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. (Opens in a pop-up window )
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 (Opens in a pop-up window ).
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. Reactivity and sensitiser classifications, based upon in silico outputs, existing information and expert interpretation are used to set priors for the model. Input data sources include the Direct Peptide Reactivity Assay (DPRA), kinetic 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 enable innovation we are working to widen the applicability of our NAM approaches by working with collaborators to push the boundaries of our current tools and approaches and explore new approaches which could enable more robust testing for "difficult-to-test" chemicals. Our ongoing partnership with the US National Toxicology Program Interagency Centre for the Evaluation of Alternative Toxicological Methods (NICEATM) continues to develop and apply Skin Sensitization Risk Assessment – Integrated Chemical Environment (SARA-ICE) (Opens in a pop-up window ) model, driven by user needs, to ensure we can use the best science available for regulatory safety assessments. Collaboration between Unilever, US NICEATM, UK Health Security Agency (UK HSA) & OECD Defined Approach for Skin Sensitisation Expert Group to evaluate the SARA-ICE Defined Approach led to the acceptance of the approach in the OECD GL No. 497 (Opens in a pop-up window ).
* There are restrictions on the data we can use in our safety assessments. For cosmetics ingredients, we do not use any animal data that was generated after March 2013 (EU Cosmetic Products Regulation 1223/2009). We apply an additional cut-off for our PETA-accredited brands of not using any animal data generated after Dec 2010.
