Updates to OECD In Vitro and In Chemico Test Guidelines

Posted on July 24, 2024

In 2024, the Organisation for Economic Co-operation and Development (OECD) finalised and adopted new or updated documents. Some are highlighted below:

  • Revision of TG 496 (In Vitro Macromolecular Test Method for Identifying Chemicals Inducing Serious Eye Damage and Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage) to include the OptiSafe Eye Irritation Test (OptiSafe EIT), which is an acellular biochemical in vitro test method that can be used to identify chemicals that do not require classification for eye irritation or serious eye damage.
  • Revision of TG 467 (Defined Approaches for Serious Eye Damage and Eye Irritation) to include a defined approach for solids (DAS). The SkinEthic/LLBO DAS describes the combination of two in vitro test methods (SkinEthic™ human corneal epithelium EIT/TG 492 and BCOP laser-light based opacitometer [LLBO]/TG 437) for the identification of the eye hazard potential of neat solids primarily for the purposes of classification and labelling.
  • Revision of TG 442D (In Vitro Skin Sensitisation). The Epidermal Sensitisation Assay (EpiSensA), using a reconstructed human epidermis (RhE) model and measuring the induction of multiple marker genes, was added to TG 442D.

In addition to the updates above, the OECD added several projects under development to its Test Guideline Work Plan. These ongoing projects include developing and revising test guidelines (TGs), and developing detailed review papers, validation studies, and adverse outcome pathways (AOPs). Some updates relevant to non-animal testing include:  

  • Endocrine Disruption
    • Project 4.179: Development of a Test Guideline for the colorimetric assessment of deiodinase 1 (DIO1) activity based on Sandell-Kolthoff reaction with human microsomes. DIO1 is an enzyme involved in the thyroid hormone pathway.
    • Project 4.180: Development of a Test Guideline for the FITC-T4 TTR binding assay, which measures the binding-activity of a thyroid hormone transport protein, using a thyroid hormone labelled with a fluorescent dye.
  • Skin Corrosion
    • Project 4.170: Revision of TG 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RhE) Test Method). An additional RhE model (KeraSkinTM) will be included in the TG as a me-too method.
  • Skin Sensitisation
    • Project 4.171: Revision of TG 442C (In Chemico Skin Sensitisation: Assays Addressing the Adverse Outcome Pathway Key Event on Covalent Binding to Proteins). The Electrophilic Allergen Screening Assay (EASA), a chemical assay that measures light absorbance or a fluorescent signal in proportion to the tendency of a chemical to bind to proteins, will be included in the TG as a me-too method.
    • Project 4.173 Revision of TG 497 (Defined Approaches on Skin Sensitisation). Addition of a defined approach for skin sensitiser potency assessment. The new approach will be based on quantitative regression models that rely on data from TGs 442C, 442D, and 442E.
    • Project 4.172: Me-too validation study to demonstrate that the EpiDerm RhE model can perform as well as or better than the LabCyte EPI-MODEL24 model in the EpiSensA test method (TG 442D).
  • Liver Toxicity
    • Project 4.176: Detailed review paper on specific target organ toxicity (liver) test method using liver organoid.
  • Genotoxicity
    • Project 4.182: Development of an AOP networkleading to genotoxicity will combine AOPs for genotoxicity into an AOP network to support the development of integrated approaches to testing and assessment for genotoxicity using non-animal animal methods.
    • Project 4.175: Development of a detailed review paper on the application of error-corrected next generation DNA sequencing (ecNGS) for gene mutation evaluation.
    • Project 4.174: Validation of the In Vitro Micronucleus assay (TG 487) for Engineered Nanomaterials. Ring trial to support the update of Guidance Document 359 (Study Report and Preliminary Guidance on the Adaptation of the In Vitro Micronucleus Assay (TG 487) for Testing of Manufactured Nanomaterials) and subsequent revision of TG 487 (In Vitro Mammalian Cell Micronucleus Test) to use this TG for testing nanomaterials.

For more information, please refer to the webpage on OECD Guidelines for the Testing of Chemicals as well as to the OECD Work plan for the Test Guidelines Programme (TGP).