The 2.7 million washing machines sold in France each year will have to be equipped with microparticle filters by 2025. A world first and excellent news for... oysters. Because according to a study published this Thursday in the journal Environmental Pollution by the French Research Institute for the Exploitation of the Sea (Ifremer) in collaboration with the CNRS, the textile microfibers rejected by our machines disrupt the health of marine organisms that ingest them. Especially shells.
How can natural or synthetic clothing residues end up at sea? "Machine washing clothes releases plastic microparticles into wastewater, too small to be completely filtered in wastewater treatment plants, and they are found everywhere in the environment and especially at the bottom of the oceans," explains the Ministry of Ecological Transition. In each cycle, up to 700,000 microscopic fibers are released into the environment. »
Natural fibers also have deleterious effects...
"A recent study revealed that 92% of microfibers collected offshore in six ocean basins of the world come mainly from cotton and wool," says Ifremer, which wanted to know if these particles affect marine life. The researchers therefore exposed cupped oysters for 96 hours to natural (wool, organic and non-organic cotton) and synthetic (acrylic, nylon and polyester) textile microfibers and their chemical additives to measure the effects of this exposure.
"A low environmental dose is enough to trigger effects on their health," says Camille Détrée, lecturer in marine biology at the University of Caen-Normandy. In particular, scientists have observed that natural fibers generate inflammation of the digestive walls of these filter-feeding organisms and affect their immune system more significantly than synthetic fibers.
"What surprised us were the deleterious effects that natural fibres have on the digestion and immunity of oysters," continues the researcher. The roughness of the surface of natural fibers is greater and probably causes a stronger inflammation of the digestive walls during transit. These results show, according to Ifremer, that the toxicity of textile microfibers is not only related to their synthetic or natural nature but also depends on "their physical characteristics, themselves related to the weaving method, and their chemical composition which varies according to the recipes and additions of additives specific to manufacturers".
... But they degrade much faster than synthetics
If cotton and wool microparticles are therefore not "less impactful" for oysters than acrylic, nylon or polyester, they have the advantage of degrading much faster at sea. "The persistence period of 100% natural fibers in the marine environment is a few weeks or months," says Arnaud Huvet, marine biologist at Ifremer and co-pilot of this study, "compared to tens or even hundreds of years for synthetic materials."
At European level, between 18,000 and 46,000 tonnes of textile fibres end up in the environment each year. According to a parliamentary report published in December 2020 and dedicated to plastic pollution, "62.1 million tons of synthetic fibers were produced in 2016, compared to 35.7 million tons for natural fibers". The rapporteurs estimated that 60 to 80% of these fibres are released at the first wash, the number of residues evacuated with the water of the machine then decreases with the repeated washing cycles. Enough to encourage us to put our foot down on compulsive purchases of new products and opt instead for second-hand clothes.