The Bacterial Reverse Mutation Test

Abstract

Bacterial mutation tests using various Salmonella typhimurium LT2 and Escherichia coli WP2 strains are by far the most widely used systems for predicting mutagenicity of chemicals and other materials including complex mixtures and environmental contaminants. The tests are generally required worldwide by regulatory authorities as an initial screen for potential long-term adverse health effects of new materials and chemicals, including drugs, agrochemicals, medical devices, and household agents. The initial sections of this chapter describe the theoretical background and the history of the test to allow a better understanding of the principles of its performance and interpretation. Rigorous standardized procedures necessary to perform tests suitable for screening and regulatory submission are presented that closely follow the recommendations of the developers of the test and regulatory guidelines and are based on the scientific community’s 40 years of experience with the test. All aspects of routine testing including bacterial strain purification, maintenance and characterization, use of S9 mix, concurrent controls, handling and interpretation of results, as well as clarification of unexpected findings or borderline results are covered. These procedures should give reproducible results in the shortest timeframe and minimize workload while avoiding problems, errors, and repeat testing. Variations of the test including screening versions used at an early stage of development, when test article supply and resources are limited, are discussed briefly.