Are we underestimating anthropogenic microfiber pollution? A critical review of occurrence, methods and reporting

, Athey Samantha, Erdle Lisa.

Anthropogenic microfibers, a ubiquitous environmental contaminant, can be categorized as synthetic, semi-synthetic or natural according to material of origin and production process. Although natural textiles fibers, such as cotton, are harvested from natural sources, chemical additives, including colorants and finishes, are applied to textiles to enhance performance and prevent degradation of the material. While most research and communication on microfibers has focused on the sources, pathways and effects of synthetic fibers in the environment, semi-synthetic and natural fibers are sufficiently persistent to undergo long-range transport and accumulate in the environment, where they may be ingested by biota. The challenges of enumeration and identification of natural and semi-synthetic fibers in environmental samples lead us to question whether current methods comprehensively capture and estimate inputs and occurrence of anthropogenic fibers in the environment. The goals of this study are to highlight gaps in research and to recommend best practices for enumeration and identification of anthropogenic fibers. We conducted a systematic literature review of 327 peer-reviewed, original research studies documenting microfibers in the environment. Our preliminary results show most microfiber studies focus on aquatic environments, with few focusing on the indoor or terrestrial environment. Roughly half of studies surveyed report the presence of natural or semi-synthetic fibers. Of the 129 studies surveyed thus far that report natural and/or semi-synthetic fibers, 71% employ digestion methods that have been demonstrated to cause destruction of naturally-derived anthropogenic fibers, indicating these studies may be underestimating anthropogenic microfiber abundance. Here we uncover major gaps in anthropogenic microfiber research, as well as identify best practice recommendations for successfully enumerating and identifying semi-synthetic and natural fibers from environmental samples. Further, we show that by focusing exclusively on the sources, pathways and effects of synthetic fibers in the environment, we are neglecting a major component of anthropogenic microfiber pollution.

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