TEXTILES.ORG
Although testing to quantify microplastics is still in its developmental stages, interest in it is on the rise, especially among textile producers, says Danielle Harrier, Ph.D., with global engineering and scientific consulting firm Exponent. Harrier is a senior associate in polymer science and materials chemistry at the company’s office in Menlo Park, Calif.
“Microplastics are a complex and evolving challenge,” she says. Though definitions of “microplastics” differ among regulatory bodies—sometimes they exclude natural, soluble or biodegradable materials or rubber—one commonality among most of them is particle size smaller than 5 millimeters. And sometimes microfibers are defined separately, specifically citing fibers shed when a synthetic textile is washed and offering a length to width ratio to differentiate it from a microplastic particle.
Microplastics can also be characterized as primary or secondary; primary are created for use as-is, such as plastic microbeads used in cosmetics: for example, exfoliating face washes. Secondary microplastics represent almost all of the microplastics found in water and soil and come from sources such as plastic products degrading in the environment, from tires to synthetic textiles.
However, manufacturing methods can also release microfibers into the air. Harrier gave the example of a company in India where researchers placed tubs of water on the floor in a room where knits were cut and elsewhere, and they found that “fabrics with compact structures released more short microfibers than those with loose structures” and were alarmed to find “cutting a medium sized T-shirt can release … approximately 50 times [more] than that released during laundry, with 40–70 percent of the fibers transported outside the factory.”
The paper also recommends future research into the occupational hazards for cutting operators, alternative cutting methods and microfiber capturing systems.
Standards and regulations
Over the past few years, several testing standards have been developed by ASTM and ISO—and others are still emerging—for analyzing the composition and quantity of microplastics in water, including some standards by Hohenstein and ISO that are specific to textiles.
They use methods including Raman spectroscopy, pyrolysis gas chromatography-mass spectrometry, infrared spectroscopy and dynamic image analysis. The challenge, Harrier says, is that no one piece of equipment or technique will take care of the entire size range or type of particle. Her firm uses a combination of techniques in its Microparticle/Microfiber Analysis Toolkit to count and classify the microplastics present in a given sample.
Research papers have shaped regulatory proposals about the issue. The only federal ban currently in effect targets primary microplastics. However, a shift is beginning, she says, as state and federal lawmakers work to address the broader issue of plastic pollution.
“Textiles are being looked at [by legislators] with increasing scrutiny,” she says, with manufacturers’ chief concern being “What regulations are they going to have to abide by?”
Laws, bills, regulations and proposals are increasingly referencing secondary microplastics sources such as synthetic textiles. Regulation proposals being introduced aim to curb microfiber pollution by requiring washing machines to include filters that capture these particles.
Cathy Jones is senior editor of Specialty Fabrics Review.