Microfiber release from real soiled consumer laundry and the impact of fabric care products and washing conditions

Abstract

Fiber release during domestic textile washing is a cause of marine microplastic pollution, but better understanding of the magnitude of the issue and role of fabric care products, appliances and washing cycles is needed. Soiled consumer wash loads from U.K. households were found to release a mean of 114 ± 66.8 ppm (mg microfiber per kg fabric) (n = 79) fibers during typical washing conditions and these were mainly composed of natural fibers. Microfiber release decreased with increasing wash load size and hence decreasing water to fabric ratio, with mean microfiber release from wash loads in the mass range 1.0-3.5 kg (n = 57) found to be 132.4 ± 68.6 ppm, significantly (p = 3.3 x 10 −8) higher than the 66.3 ± 27.0 ppm of those in the 3.5-6.0 kg range (n = 22). In further tests with similar soiled consumer wash loads, moving to colder and quicker washing cycles (i.e. 15˚C for 30 mins, as opposed to 40˚C for 85 mins) significantly reduced microfiber generation by 30% (p = 0.036) and reduced whiteness loss by 42% (p = 0.000) through reduced dye transfer and soil re-deposition, compared to conventional 40˚C cycles. In multicycle technical testing, detergent pods were selected for investigation and found to have no impact on microfiber release compared to washing in water alone. Fabric softeners were also found to have no direct impact on microfiber release in testing under both European and North American washing conditions. Extended testing of polyester fleece garments up to a 48-wash cycle history under European conditions found that microfiber release significantly reduced to a consistent low level of 28.7 ± 10.9 ppm from eight through 64 washes. Emerging North American High-Efficiency top-loading washing machines generated significantly lower microfiber release than traditional top-loading machines, likely due to their lower water fill volumes and hence lower water to fabric ratio, with a 69.7% reduction observed for polyester fleece (n = 32, p = 7.9 x 10 −6) and 37.4% reduction for polyester T-shirt (n = 32, p = 0.0032). These results conclude that consumers can directly reduce the levels of microfibers generated per wash during domestic textile washing by using colder and quicker wash cycles, washing complete (but not overfilled) loads, and (in North America) converting to High-Efficiency washing machines. Moving to colder and quicker cycles will also indirectly reduce microfiber release by extending the lifetime of clothing, leading to fewer new garments being purchased and

Plastic microfibre pollution: how important is clothes’ laundering?

“…As suggested previously, it is unlikely that such small laboratory machines will produce results similar to those from the larger domestic or commercial models. Indeed, Lant et al (2020) suggest that their results and those of Pirc et al (2016) differ from those of Hernandez et al (2017) and Carney Almroth et al ( 2018) because of the use, by the latter two groups, of these small-scale simulation devices (Washtec P and GyroWash, respectively). The physical action of agitation, especially, differs between the machines and this must affect the fibrillation and breaking processes, with resulting differences in free microfibre production.…”

“…The results of Lant et al (2020), who measured microfibre release under both European and North American laundry conditions, suggest that high water to fabric ratio increases microfibre loss, thus encouraging the current environmental aims of reducing water usage. This provides an additional reason why the appliance industry should continue to develop approaches to reduce water consumption during laundering.…”

“…In the first report of this phenomenon, that of Browne et al (2011), 1900 microfibres/wash/garment was the estimated release; later studies have used more exact measurements, such as mg.kg À1 , microfibres.m-2 (see Table 1). The effects of variables such as type of textile, detergent, temperature and washing action have been determined, some of them using special small simulation machines, in which parameters can be specified and held constant (e.g., Hernandez et al, 2017;Carney Almroth et al, 2018), whilst others (e.g., Lant et al, 2020;Dalla Fontana et al, 2020;Galvão et al, 2020; K€ arkk€ ainen and Sillanp€ a€ a 2021) have employed domestic washers of various types. Such studies can give useful insights into the effects of changes in laundry procedures and could be useful in the development of a standard test method.…”

“…After the first wash, fibre release decreases until it reaches a plateau (De Falco et al, 2019;Kelly et al, 2019;Napper and Thompson, 2016). Apparently, the recently developed North American high-efficiency top-loaders produce considerably less microfibers than the old-fashioned type (Lant et al, 2020); it has been shown that the volume of water in relation to the quantity of textiles influences the amount of microfibre release (Kelly et al, 2019) and the lower amounts of water used in high-efficiency models could be the reason for reduced fibre production. In the study of Lant et al (2020), the lower water to fabric ratio accompanied a 69.7% reduction in fibre release for polyester fleece (n ¼ 32, p ¼ 7.9 Â 10-6) and 37.4% reduction for polyester T-shirt (n ¼ 32, p ¼ 0.0032).…”

“…These authors also found that adding detergent to the wash increased microfibre numbers, and this has been confirmed by some, but not all, other authors. O'Brien et al ( 2020) stated that the presence of detergent increased microfibre release, but detergent composition and amount had little effect, a result that was echoed by Lant et al (2020). The overall length of the released fibres was not affected by detergent according to O'Brien et al ( 2020); Cesa et al (2020) however, determined that detergent actually reduced the release of microfibres from synthetic garments during machine washing.…”