Reducing the number of control animals in aquatic toxicity testing

JRC scientists have contributed to the revision of OECD Guidance Document 23 "Aqueous-Phase Aquatic Toxicity Testing of Difficult Test Chemicals" that addresses good practices to be applied in aquatic toxicity testing.

GD23 supplements OECD Test Guidelines used for regulatory purposes. The revision reflects the experience gained in handling difficult-to-test chemicals in aquatic exposures as well as progress made in developing methods for testing difficult test chemicals since its first publication in 2000.

The project at the OECD was co-led by the USA (represented by FDA) and the European Union (represented by the JRC) in collaboration with The International Council for Animal Protection in OECD Programmes (ICAPO) and ran from 2015 to 2018.

Specific focus was on the expansion of the guidance on testing of poorly-water soluble test chemicals. In particular, attention was paid to updating exposure methods that do not employ a solvent in order to eliminate the need for a solvent control, and thus, reducing the number of animals used in aquatic toxicity tests.

Another major revision was the addition of more detailed guidance for substances of unknown or variable composition, complex reaction products, and biological materials (UVCBs).

The updated GD 23 will help government agencies, industry, and contract research organisations conduct valid and reliable aquatic toxicity studies on difficult-to-test chemicals while minimising both the number of animals used and the need to repeat studies.

• OECD Guidance Document 23 "Aqueous-Phase Aquatic Toxicity Testing of Difficult Test Chemicals"

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