抄録
The frame work of chemical risk assessment consists of the four key steps: hazard identification, dose-response assessment, exposure assessment, and risk characterization. After the hazard identification step, generally, a threshold approach or a non-threshold approach is selected as a procedure of dose-response assessment, in accordance of genotoxic characterization. Traditionally, default uncertainty factors had been used for TDI(tolerable daily intake) derivation in the threshold approach, and specific mathematical models had been used for low-dose extrapolation, such as VSD (virtually safe dose) derivation, in the non-threshold approach. In order to derive more scientifically rational TDIs or to increase transparency, use of chemical specific adjusting factors (CSAFs) and/or a benchmark dose approach method have been recommended recently by WHO/IPCS for the guidance value derivation. The procedures and current trends of guidance value setting, such as TDIs or VSDs, for human health effects by chemical exposure was summarized in this article.
