6kg wash load = 700,000 microscopic fibers: Study

A single use of a household washing machine could release more than 700,000 microscopic fibers, the majority of which are likely to pass through sewage treatment systems and into the environment, a new study by PhD students at UK's Plymouth University revealed.

The researchers examined the mass, abundance and sizes of the fibers present in waste effluent after washing synthetic fabrics at standard temperatures of 30 and 40 C. They found hundreds of thousands of tiny synthetic particles in the water, confirming an earlier work at the university that a large volume of microscopic fibers in the aquatic environment comes from laundering.

Items made of polyester, acrylic and polyester-cotton blend were used in the study. These were washed using different combinations of detergent and fabric conditioner. Fibers were then extracted from the waste outflow and analyzed with an electron microscope to determine their size, mass and abundance.

The research found that a 6kg washing load could release about 138,000 fibers from polyester-cotton, 496,000 from polyester and 729,000 from acrylic. Regardless of the treatment, the first yielded consistently fewer strands than the other fabric types, although the adoption bio-detergents and conditioners tended to increase the volume.

PhD student Imogen Napper led the study, which is entitled "Release of Synthetic Microplastic Plastic Fibres from Domestic Washing Machines: Effects of Fabric Type and Washing Conditions" and was published in Marine Pollution Bulletin. It was done in conjunction with Professor Richard Thompson, an international expert on microplastics and marine debris, with more than 20 years of experience.

According to the authors: "The quantity of microplastic in the environment is expected to increase over the next few decades, and there are concerns about the potential for it to have harmful effects if ingested. But while the release of tiny fibers as a result of washing textiles has been widely suggested as a potential source, there has been little quantitative research on its relevant importance, or on the factors that might influence such discharges. That was the focus of our research."

Professor Thompson also heads the International Marine Litter Research Unit at Plymouth University and presented recently both written and oral evidence in the microplastics inquiry held by the House of Commons Environmental Committee, leading to recommendations for banning the use of microbeads in cosmetics and beauty products.

"Clearly, what we are not advocating that this research should trigger something similar to the recently announced ban on microbeads," he said.

"In that case, one of the considerations guiding policy intervention was the lack of clear societal benefit from incorporating microplastic particles into the cosmetics, coupled with concerns about environmental impacts. The societal benefits of textiles are without question and so any voluntary or policy intervention should be directed toward reducing emissions either via changes in textile design or filtration of effluent, or both," Thompson added.