Vaporization technique to measure mutagenic activity of volatiles organic chemicals in the Ames/Salmonella assay.

The purpose of this research was to develop and characterize a sensitive test method to detect mutagenic activity of volatile liquid organic chemicals (i.e, volatiles) in the Ames/Salmonella assay. A Tedlar bag vaporization technique was developed, which increased contact time between the volatiles and bacterial test system, circumvented volatilization limitations in the standard plate incorporation and preincubation methods, allowed chemical analysis during incubation, and was flexible in design. The vaporization technique was evaluated concurrently against the plate incorporation and preincubation techniques with eight liquid volatile mutagens in the Ames/Salmonella mutagenicity assay with Salmonella typhimurium strains TA100 and TA102. Results suggested that when volatile organic chemicals with boiling points below 63 degrees C were tested for mutagenic activity, the most sensitive test conditions were the vaporization technique with TA100. GC analysis of epichlorohydrin and butylene oxide concentrations within Tedlar bags suggested that these two chemicals volatilized and were contained in the media after 1 hr of incubation at 37 degrees C. The mutagenic activity of six volatile liquid mutagens was similar in single and triple plate Tedlar bags. Three general test groups of volatile organic chemicals were identified by test data: chemicals which had boiling points below 63 degrees C, for which the vaporization technique was the most sensitive test procedure (ethylene, propylene, and butylene oxides and methylene chloride); chemicals which had boiling points from 107 degrees to 132 degrees C, for which the vaporization technique was still useful, but where sensitivity was only slightly increased over the preincubation technique (1-bromo-2-chloroethane, epichlorohydrin, and ethylene dibromide); and 3) a chemical which had a boiling point at 194 degrees C, where the preincubation technique was the most appropriate test method (styrene oxide).