This project aims to establish a framework for assessing the environmental impact and risk potential of hazard chemical substances, serving as the foundation for chemical substance substitution assessments. This project intends to integrate environmental impact assessment into risk assessment methods, considering a focus on life cycle thinking. The project also aims to strengthen the mindset of non-regretable chemical substance substitution, adopting internationally-concerned environmental indicators with the integration of Taiwan's current environmental issues, to screen out key environmental impact categories for the assessment. This project also encourage consideration of chemical substitution factors during alternative assessment, which can be used toward a systematic quantitative assessment framework for key chemical substances. Two lectures on topics regarding chemical substance life cycle impact assessment and two expert consultation meetings were conducted in this project. The lectures cover topics related to the introduction of life cycle assessment methods and their development, impact results interpretation, application of hotspot analysis, and the avoidance of regrettable substitutions for hazard chemicals. Based on the discussion through the expert consultation meetings, a total of 12 impact categories related to environmental concerns in Taiwan were ranked. The project compiles chemical substance substitution case studies, including two assessments on chemical substance substitution schemes, considering both associated environmental impacts and potential risk, followed by a case study analysis through the perspective of chemical functionality (i.e., substation factor and whole prodct life cycle analysis). According to the results from the two case studies for the substitution assessment of hazard chemical substances, including Di-(2-ethylhexyl) phthalate (DEHP) and its substitute Di(2-ethylhexyl) adipate (DEHA), as well as Dimethylacetamide (DMAc) and its substitute N-Methyl-2-pyrrolidone (NMP), the assessment results indicated that substitutes generally exhibited lower human health toxicity during the usage stage. However, from a holistic life cycle environmental impact perspective, substitutes often showed little environmental advantages, meaning that their impact results were significantly higher than those of existing chemicals in multiple impact categories. In the case of the product life cycle analysis example of vinyl flooring, similar results were observed compared to the DEHP substitution case. To avoid regrettable substitutions, it is suggested to adopt a holistic life cycle perspective for chemicals substitution assessment, combining the environmental impact assessment results of chemical preparation and supply chains and potential health risk during end-use stages. This approach serves as a foundation for practical substitution assessments, with the aim of minimizing the environmental impacts and human health hazards.
