We compare the toxicity of microplastics, microfibres and nanoplastics on mussels. Mussels (Mytilus
spp.) were exposed to 500 ng mL-1 of 20 µm polystyrene microplastics, 10x30 µm polyamide
microfibres or 50 nm polystyrene nanoplastics for 24 h or 7 days. Biomarkers of immune response,
oxidative stress response, lysosomal destabilisation and genotoxic damage were measured in
haemolymph, digestive gland and gills. Microplastics and microfibres were observed in the digestive
glands, with significantly higher plastic concentrations after 7-days exposure (ANOVA, P<0.05).
Nanoplastics had a significant effect on hyalinocyte-granulocyte ratios (ANOVA, P<0.05), indicative of
a heightened immune response. SOD activity was significantly increased followed 24 h exposure to
plastics (two-way ANOVA, P<0.05), but returned to normal levels after 7-days exposure. No evidence
of lysosomal destabilisation or genotoxic damage was observed from any form of plastic. The study
highlights how particle size is a key factor in plastic particulate toxicity
