Testing of chemicals

Animal Welfare


 OECD Considers Animal Welfare
in the Development of Test Guidelines


Over 25 years ago, the OECD recognised the need to protect animals in general and in particular those used in experimental work. The Second High Level Meeting of the Chemicals Group addressed this ethical issue and adopted the following statement:


"The welfare of laboratory animals is important; it will continue to be an important factor influencing the work in the OECD Chemicals Programme. The progress in OECD on the harmonisation of chemicals control, in particular the agreement on Mutual Acceptance of Data (MAD), by reducing duplicative testing, will do much to reduce the number of animals used in testing. Such testing cannot be eliminated at present, but every effort should be made to discover, develop and validate alternative testing systems".


Mutual Acceptance of Data

The Mutual Acceptance of Data (MAD) Council Decisions have had a major impact on testing practices. MAD states that data generated in the testing of chemicals in an OECD member country in accordance with OECD Test Guidelines and OECD Principles of Good Laboratory Practice (GLP), shall be accepted in other member countries. Adhering non-member countries, of which there are an increasing number, should also accept this data.


The data should be accepted for purposes of assessment, and other uses relating to the protection of man and the environment. These Council Decisions continue to save thousands of animals every year.


Replacement, Reduction and Refinement Principles

The OECD is committed to the implementation of the 3R-principles first laid down by Russel & Burch in 1959 in their publication The Principles of Humane Experimental Technique”.


Since the adoption in 1981 of the first set of Test Guidelines, many of the short-, and long-term toxicity tests, (see Table 1) as well as the genetic toxicity tests, (see Table 2) have been developed or revised to introduce aspects of the 3R-principles.


The most noteworthy achievement is the deletion of the much criticised Test Guideline 401 on Acute Toxicity Testing, and its replacement with Test Guidelines 420, 423 and 425, introducing reduction and refinement.


Other examples are the Local Lymph Node Assay (Test Guideline 429) introducing refinement and reduction, replacing Test Guideline 406, and the Test Guideline 428 on “Skin Absorption: In Vitro Method” offering an alternative method to Test Guideline 427.

The Guidance Document on Recognition, Assessment and Use of Clinical Signs as Humane Endpoints for Experimental Animals Used in Safety Evaluations gives practical guidance on how to apply the 3R-principles, with an emphasis on Refinements when performing OECD Test Guidelines.


Validation Studies

To establish whether a new test method is suitable for a given regulatory purpose, it needs to go through a validation study.


In 1996, an OECD workshop was held in Solna, Sweden, on the harmonisation of validation principles and criteria for regulatory acceptance of alternative test methods. This successful meeting was followed by several other expert meetings.


In 2005, member countries adopted the "Guidance Document on the Validation and International Acceptance of New or Updated Test Methods for Hazard Assessment”. This guidance document provides the principles and criteria for how validation studies of new or updated test methods should be performed.  The document is crucial to animal welfare. It emphasises a harmonised approach towards the validation of a variety of different tests, including new alternative test methods. OECD has therefore increased the harmonisation of the validation and regulatory acceptance procedure.


A number of new Test Guideline proposals with animal welfare aspects are under development. (see Table 3).


See Brochure


Related Documents