Is the toxicity of nanosized polymethylmethacrylate particles dependent on the exposure route and food items?

The environmental effects of nanoplastics-NPLs have been addressed mainly through short-term exposures to a few types of polymers, neglecting other NPLs that are economically relevant like polymethylmethacrylate - PMMA. This work aimed to assess long-term effects of PMMA-NPLs on the marine primary consumer Brachionus plicatilis, evaluating the influence of different exposure routes (waterborne, foodborne and both) and food items (Nannochloropsis gaditana and Tetraselmis chuii). Rotifers were 21 days exposed to: a) control, with clean medium and food-CTR; b) contaminated medium (8.1 mg PMMA-NPLs/L) and clean algae-MC; c) clean medium and contaminated algae (pre-incubated for 96 h on 8.1 mg PMMA-NPLs/L)-AC; and, d) contaminated medium and algae-MC/AC. Mortality (lx), total number of organisms (TN), fecundity (mx), populational growth rate (r), generational time (gt), and feeding rates were assessed. Effects on r and mx were found after 21 days. Organisms from AC had higher r than MC. MC/AC organisms performed better than control in all endpoints. Overall organisms fed with N. gaditana had higher TN, m_x and r than those fed with T. chuii. In the AC treatments, rotifers fed with N. gaditana had higher m_x. Results highlight that exposure route and food type may modulate NPLs' effects, supporting the need for standardization of assays.