Identification of the skin sensitisation hazard of chemicals has traditionally relied on the use of animals. Progress in the development of alternative methods has been prompted by the increasing knowledge of the key biological mechanisms underlying this human health effect, as documented by the OECD's recent report summarising the key biological events leading to skin sensitisation ("Adverse Outcome Pathway" (AOP) for skin sensitisation). The molecular initiating event defined within this AOP is the covalent binding of chemicals with skin proteins. Thus peptide reactivity assays may provide valuable information in the context of integrated approaches such as Weight of Evidence (WoE) or Integrated Testing Strategies (ITS) for skin sensitisation hazard and safety assessment. Based on these considerations, EURL ECVAM coordinated a validation study on the Direct Peptide Reactivity Assay (DPRA) addressing mainly the test method’s transferability and within- and between-laboratory reproducibility. Following independent scientific peer review by the EURL ECVAM’s Scientific Advisory Committee (ESAC) and having considered the input from regulators, stakeholders, international partners and the general public, EURL ECVAM concluded that the DPRA may prove a valuable component of a WoE or ITS for skin sensitisation hazard assessment. In addition to this, the DPRA may also be able to contribute to the assessment of sensitising potency, e.g. by supporting sub-categorisation of sensitisers according to UN GHS. However it is recognised that further efforts are required to explore how DPRA data may contribute to potency assessmentJRC.I.5-Systems Toxicolog
