Development of an in situ microbial mutagenicity test system for airborne workplace mutagens: laboratory evaluation

Abstract

A simple on-site Salmonella mutagenicity test system for the detection of airborne mutagens in the workplace is being developed. The system permits entrapment of mutagenic airborne particles and vapors by impinging unfiltered ambient air into trapping medium containing bacterial tester cells. The trapping device consists mainly of a pump, an impinger and a cyclone. The impinging air flow generated by the pump is approximately 3 1/min. New Salmonella typhimurium testers which are resistant to streptomycin (Str) and 8-azaguanine (AG) were derived from the Ames testers TA98 and TA100 and the arabinose-resistant tester SV50, and were used as mutation indicators. Microbial contamination was sufficiently controlled by addition of ampicillin, Str, AG, and cycloheximide to the trapping and plating media. New tester strains retained a high mutagenic sensitivity from their parent strains. Laboratory studies with volatile mutagens (methyl methanesulfonate, ethyl methanesulfonate, and dimethylnitrosamine) showed that the vapor trapping of this system is promising. The study with suspended silica particles coated with a known mutagen (2,4,7-trinitro-9-fluorenone) indicated that the particle trapping of the system is satisfactory. Incorporation of metabolic activation into the trapping medium by confining S9 mix and tester cells in dialysis tubing enabled this system to detect promutagens. This in situ system may be useful for mutagenic monitoring in the workplace.