Section IV 
cigarettes also tended to have higher numbers of puffs per 
cigarette, decreased interpuff interval, increased duration per 
puff, and increased duration per cigarette, but these differences 
did not reach statistical significance. These results are consistent 
with changes in puffing topography to compensate for lower 
}deld cigarettes. 
In addition, there were significant negative correlations between 
nicotine yield and mean puff volume, total duration and volume, and flow 
rate. That is, as nicotine yield decreased, mean puff volume, total duration 
and volume, and flow rate increased significantly. In addition, multiple 
regression analysis showed that nicotine yield, alone or in combination 
with other factors, is a significant predictor of number of puffs or total puff 
volume per cigarette. 
Creighton and Lewis (1978) examined changes in smoking patterns 
when cigarettes were varied according to nicotine delivery. Specifically, 
16 smokers were monitored for 3 months. The first month, they all smoked 
medium-delivery cigarettes of about 1.4 mg nicotine; then the group was 
split for 1 month, with half smoking lower delivery cigarettes (about 
1.0 mg nicotine) and half smoking higher delivery cigarettes (about 1.8 mg 
nicotine). During the third month, the panel of 16 smokers returned to 
the 1.4 mg nicotine cigarettes. Significant changes were found in smoking 
patterns among the 16 smokers: either the increased smoking intensity 
when smoking lower delivery cigarettes or decreased intensity when smoking 
higher delivery cigarettes. However, the researchers reported that the 
smokers did not equalize nicotine and TPM delivery when they switched 
to lower delivery cigarettes, as was the case when they switched to higher 
delivery cigarettes. The number of cigarettes smoked per day remained 
about the same throughout the study. 
Russell and colleagues (1982) looked at changes in nicotine, cotinine, 
COHb, thiocyanate, and tar when 12 smokers switched to low-tar, low- 
nicotine cigarettes for 12 weeks. Plasma nicotine and cotinine were both 
reduced by about 30 percent and tar by 15 percent; plasma thiocyanate 
and COHb did not change significantly. Although mouth level of nicotine 
intake from low-tar, low-nicotine cigarettes was similar to the standard 
machine yield, the blood levels of 30 percent were substantially less than 
the anticipated level of 46 percent based on machine yields. There was 
no compensatory increase in smoke intake at the mouth level, but blood 
measures showed the increase in inhalation between 32.1 and 40.8 percent. 
Similarly, Ashton and coworkers (1979) found that, when switched from 
medium- to high- or low-nicotine brands, smokers compensated for about 
two-thirds of the difference in standard yields. Specifically, when nicotine 
yield was reduced by 50 percent, nicotine intake was about 15 percent lower. 
Furthermore, based on machine yields, it was anticipated that the nicotine 
yield of low-nicotine cigarettes would be 32.6 percent that of high-nicotine 
cigarettes; however, in the laboratory the observed yield was 59 percent that 
of high-nicotine cigarettes. 
269 
