An assay for mutagenic activity of 4CMB, 4HMB and BC, using the "microtitre" fluctuation test

4CMB, 4HMB and BC were assayed for mutagenic activity using the 'microtitre' bacterial fluctuation test without metabolic activation. 4CMB was positive in strains of Salmonella typhimurium detecting both base-substitution and frameshift mutation. BC was weakly positive only in the strain which detects base-substitution mutation. 4HMB was negative in both strains. 4CMB and 4HMB were equally toxic to the strains, whilst BC was comparatively less toxic.