Mutagenic activity ratio

Mutagenic Activity Ratio = revertants on plates with... 

Semiquantitative risk assessments may consist of rank-order statements or ratio statements. The more quantitative assessment uses ratios of mutagenicity. It would be useful to know, for example, that chemical A is consistently 10 times as mutagenic as chemical B. Unfortunately, chemical activity among different tests is often inconsistent , and such ratios are likely to vary greatly. 

Figure 4. Effects of variation of initial water content on mutagenicity of ground beef Samples are fried at 200 °C for 6 min per side and the basic fraction is tested for activity in the Salmonella mutagenesis assay. (The and O are data from two separate experiments.) The original fat-to-protein ratio of approximately 0.8 in the ground beef was maintained in these samples.

In the heptatocyte-mediated mutagenesis studies, freshly isolated hepatocytes were mixed in a ratio of about 2 1 with liver epithelial cells before inoculation into culture flasks. After attachment, the two cell types were found to be well mixed and in close contact. Exposure of mixed cultures to several activation-dependent carcinogens that produce DNA repair in hepatocytes also produced mutagenesis in the cocultivated rat liver epithelial lines (Table 7) under conditions of exposure in which the carcinogens were not mutagenic to the lines in the absence of cocultivated hepatocytes. Thus, activated metabolites produced by the hepatocytes were transferred to the epithelial cells. Efforts to simplify this assay by the use of stored frozen hepatocytes are in progress. 

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