Cigarettes may be either factory made or roll-your-own. In both cases the essential ingredients of a cigarette are cured and cut tobacco, rolled into a rod and encased in paper. Since the early 1970s, virtually all factory made cigarettes in Australia have contained filters and these days most smokers who use roll-your-own cigarettes also make them with a filter. The tobacco used in roll-your-own cigarettes is cut in long, thin strips (called 'shag') to facilitate hand rolling. The tobacco in factory made cigarettes is cut in shorter and wider pieces but is otherwise very similar to the tobacco in roll-you-own cigarettes.
Most Australian factory made cigarettes and packaged roll-your-own tobacco are 'Virginia-only' products.1 This means that all of the tobacco used in their manufacture is Virginia or flue-cured tobacco. This makes Australian cigarettes differ in taste (especially the sweetness of the smoke) and harshness/ irritation (the unpleasant sensations that accompany smoking) from cigarettes from many other parts of the world.
The other most common type of cigarette in Western countries is the blended cigarette, which contains a mixture of several different kinds of tobacco.2 A handful of brands currently sold in Australia, including Alpine and Marlboro, are blended. Smokers appear to have strong acquired preferences for either Virginia or blended cigarettes. These days, most Australian smokers strongly prefer Virginia cigarettes to blended ones, because of the sweeter, milder tasting smoke.(Staunton, 1998)
Virginia tobacco is produced by hanging tobacco leaves to dry and cure in heated barns for 5 to 7 days, after which it is ready for manufacture.2 The other kinds of tobacco include:
- A, air-cured (including Burley and Maryland), which is produced by drying tobacco in barns at ambient temperatures over longer periods;
- B, fire cured (or Oriental tobacco), which is produced by exposing tobacco directly to smoke from wood fires; and
- C, sun-cured, which is produced by hanging tobacco to dry in direct sunlight.2
Blended cigarettes contain a proportion of Virginia, air cured and fired cured tobacco. U.S. blended cigarettes contain roughly equal proportions of each kind of tobacco. Blended cigarettes developed for the Australian market, such as the Australian version of Marlboro, tend to have a greater proportion of Virginia tobacco, in an attempt to appeal more to Australian tastes.
The faster curing process for Virginia tobacco results in it having high sugar content than other tobacco types. This is the main reason why it produces sweeter-tasting smoke than other tobacco types, at least when nicotine levels are comparable. However, Virginia tobacco also produces more acidic smoke, as a number of acids are produced from the combustion of sugars and this has consequences for the delivery of nicotine to smokers. The lower smoke pH of Virginia cigarettes means that there is generally proportionately less unprotonated or 'free' nicotine in the smoke than in blended cigarettes.2,3 'Free' nicotine is the more pharmacologically active form of nicotine.3 The other form – called protonated or 'bound' nicotine – is delivered to the central nervous system more slowly during smoking and is less responsible for the rewarding sensations of a nicotine 'hit.' However, unprotonated nicotine also produces more sensations of harshness than protonated nicotine. Thus, cigarettes must deliver unprotonated nicotine within certain tolerances in order to maximize their consumer appeal. Levels of unprotonated nicotine in smoke may be increased either by increasing the ratio of unprotonated to protonated nicotine or by increasing total nicotine levels.
The smoke from Virginia cigarettes also has a different profile of known carcinogens and cardiovascular/ respiratory toxicants than the smoke from cigarettes containing other tobacco types. 4, 5 . Smokers of Virginia cigarettes probably have lower exposures to certain carcinogens and cardiovascular/ respiratory toxicants than smokers of other types of cigarette but also probably have higher exposures to other carcinogens and cardiovascular/ respiratory toxicants. We shall return to this issue at the end of the chapter when dealing with the information that is available on the emissions of specific carcinogens and other toxicants in the smoke of Australian cigarettes.
As well as containing tobacco that has been cured in different ways, cigarettes contain tobacco that has been processed in different ways and tobacco from different parts of the plant.2,4
Australian cigarettes invariably contain cut tobacco leaf (or 'lamina'), which will vary in flavour and nicotine content, depending on which part of the plant it has been taken from. Leaf taken from high on the plant will have higher nicotine content and will generally also have a richer flavour than leaf from lower in the plant.
