Effects of nano- and micro- fibers derived from surgical face masks in Danio rerio

The massive use of surgical face masks during the COVID-19 pandemic has compounded the challenge of plastic waste. Surgical face masks are made of polypropylene (PP) and tend to release nano- and micro- fibers (NMFs). The present study aims to provide insights into the impacts of NMFs in aquatic organisms by evaluating the effects of PP-NMFs derived from the artificial photodegradation of surgical face masks on the model species Danio rerio (zebrafish). The impact of NMFs on embryonic and larval developmental stages has been evaluated by investigating the effects of low (0.2 mg/L), medium (1 mg/L), and high (5 mg/L) NMF levels. Alterations in apical endpoints and transcriptomic analysis were investigated. After 6 days, a significant reduction in the eye area was observed. The upregulation of genes related to the negative regulation of developmental processes could explain the observed alterations, while the downregulation of genes involved in energy-related metabolic processes suggests an energy stress state. Increased mortality occurred between 9 and 12 days, a period when zebrafish make the transition from endogenous to exogenous feeding, suggesting an impairment in foraging behaviour due to NMF exposure. The presented findings demonstrate that environmental levels of NMFs may pose a hazard to aquatic organisms, suggesting the potential for an ecotoxicological risk associated with the improper disposal of surgical face masks.