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IS THERE A FUTURE FOR LOWER-TAR-YIELD CIGARETTES?
1111
Occasional
Survey
IS THERE A FUTURE FOR
LOWER-TAR-YIELD CIGARETTES?
Participants of the Fourth Scarborough Conference on Preventive Medicine*
An international workshop was held to consider whether the policy adopted in to countries encourage the decline in cigarette tar yields many was beneficial. The consensus was that the policy had been beneficial and that tar yields should be further reduced. In addition the yield of other smoke components should be reduced even in the absence of conclusive evidence of their specific toxicity. The lower-tar policy should be monitored to ensure that the concentration of smoke components (or their metabolites) in smokers declines as the yields decline. The public need to be made aware of the uncertainties of the policy with respect to its effects on the risk of diseases other than lung cancer and that the benefits from smoking lower-yield cigarettes are smaller than those derived from avoiding
Summary
cigarettes altogether.
1—Annual consumption of manufactured the USA and UK from 1920 to 1985.
Fig
cigarettes per adult in
(Data for men and women separately are not available for the USA.)
lower-yield policy has been beneficial.’,’ In this paper, which arose from discussions at a meeting in Maine, USA, in 1984, we consider the issues surrounding the advisability ofa lower-tar policy. The conclusion expressed in this paper represents the general view of the group involved but on some issues there were one or two dissensions. the
INTRODUCTION
CIGARETTE
smoking is the most pressing health issue in economically developed countries. Public health policy has been directed at discouraging non-smokers from starting to smoke and encouraging smokers to stop. By the early 1980s in both the US and the UK, cigarette consumption per head had decreased. In the UK it had decreased by about 35% in men from a fairly steady maximum spanning the-period 1940-75 and decreased by about 25% in women from a peak value in 1976. In the US it decreased, in both sexes combined, by about 20% from a peak in 1963. The trends are shown in fig 11,2 (and Tobacco Advisory Council, unpublished). Since the early 1970s, the US and UK authorities have also recommended that people who are unwilling or unable to give up smoking switch to cigarettes of lower tar and nicotine yield, in the expectation that the adverse health effects of smoking could be reduced. 1,3 The policy was never intended to be an alternative to encouraging smokers to give up smoking; nor was it expected that the benefits of smoking lower delivery cigarettes would be as great as those to be derived from stopping smoking altogether. Despite the decline in sales-weighted tar yields in the US and UK (fig 2),1,4 doubt has been expressed about whether *Participants: N. Benowitz, M. Feinleib, C. Feyerabend, L. Garfinkel, R. Greenberg, T. Guarino, J. Haddow (Co-chairman), V. Hawthorne, S. Jones, W. Kannel, D. Kaufman, G. Knight, L. Kozlowski, M. Kunze, J. Luoto, G. Palomaki, N. Pride, G. Rose, M. Russell, R. Stepney (Rapporteur), H. van Vunakis, N. Wald (Co-chairman), J. Wilkenfield, E. Wynder.
1. Hope-Simpson RE. The nature of herpes zoster: hypothesis. Proc R Soc Med 1965; 58: 9-20. 2 Thomas M, Robertson
A
long
term
study
and
a new
WJ Dermal transmission of virus as a cause of shingles. Lancet 1971,ii: 1349-50. 3. Berlin BS, Campbell T. Hospital-acquired herpes zoster following exposure to chickenpox JAMA 1970, 211: 1831-33. 4. Morens DM, Bregman DJ, West M, et al. An outbreak of varicella-zoster virus infection among cancer patients Ann Intern Med 1980; 93: 414-19. 5. Ederer F, Myers MH, Mantel N. A statistical problem in space and time: Do leukemia cases come in clusters? Biometrics 1964; 20: 626-36. 6 Weller TH. Varicella and herpes zoster. N Engl JMed 1983; 309: 1362-68.
HAVE LOWER-YIELD CIGARETTES BEEN OF
HELP SO FAR?
