The midnight sun is seen as the Canadian Coast Guard icebreaker Louis St-Laurent crosses into the Arctic Circle early Wednesday, July 9, 2008. Scientists say tiny particles of plastic and other manmade fibres are everywhere in the waters of Canada's eastern Arctic. THE CANADIAN PRESS/Jonathan Hayward

Chelsea Rochman wasn't surprised when her research cruise through Canada's Eastern Arctic showed tiny plastic shards and other human debris in nearly every bucket she hauled aboard.

What puzzled her was the colour. The answer changed the way she looks at her wardrobe.

"Some of the particles that we sampled weren't microplastics," said Rochman, a University of Toronto scientist who has just published her research in the journal Facets.

"(They were) cotton textiles that have been dyed and used in clothing."

Rochman sailed on the research icebreaker the CCGS Amundsen in the summer of 2017 to sample water, snow, sediment and plankton at 36 sites from south Hudson Bay all the way to Alert on the tip of Ellesmere Island.

She and her colleagues found microplastics — plastic fragments smaller than five millimetres — and other tiny pieces of human-generated debris in 90 per cent of the water and plankton studies and 85 per cent of sediment samples.

Although this was the first such survey conducted in the Eastern Arctic, the results weren't a shock.

"There have been studies that have found microplastics in Arctic waters, in snow, in ice, in sediments," Rochman said.

But this study presents important clues on where the fragments originate.

They don't come from the Arctic, for one thing. The distance to the nearest community made no difference to the amount of debris in the water.

That agrees with previous research suggesting particles move northward through air or ocean currents.

"There's little to no work that suggests this (debris) is the work of Arctic communities," Rochman said.

Secondly, most of the fragments were in the form of tiny fibres. Most of those were cotton, not plastic, and most of them were blue, probably from somebody's jeans, she said.

"There's a dye called indigo carmine that comes up a lot on (our analysis). That is known to be used in blue jeans. It's sometimes used in polyester, but the majority use is cotton."

The concentrations weren't large. The data suggests it would take, on average, more than four litres of Eastern Arctic sea water to find a single particle.

But they are everywhere. And there's little understanding of "how microplastics will impact the Arctic ecosystem."

Previous studies have found little difference in the rate at which cotton or polyester degrades.

"The cotton is, sure, a little bit faster but it's still really slow," Rochman said.

Dyes and other additives add to the mix — and the uncertainty.

"We are doing toxicity tests in our lab to look at the difference between polyester and cotton," said Rochman. "Right now, we don't see a striking difference, but it's all preliminary."

Rochman points out that gradually increasing levels of microplastics and other fragments in Arctic seas is only one stressor on an ecosystem facing change on many fronts. Sea ice is in retreat; waters are getting warmer and more acidic; human use is increasing.

The body of research is growing, she said.

"There's certainly work that suggests microplastics can reduce the population of zoo plankton. There's work that shows how microplastics impact (bottom-dwelling) organisms."

But there's very little on human health impacts.

"More research needs to be done. The question we get from the local communities is, they really want to know how it affects the ecosystem and how it affects their country food."

This report by The Canadian Press was first published June 17, 2020

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