In vitro toxicological assays have previously been used toevaluate the biological effects of tobacco products, and they havealso been recommended in the regulatory process (IOM 2011).A battery of in vitro assays, with multiple endpoints, includingcytotoxicity and genotoxicity, have been developed and usedworldwide in research and industry. The neutral red cytotoxicityassay and the Salmonella mutagenicity assay, as well as themicronucleus assay, are recommended by Cooperation Centrefor Scientific Research Relative to Tobacco (CORESTA)In vitro Toxicology Task Force (2004) and Health Canada(2004a, b, c) for testing the toxicity of tobacco smoke