Skin Allergy Safety

Some ingredients used in consumer products have the potential to cause allergic contact dermatitis (ACD), a type of skin allergy. To ensure our consumers are protected, we have been developing new approach methodologies (NAMs) for skin allergy safety assessment that are based on computational modelling and in vitro models, and these are applied using a weight-of-evidence approach.

Exposure

We estimate skin exposure via product characterisation (e.g. amount of product applied, inclusion level of the material, and surface area of application site), and the consumer and habits of the population of interest (how the product is used). An estimation of the applied local dermal dose (dose per surface area) of an ingredient or impurity is expressed in ^µg/cm2 per day. This value is used for our exposure-led safety assessments and is a parameter used within our Skin Allergy Risk Assessment (SARA) model.

Bioactivity

Our SARA model integrates using Bayesian probabilistic statistics, any combination of appropriate^* historical in vivo data and in vitro data obtained from OECD test guideline assays (including the Direct Peptide Reactivity Assay (DPRA), KeratinoSens™, Human Cell Line Activation Test (h-CLAT), and U937 Cell Line Activation Test (U-SENS)). The model predicts a human-relevant metric of sensitiser potency which can be used as a point of departure (PoD) alongside defined risk benchmarks to determine risk to an ingredient exposure.

To build our clinical and mechanistic knowledge, we have research collaborations on the mechanistic understanding of chemical-induced human skin allergy, and this will continue to improve the clinical relevance and predictive capacity of our approach. Our partnership with the US National Toxicology Program Interagency Centre for the Evaluation of Alternative Toxicological Methods (NICEATM) is testing and developing the SARA model further and the tool will be publicly available on the Integrated Chemical Environment (ICE) platform.