PubMed · 4511706
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L Gorban. [Early nicotinic stomatitis].. https://pubmed.ncbi.nlm.nih.gov/4511706/
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BACKGROUND: and Aims High nicotine concentrations in leaves, especially in the upper leaves, offer a serious problem for the cultivation of tobacco (Nicotiana tabacum). Preliminary field experiments showed that rapid mineralization of soil N during late stages of growth may contribute to high nicotine concentrations in leaves. METHODS: A sand-culture experiment was carried out in the greenhouse. The N supply was controlled during the experiment, and different amounts of 15N were supplied during late stages of growth (after removal of the shoot apex), to investigate the contribution of the N taken up at this time to the N content of and nicotine concentration in tobacco plants. KEY RESULTS: Addition of 1.6 g or 4 g 15N-labelled NH4NO3 after removing the shoot apex and flushing out the 14N did not increase leaf dry weights; however, it did result in delayed leaf senescence, more lateral bud formation, and an increase in 15N as a proportion of total N, and nicotine-15N as a proportion of total nicotine-N in each organ. The nicotine concentration, 15N and nicotine-15N abundances were increased from the bottom to the top leaves. When more 15N-labelled NH4NO3 was supplied, the nicotine concentration in leaves increased, and so did the 15N abundance in nicotine-N. CONCLUSION: Enhanced N supply in the later growth stages (after removing the apex) increased N content and nicotine concentration in tobacco plants. Nicotine was synthesized de novo during the late growth stages.
The available evidence suggests that most of the nicotine in mainstream tobacco smoke is in the smoke particle matter (PM) phase. Nicotine can exist in protonated and free base forms in the smoke PM, and alpha(fb) is the fraction of the PM nicotine that is in the free base form. Because only the free base form can volatilize from the smoke PM phase to the gas phase of an inhaled aerosol and because gaseous nicotine deposits rapidly in the respiratory tract (RT), the magnitude and rate of nicotine deposition in the RT will depend on alpha(fb). The types of values that alpha(fb) can assume in the PM of cigarette smoke aerosols have not been well-known. The conventional view has been that mainstream cigarette smoke PM contains relatively little free base nicotine so that the cigarette smoker must absorb nicotine mostly from deposited particles. A prior study concluded that because cigarette smoke is at "pH 5.3", there is very little free base nicotine in such smoke. A 1994 internal tobacco company document discusses the view that "smoke pH" values for cigarette smoke are "approximately 6.0". This work uses volatility-based measurements to provide determinations of equilibrium nicotine alpha(fb) values for mainstream smoke PM from selected cigarettes. The effective pH (i.e., pH(eff)) of the smoke PM from selected brands of commercial cigarettes was found to span a range of 6.0-7.8 (nicotine alpha(fb) = 0.01-0.36), with all pH(eff) values much larger than 5.3 and most larger than 6.0.
INTRODUCTION: Several studies have demonstrated the relationship between environmental tobacco smoke (ETS) and different types of health risk. Despite this evidence, measurement of ETS was highly inaccurate until a few years ago. The objective of this study was to review different studies using nicotine as an ETS airborne marker. METHODS: We reviewed the various methods used in ETS measurement, especially the use of nicotine as an airborne marker. Nicotine was compared with other markers, and data from different studies measuring airborne nicotine concentration in public places and workplaces were collected. RESULTS: Nicotine has all the desirable characteristics of an ETS marker. Several studies using nicotine as an airborne marker of ETS reported a wide range of values. In cafeterias and restaurants the concentration varied from 2.3 to 6.8 microg/m3. In workplaces without smoking regulations the concentration ranged from 3.4 to 14 microg/m3, whereas in places with smoking bans the concentration ranged from 0.09 to 0.7 microg/m3. Pubs and nightclubs had the highest concentrations, with values higher than 65 microg/m3. DISCUSSION: The use of nicotine as an airborne marker provides an objective measurement of ETS exposure. The values obtained in studies using this marker show that in places with smoking restrictions or bans, ETS exposure is much lower than in places without smoking restrictions.