Emission of fibres from textiles: A critical and systematic review of mechanisms of release during machine washing

Research about health and environmental impacts of pollution caused by natural and plastic fibres is increasing, however, the role of textile characteristics in microfibre release during washing remains poorly understood. Given that machine washing is thought to be the main contributor to microfibre pollution, we systematically and critically reviewed previous publications looking at how textile features affect fibre emissions during washing. We examined the evidence related to findings from previous studies based on their research aims, ability to control variables that could confound results, use of procedural blanks and controls, and statistical methodologies. We observed that small-scale laboratory equipment frequently used to evaluate microfibre release (e.g. Gyrowash) generates significantly more fibres than domestic washing machines and should not be used to generate environmental estimations. Our findings have implications for ecotoxicology and risk assessment, particularly regarding the overlooked role of natural and cellulosic fibres. While synthetic fibres are widely recognised as the dominant form of microplastic in the environment, environmental surveys often report larger numbers of natural and cellulosic fibres. These fibres, however, account for only 18 % of those tested in the experiments analysed, indicating the need for further research to understand the underlying causes of their release. We concluded that although many textile characteristics are perceived as having an impact on fibre release, 81 % of studies failed to demonstrate clear evidence of the findings associated with such impacts. This work highlights the need for robust experiments to clarify these gaps, which could then allow the development of textiles with minimised shedding potential. We propose a stepwise approach to first build a foundational understanding of how individual washing parameters and textile features influence fibre release, followed by exploring the complexity of how the interaction between these variables impacts emissions.