Cigarettes may also contain expanded and reconstituted tobacco. Expanded tobacco is lamina or stem that has been puffed up with carbon dioxide (and formerly freon) in order to restore individual cells to their thickness prior to curing. It is used to control burning properties, as well as to control the weight/ firmness combination of the tobacco rod. Expanded stem, in particular, imparts firmness to tobacco rods. Reconstituted tobacco is a paper-like sheet that is produced from 'tobacco fines' – the small scraps that are produced at all stages of processing tobacco. Thus incorporating reconstituted tobacco in cigarettes is a means for utilizing material that would otherwise be discarded. It can also be used as a means for reducing standard ISO tar and nicotine yields (which are explained in section 12.2).2,4
Tobacco industry documents, which have been made public as a result of legal action in the US, strongly suggest that the use of reconstituted tobacco was phased out in Australian cigarettes in the 1980s and 1990s.6 It also appears that unusually high levels of expanded leaf and stem were used in Australian cigarettes during this period (as is explained below when Australian and US cigarettes are compared).
During the 1980s and 1990s, Australian cigarettes were re-engineered to minimize tobacco weight.1 This occurred in response to a by-weight excise system that remained in place until 1998 and had involved marked increases in duties levied during the early 1980s–see Chapter 13. Australian manufacturers thus had a very strong incentive to minimize the weight of their cigarettes. In order to produce low weight cigarettes that were sufficiently firm to hold together prior to smoking and also to retain the integrity of the burning coal during smoking, it was apparently necessary to replace reconstituted tobacco with expanded tobacco, especially expanded stem. After the excise system changed in 1998, the Australian manufacturers re-engineered most brands to increase their tobacco weights and filter weights, presumably because this increased their consumer attractiveness over the previous designs. The most recent findings show that the majority of Australian brands have remained stable in construction since they were re-engineered after 1998.7,8
1. Staunton D. Letter to Michael Wooldridge, Minister for Health and Family Services. Philip Morris, 1998. Available from: http://www.pmdocs.com/PDF/2064813389_3399_0.PDF
2. Wynder E and Hoffmann D. Tobacco and tobacco smoke: studies in experimental carcinogenesis. New York: Academic Press, 1967.
3. Bates C, McNeil A, Jarvis M and Gray N. The future of tobacco product regulation and labelling in Europe: implications for the forthcoming European Union Directive. Tobacco Control 1999;8(2):225–35. Available from: http://tobaccocontrol.bmj.com/cgi/content/full/8/2/225
4. Hoffmann D, Djordjevic, MV and Brunnemann, KD. Changes in cigarette design and composition over time and how they influence the yields of smoke constituents., In: The FTC Cigarette Test Method for Determining Tar, Nicotine, and Carbon Monoxide Yields of U.S. Cigarettes. Smoking and Tobacco Control Monograph 7. Bethesda, MD: U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health., 1996. 15-37.
5. Hoffmann D and Hoffmann I. The changing cigarette: chemical studies and bioassays. In: Risks Associated with Smoking Cigarettes with Low Machine-Measured Yields of Tar and Nicotine. Smoking and Tobacco Control Monograph 13. Bethesda, MD: U.S. Department of Health and Human Services, National Institutes of Health, National Cancer Institute, 2001. 159-192.
6. Ruff R. Philip Morris Limited (Australia) C.I. report no. 84. Philip Morris: 1994.
7. PM2082556336, 10 Jan 2001. Bates: 2082556336-2082556338. Philip Morris Limited Australia, 2001. Available from: http://tobaccodocuments.org/pm/2082556336-6338.html
8. O'Connor R, Hammond D, McNeill A, King B, Kozlowski L, Giovino G, et al. How do different cigarette design features influence the standard tar yields of popular cigarette brands sold in different countries? Tobacco Control 2008;17(1):i1–i5. Available from: http://tobaccocontrol.bmj.com/cgi/content/full/17/Suppl_1/i1