Environmental Migration,Toxicity Testing and Risk Screening for Plastic Additives:Advances and Challenges
Plastic and microplastic pollution have become increasingly severe,raising widespread concern,and spe-cifically regarding the risk of the release of plastic additives(PAs).The disposal and recycling of plastic solid waste,particularly in landfill and incineration processes,result in the substantial release of PAs into the environ-ment.These additives are predominantly discharged by wastewater treatment plants,and infiltrate the water envi-ronment through various processes such as atmospheric deposition,soil erosion,groundwater infiltration,and sur-face runoff.The leaching of PAs poses threats to aquatic organisms as these additives can persistently migrate through various biological carriers.Micro-and nano-plastics(MNPs),acting as carriers,also make key contribu-tions to the continuous release and accumulation of PAs in aquatic environments.However,the extensive variety,functions,quantities and complex compositions of plastic additives present formidable challenges in their assess-ment.This study presented the state-of-the-art research on the environmental release and migration,toxicity testing and risk prediction methods of existing PAs,and screened the risk of typical currently unregulated PAs via a step-by-step workflow combining toxicological priority index(Tox Pi)framework.The public information of existing PAs was retrieved and screened step by step based on the factors such as type,function,additive proportion,regula-tion,data availability,and so on.Finally,106 currently unregulated PAs of concern were selected for further risk e-valuation.Then,four hazard variables were selected,including the mode of action and hazard classification level predicted by QSAR models,the PBT/PMT hazard(P-persistence,B-bioaccumulation,M-migration,T-toxicity),the ecotoxicity data availability(abundance of available toxicity data for aquatic organisms),as well as the hit count to be included in the community rolling action plan(CoRAP)by ECHA.Comprehensive scale-transformed scores of the variables were calculated and ranked via the framework of ToxPi.The 106 evaluated plastic additives were fi-nally classified into five priority levels for risk assessment and three classifications for research concerns using hierarchical cluster analysis.The results suggested that the ecological risk of currently unregulated PAs might be underestimated.Due to the data gap of hazard(especially for ecotoxicity)and limitations in methodology,we proposed the challenges in the scientific research and risk management of PAs,including the mechanism of migration and transformation,the mixture effects,and potential threats on ecosystems.
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