Oecd Guidelines For The Testing Of Chemicals Section 4 Guideline No 497 Defined Approaches On Skin Sensitisation

A Defined Approach (DA) consists of a selection of information sources (e.g in silico predictions, in chemico, in vitro data) used in a specific combination, and resulting data are interpreted using a fixed data interpretation procedure (DIP) (e.g. a mathematical, rule-based model). DAs use methods in combination and are intended to overcome some limitations of the individual, stand-alone methods.

The present Key Event based Test Guideline addresses the human health hazard endpoint skin sensitisation, following exposure to a test chemical. Skin sensitisation refers to an allergic response following skin contact with the tested chemical, as defined by the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS). This Test Guideline is proposed to address the Molecular Initiating Event leading to skin sensitisation, namely protein reactivity, by quantifying the reactivity of test chemicals towards model synthetic peptides or amino acid derivatives containing either lysine or cysteine. This Test Guideline provides three in chemico test methods addressing the same Key Event on the Adverse Outcome Pathway for Skin Sensitisation: (i) the Direct Peptide Reactivity Assay – DPRA, (ii) the Amino Acid Derivative Reactivity Assay – ADRA and (iii) the kinetic Direct Peptide Reactivity Assay – kDPRA. The DPRA and ADRA are used for supporting the discrimination between skin sensitisers and non-sensitisers in accordance with the UN GHS. In contrast, the kDPRA allows discrimination of UN GHS subcategory 1A skin sensitisers from those not categorised as subcategory 1A, i.e. subcategory 1B or no category but does not allow to distinguish sensitisers from non-sensitisers.

This Test Guideline describes an in vitro procedure that may be used for the hazard identification of irritant chemicals (substances and mixtures) in accordance with the UN Globally Harmonized System of Classification and Labelling (GHS) Category 2.

This method provides information on health hazard likely to arise from exposure to test substance via intradermical injection and/or epidermical application. In this Test Guideline, the methods preferred over other are: the Guinea Pig Maximisation ...

The present Key Event based Test Guideline addresses the human health hazard endpoint skin sensitisation, following exposure to a test chemical. Skin sensitisation refers to an allergic response following skin contact with a tested chemical, as defined by the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS). This Test Guideline is proposed to address a Key Event leading to skin sensitisation, namely keratinocyte activation. This Key Event on the Adverse Outcome Pathway (AOP) leading to skin sensitisation takes place in the keratinocytes and includes inflammatory responses as well as gene expression associated with specific cell signalling pathways such as the antioxidant/electrophile response element (ARE)-dependent pathways. This Test Guideline provides three in vitro test methods addressing the same Key Event on the AOP for skin sensitisation: (i) the ARE-Nrf2 luciferase KeratinoSensTM test method, (ii) the ARE-Nrf2 luciferase LuSens test method and (iii) the Epidermal Sensitisation Assay – EpiSensA. The KeratinoSens and the Lusens are in vitro ARE-Nrf2 luciferase-based test methods and the EpiSensA is based on gene expression quantification using Reverse Transcription- quantitative PCR in reconstructed human epidermis models. The proposed test methods are used for supporting the discrimination between skin sensitisers and non-sensitisers in accordance with the UN GHS. Performance standards have been developed to enable the validation of similar test methods.

The present Key Event based Test Guideline (TG) addresses the human health hazard endpoint skin sensitisation, following exposure to a test chemical. Skin sensitisation refers to an allergic response following skin contact with the tested chemical, as defined by the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS). This TG is proposed to address the activation of dendritic cells, which is one Key Event on the Adverse Outcome Pathway (AOP) for Skin Sensitisation. It provides four in vitro test methods addressing the same Key Event on the AOP: (i) the human cell Line Activation Test or h-CLAT method, (ii) the U937 Cell Line Activation Test or U-SENS, (iii) the Interleukin-8 Reporter Gene Assay or IL-8 Luc assay and (iv) the Genomic Allergen Rapid Detection for assessment of skin sensitisers (GARDTMskin). All of them are used for supporting the discrimination between skin sensitisers and non-sensitisers in accordance with the UN GHS. The test methods described in this TG either quantify the change in the expression of cell surface marker(s) CD54 and CD86, the cytokine IL-8, or a series of genes (genomic biomarker signature) that are associated with the process of activation of monocytes and DC following exposure to sensitisers.

The in vivo percutaneous absorption study set out in this Test Guideline provides the linkage necessary to extrapolate from oral studies when making safety assessments following dermal exposure. The in vivo method, described in this guideline ...