Assessing the environmental transformation of alternative chemicals using in silico tools, (bio)degradation testing and suspect screening – A case study of emerging alternative plasticizers

Chemical safety assessment requires the inclusion of information on potential transformation products. Such information is often lacking for chemicals considered as alternatives making a comprehensive safety assessment for chemical substitution challenging. To address this challenge a methodological framework for investigating the environmental transformation of alternative chemicals is presented. The developed methodology involves the combined use of in silico tools, biodegradation testing and suspect screening analysis for the prediction and identification of environmental transformation pathways and products. The proposed framework was applied on three emerging alternative plasticizers to phthalate esters (i.e., DINCH, DEHA and ATBC) under which major first-, second- and third-step transformation products predicted in silico were also successfully identified experimentally. This allowed for a preliminary evaluation of the performance of in silico tools in terms of the predicted transformation pathways and their likelihood of occurrence. At the same time the fast chemical degradation method showed good potential in identifying the key transformation products. The proposed framework can be used to support safety assessments for chemical substitution. Further application of the developed methodology on different chemical groups along with proper optimization of the individual method components is recommended to showcase its efficacy over a larger application area.