Quantitative risk assessment of contact sensitization: Clinical data to assess utility of the model

Background: Contact hypersensitivity quantitative risk assessment (QRA) for fragrance ingredients is being used to establish new international standards for all fragrance ingredients that are potential skin sensitizers. Objective: The objective was to evaluate the retrospective clinical data on three fragrance ingredients in order to provide a practical assessment of the predictive value of the QRA approach. It is important to have data to assess that the methodology provides a robust approach for primary prevention of contact sensitization induction for fragrance ingredients identified as potential sensitizers. Methods: This article reviews clinical data for three fragrance ingredients-cinnamic aldehyde, citral, and isoeugenol - to assess the utility of the QRA approach for fragrance ingredients. Results: This assessment suggests that had the QRA approach been available at the time standards were established for these fragrance ingredients, the clinical response might have been noticeably improved. Prospectively, with the establishment of QRA-derived standards, there should be a continued downward trend in patch test-positive rates for cinnamic aldehyde, citral, and isoeugenol over time. Conclusion: While it is recognized that the availability of retrospective data is limited, a longitudinal review of these data gives confidence that the QRA approach should be an effective tool for primary prevention. This study also highlights the importance of continued active monitoring of clinical patch-test data for fragrance ingredients.