English Abstract

Evaluation of Skin Sensitization Potential of Chemicals and GHS Subcategorization by Local Lymph Node Assay: BrdU-ELISA

Chemicals Evaluation and Research Institute, Hita-shi, Oita, Japan
Nippon Gomu Kyokaishi,(2022),95(4),118-123 General Review in Japanese

The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is a hazard classification and communication system for the safe chemical substance handling. The hazard class of the skin sensitization is defined as Category 1: sensitizer, and if applicable, subcategorized to 1A: strong sensitizer or 1B: other. Traditional radioisotopic Local Lymph Node Assay (LLNA-RI) is one of the tests available for GHS subcategorization by obtaining an estimated concentration that produces a stimulation index=3 (EC3) with criterion of 1A: EC3≤2% and 1B: 2%<EC3. The LLNA: BrdU-ELISA is a non-radioisotopic alternative to the LLNA-RI although criterion for the subcategorization has not been clarified in GHS document. Therefore, we proposed a new criterion for the LLNA: BrdU-ELISA as 1A: EC1.6≤6% and 1B: 6%<EC1.6 by retrospective analysis of the existing data of 32 sensitizers (1A: 13, 1B: 19) : the criterion was confirmed to be valid for the commonly used mouse strain of CBA/J with 15 sensitizers (1A: 6, 1B: 9). We also found incorrect application cases of existing subcategorization criterion to LLNA: BrdU-ELISA. To avoid incorrect application, immediate revision of the GHS document is necessary to include the new criterion for LLNA: BrdU-ELISA.

Keywords: Skin Sensitization, LLNA: BrdU-ELISA, GHS Subcategorization, OECD TG442B, CBA/J mice