Urinary excretion of mutagens in passive smokers

Six healthy young volunteers with no history of active smoking were asked to keep on their Western diets avoiding the consumption of alcoholic beverages, excess coffee, any sort of medicament, and the known pro- and/or anti-mutagen-containing foods and drinks, 24 h before and during the experiments. They were exposed passively to cigarette smoke produced by 4 habitual smokers in an unventilated 48.6 m3 room for 8 h. The carbon monoxide concentration was 18.85 +/- 7.3 ppm during the 8-h exposure. Frameshift mutagens were isolated from 10-h urine samples using chloroform and were tested for mutagenicity in the Salmonella/mammalian microsome assay employing Salmonella typhimurium TA98. Although clearly enhanced, no significant mutagenic activity could be found with 25 ml equivalent urine/plate after passive exposure to cigarette smoke. The weak mutagenicities found were highly significant when 50 ml equivalent urine/plate was tested. No direct correlation was observed between urine mutagenicity and the urinary cotinine concentration. The results obtained are discussed with reference to inconsistent reports in the literature concerning the mutagenicity of urine after passive smoking.