Impacts of non-petroleum and petroleum-based microfibres on aquatic organisms: a meta-analysis

Contamination of aquatic ecosystems with microfibres (fibres < 5 mm in size) shed from textiles and other consumer items is a global conservation concern. While generally considered to be less persistent compared to petroleum-based materials, the relative ecotoxicological impact of non-petroleum microfibres is understudied. Here, we present the first meta-analysis to compare the ecotoxicity of petroleum-based and non-petroleum based microfibre classes on aquatic organisms. Data were extracted from 38 eligible microfibre ecotoxicological studies (472 suitable endpoints) and both non-petroleum and petroleum-based microfibre classes had overall significant biological effects on organisms. Many polymers had significant negative biological impacts including cotton, viscose, asbestos, polyester and polypropylene exposures although non-petroleum exposures were underrepresented within the literature (non-petroleum = 89, petroleum-based = 383 endpoints). Mixed effects models comparing effect sizes within polymer classes for different microfibre (response, concentration, size etc) and organism subgroup levels (taxonomic grouping and environment) found mostly non-significant with fewer negative biological responses for non-petroleum (2/30; 3/27 when excluding glass and asbestos exposures) compared to petroleum-based exposures (27/48). Additionally, positive biological effects were observed for non-petroleum microfibre exposures within Plantae, for microfibres 501-2000 µm in length as well as at microfibre doses of 10¹-10³ µg L⁻¹ when excluding glass and asbestos exposures. Considering the observed ecotoxicological impacts of both microfibre classes, we suggest complementary better-by-design approaches combined with best management practices to reduce the shedding, accumulation and residence time of microfibres of all categories within aquatic ecosystems.