Chapter 3 
processing. The major source of diethanolamine in tobacco in 1981 was 
the sucker growth inhibitor MH-30, which is the diethanolamine salt of 
maleic hydrazide (Brunnemann and Hoffmann, 1981). Because of the ban 
on MH-30 for tobacco treatment, NDELA levels have decreased to less than 
100 ppb in cigarette tobacco (Brunnemann and Hoffmann, 1991). The 
remaining NDELA may be at least partially due to the contamination with 
diethanolamine from packaging materials. 
Several pesticides are still being used on tobacco; these include 
insecticides, fumigants, and insect growth regulators (Benezet, 1989). 
There is only limited knowledge about the residues of these agents on 
cigarette tobacco and about their role during smoking. 
Additives In April 1994, the major U.S. cigarette companies released a list of 
599 additives used in the manufacture of cigarettes (Tobacco Reporter 
Staff, 1994). Little is known about the fate of such additives during the 
smoking of cigarettes. An exception is menthol, which amounts to less 
than 2.5 mg in U.S. mentholated cigarettes (Perfetti and Gordin, 1985). 
Menthol is not carcinogenic in rodents (National Cancer Institute, 1979), 
nor does this readily volatilized compound give rise to measurable amounts 
of carcinogenic hydrocarbons, including BaP, during the smoking of 
cigarettes (Jenkins et al., 1970). 
The list of additives also contains inorganic salts, such as ammonium 
and potassium carbonates, and bicarbonates. These additives possibly 
increase the pH of cigarette smoke. Beyond pH 6.0, cigarette smoke contains 
increasing amounts of unprotonated nicotine; with smoke pH at 6.9, about 
10 percent of the nicotine is present in the smoke in free form; at pH 7.85 
this rises to 50 percent (Brunnemann and Hoffmann, 1974). The free 
nicotine is present predominantly in the vapor phase of the smoke and is 
more quickly absorbed through the oral mucosa than nicotine in salt form 
(Armitage and Turner, 1970). Data are urgently needed for examining the 
change in pH of the smoke of cigarettes with additives. 
Although most additives that are used as flavor-enhancing agents are 
sprayed onto tobacco in milligram amounts and may therefore generate at 
most microgram amounts of toxic or tumorigenic agents in the smoke, it is 
nevertheless important to document the fate of such compounds when they 
are added to cigarettes, cigars, or pipe tobacco. 
Tobacco Blend Most U.S. cigarettes manufactured worldwide are blended cigarettes. 
The composition of the tobacco blend has a major influence on the pH, 
toxicity, and tumorigenicity of the smoke. Many tobacco lines are available, 
including about 60 species and about 1,000 different tobacco varieties (Tso, 
1972). The wealth of this source permits the manipulation of the tobacco 
plant and its components and leads to selective use of those portions of 
the plant that enhance or reduce specific agents in the smoke. This is then 
reflected in the toxicity and/or carcinogenicity of the smoke. For example, 
there are flue-cured tobacco lines that contain 0.2 to 4.75 percent nicotine 
and hurley lines with 0.3 to 4.58 percent nicotine (Chaplin, 1975). 
I 
29 
tAllNi 
