Comparative Study of Risk Assessment Approaches Based on Different Methods for Deriving DNEL and PNEC of Chemical Mixtures

Abstract

Most living organisms are actually exposed to chemical mixtures rather than individual substances. But current chemical risk assessment frequently focuses on the single chemical substances. The European Union presented some methods in the draft technical guidance notes for deriving DNEL (Derived No Effect Level) and PNEC (Predicted No Effect Concentration) for risk assessment of mixtures. This case study shows that the differences of DNELs and PNECs of mixtures (2 coating materials) based on two methods (KCC and CR methods) and explains why such differences are generated. The differences of DNELs and PNECs of the mixtures based on the two methods were estimated by 1.21 and 2.31 times respectively. Through the theoretical analysis on influence factors affecting DNEL and PNEC, it could be recognized that the difference between two methods can significantly increase in proportion to the number of substances having similar hazard and weight fraction.