Microplastic Fiber Release by Hand-Washing and Estimated Emissions in China

Microplastic fibers (MPFs) shed during textile washing is one of the most common sources of microplastics in the aquatic environment. There have been many studies on MPF release by machine washing of textiles. However, traditional hand-washing remains very common in many regions around the world, especially in developing countries. Fiber release from hand-washing remains unquantified, which imparts difficulties to accurately estimating the total fiber release from domestic laundering. We conducted such a study by using two types of synthetic textiles, and examined the effects of various washing factors. Results showed that MPF emission factor of polyester fabric was 0.040 mg MPF / g or 329 fibers / g textile during hand washing by adding powder detergent and 0.037 mg MPF / g or 353 fibers / g textile by adding liquid detergent under the routine conditions; MPF release was significantly correlated with the use of a detergent or brush, and the soaking time (P < 0.05). Moreover, we also calculated approximate MPF emissions and discharged into the water environment per year in China. Differences in the geographical distribution of MPF emissions in China mainly depended on the population density at the provincial and grid (1 km × 1 km) scale. Based on the results of this study, several relevant policy recommendations are proposed that will help reduce the discharge of MPFs into the water environment.