Washing denim releases microfibers into sewage and even finds them in remote Arctic marine sediments, Canadian experts said in a study published September 2 in the U.S. journal Environmental Science and Technology Communications.
A team of researchers led by Samantha Assy of the University of Toronto in Canada investigated whether denim is considered an important source of microfibers for aquatic use.
The team said it was not clear how microfibers affect aquatic life, if any, but they believed the discovery of microfibres in the Arctic was “strong evidence of human impacts on the environment.”
Reported that denim and other fabrics in the washing process will release microfibers, although most will be treated by wastewater treatment plants, but some may be through the discharge of wastewater into the environment.
Denim is made from natural cotton fibers and is processed with synthetic indigo dyes and other chemical additives to improve its performance and durability.
Using a combination of microscopy and spectroscopy, the researchers identified and counted the microfibers of indigo denim in a variety of water samples collected throughout Canada.
The study found that indigo denim microfibers accounted for 23 percent, 12 percent and 20 percent of all microfibers in sediments in the Great Lakes, shallow lakes near Toronto and the Canadian Arctic Islands, respectively, the report said.
Based on the levels of microfibers found in wastewater, the researchers estimate that the sewage treatment plants studied emit about 1 billion indigo denim microfibers per day.
Through washing experiments, the team found that a pair of used jeans released about 50,000 microfibers per washing cycle, the report said.