Refinement of the Dermal Sensitisation Threshold (DST) approach using a larger dataset and incorporating mechanistic chemistry domains

An essential step in ensuring the toxicological safety of ingredients in consumer products is the evaluation of their skin sensitising potential. Where skin exposure is low, it is possible to conduct a risk assessment using the Dermal Sensitisation Threshold (DST), a process similar to that of the Threshold of Toxicological Concern. This paper describes work building on that previously published, whose aim was to produce a more robust tool for assessing the safety of consumer products. This consisted of expanding the Local Lymph Node Assay dataset used to define the original DST and classifying chemicals in the dataset according to their mechanistic chemistry domains. A DST of 900 μg/cm2 was derived for chemicals classified as non-reactive and non-proreactive. This value was benchmarked against human potency data for 58 fragrance allergens and was lower than the measured No Expected Sensitisation Levels for those classified as non-reactive. Use of this DST will help to eliminate the need for animal testing of non-reactive and non-proreactive chemicals where skin exposure is sufficiently low. For chemicals where a Quantitative Risk Assessment based on the DST does not give an adequate margin of safety, and those classified as reactive, a case-by-case risk assessment will be required.