Chapter 3 
hazardous cigarette. The results documented that RT, especially RT 
resulting from the paper process with cellulose fiber as an additive, offered 
an opportunity to significantly reduce the cigarette smoke yields of tar, 
nicotine, phenols, and PAHs, as well as the tumorigenicity of the resulting 
tar. The most encouraging results were achieved with RT resulting from 
the paper process using only tobacco stems (Table 2). 
Today, most blended U.S. cigarettes contain 20 to 30 percent RT, which 
is also now widely used in Europe, Canada, and Japan. 
Puffed, Expanded, In the early 1970's a new tobacco preparation was introduced for 
and Freeze-Dried the blended cigarette, that of "puffed," "expanded," or "freeze- 
Tobaccos dried" tobacco. Using these materials, less tobacco is required 
to fill a cigarette. The principle is to expand the tobacco cell walls by quick 
evaporation of water and other vaporizable agents. This causes a rapid 
pressure increase in the cells by heat and/or the reduction of external 
pressure. 
Table 3 summarizes the smoke yields of experimental cigarettes made 
exclusively from puffed, expanded, or freeze-dried tobaccos. The smoke data 
are compared with those from the smoke of the control cigarette. The tars 
from the smoke of cigarettes made from expanded and freeze-dried tobaccos 
were significantly less tumorigenic than tar from the control cigarettes 
(National Cancer Institute, 1980). 
Table 2 
Smoke yields of cigarettes made from reconstituted tobacco (RT) by paper 
processes and from control cigarettes 
Components 
RT 
Stems Only 
RT 
Blend 
Control 
Weight (mg) 
1,011.0 
1 ,060.0 
1 ,226.0 
Tar (mg) 
11.3 
11.7 
25.9 
Nicotine (mg) 
0.2 
0.7 
1.7 
Carbon Monoxide (mg) 
11.9 
11.8 
16.1 
NO, (ixg) 
586.0 
343.0 
367.0 
Hydrocyanic acid (pg) 
73.5 
81.9 
201.0 
Acetaldehyde (pg) 
1 ,027.0 
948.0 
1 ,065.0 
Acrolein (pg) 
99.0 
105.0 
109.0 
Benz(a)anthracene (ng) 
13.1 
9.8 
46.3 
Benzo(a)pyrene (ng) 
8.9 
7.4 
27.8 
Key: NO^ = N (>95 percent) + NO^ (<5 percent). 
Source: National Cancer Institute, 1976a and 1976b. 
25 
