Contact hypersensitivity: Integrated approaches to testing and assessment

Considerable progress has been made over the past few years in the development and regulatory adoption of in vitro and in chemico methods addressing key events of the skin sensitisation pathway. When used in isolation these methods are not able to generate information on skin sensitisation potential and potency comparable to that of the standard in vivo tests and for this reason they are proposed to be used in a weight-of-evidence assessment context within integrated approaches to testing and assessment. The integration of non-animal data from these methods using fixed data interpretation procedures, within so called defined approaches, have been shown to have high accuracy in distinguishing between sensitisers and non-sensitisers and to provide information useful for the purpose of skin sensitisation potency subcategorization. This review provides an overview of the features of some of the defined approaches developed for skin sensitisation assessment and of their potential role within integrated approaches to testing and assessment. Challenges related to the international adoption and uses of defined approaches are also discussed.