Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy
Where consideration has been given to specific components of cigarettes, attention has tended to concentrate on tar and nicotine. Even then, it is not uniformly applied since, for example, it is still voluntary to put tar and nicotine yield information on cigarettes for sale in the USA. Tar is a catch-all name for a wide range of chemicals which are generated in cigarette smoke. It is only recently that consideration has been given to having a clearer definition of what are the relative contributions of specific chemicals in cigarette smoke, and little attention has been given to the development of limits to their exposure In 1998 [1] we proposed a system for regulating toxins and carcinogens in cigarettes by the establishment of upper limits based on the median of the existing market. We illustrated this with data on nitrosamines from Poland, which was all that was available at the time. We believe that the system should be applied progressively to carcinogens and to other toxins until yields are a great deal lower than at present.
In August 2000 [2] we canvassed the concept of regulation of the constituents of cigarette smoke in detail, reinforcing the above proposal and seeking new systems of measurement for nicotine and the constituents of tar, as well as regulatory control of both smoke constituents and tobacco nicotine by the same system of regulation that applies to clean nicotine such as nicotine replacement therapy.
Data are now available [3] for yields of some 43 smoke constituents in 25 different brands of American cigarette. This information is part of a benchmark study performed at the behest of the Massachusetts Department of Public Health by the tobacco industry in the USA. Analysis of each substance was performed in a single industry laboratory by methods standard to that laboratory. Laboratories from Philip Morris, R.J. Reynolds, Brown and Williamson, and Lorillard participated. Five replicate analyses were carried out for the substances we have considered and the average taken.
We applied our principle to these data for 34 of the substances, which are listed in Table 1. It is striking that there is a variation of between three-fold and 20-fold in the concentrations of the various toxins/carcinogens measured between brands.
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However, one brand, Merit, was below the median for all 34 substances tested. Our conclusion from this is that the industry is capable of producing cigarettes with substantially lower yields of toxins/carcinogens, as evidenced by the fact that it is actually doing so.
This is not a statement that Merit in its current form is less dangerous than other brands, as it delivers less nicotine (0.1 mg/cigarette) by Federal Trade Commission measurement (Marlboro 0.8 mg/cigarette, Camel 1.8 mg/cigarette), and it is therefore likely that smokers seek to compensate for this by inhaling more deeply, as has been shown in several studies since the early 1980s [4]. It is, however, a clear statement that the industry could meet these emission standards if it wished, or was required to do so.
While control of nicotine delivery by cigarettes is controversial and no consensus exists at this time, there can be no doubt that reducing the dose of major carcinogens such as benzo[a]pyrene (seven-fold variation) and 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone (NNK) (four-fold) would be nothing other than beneficial. Furthermore, there seem to be no good reasons for not reducing levels of such nicotine facilitators as ammonia (nine-fold) and acetaldehyde (three-fold), or such poisons as lead (eight-fold), arsenic (ten-fold) and mercury (five-fold).
Two other issues emerge from these data. The first is the obvious need for such information to replace the present simplistic and misleading listing of tar yield on the cigarette packet. Tar is not homogeneous and, while it correlates quite well with some carcinogens (polyaromatic hydrocarbons, for example), it does not correlate with nitrosamines.
The second is the need for epidemiological studies to focus on levels of these substances in active and passive smokers and controls. It seems plausible that cigarette emissions might contribute to environmental health risks just as leaded petrol was deemed to.
On the basis of this information the need for relevant legislation is urgent. The recently passed European Directive on Tobacco took major steps forward, including a requirement for the tobacco industry to disclose additives, the reason for their presence, the toxicology both burnt and unburnt, plus reductions in tar, nicotine and carbon monoxide. However, the information set out here on the chemical variations in tar, both within and between brands, makes the setting of upper limits on cigarette emissions as well as ingredients, both practical and necessary. Clearly the use of the word tar should cease. It is time to look toward the next European Tobacco Directive.
Acknowledgements
It is a pleasure to acknowledge that this was conducted within the framework of support from the Associazione Italiana per la Ricerca sul Cancro (Italian Association for Research on Cancer).
N. Gray & P. Boyle
Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy
References
1. Gray N, Boyle P, Zatonski W. Tar concentrations in cigarettes and carcinogen content. Lancet 1998; 352: 787788.[ISI][Medline]
2. Gray N, Boyle P. The regulation of tobacco and tobacco smoke. Ann Oncol 2000; 11: 909914.[ISI][Medline]
3. Anon. 1999 benchmark study. Conducted for Massachusetts Department of Public Health by the US tobacco industry. Department of Public Health, Massachusetts, 2001.
4. Benowitz NL, Hall SM, Herning RI et al. Smokers of low-yield cigarettes do not consume less nicotine. N Engl J Med 1983; 309: 139142.[Abstract]