Nitrate in tobacco

Figure 2. Effect of nitrate in tobacco on nitrosamine yield in mainstream smoke...

As noted previously, as the level of nitrate in tobacco and subsequently the levels of the TSNAs in CSC increase, the tumorigenicity of cigarette smoke condensate to mouse skin decreases [Wynder and Hoffmann (4332), Hoffmann and Wynder (1801, 1802)] but its mutagenicity in the Ames system with Salmonella typhimurium increases [Mizusaki etal. (2569)]. 

Jacin, H. Quantitative determination of nitrate in tobacco using a specific ion electrode 23rd Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 23, Paper No. 5, 1969, p. 5 Tob. Sci 14 (1970) 28-30. 

Kallianos, A.G., R.E. Means, and J.D. Mold Effect of nitrates in tobacco on the catechol yield in cigarette smoke 20th Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 20, Paper No. 18, 1966, pp. 21-23 Tob. Sci. 12 (1968) 125-129. Kallianos, A.G., R.E. Means, and J.D. Mold Alkyl catechols in cigarette smoke 21st Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 21, Paper No. 21, 1967, p. 12. 

Judged by enzyme induction, Menary and Jones (1972) indicated that nitrate was unable to move from a storage pool (vacuole) to the cytoplasm of ripe paw paw fruit. Using a modified in vivo assay, Ferrari et al. (1973) estimated sizes of active (metabolic) and inactive (storage) pools of nitrate in tobacco cells, barley aleurone layers and maize leaves. The location and nature of the pools was not defined. 

In Tobacco. At the time of harvesting, fresh tobacco leaves do not contain measurable amounts of nitrosamines (<5 ppb). However, these compounds are formed during curing, aging and fermentation. Their concentrations depend primarily on the content of proteins, alkaloids, agricultural chemicals and nitrate in the tobacco, as well as on the processing conditions which lead to the reduction of the nitrates. 

Table I lists the concentrations of nitrosodimethylamine (NDMA) and nitrosodiethylamine (NDEA) in some of the tobacco products which had greater than 0.5% nitrate content. Tobacco with less than 0.5% nitrate content, such as Bright tobaccos, yielded NDMA, NDEA and nitrosopyrrolidine (NPYR) generally below 5 ppb. The relatively high concentrations of NDMA in fine cut tobaccos and in snuff are possibly of significance in the increased risk for oral cancer among snuff dippers who use these tobacco types repeatedly each day by placing a pinch of the product directly into the gingival buccal fold (6,7).

In Smoke. We compared the gas chromatograms of nitrosamines in matching aliquots of mainstream smoke derived from Burley type cigarettes that were identical except for the degree of nitrate fertilization during cultivation (Figure 2). This comparison supports the concept that the nitrate concentration in tobacco is a determining factor for the nitrosamine yields in the smoke. The data in Table II confirm this concept. These studies have... 

Nonvolatile Nitrosamines In Tobacco. A method which we developed several years ago for the analysis of tobacco-specific nitrosamines (TSNA 31) involves extraction of tobacco with buffered ascorbic acid TpH 4.5) followed by partition with ethyl acetate, chromatographic clean-up on silica gel, and analysis by HPLC-TEA (Figure 9). Results obtained with this method for a large spectrum of tobacco products (Table IV), strongly support the concept that the levels of nitrate and alkaloids, and especially the methods for curing and fermentation, determine the yields of TSNA in tobacco products. Recent and as yet preliminary data from snuff analyses indicate that aerobic bacteria play a role in the formation of TSNA during air curing and fermentation. 

Nonvolatile Nitrosamines In Tobacco Smoke. Although there are more than 10 million exsmokers in the U.S.A., 53 million adults continue to smoke cigarettes and an additional 10 million still smoke cigars or pipes (39). The cigarette smokers are exposed to about 10 ng of volatile nitrosamines, 20-40 ng of NDELA and, most importantly, to 1-10 pg of tobacco specific N-nitros-amines with each cigarette smoked (Table IV). Similar quantities of the TSNA are found in sidestream smoke. The quantities of TSNA in the smoke are dependent on nitrate, nitrite, tobacco alkaloids and on NNN, NNK and NAT in the tobacco itself (31)>... 

Supplementation of Gamborg s B5 medium with 0.1% KN03 (in addition to the 0.25% KN03 usually present in B5 medium) resulted in a significant increase in antibody levels in tobacco hairy root cultures [19]. The antibody concentration in the medium increased 2.8-fold and the total antibody accumulation increased by 90% relative to cultures without added nitrate. 

Burton HR, Dye NK, Bush LP (1992) Distribution of tobacco constituents in tobacco leaf tissue, 1, Tobacco-specific nitrosamines, nitrate, nitrite and alkaloids, J Agric Food Chem 40 1050-1055 Burton HR, Dye NK, Bush LP (1994) Relationship between tobacco-specific nitrosamines and nitrite from different air cured tobacco varieties, J Agric Food Chem 42 2007-2011 Calafat AM, Polzin GM, Saylor J, Richter P, Ashley DL, Watson CH (2004) Determination of tar, nicotine, and carbon monoxide yields in the mainstream smoke of selected international cigarettes, Tob Control 13 45-51... 

There are several natural deposits of sodium nitrate in various parts of the world, including Chile, Mexico, Egypt, and the United States. The most important application of sodium nitrate is its use as a fertilizer in agriculture. It is an effective fertilizer for cotton, tobacco, and vegetable crops. Its agricultural applications, however, have dwindled considerably in recent years because of the growth of ammonium nitrate and other fertilizers. 

The identification of various volatile and tobacco-specific A-nitrosamines in tobacco and its smoke and the positive dependence of their levels in both tobacco and smoke on the nitrate level of the tobacco [Morie and Sloan (2635), Tso et al. (3985), Brunnemann et al. (499)]. 

The identification of a series of nitrophenols, many of which are known to be highly toxic, in the MSS from cigarettes fabricated with nitrate-treated tobacco and/ or with high-nitrate tobaccos in the blend [Kallianos et al. (2016), Klus and Kuhn (2137)]. 

Precursors of TSNAs in tobacco and smoke are nicotine, nornicotine, anabasine, and anatabine [Hecht et al. (1564), Adams et al. (29)]. Both nicotine and nornicotine are considered precursors of A -nitrosonornicotine (NNN). Direct transfer of TSNAs from tobacco to the smoke accounts for about 40% of NNN and 30% of 4-(A-methylnitrosamino)-l-(3-pyridinyl)-l-butanone (NNK) in MSS. The remainder of these two TSNAs in the MSS is formed during the smoking process [Hoffmann et al. (1734), Hecht et al. (1564)]. Like the levels of the volatile NNAs in MSS, the yields of the TSNAs in MSS are proportional to the nitrate content of the tobacco filler (3985). 

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