Reference source : OECD
OECD Test Guidelines Chemical Testing Non-Animal Testing In Vitro Methods Nanomaterials Ecotoxicity Chemical Safety
The Organisation for Economic Co-operation and Development (OECD) has published its update to the OECD Guidelines for the Testing of Chemicals for 2026, introducing seven new, five updated, and six corrected Test Guidelines (TGs). The update expands the range of internationally recognised testing methods to include new in vitro approaches, additional guidance for nanomaterials as well as new ecotoxicity methods.
Growing Use of Non-Animal Test Methods
Non-animal test methods are playing an increasingly important role in the assessment of the safety of chemicals. Many of these approaches use human-derived cells, tissues or computational models, to provide mechanistic information on how chemicals interact with biological systems. In recent years, regulatory authorities have expanded the acceptance of validated in vitro methods as alternatives to, or complements of animal testing, where scientifically appropriate. The 2026 OECD update continues this trend by introducing several new in vitro Test Guidelines alongside new methods for nanomaterials and environmental hazard assessment
Key 2026 Test Guidelines
1. New In Vitro Human Health Guidelines
Three new guidelines offer non-animal mechanistic perspectives on how chemicals interact with human biology:
TG 445A (Metabolism): Analyzes CYP enzyme induction in metabolically capable human liver cells to determine toxicokinetics.
TG 446A (Genotoxicity): Uses the ToxTracker stem cell assay to differentiate between direct DNA damage and overall cellular stress.
TG 454A (Endocrine disturbance): Introduces a Human Glucocorticoid Receptor Transactivation Assay for detecting hormonal disturbance beyond the usual estrogen/androgen routes.
2. New Nanomaterial Safety Guidelines
Two new standards address the physical and environmental properties of innovative materials:
TG 127 (Dustiness) assesses how easily nano-objects in powders become airborne during industrial handling.
TG 322 (Environmental Fate) evaluates the dissolution rate and solubility of nanomaterials at different pH levels to estimate their environmental persistence.
3. New Ecotoxicity Guidelines
Two new standards offer higher-level environmental risk evaluations for essential non-target organisms:
TG 255 (Bumblebees): A 10-day chronic oral toxicity feeding test designed for non-Apis pollinators.
TG 256 (Earthworms): Outlines field research to assess the impact of chemicals on wild earthworm populations in real-world scenarios.
4. Updated and Corrected Guidelines
Updated Skin Sensitization (TG 429, TG 442D, TG 497) with more validated in vitro methodologies and defined approaches for mapping skin allergens.
Improved cell-based testing methodologies with updates to TG 442C (protein binding) and TG 444A (immunotoxicity).
Corrections: Six guidelines received technical fixes and editorial updates to harmonize data.
Regulatory Impact
The OECD Test Guidelines are internationally recognised standard methods for chemical safety testing. They are used to support chemical safety regulations in many countries through the OECD Mutual Acceptance of Data system.