Microplastics in Activewear: What They Are and How to Reduce Exposure
Microplastics are fragments of synthetic plastic smaller than 5 millimetres. In the context of activewear, they are shed from synthetic fabric during washing and wear as microscopic fibers called microfibers. Polyester, nylon, acrylic, and spandex all shed synthetic microfibers. These particles enter waterways, accumulate in marine and freshwater ecosystems, and have been detected in human blood, lung tissue, breast milk, and placental tissue. Reducing microplastic exposure from clothing means choosing activewear made primarily from natural or plant-derived fibers that do not shed synthetic polymer fragments.
- A single synthetic garment can shed hundreds of thousands of microfibers per wash cycle (Napper and Thompson, 2016)
- Microplastics have been found in human blood (Leslie et al., 2022), lung tissue, breast milk, and placental tissue
- Polyester, nylon, acrylic, and elastane all shed synthetic microfibers during washing and wear
- TENCEL Lyocell is a plant-derived cellulose fiber and does not shed synthetic microplastics
- Cellulose microfibers shed by natural fibers biodegrade significantly faster than synthetic polymer microfibers
- Most natural fiber activewear contains spandex for stretch — that component does shed synthetic microfibers
- Washing garments less frequently, at lower temperatures, and using a microplastic filter bag reduces shedding
What Are Microplastics?
What are microplastics?
Microplastics are synthetic plastic particles smaller than 5 millimetres. They are divided into two categories by origin. Primary microplastics are manufactured at small size from the outset, such as the microbeads previously used in personal care products. Secondary microplastics result from the fragmentation of larger plastic items through physical, chemical, and UV degradation over time, or from the shedding of synthetic fibers during washing and wear. Textile microfibers, the category relevant to activewear, are secondary microplastics. They are microscopic filaments of synthetic polymer that detach from fabric during laundering and use.
How do microplastics from clothing enter the body?
Textile microfibers enter the environment through wastewater from domestic washing machines. Standard wastewater treatment plants capture a significant proportion but not all microfibers, and those that pass through discharge into rivers, lakes, and oceans. From there, microplastics enter the food chain through marine organisms, drinking water sources, and airborne particles. Research by Leslie et al. (2022), published in Environment International, detected microplastic particles in the blood of 77% of human donors tested, demonstrating systemic human uptake from environmental exposure. Inhalation of airborne textile fibers is also a documented exposure route, with Amato-Lourenco et al. (2021), in Science of the Total Environment, detecting microplastic fibers in human lung tissue samples.
Are microplastics dangerous?
The research on human health effects of microplastics is developing rapidly and the picture is not yet complete, but the findings to date are serious enough to warrant concern. Microplastics have been detected in human blood, lungs, breast milk, placental tissue, and stool. A study by Ragusa et al. (2021) in Environment International found microplastic particles in human placental tissue, raising questions about fetal exposure. The physical presence of foreign particles in tissue triggers inflammatory responses, and the chemical additives within plastic polymers, including plasticisers and flame retardants, can leach from the particles once inside the body. The World Health Organization (WHO, 2019) characterised the current evidence as insufficient to draw firm conclusions about human health harm but called for urgent further research and precautionary action.
Microplastics in Activewear Specifically
Do leggings shed microplastics?
Synthetic leggings do. Research by Napper and Thompson (2016), published in Marine Pollution Bulletin, found that a single synthetic garment can shed more than 700,000 microfibers per wash cycle depending on fabric type, construction, and washing conditions. Polyester fleece shed the most in their study. Polyester-spandex blends commonly used in activewear shed substantial quantities as well. The volume of shedding varies by fabric construction, washing temperature, agitation intensity, and wash cycle duration, but no synthetic fabric has been shown to shed zero microfibers under realistic laundering conditions.
Which fabrics shed the most microplastics?
