Microplastics in the Textile Industry: Part I - Characterization
New research on microplastics is changing how we think about textile processes. These pernicious substances, most commonly found in fiber form, have the potential to impact bodily function in humans due to physical and chemical interactions when ingested.
When formed into highly-engineered structures, manufactured textiles have the potential to impart comforts, advantages, and critical attributes, including (but certainly not limited to) moisture wicking, thermal resistance, and flame retardancy. Textile innovators heavily rely on the beneficial properties of plastics. From antimicrobial one-way moisture vapor transport found in medical gowns, to high-efficiency water and air separation in HEPA filters, to the durability and abrasion resistance in harnesses and parachutes, countless professionals and individuals across varied fields depend on the properties that engineered plastic fibers can provide to be comfortable and safe in any article of clothing or piece of equipment.
“The advent of plastics has ushered in a new era of functionality and convenience to our textile goods.”
The advent of plastics has ushered in a new era of functionality and convenience to our textile goods; however, these materials lack the biodegradability of their natural predecessors. The soft nature of polymeric materials allows them to be molded and formed into any shape of our desire, yet this property also promotes easy breakdown of these plastics into small particles. When the size of these polymeric materials is reduced to less than 5mm, they are referred to as microplastics, and can easily pass through filtration mechanisms to enter waterways, soil, and breathable air.
Often, plastics are intentionally designed at small dimensions to provide key properties. Known as primary microplastics, they commonly take the form of microbeads, microfibers, and polymer powders. Microbeads are used in cosmetics to provide gentle scrubbing and exfoliation. Though perhaps most recognizable in commercial face washes, they can also be found in deodorants, makeup, and toothpaste.
Microfibers provide warmth in apparel due to increased loft capabilities and can also provide wicking due to surface area capillary action. Fine polymer powders, meanwhile, can be used in various applications such as for adhesives, construction binders, powder-based 3D printing, and in nail salons (in the form of dipping powder, a common method of manicure).
Secondary microplastics, however, are not engineered with the express intent to produce small plastic particles, yet these particles become released due to the effects of abrasion, wind, UV damage, degradation, and aquatic degradation.
Unfortunately, the textile industry is a major contributor to the production and release of microplastics. In a recent analysis from the American Chemical Society, researchers compiled data from 11 studies of microplastics in aquatic and sediment locations and found that the most abundant shape category in both locations was fiber, with textile fibers making up 48.5% of the collected data [1]. This finding has been corroborated in repeated studies for microplastics found in aquatic, atmospheric, and sediment locations; most research points to the vast majority of microplastics coming from fibers [2, 3, 4, 7]. The frequency of microplastic size is thought to follow a power law distribution [6, 7]. As larger pieces fracture into smaller pieces over time, microplastic concentration generally increases with decreasing particle size [1, 5, 11].
The most common polymers found in microplastic form are polyethylene (PE) and polyethylene terephthalate (PET), closely followed by polyamide (PA) and polypropylene (PP) [1, 2, 4]. PE is the most widely used polymer in the world, with production of over 100 million metric tons per year [8]. Even if you don’t know it by name, you’ve met it before. In the textile market, PE is typically used for outdoor applications such as geotextiles and outdoor furniture. However, most applications are for non-textile use such as packaging materials, films, and plastic bags.
PET, commonly known as “polyester”, is the most ubiquitous fiber in the textile industry, with annual production of 63 million metric tons per year in fiber form [9]. PET accounts for 70% of total fiber production and is commonly used in microfiber applications for bedding and apparel [9]. Polyester fabric is also commonly found in sports wear and outdoor apparel due to wicking properties.
PA, commonly referred to as “nylon,” is omni-present in microplastic form. This polymer, with 4 million metric tons of annual production volume in fiber form, is often used in carpeting and outdoor apparel for the textiles industry [9].
PP production is 3.1 million metric tons per year. Although used in fibers for industrial applications, most PP is used in non-textile applications, such as packaging and consumer goods.
Although plastics are an integral part of the textile industry, the current body of modern research into the long-term effects of their production and degradation suggests these textile materials will percolate into the environment. In future editions, we will explore how these materials can impact our health and the ecological condition of our world.
Long Story Short: Although plastic materials provide properties crucial to the functionality of many textile products, when these materials break down or are manufactured in small particle sizes, they can enter our environment. The most common shape of microplastics is “fiber,” indicating the textile industry is a major contributor to the production of microplastics. PE and PET are the most common polymers found in microplastics form.
References:
[1] Kooi, M., & Koelmans, A. A. (2019). Simplifying Microplastic via Continuous Probability Distributions for Size, Shape, and Density. Environmental Science & Technology Letters, 6(9), 551–557. 10.1021/acs.estlett.9b00379
[2] Heshmati, S., Makhdoumi, P., Pirsaheb, M., Hossini, H., Ahmadi, S., & Fattahi, H. (2021). Occurrence and characterization of microplastic content in the digestive system of riverine fishes. Journal of Environmental Management, 299(1). doi:10.1016/j.jenvman.2021.113620
[3] Wright, S. L., Ulke, J., Font, A., Chan, K. L. A., & Kelly, F. J. (2020). Atmospheric microplastic deposition in an urban environment and an evaluation of transport. Environment International, 136. doi:10.1016/j.envint.2019.105411
[4] Burns, E. E., & Boxall, A. B. A. (2018). Microplastics in the Aquatic Environment: Evidence for or Against Adverse Impacts and Major Knowledge Gaps. Environmental Toxicology and Chemistry, 37(11), 2776–2796. doi:10.1002/etc.4268?src=getftr
[5] Uurasjärvi, E., Hartikainen, S., Setälä, O., Lehtiniemi, M., & Koistinen, A. (2020). Microplastic concentrations, size distribution, and polymer types in the surface waters of a northern European lake. Water Environment Research, 92(1), 149–156. doi:10.1002/wer.1229
[6] McDowell, G. R., & Bolton, M. D. (1998). On the micromechanics of crushable aggregates . Géotechnique, 48(5), 667–679. doi:10.1680/geot.1998.48.5.667
[7] Dris, R., Gasperi, J., Saad, M., Mirande, C., & Tassin, B. (2016). Synthetic fibers in atmospheric fallout: A source of microplastics in the environment. Marine Pollution Bulletin, 104(1-2), 290–293. doi:10.1016/j.marpolbul.2016.01.006
[8] Geyer, R., Jambeck, J. R., & Law, K. L. (2017). Production, use, and fate of all plastics ever made. Science Advances, 3(7). doi:10.1126/sciadv.1700782
[9] Global Textile Production by Fiber Type 2024. (n.d.). Retrieved from https://worldostats.com/global-textile-production-by-fiber-type-2024/
[10] Production of polypropylene fiber worldwide from 2017 to 2022 . (2023, December 11). Retrieved from https://www.statista.com/statistics/1260421/polypropylene-fiber-production-worldwide/
[11] Railo, S., Talvitie, J., Setälä, O., Koistinen, A., & Lehtiniemi, M. (2018). Application of an enzyme digestion method reveals microlitter in Mytilus trossulus at a wastewater discharge area. Marine Pollution Bulletin, 130, 206–214. doi:10.1016/j.marpolbul.2018.03.022