Source Article: Zambrano, M. C., Pawlak, J. J., Daystar, J., Ankeny, M., Cheng, J. J., and Venditti, R. A. “Microfibers generated from the laundering of cotton, rayon and polyester based fabrics and their aquatic biodegradation” Marine Pollution Bulletin, 142 (2019) p. 394-407. https://doi.org/10.1016/j.marpolbul.2019.02.062
Microplastics and Microfibers: What’s the problem, and where does it come from?
Due to mismanaged waste and its extremely slow environmental breakdown, plastic litter is accumulating all over the globe, especially in our oceans. It’s estimated that there are ~ 270,000 tons of plastic in the ocean, with 93% of these being microplastics (1μm-5 mm in size).1 These microplastics don’t interact with much themselves, but they can absorb toxic chemicals and aid in their transport and transfer. Furthermore, microplastics have been swallowed by a variety of animals, including humans. Added to this large environmental impact are 0.3-0.9 million tons/year of microplastics entering the oceans from a very relatable source: laundering textiles.2 These microplastics are in the form of micro-sized fibers (or microfibers) released from synthetic textiles. Although waste water treatment plants are fairly adept at removing the majority of these microfibers, many still pass through. Plus, a significant fraction of the world’s population washes laundry directly in waterways.
It will all come out in the wash…
A lot more goes into designing clothing than just color and fit. Fabric design and selection is a major area of innovation and optimization in the textile industry. Generally, clothing fabric is made up of yarn that is held together in a variety of different constructions (for example: knit, woven, fleece). Yarns are composed of fibers of different source materials. For example, cotton fiber is made from a natural cellulose-based material, while polyester fiber is made from a synthetic material—a plastic. A polyester-cotton blend yarn contains both natural and synthetic fibers. The type of yarn, fiber thickness, and fabric construction all influence properties of the fabric, such as stretch, drape, durability, water resistance, and breathability… not to mention aesthetics! These differences in fabrics also influence their release of microfibers into the environment. Since some of these fabrics are made of plastic fibers, their microfibers are also microplastics.
Marielis Zambrano and collaborators recently published a journal article detailing their investigation into the generation of microfibers from different types of fabric during laundry wash cycles and how these microfibers break down in the environment. In order to best isolate the source material and reduce differences due to fabric construction, the research team used materials that were all knit. Squares of cotton, polyester, rayon, and polyester-cotton blend were sent through several washing and drying cycles. These fabrics were carefully selected to represent a variety of common clothing material, and different washing temperatures were used to simulate cold and warm-water laundry cycles.
Each fabric type was washed separately, and microfibers generated during the wash cycle were collected with a metal fine-mesh sieve in the water outflow from the laundry machine. These fibers were then analyzed both in terms of quantity and size distribution. The researchers found that cotton and rayon released the most microfibers, followed by polyester-cotton blend, and polyester released the least amount of microfibers. Polyester microfibers were also smaller in diameter than those generated from cotton and rayon. The use of laundry detergent increased the amount of microfibers released from all fabrics, because the detergent makes it easier for small broken or loose fibers to escape the fabric. Warmer washing water also increased the amount of microfibers released, especially cotton and rayon—this is believed to be because warmer water causes cellulose-based materials to swell more (which also makes it easier for loose and broken fibers to escape).
The authors explained that yarn strength and quality also play a role in the likelihood of fibers breaking and/or loosening. The ease with which these events occur largely influences how many microfibers they generate in the wash. Generally, polyester fabrics are made with yarns are stronger and smoother than those of many natural fabrics. These trends also apply within a single fabric type: low-quality fabrics are made of yarns that are weaker, less uniform, and hairier (they have more loose fibers sticking out of the yarn), making them more susceptible to generating microfibers. Pilling and fuzz-generation by fabrics are signs of these fibers breaking.
How do microfibers breakdown in the environment?
Zambrano and collaborators simulated natural aquatic environments (where these microfibers might be released) and studied aquatic biodegradation of the various yarns over 243 days. They observed that cotton and rayon yarns underwent ~ 76 and ~ 62% biodegradation while polyester was less than 5% biodegraded. The polyester-cotton blend was ~ 40% biodegraded, largely due to its cotton fraction. This emphasizes the difference between synthetic microfibers (microplastics) like polyesters and natural microfibers, like cotton. Although polyester fabric releases fewer microfibers than cotton and rayon, its takes much longer to break down in the environment, and is therefore a larger contributor to the microfiber, microplastic, and overall pollution, problem.
What can we do?
- Choose your clothing wisely. As these researchers indicated, higher quality clothing is less-likely to shed microfibers than lower-quality equivalents. Because the reduction in microplastic generation means that fewer fibers are breaking loose, this also means that your clothes will last longer. So, while they might be more expensive up-front, you won’t have to replace them as often. Once you stop growing out of clothes, consider making the long-term investment. (Cool fact: clothing brands, like Patagonia, are starting to seek solutions to the microfiber problem.)However, if you are reluctant to increase your clothing budget, you can still…
- Increase the lifetime of your clothes. Research shows that the amount of microfibers coming off clothes levels out after a certain amount of washes. So, if you wear older clothing, it releases less microfibers in the wash. Are you desperate to keep up with the latest fashion? Consider donating your clothes rather than throwing them away, so at least someone can avoid buying new.
- Wash your clothes in cold water. As mentioned above, this setting releases fewer microfibers.
- Re-wear clothes. The best way to avoid generating microplastics in the wash is to reduce the amount of washing you do! Certainly don’t sacrifice smelling fresh, but for those clothes that you only wear for a brief amount of time, or clothes that can handle re-wear (like jeans), take a minute to evaluate if they really need to be washed.
- Use a fiber catcher. While these will not remove 100% of the microfibers from you’re wash, they’ll make a significant dent in your footprint. Some examples are a Cora Ball and a GuppyFriend.
- Eriksen, M., Lebreton, L. C. M., Carson, H. S., Thiel, M., Moore, C. J., Borerro, J. C., Galgani, F., Ryan, P. G., Reisser, R., 2014. PLoS One 9, 1-15. https://doi.org/10.1371/journal.pone.0111913
- Boucher, J., Friot, D., 2017. IUCN, Glan, Switzerland. https://doi.org/10.2305/IUCN.CH.2017.01.en.