Lung Cancer The carcinogenic activity of tobacco smoke seems to reside in the tar,7 so it is reasonable to expect that cigarettes yielding less tar will be less likely to cause lung cancer. However, the relation may not be straightforward. One cause of uncertainty involves "compensatory" smoking-the tendency of smokers to increase the amount of smoke inhaled from a cigarette of lower tar yield and, to a lesser extent, to increase the number of cigarettes smoked. Several studies in which the intake of carbon monoxide or nicotine have been used as an indirect of tar exposure have found that the estimated reduction in tar intake is only about half of what might be expected from the difference in cigarette tar yields.8-11 Prospective epidemiological studies12-14 of lung cancer show, on average, an approximate 20% reduction in risk associated with lower-tar (or filter) cigarettes compared with higher tar (or plain)-a difference that is very much what would be expected from the intake studies. Most lung cancers still occur in filter cigarette smokers who have switched from plain cigarettes, so the full effects of filter cigarettes have not yet been seen. One case-control study that has looked at lifelong filter smokers suggests that the reduction in risk may be between 30 and 40%.15 Secular trends in lung cancer mortality and cigarette consumption in Britain indicate that the lower risk of lung cancer in smokers of lower tar compared with high-tar measure
CAC, Brown WK, Clarke A, et al Herpes zoster in general practice JR Coll Gen Pract 1975; 25: 29-32. 8. Cradock-Watson JE, Ridehalgh MKS, Bourne MS. Specific immunoglobulin responses after varicella and herpes zoster J Hyg (Camb) 1979; 82: 319-36. 9. Weller TH. Varicella and herpes zoster. N Engl J Med 1983; 309: 1434-40. 10. Arvin AM, Koropchak CM, Witter AE. Immunologic evidence of reinfection with varicella zoster virus. J Infect Dis 1983; 148: 200-05. 1 1. Gershon AA, Steinberg SP, Gelb L. Clinical reinfection with varicella-zoster virus. J Infect Dis 1984; 149: 137-42. 12. Gershon AA, Steinberg SP. Cell-mediated immunity to varicella-zoster virus measured by virus inactivation. Mechanism and blocking of the reaction by specific antibody Infect Immun 1979, 25: 164-69 7. Ross
1112 increased threefold in cigarette smokers, was unrelated to nicotine or carbon monoxide yield. Therefore, apart from one study (the largest),12 reductions in tar and nicotine yields have been found to have essentially no effect on the risk of coronary heart disease. Chronic Obstructive Lung Disease
Chronic obstructive lung disease has not been extensively studied in relation to tar yields and, though the smoke components responsible for it are unknown, interest has extended to oxides of nitrogen as a possible cause. Several cigarette brands yielding lower amounts of tar and nicotine have relatively high deliveries of nitric oxide and other gases (unpublished results, UK Laboratory of Government Chemist). The evidence that lower-tar cigarettes confer a health advantage rests mainly on results from only two prospective studies. The American Cancer Society Study" found an association between lower-tar-yield cigarettes and a (non-significant) reduction in deaths due to emphysema. The Whitehall Study reported that lower-tar smokers produced less phlegm2° and had a slightly higher FEV 121 than smokers of the same number of high-tar cigarettes. DOUBTS ON THE FUTURE OF THE LOWER-YIELD POLICY
Year
Fig
2-Sales-weighted
from 1968
to
tar
and nicotine
yields
in the UK and USA
1984.
cigarettes observed in epidemiological studies is not the result of self-selection. Male per head cigarette consumption changed only slightly between 1946 and 1975 (fig 1), but tar levels per cigarette decreased substantially, beginning in 1965 (fig 2). In the next few years the incidence of lung cancer began to decrease in younger men.16 Since then, a similar trend has become apparent for older men as well. During the same period, while tar yields decreased, cigarette consumption per head increased among women, and no reduction in female lung cancer mortality occurred.
Coronary Heart Disease The component of cigarette smoke that is responsible for the excess risk of coronary heart disease is not known, though nicotine and carbon monoxide are suspect. The nicotine and carbon monoxide yields of lower yielding cigarettes have, on 4 average, been reduced by less than their tar yields.4 Therefore, compensatory smoking results in an intake of nicotine and carbon monoxide which is not much less than that of smokers of higher yielding brands. On the assumption that coronary heart disease is due to nicotine, carbon monoxide, or a smoke constituent closely related to either, the disease is thus unlikely to be materially reduced by smoking currently available cigarettes with lower nicotine or carbon monoxide yields. Recent epidemiological observations indicate that the risk of coronary heart disease is not greatly affected by the yield of the cigarette. The American Cancer Society Study suggested a small decrease in coronary heart disease mortality among smokers of relatively low tar or nicotine cigarettes compared with smokers of higher yields.12 In the Framingham study, however, filter cigarette smokers had a greater risk of coronary heart disease than smokers of non-filter cigarettes. 17 Data from the Whitehall Study14 were inconclusive, and the West of Scotland Study’3 found no significant difference in coronary heart disease mortality between smokers of plain and filter cigarettes. A recent study from Boston’8 showed clearly that the risk of non-fatal myocardial infarction, while
The wisdom of advocating further reductions in cigarette yield has been challenged on three main grounds. We present the argument and the response in each
case.
