Statistical modeling and analyses of a base-specific Salmonella mutagenicity assay

Statistical features of a base-specific Salmonella mutagenicity assay are c onsidered in detail, following up on a previous report comparing responses of base-specific Salmonella (Ames II(TM)) strains with those of traditional tester strains. In addition to using different Salmonella strains, the new procedure also differs in that it is performed as a microwell fluctuation test, as opposed to the standard plate or preincubation test. This report d escribes the statistical modeling of data obtained from the use of these ne w strains in the microwell test procedure. We emphasize how to assess any s ignificant interactions between replicate cultures and exposure doses, and how to identify a significant increase in the mutagenic response to a serie s of concentrations of a test substance. (C) 2000 Elsevier Science B.V. All rights reserved.