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Why the radiolabelling approach is the gold standard for ecotoxicological investigation of nanoplastics?

AL SID CHEIKH M¹, De Maria D², Kaegi R³, Wacker L²

¹University Of Surrey, Guildford, United Kingdom, ²Swiss Federal Institute of Technology (ETH), Laboratory of Ion Beam Physics (LIP), Zurich, Switzerland, ³Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Dubendorf, Switzerland

Studies investigating the effects of nanoplastics (NPs) on aquatic organisms used concentrations 2 to 7 order-of-magnitudes higher than those predicted in the open ocean to detect NPs. These studies divided the community into those who sounded the alarm based on observed ecotoxicological effects, and those who predicted that concentrations of NPs in the environment were well below any threshold-effect. In reality, most experiments were inadequately designed, and the results were therefore unsatisfactory. Fit-to-purpose experimental designs have been hindered by a lack of appropriate NP models, tracking methods, and monitoring strategies for environmentally realistic concentrations.

Using ¹⁴C-labelled NPs and conventional nuclear techniques, I recently modelled that scallops chronically exposed (over a year) to environmentally realistic NP concentrations (15 µg/L) could accumulate NPs and reach concentrations in body tissues at which effects were observed by those who raised sounded the alarm. Surprisingly, this suggests that NPs in organisms have already exceeded threshold levels and could be damaging the marine biota.

Here, I present an innovative approach to overcome the analytical limitations for the detection and quantification of NPs under realistic environmental conditions. By combining ¹⁴C-labelling of NPs with the ultimate sensitivity of Accelerator Mass Spectrometry (AMS), we will be able to conduct exposure experiments under realistic conditions. The ¹⁴C-labelling coupled with the AMS will provide an unprecedented level of sensitivity, allowing us for the first time, to account for any ¹⁴C when performing long-term experiments, closing the gap on many critical environmental questions about plastics.