Anyone with an environmental conscience has by now given up on single-use plastic bags for their shopping, because of all the microfibres that end up in the sea, inside the fish we eat and inside the stomachs of the seabirds that eat the fish.
But if you thought your organic clothes, your cotton, wool and linen, were no danger to the planet, think again.
According to research carried out by scientists from the university of Toronto, fibres from dyed blue denim have been found in some quantity in sedimentary layers under the Arctic Ocean, far in the north of Canada where there is no human activity.
“It does suggest that they ended up there through long-range transport processes,” lead researcher Sam Athey told Wired magazine.
“Whether they’re oceanic or atmospheric—we don’t know exactly.”
Or perhaps both. We know the ocean currents can carry microplastics over huge distances. And it has been suggested that winds carry particles to the Arctic regions that can only have come from population centres.
The fibres are made of cotton – or ‘anthropogenically modified cellulose’ in the language of scientists – but it is the indigo dye used to colour them that makes it certain they are of human origin. The composition of the dye, together with the other environmental compounds they pick up as they make their way through the modern world, acts as a unique fingerprint.
The researchers also used a special spectroscopy technique to identify how the light interacts with the chemicals in the fibres, as well as using the plain old microscope to ascertain that the fibres were cotton and not plastic – the two fibres have a quite different form.
The study looked at sediment from three very different environments: the two Great Lakes Huron and Ontario; shallow lakes around Toronto; and the Arctic wastes.
The number of fibres found in the two populated areas, lakes and suburbs, was 2,490 and 780 respectively per kilogram of sediment. At the Arctic, the number was 1,930/kg.
In general 22% to 51% of all fibres were cotton, and 41% to 57% of those were blue denim.
“I think what’s interesting is that a majority of these fibres that we were finding were these anthropogenic cellulose fibres, even in the deep ocean sediments,” Athey said. “And that shows that they are sufficiently persistent to accumulate in these remote regions.”