Critical review of microfiber release from textiles: Results, comparative challenges, mitigation strategies, and legislative perspectives.

The release of microfibers (MFs) from laundry has emerged as a significant environmental concern, drawing extensive attention from the scientific community. This review aims to provide a comprehensive overview of the current state of research on MFs release during washing, focusing on the factors influencing this phenomenon and the methods used to assess it. The results highlighted that, despite the proliferation of studies, a standardized protocol for measuring MFs release remains absent, leading to inconsistencies and challenges in data comparison. Direct and indirect methods have been used, both presenting different disadvantages that make the comparison quite challenging, with the first being more operator-dependent and likely giving lower magnitude value and the second being more prone to the error induced by the presence of other substances (like the detergent used during the washing). Moreover, the lack of a unified measurement unit further complicates cross-study comparisons. Factors such as the type of washing machine, washing program, detergent, and softener significantly impact the quantity of MFs released. While internal and external devices directly developed for MFs retention show promise in lowering the release, their current efficiency is low. Additionally, this review examines legislative efforts to address MFs' pollution, emphasizing the critical need for a thorough investigation within the scientific community. The results presented are intended to benefit both (i) the scientific community by identifying current gaps in the literature and offering guidance for future research, and (ii) technical stakeholders, such as washing machine manufacturers and developers of MFs mitigation systems, by providing insights into reducing microfiber release during laundry activities.