OECD 471: Bacterial Reverse Mutation Test (Ames Assay)

The bacterial reverse mutation test (also known as the Ames Assay) uses amino-acid requiring strains of Salmonella typhimurium and Escherichia coli to detect point mutations, which involve substitution, addition or deletion of one or a few DNA base pairs.  Following the OECD 471 Guideline for the Testing of Chemicals, four S. typhimurium strains, TA98, TA100, TA1535, and TA1537, and one E. coli strain, WP2 uvrA, will be used. A dose range-finding test and a primary and a confirmatory mutagenicity test will be conducted.  This test will be conducted with and without the presence of rat liver S9 that is induced with Aroclor 1254. At least five exposure concentrations will be included in each experiment.

Triplicate plates will be used at each dose level in the mutagenicity tests. A positive result is demonstrated by a dose-related increase or a reproducible increase in the number of revertants per plate. Usually, a clear positive result does not need to be confirmed. A negative result is always followed with the confirmatory test under slightly modified test conditions.

The experiments will start after the receipt of signed protocol and the test substance. A draft report will be ready for review within 4-6 weeks after the experiment start date. Archiving of all documents will be for six years.

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