US scientists assess synthetic fibres pollution on land

September 24, 2020 - United States Of America

Scientists in the US have said that the volume of synthetic microfibres released to terrestrial environments from wash cycles is huge, and may actually surpass, that which winds up in the oceans, rivers and lakes. About half of the total synthetic microfibre emissions since 1950, when synthetic fibre mass production began, are from the last decade alone.

The findings are from a study carried out at the UC Santa Barbara's Bren School of Environmental Science and Management. The study has been published in the journal PLOS ONE.

“The emissions of microfibres onto terrestrial environments — that was a known process. But the magnitude of the issue was not well known,” said Jenna Gavigan, who led the study, the first ever to examine the problem on a global scale.

Using global datasets on apparel production, use and washing with emission and retention rates during washing, wastewater treatment and sludge management, the team estimates that 5.6 million metric tonnes (Mt) of synthetic microfibres have been emitted from apparel washing between 1950 and 2016, with 2.9 Mt finding their way into waterbodies and a combined 2.5 Mt emitted onto terrestrial environments (1.9 Mt) and landfilled (0.6 Mt).

“If you look at the figures you can see the enormous growth in synthetic clothes production, and as a result, increased synthetic microfibre pollution,” said industrial ecology professor and paper co-author Roland Geyer.

According to the study, about half of the total synthetic microfibre emissions since 1950 (the dawn of synthetic fibre mass production) were generated in the last decade alone. Thanks in large part to the global appetite for fast fashion and its tendency toward cheaper, mass-producible synthetic fibres, as well as increased access to washing machines, laundry is polluting not just the ocean, but the land, too.

Talking about the source of synthetic microfibres accumulating on the land, the scientists said that in an effort to keep microfibres from getting in the waterways, these fibres were accumulating in the sludge of wastewater treatment plants.

“Wastewater treatment is not the end of the pollution,” said industrial ecology professor Sangwon Suh, who also is a co-author on the study. With a roughly 95-99 per cent removal efficiency, all but the tiniest microplastics are caught in the sludge, which is treated and turned into biosolids, and “predominantly used in land applications,” as fertilizer and soil amendments.

“A smaller percentage goes to the landfill,” Gavigan said. “The smallest percentage gets dumped into the ocean in some countries, and some of it is incinerated.”

“So then it becomes a terrestrial pollution issue,” Geyer pointed out. “We just turned it into a different environmental pollution issue rather than having actually solved it.”

According to the researchers, preventing emissions at the source — whether by using a microfibre capture device, selecting a gentler wash method, washing clothes less often or foregoing synthetic fabrics — would be more effective at mitigating microfibre pollution than trying to capture the fibres after the wastewater is sent to the treatment plant.

The study has its roots in a 2016 Bren group project in which several graduate students, in research conducted for the outdoor apparel company Patagonia, sought to study the conditions that affect garment shedding. That undertaking focused primarily on the microfibre-laden effluent leaving the washing machine, and produced influential research that raised awareness of the synthetic microfibre problem.

The collaboration also inspired a 2017 microfibre leadership summit co-hosted by the Bren School and the environmental organisation Ocean Conservancy, in which more than 50 stakeholders, including representatives from industry, government, the research community, the apparel sector and environmental nonprofits convened and charted out a road map based on a shared vision, and action items for each stakeholder to steer toward solutions.

“When it comes to microfiber pollution, these new findings show that the ocean has been the canary in the coal mine, and that plastic pollution is far more pervasive in our environment than originally thought,” said Nick Mallos, senior director of Trash Free Seas at the Ocean Conservancy. “Fortunately, simple and effective solutions — like adding filters to washing machines — exist. We urge manufacturers to make these modifications standard.”

This global assessment of synthetic microfiber emissions is part of a larger picture of microplastics in the environment that the researchers hope to fill in as they uncover the pathways these tiny fibres take.

The amount of synthetic microfibre shed into the waterways has been a matter of great concern over the last few years, Every laundry cycle releases in its wastewater tens of thousands of tiny, near-invisible plastic fibres whose persistence and accumulation can affect aquatic habitats and food systems, and ultimately humans in ways yet to be discovered.