Diminishing Returns and Possibility of Encouraging Smoking The reductions in male lung cancer risk observed so far in the UK and US are largely attributable to the switch from non-filter to filter cigarettes during the 1950s and 1960s. There is
direct evidence that the beneficial effects which the reduction in yield from around 35 mg to around 18 mg tar will also be found when yields fall from the present average of 15 mg to 10 mg or below. More research on the effects of smoking modern lower-tar cigarettes is needed. Compensation might increase with further reductions in yield, leading to diminishing returns in disease prevention. If this were true and if the lower-tar policy were to encourage people to start smoking or discourage smokers from giving up the habit, the balance could be tipped against the lower-tar policy. On a larger scale, by appearing to legitimise the habit, the lower-tar policy may also militate against government efforts to encourage the avoidance of smoking. The importance of compensatory smoking should not be overemphasised. Even if further reductions in tar yields produce proportionately less benefit, any benefit would be worthwhile. Concerns that a lower-tar policy will encourage smoking do not seem to be well grounded and tar-reduction programmes may actually help people to give up smoking. In both the US and the UK, which have active tar-reduction programmes, there have been notable reductions in general smoking rates and cigarette consumption. In the American Cancer Society Survey, people who had switched to lower-tar cigarettes at the start of the study were more likely to have become ex-smokers by the end, irrespective of the number of no
accompanied
cigarettes originally smoked.
Possibility that Cigarette Engineering Might Increase Risk of Disease
Changes in cigarette design might increase the risk of chronic obstructive lung disease or cardiovascular disease by increasing the concentration of harmful smoke components
1113
other than those specifically being reduced and possibly also bv increasing the extent of inhalation. However, although it is possible that certain toxic smoke components may be increased in cigarettes with otherwise lower yields, there is at present no satisfactory evidence that lower-tar cigarettes materially increase the risk of cardiovascular or chronic obstructive lung disease in comparison with current higher tar brands.
Possibility that Tar-tables May Mislead Smokers It has been argued that compensatory smoking defeats the purpose of Government tables of tar yields, based as they are on a standard set of machine-smoking variables.22 Tar-tables may mislead smokers and reduce the credibility of the lowertar strategy. Furthermore, it is possible for manufacturers to "cheat the machine". One brand of cigarette, in particular (the US brand ’Barclay’, which uses the ’Actron’ filter) represents a special case of a general problem of blockage of the ventilation holes of cigarettes with ventilated filters. These cigarettes have holes in the side of the filter tip which allow smoke drawn through the cigarette to be diluted. ’Barclay’is alleged to occupy a lower rank in the tar-table than is appropriate." Its filter has ventilation channels which are typically crushed and blocked iri the normal course of smoking by lips and fingers, but are not obstructed during machine smoking. With ventilated cigarettes that do not have these channels, hole blocking is thought to be a sporadic rather than a systematic consequence of normal smoking. Canadian and British data24,25 and the results of unpublished studies by the UK Government Chemist largely counter the argument that the tar-tables mislead smokers. Altering the machine-smoking conditions does not materially affect the ranking of different brands. As intended, the figures are therefore fair indications of relative yields, although they do not reflect the absolute yields to the smoker. Undoubtedly, attempts should be made to prevent particular brands from having an unreasonable advantage under conditions of machine smoking. For example, the grip with which the cigarettes are held in the machine could be made to simulate’ more closely that produced by human lips-for instance, the gripping device could be elliptical instead of circular, but efforts have to be made to ensure that there is no leak. THE WAY FORWARD
Continue the Lower-tar Approach while Reducing Yield of Other Noxious Agents
Despite uncertainties about the medical effects of reducing yield further, there is insufficient reason to abandon the policy altogether. It needs to be modified, though. More emphasis needs to be given to the reduction of carbon monoxide yields and those of other noxious agents. Control of tar yields, albeit by "voluntary agreements" between the Government and the tobacco industry, are already in force in tar
the UK, and similar controls could be instituted for other specified smoke components. Yield reductions could also be encouraged by taxing higher-yielding brands more heavily. This policy was followed in the UK26 but was unfortunately withdrawn, despite successful reductions in the sale of cigarettes with tar yields over 20 mg. The tobacco industry has complied with the lower-tar policy in the US and the UK. It has recently also curtailed exports of high-tar cigarettes to developing countries. The mdustry, however, may be less enthusiastic about price controls or the control of the yield of other noxious agents, on the grounds that evidence of toxicity for a specific smoke
Fig 3-Diagram by smoking.
