Classification of contact allergens according to potency: proposals

Area of Science:

• Toxicology and Ecotoxicology
• Dermatology
• Chemical Safety Assessment

Background:

• Contact allergens exhibit significant variability in their capacity to induce skin sensitization.
• Potency assessment is crucial for classifying skin-sensitizing chemicals.
• Existing knowledge on potency and thresholds for skin sensitization induction and elicitation needs consolidation.

Framework:

• This paper, by a European Centre for Ecotoxicology and Toxicology (ECETOC) Task Force, recommends approaches for measuring potency and defining thresholds for contact sensitization.
• Builds upon previous ECETOC recommendations for hazard identification and risk assessment of skin sensitizers.
• Focuses on standard, OECD-guideline-available methods: Local Lymph Node Assay (LLNA), Guinea Pig Maximisation Test, and Buehler Patch Test.

Implementation:

• Primarily addresses categorization of chemical allergens and threshold identification for sensitization induction.
• Evaluates the utility of LLNA, Guinea Pig Maximisation Test, and Buehler Patch Test for potency assessment.
• Provides specific recommendations for using these test methods for categorizing chemical allergens by sensitization potency.

Implications:

• The Local Lymph Node Assay (LLNA) is identified as the preferred method for determining skin sensitization potency for categorization.
• Judicious interpretation of existing Guinea Pig test data can also inform potency determinations and categorization.
• Standardized potency assessment facilitates improved classification and risk management of chemical allergens.