News | Jun 21, 2021

Exciting Updates to the OECD Test Guidelines Program

By Esther Haugabrooks, PhD and Jessica Ponder, PhD

Physicians Committee for Responsible Medicine

The OECD has released this year’s new updates from the 33rd Meeting of the OECD Working Group of the National Coordinators of the Test Guidelines Programme that was held (virtually) in April 2021. Four new Test Guidelines were published, three of which were nonanimal methods. Most notable is the long-awaited Defined Approaches guideline for skin sensitization. In concordance, TG 406 was updated for the first time since 1991, when “quantitative structure-activity relationships and in vitro models [were] not yet sufficiently developed to play a significant role in the assessment of the skin-sensitisation potential of substances.” Updates to TG 442C, TG 439, TG 494, and TG 405, and Guidance Document 331 with best practices for Physiologically Based Kinetic (PBK) model use for regulatory purposes were also adopted.

New Test Guidelines Adopted: 

  • Guideline 497: Defined Approaches on Skin Sensitisation 
  • TG 249: Fish Cell Line Acute Toxicity - The RTgill-W1 cell line assay 
  • TG 498: In vitro Phototoxicity - Reconstructed Human Epidermis (RhE) Phototoxicity test method 
  • TG 250: EASZY assay - Detection of Endocrine Active Substances, acting through estrogen receptors, using transgenic tg(cyp19a1b:GFP) Zebrafish embrYos 

Test Guideline Updates: 

  • TG 442C was updated to include the kinetic DPRA test method for in chemico characterization of skin sensitization chemical potency. 
  • TG 439 on in vitro skin irritation using RhE tissue models was updated to include KeraSkin™ following successful validation and peer review in 2020.
  • TG 494 on Vitrigel® eye irritancy test method was updated to include solids in the applicability domain.
  • TG 405 on in vivo eye irritation and serious eye damage guideline was updated for corrections to reference IATA guidance and editorial changes.   
  • TG 406 on in vivo skin sensitization was updated to reflect that the guinea pig test should be considered a last resort for animal welfare reasons.

Additional topics included:

  • Procedural documents: protected elements or confidential business information in the test guidelines program 
  • Study report on removal of nanomaterials from wastewater 
  • Detailed review paper on retinoid pathway signaling
  • Guidance on honey bee homing flight testing 
  • Guidance on leaching of nanomaterials in soil 

These updates (and more) can be accessed from the Test Guidelines and the Series on Testing and Assessment pages:

Find out more about the Test Guidelines Programme: