We rarely think about it when launching a laundry… The water discharged by our domestic washing machines is one of the main sources of pollution by microfibers in the oceans. Each year, it is estimated that around 2 million tonnes of microfibers are rejected in this way by domestic washes, recalls the French research institute for the exploitation of the sea (Ifremer).
With what consequences for marine organisms? This is the question that Ifremer has looked into, in collaboration with the CNRS and the universities of Western Brittany and Le Mans.
The results of their research have been published in recent days in the magazine Environmental Pollution. The study consisted of exposing cupped oysters for 96 hours to natural (wool, organic and non-organic cotton) and synthetic (acrylic, nylon, polyester) textile microfibers as well as their associated chemical additives, studying the ability of these oysters to ingest these microfibers and comparing the effects on their biological functioning.
Greater impacts with natural fibres?
Two scenarios were taken into account, specifies Ifremer in a press release: the first, “realistic” from an environmental point of view, with a concentration of 10 microfibers per liter, and a “catastrophe” scenario, with a concentration of 10,000 microfibers per liter.
Whether natural or synthetic, these fibers have effects on the metabolism of oysters even at low doses. This is an initial lesson on which Camille Détrée, post-doctoral student at Ifremer at the time of the study and now lecturer in marine biology at the University of Caen-Normandy, insists. “We did not observe more effects on oysters exposed to high or low concentrations of microfibers. This suggests that a low environmental dose is sufficient to trigger effects on their health,” she explains.
More surprisingly, the authors of the study observed that natural fibers generate inflammation of the digestive walls of these filtering organisms and affect their immune system more significantly than synthetic fibers.
What about persistence in the environment?
However, the study does not deduce that natural fibers are more harmful than synthetic ones. “But the roughness of the surface of the natural fibers is greater and probably causes greater inflammation of the digestive walls during transit”, specifies Camille Détrée in the Ifremer press release. Clearly: the toxicity of microfibers would be more related to their roughness and their chemical composition than to their plastic nature or not.
There is still a parameter to add to the equation on which Arnaud Huvet, marine biologist at Ifremer, invites to take into account: that of the persistence in the marine environment of these microfibers. It is “a few weeks or months for 100% natural fibres, compared to tens or even hundreds of years for synthetic materials”.