Blue Jean Microfibers Are Everywhere

Despite being cotton-based, they're still a big problem.

jeans in the washing machine
Jeans in the washing machine.

@SmitBruins via Twenty20

Blue jeans are arguably the most popular pants in the world. At any given moment, half of the human population is wearing them (or other denim garments). Jeans may be comfortable, versatile, and long-lasting, but they do come with a downside: like so many other articles of clothing, they shed microfibers in the wash.

You've likely heard about the microfiber pollution problem before, but it is usually discussed within the context of synthetic clothing. Polyester and nylon clothes are notorious for shedding tiny fibers in the washing machine, which then pass through water treatment plants and do not get entirely filtered out because they are so small. But it turns out that clothes made from natural, non-synthetic materials (a.k.a. "anthropogenically-modified cellulose," or AC) can be messy for the environment, too.

A group of researchers from the University of Toronto set out to learn more about denim microfiber pollution. In a new study published in the journal "Environmental Science and Technology Letters," they describe the extent to which these fibers have infiltrated aquatic environments in Canada. The researchers took sediment samples from the deep-sea Arctic, several of the Great Lakes, and lakes in the suburban region around Toronto; and they found, respectively, an average of 1,930, 780, and 2,490 microfibers per kilogram of dry sediment. 

Of those microfibers, 22 to 51 percent were anthropogenically-modified cellulose, and of those, 41 to 57 percent were found to be indigo-dyed denim. The indigo strands were identifiable by their blue color, which gives them a unique chemical makeup detected using a method called Raman spectroscopy. The AC fibers also have more of a twist than the smoother, more uniform synthetic fibers.

Curiously, when the researchers analyzed different styles of jeans, they did not find a significant difference between trendy frayed ones and non-distressed, intact ones. Both shed similar quantities of fibers. The most noticeable difference was with brand new jeans, which shed more initially (presumably loose fibers left over from manufacturing), but then leveled off. Regardless, the team was shocked to figure out just how many fibers are released every time a pair of jeans is washed – as many as 56,000! 

After collecting samples from two wastewater treatment plants in the Toronto region, the researchers estimated that these two plants alone are responsible for dumping one billion denim microfibers into Lake Ontario daily. From Wired's report: "That’s in keeping with the country’s washing habits, as about half of the Canadian population wears jeans almost every day and the average Canadian washes their jeans after just two wears."

As for the glut of fibers in the Arctic Ocean, that is attributed to currents moving polluting materials around the world in a sort of natural conveyor belt and dumping them in the far north. This causes all kinds of problems, as told to Wired by one of the study authors, Miriam Diamond:

"'In the Arctic, there's very little material that falls out of the water column and accumulates as sediment,' says Diamond. 'That has implications, right?' Because there’s less sediment, there’s less biological activity — not so many seafloor critters scurrying around processing organic material. 'If you don't have a lot of food around, you eat what's available. You can't be fussy.'"

And just because these fibers come from a plant-based source, rather than a petroleum-based source, does not mean they're entirely natural or safe for deep-sea creatures to be ingesting. Study co-author Samantha Athey said that they do contain chemical additives: "They also pick up chemicals from the environment, when you're wearing your clothes, when they're in the closet." 

The takeaway? It's pretty obvious. We all need to stop washing our jeans so regularly. They don't need it, especially not after every second wear. Take some advice from denim maker Nudie Jeans, which says that wiping with a damp cloth to remove stains is adequate, or San Francisco's Tellason, which recommends using next to no soap in cold water, or Hiut, which says wearing a pair for six months unbroken isn't an issue (and you can join their special club once you hit that milestone).