P30-67 Enhancing Photoallergy Risk Assessment of Fragrance Chemicals through Adopting the ROS Assay into a Tiered Testing Strategy

The Research Institute for Fragrance Materials (RIFM) evaluates photosafety through a tiered strategy, addressing both photoirritation and photoallergy. While photoirritation assessment follows established guidelines, no validated in vitro models exist for photoallergy, making its evaluation challenging. RIFM identified ~100 fragrance materials with significant UV absorbance but insufficient photoallergy data. Since comprehensive in chemico and in vitro testing is resource-intensive, RIFM explored integrating the reactive oxygen species (ROS) assay with UV-vis spectroscopy for rapid screening. The ROS assay, recognized in OECD 495 and ICH S10 guidelines, measures photoreactivity by detecting ROS generation (superoxide anion and singlet oxygen) upon UV exposure. Despite its established use in the pharmaceutical and cosmetic industries, applying the ROS assay to fragrance materials is a novel approach. By pioneering this strategy, RIFM aims to enhance the efficiency of photoallergy risk assessment while minimizing unnecessary in-depth testing. • UV-vis spectroscopy identified materials with significant UV absorbance. • ROS assay screened these materials, providing rapid results. • ROS-negative materials were deprioritized due to minimal photoreactivity risk. • ROS-positive materials underwent further in chemico and in vitro testing. While the ROS assay has high sensitivity in predicting direct in vivo phototoxicants, its low specificity can lead to a higher rate of false positives. Therefore, a negative result strongly suggests minimal photoreactivity risk, whereas a positive result indicates further evaluation rather than a definitive conclusion. • Testing of 14 proficiency chemicals aligned with literature, except one false negative due to UVB filtering. • Among 35 fragrance materials, 21 (~60%) were non-photoreactive, reducing the need for extensive testing. To refine the approach, RIFM is tracking UV absorbance to identify UVB absorbers and retesting ROS-negative materials with UVA+UVB exposure. Incorporating the ROS assay alongside UV-vis spectroscopy represents a transformative advancement in photoallergy risk assessment. This tiered testing strategy leverages the ROS assay's speed, cost-effectiveness, and reliability to streamline the evaluation process and reduce dependence on labor-intensive, expensive in chemico and in vitro assays. This approach enhances scientific rigor, promotes sustainable safety assessment practices, and aligns with international regulatory frameworks by prioritizing materials with confirmed photoreactivity potential. This novel application of the ROS assay to fragrance chemical safety assessment showcases its potential as an effective tool across multiple industries. By addressing gaps in validated in vitro methods for photoallergy evaluation, this strategy marks a pivotal step forward in consumer product safety, regulatory alignment, and resource-efficient risk assessment.