Synthetic fibers as microplastics in the marine environment: A review from textile perspective with a focus on domestic washings

The ubiquity of plastic materials in the environment has been, for long, a matter of discussion. Smaller particles, named microplastics (<5mm), gained attention more recently and are now the focus of many studies, especially for their particularities regarding sources, characteristics and effects (e.g., surface-area-to-volume ratio which can increase their potential to transport toxic substances). Fibers from textile materials are a subgroup of microplastics and can be originated from domestic washings, as machine filters and wastewater treatment plants (WWTPs) are not specifically designed to retain them. Once in the environment, fibers can reach concentrations up to thousands of particles per cubic meter, being available to be ingested by a broad range of species. In this scenario, this review adds and details the textile perspective to the microplastics exploring nomenclature, characteristics and factors influencing emission, but also evidencing gaps in knowledge needed to overcome this issue. Preliminarily, general information about marine litter and plastics, followed by specific aspects regarding textile fibers as microplastics, were introduced. Then fiber sources to microplastic pollution were discussed, mainly focusing on domestic washings that pass through WWTPs. Studies that reveal domestic washing as microplastic sources are scarce and there is a considerable lack of standardization in methods as well as incorporation of textile aspects in experimental design. Knowledge gaps include laundry parameters (e.g., water temperature, use of chemicals) and textile articles characteristics (e.g., yarn type, fabric structure) orchestrated by consumers' choice. The lack of information on the coverage and efficiency of sewage treatment systems to remove textile fibers also prevent a global understanding of such sources. The search of alternatives and applicable solutions should come from an integrated, synergic and global perspective, of both environmental and textile area, which still need to be fostered.