Carbon monoxide exposure from commercial brand cigarettes under controlled smoking conditions

Blocking filter vents increases carbon monoxide levels from ultralight, but not light cigarettes

Effect of vent blocking on carbon monoxide (CO) exposure from a best-selling light cigarette was examined in 12 daily cigarette smokers. Mean CO boosts were not different from each other with (a) 0% filter vents blocked (5.0 ppm), (b) vents covered with lips (4.9 ppm), (c) 50% of vents covered with tape (4.8 ppm), and (d) vents covered with a pinch of the fingertips (4.9 ppm). A second study in another 12 smokers was conducted to replicate these findings as well as earlier findings that blocking vents doubles CO intake from 1-mg tar cigarettes. While blocking half the vents with fingers significantly increased CO boost from ultralight cigarettes (2.8 vs. 5.4 ppm, p < 0.001), it did not influence boosts from light cigarettes (6.3 vs. 6.5 ppm, p = 0.8). The lowest yield cigarettes (1 mg tar) may be special. Smoking machine simulations provide poor models of human smoke intake. It is unclear whether tar and nicotine intake from light cigarettes was influenced by vent blocking.

Smokers' behaviour and exposure according to cigarette yield and smoking experience

The influence of cigarette yield and length of smoking experience on smoking behaviour and biomarker levels was sought in 108 smokers who have never changed cigarette class. Smoking parameters carboxyhaemoglobin percentage (COHb), urinary nicotine, and its metabolites, mutagens, and thioethers were measured. Cigarette yield does not affect daily consumption or smoke volume puffed per cigarette. But the inhalation depth increases with decreasing cigarette yield and with length of smoking habit. The COHb level after the first cigarette in the morning increases significantly with CO cigarette yield and length of smoking experience. In the evening, only the cigarette yield has an effect on COHb level. Biomarker levels excreted in urine are generally lower for females than for males. They tend to increase with smoking history. Only COHb level and total urinary nicotine metabolites (Barlow index) are weakly correlated with cigarette yield. The absence of significant differences due to cigarette class in urinary biomarkers can be explained by changes in inhalation depth, individual differences of metabolism, and limited specificity of some markers (mutagens, thioethers).

Phase-out filter perforation: effects on human tobacco smoke exposure

Phase-Out is a mechanical device that dilutes the cigarette smoke stream by mechanically perforating cigarette filters. Machine testing of Phase-Out-treated cigarettes suggested that smoke exposure reductions of 90-95% could be achieved with the device. This study evaluated exposure to carbon monoxide (CO) and nicotine when humans (N = 10) smoked Phase-Out-treated cigarettes under controlled laboratory conditions. Using boost (i.e., change from baseline) measures of constituent exposure, reductions ranging from 30-80% were seen for both nicotine and carbon monoxide. Orderly graded reductions in constituent exposure were observed for both nicotine and carbon monoxide as the number of filter perforations increased from zero to six holes, with no further reduction at the eight-hole condition. Percentage reductions in constituent exposure generally corresponded well to those anticipated from machine testing, indicating that the controlled smoking technology was valid and that the Phase-Out device operated as expected in a human smoking assay. The utility of partial constituent-level reductions is discussed both with regard to lowered health risks of smoking and ease of quitting when partial reduction is used as a gradual weaning preparation for quit attempts.

Nicotine yield as determinant of smoke exposure indicators and puffing behavior

Relationships between machine smoking nicotine yield and different smoke exposure indicators were investigated in a cross-sectional study. For each of the four yield classes H (1.0-1.2 mg), M (0.7-0.9 mg), L (0.4-0.6 mg) and U (0.1-0.3 mg) 18 male and 18 female subjects were recruited. The experimental design (2 x 2) included smoking with lip contact or with a flowmeter holder, natural smoking of one cigarette or forced smoking (30 puffs). The analysis of presmoking measures revealed for plasma nicotine H greater than L, U; M greater than U, for plasma cotinine H, M greater than U, and no differences for respiratory CO. Pre- to postsmoking boosts of CO and nicotine increased with yield, but the differences were smaller than those in yield. This partial compensation can be attributed to puffing behavior as revealed by the differences between yield classes with respect to flowmeter measures (puff volume, flow parameters, number of puffs). Contact condition hardly influenced the results. Forced puffing revealed down regulation mechanisms in smoke absorption and, less pronounced, in puffing behavior. Cardiovascular and subjective effects were widely independent of yield. Plasma cotinine appeared as the best smoke exposure indicator, due both to its high retest reliability and its relationship to nicotine yield.

Effects of puff number and puff spacing on carbon monoxide exposure from commercial brand cigarettes

Six chronic smokers of mid- to high-carbon monoxide (CO) yield cigarettes smoked ultralow- (1.6 mg CO), low- (5.9 mg CO) and high- (14.3 mg CO) yield commercial cigarettes under controlled smoking conditions in which either puff number or puff spacing was manipulated. CO exposure (pre- to postsmoking increments) was directly related to the number of puffs taken for all cigarette yields. CO exposure from the high- and low-yield cigarettes was equivalent when the number of puffs taken from the low-yield cigarettes was increased by 50% (from 8 to 12 puffs). In contrast, CO exposure from ultralow-yield cigarettes was still marginally lower than exposure from high-yield cigarettes after a 4-fold increase in puff number (8 to 32 puffs). Puff spacing did not affect biological exposure to CO. The study showed that the number of puffs taken during smoking can clearly affect biological exposure to CO, but that compensation for lowered yield using increased puffs is much more difficult when ultralow- as compared with low or "light"- yield cigarettes are smoked.