To Örebro University

As plastic debris breaks down in environments, it forms micro(nano) plastics that threaten organisms across ecosystems. These tiny particles are potentially harmful due to industrial additives ingested by organisms. Given the growing concern related to micro(nano) plastics, this study compared the toxicity of leachate from tire wear particles (TWPs) and a bioplastic alternative (Mater‑Bi ®) using two model organisms: zebrafish (Danio rerio) and nematodes (Caenorhabditis elegans). We investigated embryotoxicity and behavioral changes (photomotror response and tapping test) in zebrafish, alongside survival rates and swimming activity in nematodes. Interestingly, in zebrafish embryos, TWPs caused significant depigmentation (0.6 and 1.2 μg peq/mL, p<0.05 reducing visibility and decreasing activity under dark conditions in the larval photomotor response. Notably, activity in the tapping test increased across all tested concentrations of TWPs in zebrafish (p<0.05). In nematodes, the leachate was inducing hyperactivity (1.5 to 5 μg/mL), approximately a 1.5-fold increase in activity at 1.5 μg/mL (p<0.0001) without significantly impacting their survival. Although seemingly harmless to zebrafish a tall tested concentrations, bioplastics significantly reduced nematode activity (approximately 1.2 fold, p<0.008) at higher concentrations (>5 μg/mL). These findings emphasize the need for multi-species studies to understand the complex and variable impacts of micro(nano) plastics on various ecosystems.