Mixture toxicity of 6PPD-quinone and polystyrene nanoplastics in zebrafish

Tyre-wear particles are the second largest source of microplastics in the ocean following abrasion of synthetic fibres. In addition to the particles themselves, TWPs contain many harmful chemicals, including 6PPD. This chemical reacts with atmospheric ozone and forms the toxic compound 6PPD quinone, which poses a danger to aquatic life. There is a knowledge gap in understanding risks associated with thecombined toxicity of nanoplastics and 6PPDq. The present study aimed to investigate the toxicity of NPs and 6PPDq on adult zebrafish. However, we found significant hyperlocomotion in zebrafish exposed to 6PPDq and this effect was even more substantial after co-exposure with PSNPs. The more pronounced toxic response in coexposed zebrafish was also observed at the transcriptomic level. KEGG pathways analysis identified mitochondrial dysfunction in the intestine and metabolic disturbances in the liver. These results highlight the significance of mixture toxicity when studying the effects of NPs and associated chemicals like 6PPDq.