The use of cigarette equivalents to assess environmental tobacco smoke exposure

The development and use of the cigarette equivalent (CE) concept for estimating exposure to environmental tobacco smoke (ETS) is reviewed. CE is a legitimate conceptual device for reporting and comparing ETS exposures. However, extension of the CE concept to predicting potential increases in health risk is fraught with numerous assumptions and is, therefore, not as often used or as well accepted. Mathematically, the CE concept relates the magnitude of a nonsmoker's ETS exposure to the magnitude of mainstream smoke inhaled by a smoker. Historically, the CE concept has overestimated nonsmoker exposure in that it has ignored smokers' exposure to their own ETS. The equation defining CE exposure has been modified to include a term for the relative exposure of smokers versus nonsmokers which corrects this anomaly. To be meaningful, the CE equation requires as input both the ETS exposure concentration to which nonsmokers are typically exposed and the mainstream yield for typical cigarette brand styles. To date, this type of information has existed for only a few ETS tracers (e.g., nicotine and respirable suspended particles (RSP)). In an attempt to partially fill this void, mainstream smoke yields of several tracers used to assess ETS exposure were determined for the 50 leading U.S. cigarette brand styles representing 65% of cigarettes marketed in the U.S. during 1991. ETS tracers and other endpoints included tar, nicotine, ultraviolet particulate matter (UVPM), fluorescent particulate matter (FPM), solanesol, and scopoletin. Sales-weighted, arithmetic mean yields in mainstream smoke on a per cigarette basis were: tar, 13.8 mg; nicotine, 0.98 mg; UVPM, 10.42 mg; FPM, 7.83 mg; solanesol, 403 mu g; and scopoletin, 14.4 mu g. These results are used in conjunction with ETS concentration data for the same markers obtained in several large ETS exposure-monitoring surveys conducted in the U.S. among nonsmokers. Typical home and workplace CE exposures are both shown to be less than one cigarette per year for all tobacco-selective analytes studied. Copyright (C) 1997 Elsevier Science Ltd.