Enhanced uptake of perfluorooctanoic acid by polystyrene nanoparticles in Pacific oyster (Magallana gigas)

The effects of plastic pollution on marine organisms is of growing concern. The hydrophobic surface of plastics adsorbs organic contaminants and can alter the rate of chemical uptake in fishes. Per-fluorinated organic chemicals such as Perfluorooctanoic acid (PFOA) are highly hydrophobic toxic chemicals that adsorb to hydrophobic surfaces. We hypothesized that the presence of nano-sized plastic particles adsorbs PFOA and alter both the physical-chemical properties of the plastics and also enhance PFOA uptake into organisms. Using radiolabelled ¹⁴C-PFOA, we measured direct unidirectional uptake of PFOA in juvenile Pacific Oysters (Magallana gigas) at different (0.025, 0.50, and 0.100 mg/L) concentrations, for different exposure periods (1, 2, 4, and 6 h) and investigated whether varying concentrations (0.1, 0.5, 1 mg/L) of either 500 nm or 20 nm polystyrene nanoparticles (PS-NPs) differentially altered the uptake rate of PFOA. Our results demonstrate that PFOA adsorbs to the surface of PS-NPs, altering PS-NP behaviour in solution and significantly increases the rate of uptake of PFOA in exposed Pacific oysters. PFOA uptake at 0.1 mg/L was increased 2.3-fold in the presence of 1 mg/L 500 nm PS-NP and 3.2-fold in the presence of 1 mg/L 20 nm PS-NP. In a separate study to examine if PS NPs potentiate the biochemical response to PFOA, both 500 and 20 nm PS-NP at 100 mg/L increased the 1 mg/L PFOA-induced oxidative stress by 2.5-fold and 3-fold respectively. These findings demonstrate that nanoplastics as co-contaminants in marine systems are able to adsorb PFOA and significantly potentiate its uptake and toxicity.