a review to assess the risk of plastics in drinking water.

Lanternfish or myctophids from the North Pacific garbage patch are shown with some of the plastics that were pulled up in a surface water trawl at night, when the fish come from the surface to feed. (Scripps Institution of Oceanography)

McGill emulated SUNY's methodology and used Nile Red fluorescent tagging, a dye which detects microplastics in water. Certain particles from a filter are then analyzed using a Fourier-Transform Infrared Spectroscopy (FTIR) machine.

Because of limitations at SUNY's lab, nothing below 100 microns could be identified as microplastic, and was instead labelled "probable microplastic."

McGill decided to take it a step further, trying to identify some of the particles under 100 microns. Using a relatively new peer-reviewed way of detecting microplastics, the researchers burned a portion of a filter sample looking for chemical fingerprints.

McGill found polystyrene in the one sample it tested. The lab said these are preliminary results and more tests need to be conducted.

"We were able to show using a very specialized technique that some of these particles are in fact plastic," said Tufenkji. "We don't know how many of them, but we can indeed say now that some of these particles are plastic."

These slides from samples of Japanese medaka fish livers show a healthy liver on the left, one from a fish fed virgin polyethylene plastics for two months with signs of stress or tumour promotion and one from a fish fed plastics with a combination of pollutants absorbed from oceans that has a tumour in 25 per cent of the liver. ( Dr. Swee Teh)

McGill also acknowledged Nile Red dye could adhere to unknown substances other than plastic, which made it especially important to take additional steps to verify the particles under 100 microns.

Multiple experts reviewed McGill's study at Marketplace's request. Peter Ross, an ocean pollutions expert at the Vancouver Aquarium, said McGill took a "more defensible (science-based) approach to couching their findings."

Rochman said she "trusts the results" of the lab's latest method for detecting plastics under 100 microns.

There are no rules or standards for allowable limits for microplastics in bottled water in Canada.

"Should Health Canada become aware of such a health risk, we would take appropriate action to address the issue," the department said in a statement.

'Emerging field'

Nestle told Marketplace it found microplastic at a trace level in its water but because such a minute amount was detected "it was not possible to determine if these traces are intrinsic to our bottled water operations or merely the result of cross-contamination from the lab environment."

The company said it considers "the presence of microplastic in our environment one of the major sustainability challenges society is facing today." It also noted the possibility Nile Red might create false positives in the test results.

Pepsi-owned Aquafina said the science on microplastics and microfibres "is an emerging field … which requires further scientific analysis, peer-reviewed research and greater collaboration across many stakeholders."

Coca-Cola, which makes Dasani, said the "quality of our products and safety of our consumers are of paramount importance to us and we take them extremely seriously."

Nathalie Tufenkji’s team at McGill University tested bottled water purchased in Vancouver, Calgary, Toronto and Montreal.

It said that it has "some of the most stringent quality standards in the industry, and the water we use in our drinks is subject to multi-step filtration processes prior to production."

Quebec-based Naya said its "stringent quality control measures and sanitary production methods, such as microfiltration, bottle rinsing before filling and other food safety procedures, result in a safe and reliable product."

The Canadian Bottled Water Association and the Canadian Beverage Association on behalf of Eska said in a statement: "Marketplace's study on bottled water … used a testing method with several limitations that [CBC's] Marketplace has acknowledged.… Consumers can remain confident that bottled water products are safe."