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By Chris Stokel-Walker

Erik Von Weber/Getty Images

They may be a comfortable, convenient choice for those working at home, but blue jeans could be harming the planet.

Microfibres of indigo denim have been discovered in vast quantities in water samples taken across Canada, from Toronto up to the Arctic. The survey, conducted by Miriam Diamond at the University of Toronto and her colleagues, found that between one in eight and one in four of all microfibres in the samples were blue denim.

Some of the microfibres were found at a depth of 1500 metres, and the researchers say this means that they are able to withstand travelling long distances. The highest concentrations of jean microfibres were found in shallow suburban lakes. While the survey was limited to Canada, the team believes the results would be repeated elsewhere.

“The finding of fibres in the Arctic is symbolic of the spread of human impact,” says Miriam Diamond at the University of Toronto.

Separately, the researchers also monitored how many microfibres are lost from a pair of jeans during the average wash. They found that around 50,000 microfibres were sloughed off from the surface of jeans every time they were cleaned.

“Unfortunately, the results are not surprising to environmental scientists; they are even expected,” says Caroline Gauchotte-Lindsay at the University of Glasgow in the UK. However, she calls it an important paper because it looks at natural microfibres, which have previously been overlooked in microplastic studies focusing on synthetic materials.

Diamond and her colleagues weren’t sure of the effect of denim microfibres on the environment. “While they’re not plastic, they are anthropogenically modified,” says Samantha Athey at the University of Toronto.

Denim picks up chemicals and jeans are chemically treated during production. “What impact that chemical modification has is a question that remains to be answered,” says Athey. “But they’re so abundant we should look at it.” In the meantime, the team advises that you wash your jeans less. One jeans company, whose products were used in the study, suggests a wash once a month.

Journal reference: Environmental Science & Technology Letters, DOI: 10.1021/acs.estlett.0c00498

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