ENVIRONMENTAL TOBACCO-SMOKE RETENTION IN HUMANS FROM MEASUREMENTS OF EXHALED SMOKE COMPOSITION

Twelve male volunteers were exposed for 60-min periods to 2 concentrat ions of aged and diluted sidestream tobacco smoke (150 and 920 mu g.m( -3) particulate), generated from a cigarette type representative of mi ddle-tar brands available in the United Kingdom and at concentrations (for the lower level) similar to those reported from environmental sur veys. Twelve female volunteers were exposed at the high level only. Me asurements were carried out using an inhaled-exhaled technique. For th e 12 male volunteers, mean retention and standard deviation of particu late material as measured by UVPM (UV absorbance at 325 nm) for the hi gh and low exposure levels, respectively, were 41+/-14% and 36+/-20% ( 95% Cl, higher level, 30-50%), consistent with data from radiotracer s tudies (43+/-17%) and from computer models of lung deposition for meas ured breathing patterns (34+/-8%). Mean solanesol retention at the hig her level exposure was 40+/-20% (95% Clac, 30-50%). Mean nicotine rete ntion at the high and low exposure levels was 77+/-17% and 71+/-12% (9 5% Cl, 62-88%), significantly greater than particulate retention. For women, mean nicotine retention was 81+/-16% (95% Cl, 70-91%), consiste nt with male data, but ETS particulate retention was significantly low er when measured by UVPM (17+/-10%; 95% Cl, 10-23%). Particulate reten tion as determined by solanesol measurements (27+/-14%; 95% Cl, 14-40% ) was not significantly different from male values. The female particu late retention data were in agreement with model predictions of retent ion for measured breathing patterns (26+/-5%). High intersubject varia tion was observed for both men and women for all three markers. In add ition, the ratio of airborne particles to nicotine in the exposure cha mber was variable with concentration, which is consistent with data fr om environmental surveys. It is concluded that these variations preclu de calculations of particulate retention when only environmental nicot ine concentrations are known, or when nicotine exposure has been extra polated from biomarker data for nicotine or cotinine (a major nicotine metabolite).