Among commonly used activewear fabrics, acrylic sheds the most microfibers per wash, followed by polyester, then nylon. Spandex and elastane, used in almost all stretch activewear as a small percentage component, also shed synthetic microfibers. Fabric construction matters as well as fiber type: looser knit structures shed more than tighter interlock constructions because there is more fiber surface exposed and less structural cohesion holding fibers in place. Heavier fabric weights with tighter constructions shed fewer fibers per wash than lightweight open-knit fabrics of equivalent fiber composition.
Does TENCEL Lyocell shed microplastics?
No. TENCEL Lyocell is a plant-derived cellulose fiber, not a synthetic plastic. When TENCEL fibers shed during washing, the particles are cellulose microfibers rather than synthetic polymer fragments. Research by De Falco et al. (2020), in Scientific Reports, found that cellulose microfibers biodegrade significantly faster than synthetic microplastics under comparable conditions, making them substantially less persistent in the environment. Bellissima's Sempre collection is 92% TENCEL Lyocell and 8% spandex. The TENCEL Lyocell component does not shed synthetic microplastics. The spandex component, being a synthetic elastane, does shed synthetic microfibers during washing. Bellissima does not claim its garments are microplastic-free. The 8% spandex content makes that claim inaccurate, and this is stated clearly.
Does wearing activewear release microplastics without washing?
Yes, though at lower volumes than washing. Mechanical friction during wear causes fiber fragmentation and release from fabric surfaces. Wearing synthetic activewear during exercise, where fabric moves repeatedly against skin and itself, generates microfiber release in addition to what occurs during laundering. Lint on skin and surfaces after wearing synthetic garments is a visible indicator of this process. Research by De Falco et al. (2020) compared microfiber release during wearing and washing and found both to be meaningful exposure routes, with washing generating higher volumes per event but wear-based release accumulating continuously across the use life of a garment.
Is microplastic shedding worse when exercising in synthetic activewear?
During exercise, several factors combine that may increase microfiber release and skin exposure relative to casual synthetic clothing wear. Increased movement creates more friction between fabric and skin and between fabric layers. Elevated skin temperature and sweat production may increase the rate of microfiber transfer to the skin surface. The close-fitting nature of activewear compared to looser garments means fabric is in constant contact with the body. None of these factors have been quantified precisely in published research specific to activewear, but the mechanisms are established. The precautionary logic for prioritising natural fiber activewear over synthetic alternatives is stronger for garments worn in close skin contact during physical activity than for outerwear or loosely worn garments.
How to Reduce Microplastic Exposure from Clothing
How do I reduce microplastics from my activewear?
Six evidence-supported approaches reduce microplastic shedding from clothing. First, choose natural or plant-derived fiber activewear where possible: TENCEL Lyocell, organic cotton, and merino wool do not shed synthetic microplastics at the fiber level. Second, wash synthetic garments less frequently: each wash cycle generates shedding, so wearing garments more times between washes reduces total lifetime shedding volume. Third, wash at lower temperatures: higher temperatures increase fiber degradation and shedding. Fourth, use a shorter, gentler wash cycle: reduced agitation and cycle duration lower shedding volume. Fifth, use a microplastic filter bag or washing machine filter: products such as the Guppyfriend bag capture microfibers before they enter wastewater. Sixth, wash synthetic garments inside out: this reduces surface abrasion against other garments.
Do microplastic filter bags actually work?
Yes, meaningfully. Research by Napper et al. (2020), published in Marine Pollution Bulletin, tested the Guppyfriend washing bag and found it reduced microfiber release into wastewater by more than 50% compared to unfiltered washing of the same garments. Washing machine drum filters, fitted directly to the appliance, have shown similar or higher capture rates in independent testing. Neither approach captures 100% of microfibers shed, but both represent a meaningful reduction in the volume entering wastewater systems from domestic laundering.
Is it better to hand wash synthetic activewear to reduce microplastics?
