By Janet Raloff
Every time a garment made from polyester or other synthetic fabric goes through the wash, it sheds tiny plastic fibers. Thousands of them. It turns out that these fibers end up fouling coastal environments throughout the globe, a global research team finds.
Itsy bitsy plastic pellets, such as those used for their abrasive qualities in products like skin cleansers and paint removers, also turn up in coastal sand, a separate study reports. Like polyester lint, these micropellets also go down the drain, through water treatment plants and into coastal waters.
The mass that microplastic bits contribute to marine pollution is small, concedes Mark Browne of University College Dublin, who led the fiber study. But that doesn’t mean their impact is benign, he adds.
Browne’s group sampled shoreline habitats at 18 sites on six continents. Plastic fibers polluted every one, with sites nearest urban centers hosting the most. At any site, microplastic fibers constituted more than 65 percent of the plastic pieces, by number (with the exception of sand-size pellets, which this study ignored).
Since earlier work had uncovered plastic fibers at land sites treated with sewage, the researchers sampled outflows from sewage-treatment plants. These waters also hosted acrylic and polyester fibers anywhere from 1 millimeter down to 10 micrometers in diameter.
This suggested that laundry might be a source. So over the next year, the researchers laundered individual garments and blankets in washing machines, running several empty cycles to clean out residual fibers between each wash. These tests “demonstrated that a single garment can produce greater than 1,900 fibres per wash,” the researchers report online September 6 in Environmental Science & Technology. Fleece fabrics shed the most.
What really makes microplastics potentially dangerous is the contaminants they ferry, argues Anthony Andrady of North Carolina State University in Raleigh, a materials scientist and polymers specialist not connected with the new study. “In the ocean, plastics act like a sponge,” he explains, absorbing and concentrating fat-soluble pollutants.
Indeed, in a study in the November 2010 Marine Pollution Bulletin, researchers in Portugal reported finding pollutant-tainted microplastic pellets.
The Portuguese team collected sand from two coastal beaches and carefully filtered out tiny sand-size pellets. Those polystyrene and polypropylene bits hosted a range of persistent organic pollutants — many of them toxic — including DDT, polychlorinated biphenyls and polycyclic aromatic hydrocarbons (some of which are constituents of crude oil).
“Every sample was contaminated,” reports lead author João Frias, an ecological engineer at the Institute of Marine Research at the New University of Lisbon in Caparica, Portugal. His team is now beginning tests to evaluate the pellets’ toxicity to marine organisms.
“I think these findings are a big deal,” says marine ecologist Henry Carson of the University of Hawaii at Hilo. “These tiny pieces have the potential not only to get inside tissues of mussels and other animals,” he says, “but to actually move into their cells. That’s pretty frightening.”
And beaches aren’t the only places these tainted microplastics are ending up. In the August Marine Pollution Bulletin, a second international research team describes finding organic contaminants similar to those measured by Frias’ group in somewhat larger pieces of plastic debris (around 10 millimeters in diameter) that had been collected in the open ocean.
Andrady has shown that some microplastics are indistinguishable by size from algae and are eaten by Pacific krill, small organisms at the base of the marine food web. Plastic should not be inherently toxic to such critters, he says, “because animals and humans have no enzymes capable of digesting the plastics.” But any pollutants tainting the plastics will be available to animals and their predators.
A large surface-to-volume ratio allows microplastics to rapidly absorb toxic pollutants and to release them just as quickly to fatty substances inside an animal. This, Andrady says, coupled with their ability to be ingested by a wide range of the animal kingdom, “explains why microplastics are so worrisome.”