which smokers
can
gauge their
intensity of
Middle circle indicates the staining of a cigarette butt with standard smoking procedure; left circle represents relative "under-smoking" and right circle relative "over-smoking". (Supplied by L. Kozlowski.) .
component should be provided before the yield of that component is restricted. At first sight, this seems reasonable. However, the chances of showing that any single component of tobacco smoke is responsible for a particular disease is small, not because the component is harmless, but because the studies required are difficult, if not impossible, to carry out. Cigarette smoke inhaled into the lungs is one of the most toxic environmental hazards in general life, but the exact chemicals responsible and their modes of action remain largely unknown. In the face of these difficulties it is unreasonable to demand evidence of toxicity for individual chemicals before preventive action is taken. To do so would be like resisting demands for clean drinking water until the precise microorganisms responsible for disease were known. It is sensible public health policy to focus attention on broad components of tobacco smoke for which there is general evidence of toxicity, such as tar, while at the same time ensuring that the concentration of other components likely to be harmful are reduced as well. A gradual reduction in the concentration of components such as carbon monoxide and oxides of nitrogen, based on knowledge of their biological effects; is more likely to change mortality and morbidity for the better than for the worse. Publicising the reduction in yields other than tar (preferably on the packet as well as in separate tables) will draw attention to the risk of diseases other than lung cancer, such as coronary heart disease, which are caused by cigarette smoking.
Implement Biochemical Epidemiological Monitoring The continuation of the lower-tar policy and its possible extension to other noxious agents in cigarette smoke needs to be monitored. There are practical difficulties in doing this with disease or death as end-points. An alternative and more manageable approach is to measure exposure to smoke components directly, by the use of biochemical markers such as cotinine and carbon monoxide in blood. The application of such "biochemical epidemiological" techniques may help predict changes in mortality and morbidity without having to wait for the full pathological effects. Investigate Compensatory Smoking A medium-nicotine low-tar cigarette has been proposed as one which might reduce the extent to which smoke from a cigarette is inhaled.27 The effect of nicotine yield (and other features of a cigarette, such as its draw resistance) on the extent of compensation in the general population needs further investigation. The public health position on whether nicotine yields should be maintained can then be clarified. Increase Awareness
of Possible Dangers of Compensatory
Smoking At the same time as the lower yield approach is pursued, governments should make smokers more aware of the reality and potential risks of compensatory smoking. Kozlowski28
1114
has suggested that cigarette packets might contain a simple illustration (fig 3) showing the extent to which the end of a filter is stained by smoking. Darker,staining would suggest oversmoking relative to the machine and so provide a guide to the absolute yield being obtained, and how it can be reduced.