The evidence is mixed. Some studies find hand washing generates lower microfiber release than machine washing due to reduced mechanical agitation. Others find comparable or higher release because hand washing often involves more direct manual friction on the fabric. The most consistent finding across studies is that reducing agitation intensity, water temperature, and cycle duration in machine washing produces lower shedding than standard cycles. If machine washing with a gentle cycle and cold water produces similar results to hand washing, the machine wash option is more practical without meaningful additional environmental cost.
The Broader Picture
How significant is activewear as a source of microplastic pollution?
Textiles are one of the largest sources of microplastic pollution globally. A report by the International Union for Conservation of Nature (IUCN, 2017) estimated that synthetic textiles account for approximately 35% of primary microplastic pollution in the ocean. Activewear represents a subset of total synthetic textile volume, but it is a high-friction, high-wash-frequency category compared to other garment types, which means per-garment microfiber contribution is likely higher than for less frequently worn or washed items. The scale of the problem is environmental as much as individual: choosing natural fiber activewear reduces personal contribution to microplastic pollution and removes a source of synthetic polymer shedding from the immediate skin environment simultaneously.
Will microplastics from my laundry end up in drinking water?
Some will. Microfibers that pass through wastewater treatment enter river and lake systems, and surface water sources used for drinking water supply contain detectable microplastic contamination in multiple studies. Tap water and bottled water have both been found to contain microplastic particles in independent testing across multiple countries. The contribution of any individual household's laundry to drinking water contamination is small in absolute terms, but textile microfibers from domestic washing have been identified in drinking water treatment plants and in treated tap water in several studies. Reducing shedding at source through fabric choice and washing practice is the most direct individual-level intervention available.
Bellissima and Microplastics
Why does Bellissima use TENCEL instead of polyester?
The decision to use TENCEL Lyocell rather than polyester as the primary fiber in the Sempre collection was made specifically because polyester sheds synthetic microplastics, contains no PFAS at fiber level, and does not provide the same skin-contact comfort properties as TENCEL. At 92% TENCEL Lyocell and 8% spandex, the Sempre collection minimises synthetic fiber content to the functional minimum required for activewear stretch performance. The spandex component is disclosed. The microplastic shedding from the spandex component is acknowledged. The goal is the highest possible natural fiber content with honest disclosure of what the remaining 8% means in practice. Browse Bellissima's non-toxic activewear and natural fiber activewear collections for the full Sempre range.
Can I buy truly microplastic-free activewear?
Only if the garment contains zero synthetic fiber content, including spandex, elastic in waistbands, and synthetic thread. In practice, virtually all structured activewear contains some percentage of synthetic elastane for stretch and shape retention. 100% natural fiber garments without any elastane exist, primarily in casual or lifestyle categories rather than performance activewear. For functional activewear that holds shape, compresses, and recovers through repeated movement, some synthetic component is currently required with available manufacturing technology. The realistic goal for most buyers is minimising synthetic content to the functional minimum, choosing the highest natural fiber percentage available, and reducing laundering frequency. Bellissima's PFAS-free leggings collection reflects this approach: 92% TENCEL Lyocell, 8% spandex, with full transparency about what that means.
Sources
Amato-Lourenco, L.F., et al. (2021). Presence of Airborne Microplastics in Human Lung Tissue. Science of the Total Environment.
De Falco, F., et al. (2020). Microfiber Release to Water, Via Laundering, and to Air, via Everyday Use. Scientific Reports.
International Union for Conservation of Nature (2017). Primary Microplastics in the Oceans. IUCN.
Leslie, H.A., et al. (2022). Discovery and Quantification of Plastic Particle Pollution in Human Blood. Environment International.
Napper, I.E., and Thompson, R.C. (2016). Release of Synthetic Microplastic Fibres from Domestic Washing Machines. Marine Pollution Bulletin.
Napper, I.E., et al. (2020). The Efficiency of Devices Designed to Reduce Microfibre Release During Clothes Washing. Marine Pollution Bulletin.
Ragusa, A., et al. (2021). Plasticenta: First Evidence of Microplastics in Human Placenta. Environment International.
World Health Organization (2019). Microplastics in Drinking Water. WHO.