Polyester clothing sheds microplastics every time it is washed. Polyester, or polyethylene terephthalate (PET), is a synthetic polymer derived from petroleum that forms the basis of many textiles. These shed fragments are defined as microplastics because their longest dimension is less than five millimeters. Synthetic textiles constitute a significant source of global pollution, accounting for approximately 35% of all primary microplastic released into the oceans. Since synthetic fibers now make up about 60% of all global fiber production, the washing machine’s role as a source of this pervasive contamination is substantial.
The Physical Process of Fiber Release
The physical act of washing subjects garments to mechanical stresses that cause fiber detachment. The primary mechanism for microplastic release is the intense friction and abrasion between individual garments inside the washing machine drum. This constant rubbing weakens the polyester threads, leading to breakage and the formation of microscopic plastic fragments.
Agitation and beating actions further accelerate the process by loosening fibers from the fabric structure. The resulting microplastic fibers are typically very short, with most fragments measuring between 100 and 800 micrometers in length. Machine washing releases a vastly greater quantity of fibers than gentler methods like handwashing.
Shedding is also attributed to “floating fibers,” which are loose fragments left over from the manufacturing process. These are released rapidly during the first few wash cycles of a new garment, but continuous mechanical breakdown ensures shedding remains a persistent problem throughout the garment’s usable life.
Factors Governing Microplastic Release Rates
The quantity of microplastics released is heavily influenced by the textile’s construction and the washing conditions employed. Fabrics with a loose knit structure, such as fleece or brushed textiles, shed significantly more fibers than tightly woven materials. Garments made with low-quality or already worn fabrics also exhibit higher release rates because their fibers are structurally compromised.
Washing conditions play an immediate role in fiber detachment. Hot water weakens the polymer structure of the polyester fibers, making them more susceptible to mechanical breakdown during the wash cycle. Detergent also increases the overall quantity of fibers released compared to washing with plain water.
The design of the washing machine is another variable. Top-loading models that use a central agitator cause the most damage, leading to substantially greater shedding—up to seven times more—than gentler, high-efficiency front-loading machines. Conversely, running a wash with a low load increases mechanical stress, which can lead to a five-fold increase in microplastic release compared to a full load.
Practical Steps to Reduce Shedding
Consumers can implement specific changes to their laundry routine to mitigate the release of polyester microplastics. Washing synthetic garments less frequently is one of the simplest and most effective steps. When washing is required, opting for a cold water setting helps preserve fiber integrity by preventing the thermal weakening associated with hot water.
Selecting a shorter, gentle wash cycle can reduce shedding by as much as 70% compared to a standard cycle, minimizing mechanical stress. Washing full loads helps reduce abrasion between items by dampening the intensity of the agitation. Minimizing the spin cycle speed also prevents excessive tugging and stress on the polyester fibers.
Specialized products are available to intercept microfibers during the wash:
- Washing bags, such as the Guppyfriend, catch shed microfibers and reduce fiber breakage by up to 86% due to their smooth material.
- Simpler devices like the Cora Ball, tossed directly into the drum, use a textured surface to capture microfibers, offering an average reduction of about 26%.
- External filtration systems, such as the LINT LUV-R, install on the discharge hose and capture 87% of microfibers before they enter the wastewater system.
These external filters require the user to collect and dispose of the captured lint and microplastics in the trash every two to three loads.
Environmental Pathway and Impact
Microscopic plastic fibers follow a dual pathway into the environment. The majority are flushed out with laundry wastewater toward municipal wastewater treatment plants (WWTPs). Although WWTPs filter out a large percentage of microplastics, the smallest fibers often escape and are discharged into local rivers and coastal waters.
The second pathway involves air release from tumble dryers, which can be a significant source of atmospheric microplastic pollution. High-speed tumbling creates friction that generates and propels microfibers through the dryer’s unfiltered vent. A single household dryer is estimated to release up to 120 million microfibers into the air per year, a quantity that can be 1.4 to 40 times greater than that released via the washing machine.
In the environment, these polyester microfibers threaten ecosystems. Marine organisms commonly ingest the fibers, leading to physical harm and blockages in their digestive systems. The plastic fragments act as carriers for environmental toxins, readily adsorbing persistent organic pollutants like polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). The fibers can also leach manufacturing chemicals, such as bisphenols and UV stabilizers, into the surrounding water.