Urine Mutagenicity as a Measure of Exposure to Tar-Reply

Abstract

In Reply.— At present, no direct assays of human biologic fluids for exposure from cigarettes are available. Urine mutagenicity was selected as an indirect measure for several reasons: (1) The urine of most cigarette smokers is strongly mutagenic whereas the urine of nonsmokers (or of smokers after 24 to 48 hours of abstinence) is in most cases only weakly mutagenic. (2) The mutagenic components of tobacco smoke are found primarily in the tar rather than the gaseous phase of tobacco smoke.1(3) Tobacco smoke condensate (tar) from different brands of cigarettes has approximately the same mutagenic activity per milligram.2(4) The urine of a person smoking the same brand of cigarette has approximately the same mutagenicity from day to day.3Thus, there is a theoretical basis for assuming proportionality between tar exposure and urine mutagenicity. As we and others have pointed out, there is considerable variability