Hazard associated with the synthesis of epoxy-vitrimer: In vitro risk assessment and scoring strategy

In the framework of a Safe, Sustainable, and Recyclable by Design approach for the synthesis of novel plastics, we investigated the toxicological impact of epoxy vitrimers' synthesis. Emphasis was placed on the substitution of conventional hardeners and flame retardants with alternative ingredients. Data were also obtained on the leachates extracted from the final materials. Several toxicological endpoints (cytotoxicity, oxidative stress, epigenetics, genotoxicity, endocrine disruption) were assessed on human cell lines, and aquatic toxicity was evaluated in Daphnia and zebrafish embryo. The bulk of the results showed that use of alternative products did not increase, and in some cases decreased, the toxicological impact of the synthesis of the vitrimers. To facilitate the use of the numerous collected data, they were combined in scores. We first designed a toxicity score that compared each substance with the positive controls of the assays. This score was found to be valuable to report the results in a convenient and easily understandable way. We also developed a performance score that compared the properties of each alternative substance to the conventional reference. This score aimed to be used in a digital decision-making tool for the development of new industrial processes. • The toxicological profile of 13 substances used in epoxy vitrimer was determined. • Chemical toxicity was assessed on 5 biological models through 9 different endpoints. • Nontoxic alternatives to conventional hardeners and flame retardants were identified. • Toxicological data were normalized and combined in simple toxicity scores. • Performance scoring was used to categorize substances in a safer by design approach.