Abstract
Next Generation Risk Assessment (NGRA) is supported by New Approach Methodology (NAM), which consists of various in vitro and in silico approaches, and their integrated use is expected to improve the confidence of human safety assessment of chemical substances. A varieties of case studies have been recently developed for proof-of-concept of NGRA. Case studies are useful for understanding the strengths and limitations of NAM across different decision contexts. Read-across (RAx), a method of filling a data gap for a target substance using existing data of similar substances, has been applied for many years in the screening-level risk assessment of industrial chemicals. By building the scientific confidence using NAM, RAx can become one of the foundations of the NGRA. This presentation will summarize the challenges to improving confidence in RAx and trends toward the use of NAM. For regulatory acceptance of RAx prediction results, it is necessary to scientifically justify the similarity hypothesis and provide the supporting information. It is required to verify how in vitro NAMs related to endpoints can improve the approach of analogue selection. Importance of these issues identified in case studies will be presented. In addition, the OECD (Q)SAR Assessment Framework is a systematic and harmonized framework for the regulatory assessment of (Q)SAR models and results based on single or multiple predictions. This guidance is useful for increasing confidence in NGRA when applying in silico NAMs. An overview of the guidance in the regulatory context will also be introduced.
