Environmental Tobacco Smoke Retention in Humans from Measurements of Exhaled Smoke Composition

Abstract Twelve male volunteers were exposed for 60-min periods to 2 concentrations of aged and diluted sidestream tobacco smoke (150 and 920 μg m-3 paniculate), generated from a cigarette type representative of middle-tar brands available in the United Kingdom and at concentrations (for the lower level) similar to those reported from environmental surveys. Twelve female volunteers were exposed at the high level only. Measurements were carried out using an inhaled-exhaled technique. For the 12 male volunteers, mean retention and standard deviation of paniculate material as measured by UVPM (UV absorbance at 325 nm) for the high and low exposure levels, respectively, were 41 ±pM 14% and 36 ±pM 20% (95% Cl, higher level, 30-50%), consistent with data from radiotracer studies (43 ±pM 17%) and from computer models of lung deposition for measured breathing patterns (34 ±pM 8%). Mean solanesol retention at the higher level exposure was 40 ±pM 20% (95% Cl, 30-50%). Mean nicotine retention at the high and low exposure levels was 77 ±pM 17% and 71 ±pm 12% (95% Cl, 62-88%), significantly greater than paniculate retention. For women, mean nicotine retention was 81 ±pM 16% (95% Cl, 70-91%), consistent with male data, but ETS paniculate retention was significantly lower when measured by UVPM (17 ±pM 10%; 95% Cl, 10-23%). Paniculate retention as determined by solanesol measurements (27 ±pM 14%; 95% Cl, 14-40%) was not significantly different from male values. The female paniculate retention data were in agreement with model predictions of retention for measured breathing patterns (26 ±pM 5%). High intersubject variation was observed for both men and women for all three markers. In addition, the ratio of airborne particles to nicotine in the exposure chamber was variable with concentration, which is consistent with data from environmental surveys. It is concluded that these variations preclude calculations of paniculate retention when only environmental nicotine concentrations are known, or when nicotine exposure has been extrapolated from biomarker data for nicotine or cotinine (a major nicotine metabolite).