In recent years, several incidents of improper use of chemical substances have occurred in Taiwan, causing harm to the environment and the public. In order to more effectively control the source, in 2016, the Toxic and Chemical Substances Bureau of the Environmental Protection Administration of the Executive Yuan was established to strengthen the control, management and supervision of hazardous chemicals for the safeguard of people's health.
This project consolidates the classification and assessment frameworks of chemical substances in the European Union, the United States and Canada to discuss the risk-assessment-based classification methods of chemical substances, specifically focusing on their regulatory framework, evaluation and screening process, and use of tools and selection criteria. In addition, the current international trend of advancements in the process of chemical screening are also discussed. The management and evaluation of chemical substances has gradually begun to transform from evaluating single substances to a grouping approach where chemical substances are first classified into groups with similar characteristics, and then evaluating the same class of substances at the same time. Among the many classification schemes, classification based on the chemical’s mode of action is gradually being emphasized, not only for carcinogens, but also non-carcinogenic effects, endocrine effects and ecological assessments.
The risk assessment process relies heavily on relevant toxicological information, especially in the steps of hazard identification and dose-response assessment, which make use of data collected from animal experiments. Research has begun to establish methods for data quality assessments and the use of non-experimental toxicological data, including high-throughput screening, computational toxicology, in-silico methods, and integrated testing strategy in risk assessment in hope to replace traditional in-vitro and in-vivo approach.
Based on current international trends of chemical substance management framework, this project analyzes the definition of the class 4 toxic chemical substances and concerned chemical substances under the current regulatory framework. The feasibility of distinguishing the two classes of chemicals by their mode of action and human relevance is discussed. Recommendations are made for planning future development and applications of automated chemical screening tools based on existing data analysis tools and Quantitative Structure Activity Relationship (QSAR) models. For risk assessment report criteria, recommendations are made to strengthen requirement for characterizing problem formulation, dose response and uncertainty analysis. Finally, for risk management decision-making, we recommend consideration for adopting multi-criteria decision analysis and evidence map development. This project summarized the risk assessment criteria of various countries, including the European Union, the United States, and Canada. The description of each criteria, such as the scope, problem formulation, toxicity, dose-response assessment, uncertainty analysis, and the presentation of information were investigated. In comparison, Taiwan's risk assessment guidance lacks the emphasis on the characterization of the exposure scenario, mode of action and the use of benchmark dose methods.
In the process of managing chemical substances, it is often necessary to make decisions without complete information. However, the difficulty of decision-making is not necessarily due to the lack of information, but from the lack of clear definition of decision goals and benchmarks. The uncertainty of the decision-making benchmark comes from the difficulty of its definition. In the process, all aspects of the stakeholders must be considered. It often takes a long time to communicate to reach a consensus. To adequately consider social, economic, political and technical objectives in addition to health and environmental risks, tools and case studies for chemical management considering economic, policy, technical and social aspects were examined. Reviewed tools include socio-economic analysis (SEA), multiple criteria decision analysis (MCDA), Evidence Map and other tools to assist in screening and decision-making recommendations based on the exposure status of chemical substances.