Green Games

Laundry lint is polluting fresh water

Nearly 2,000 polyester fibers can float away, unseen, from a single fleece sweater in one wash cycle, a new study reports.

That synthetic lint likely makes its way through sewage treatment systems and into oceans around the world. Environmental scientists say the microscopic plastic fibers have the potential to harm marine life.

The diffusion of so-called microplastics in marine environments is not a revelation. Larger bits of plastic, gradually break down into microscopic fragments. Minute plastic fibers have turned up before in treated sewage and on beaches. However, no one had looked at the issue on a global scale, said ecologist Mark Browne of University College Dublin.

Browne and his team recruited colleagues from all over the world, they took samples of sand from 18 beaches. Back in the lab, the researchers separated the plastic from the sand. Then they made a chemical analysis which showed that nearly 80 percent of those filaments were made of polyester or acrylic, compounds, common in many different textiles.

Not a single beach was free of the colorful synthetic lint. Each cup of sand contained at least two fibers and as many as 31. In areas with the highest human population density scientist found the highest quantities of lint in the water.

Cities come with sewers, and Browne’s team thought the plastic fibers might enter the ocean via sewage. Sure enough, synthetic lint was relatively common in both treated wastewater and in ocean sediments from sites where sewage sludge had been dumped. In all the samples, the fibers were mainly polyester and acrylic, just like the ones from the beaches.

To understand how this tiny filaments got in the sewage they purchased a pile of polyester blankets, fleeces and shirts and used three volunteers’ home washing machines for several months. They collected the wastewater from the machines and filtered it to recover the lint. Each polyester item shed hundreds of fibers per washing, the team reports in the Nov. 1 issue of Environmental Science and Technology.

This is how it works

A polyester t-shirt’s fibers could be bad news in marine environments, Browne said. Other studies have found that microplastics in the ocean absorb pollutants such as DDT. Browne’s own work has shown that filter-feeding mussels will consume tiny plastic particles, which then enter the animals’ bloodstreams and even their cells. If the same thing happens in nature, the plastic fibers could “end up on our dinner plates,” incorporated into seafood, Browne warns.

He says that textile and washing machine manufacturers, as well as sewage treatment plants, should be looking for ways to keep the fibers out of the ocean. Garments that shed less lint or new washing machine filters might help.