Short Depuration of Oysters Intended for Human Consumption Is Effective at Reducing Exposure to Nanoplastics

Nanoplastics (NPs; <1 mu m) have greater availability to marine organisms than microplastics (1-5000 mu m). Understanding NP uptake and depuration in marine organisms intended for human consumption is imperative for food safety, but until now it has been limited due to analytical constraints. Oysters (Crassostrea gigas) were exposed to polystyrene NPs doped with palladium (Pd), allowing the measurements of their uptake into tissues by inductively coupled plasma mass spectrometry (ICP-MS) combined with electron microscopy. Oysters were exposed for 6 days (d) to Smooth or Raspberry NPs, followed by 30 d of depuration with the aim of assessing the NP concentration in C. gigas following exposure, inferring the accumulation and elimination rates, and understanding the clearance of Pd NPs during the depuration period. After 6 d, the most significant accumulation was found in the digestive gland (106.6 and 135.3 mu g g(-1) dw, for Smooth and Raspberry NPs, respectively) and showed the most evident depuration (elimination rate constant K-Smooth = 2 d(-1) and K-Raspberry = 0.2 d(-1)). Almost complete depuration of the Raspberry NPs occurred after 30 d. While a post-harvesting depuration period of 24-48 h for oysters could potentially reduce the NP content by 75%, more research to validate these findings, including depuration studies of oysters from the field, is required to inform practices to reduce human exposure through consumption.

Automated summary

Nanoplastics can be accumulated and gradually eliminated in oysters, indicating the potential risk of human consumption. Further research is needed to validate the findings and develop practices to reduce human exposure through food consumption.