Point of View COMMUNITY GENERAL PRACTITIONER DAVID MANT
CONCLUSION
There is a future for lower-tar yield cigarettes, but the aim should be to reduce the yield of other smoke components as well as of tar. Biochemical monitoring of the concentration of smoke components (or their metabolites) in smokers can ensure that exposure is on average reduced even if this reduction is less than would be expected from the reduction in machine-smoked yields on account of human compensatory smoking. The public needs to be made aware of the uncertainties of the policy, particularly those arising from compensatory smoking, and also that the benefits of smoking lower-yield cigarettes can only be small compared with those of avoiding the smoking habit altogether. The lower-yield approach is but one facet of a general strategy aimed at reducing the extent of disease caused by smoking in societies in which some people will continue to smoke regardless of the adverse long-term consequences to their health. This paper arose from papers and discussion at the Fourth Scarborough Conference on Preventive Medicine held in September, 1984, in Scarborough, Maine, USA. The meeting was sponsored and supported financially by the American Cancer Society, Maine Division, Esther G. Dachslager Fund, and the American Heart Association, Maine Affiliate Inc. We thank the Tobacco Advisory Council, the Laboratory of the GovernChemist, the US Office of Smoking and Health, and Stephanie Kiryluk for helping to provide certain data referred to in the paper. ment
Correspondence Environmental Bartholomew’s
should be addressed to N. J. W., Department of and Preventive Medicine, Medical College of St Hospital, Charterhouse Square, London ECIM 6BQ. REFERENCES
smoking: A report of the surgeon general. US Department of Health and Human Services, Public Health Service, Office of Smoking and Health, 1981. 2. Lee PN, ed. Statistics of smoking in the United Kingdom, research paper I. 7th ed. London. Tobacco Research Council, 1976. 3. Third Report of the Independent Scientific Committee on Smoking and health. Chairman: Peter Froggatt. London: HM Stationery Office, 1983: 11. 4. Wald NJ, Doll R, Copeland G. Trends in tar, nicotine, and carbon monoxide yields of UK cigarettes manufactured since 1934. Br Med J 1982; 282: 763-65. 5. Prevention of coronary heart disease: report of a WHO expert committee. WHO Tech Rep Ser, 678. Geneva: World Health Organisation, 1982: 27. 6. Gerstein DR, Levison PK, eds. Reduced tar and nicotine cigarettes: smoking behavior and health. Washington DC: National Academy Press, 1982: 5. 7. Wynder EL, Hoffman D. Tobacco and tobacco smoke: studies in experimental carcinogenesis. New York: Academic Press, 1967. 529. 8. Wald NJ, Idle M, Boreham J, Bailey A. Inhaling habits among smokers of different types of cigarette. Thorax 1980; 35: 925-28. 9. Ashton H, Stepney R, Thompson JW. Self-titration by cigarette smokers. Br Med J 1979; ii: 357-60. 10. Russell MAH, Sutton SR, Iyer R, Feyerabend C, Vesey CJ. Long term switching to low-tar low nicotine cigarettes. Br J Addict 1982; 77: 145-48. 11. Stepney R. Would a medium-nicotine, low-tar cigarette be less hazardous to health? Br Med J 1981; 283: 1292-96. 12. Hammond EC, Garfinkel L, Seidman H, Lew EA "Tar" and nicotine content of cigarette smoke in relation to death rates. Env Res 1976; 12: 263-74. 13. Hawthorne VM, Fry JS. Smoking and health the association between smoking behaviour, total mortality, and cardiorespiratory disease in West Central Scotland. J Epidemiol Comm Hlth 1978; 32: 260-66. 14. Higgenbottam T, Shipley MS, Rose G. Cigarettes, lung cancer, and coronary heart disease: the effects of inhalation and tar yield.] J Epidemiol Comm Hlth 1982; 36: 113-17. 15 Lubin JH, Blot WJ, Berrino F, et al Patterns of lung cancer according to type of cigarette smoked. Int J Cancer 1984, 33: 569-76. 16. Wald NJ. Smoking. In Vessey MP, Gray MJA, eds. Cancer risks and prevention. Oxford: Oxford University Press, 1985 44-67. 17. Castelli WP, Dawber TR, Feinleib M, Garrison RJ, McNamara PM, Kannel WB. The filter cigarette and coronary heart disease: the Framingham study. Lancet 1981; ii: 109-13. 18. Kaufman DW, Helmrich SP, Rosenberg L, Miettinen OS, Shapiro S Nicotine and carbon monoxide content of cigarette smoke and the risk of myocardial infarction in young men. N Engl J Med 1983; 308: 410-13. 1. The health consequences of
PETER ANDERSON
Oxfordshire Health Authority, Manor House, Headley Way, Oxford OX3 9DZ The attainment of quality in general practice entails explicit recognition of the public-health content of primary care. General practitioners should accept responsibility for auditing the state of the practice health, monitoring and controlling environmental disease, planning local services, auditing the effectiveness of preventive programmes, and evaluating the population effects of medical intervention. This requires specific training in the skills of population medicine, reallocation of scarce resources, and cooperation with existing public-health doctors. Eventual integration of community medicine and general practice is desirable.
Summary
INTRODUCTION
"The world needs a new kind of doctor, one who combines clinical skills with the skills of population medicine." This exhortation by Hartl applies not only to general practice but to all areas of medicine. It is ironic that this dichotomy exists in the United Kingdom, which boasts a population-based system of primary care, an expertise in population medicine which is unrivalled in Europe, and a National "Health" Service. The divisions in the structure of the health service which have led to a community-medicine specialty without access to the community and a primary-health-care system without responsibility for the community’s health is not an evolutionary accident. Some of the political forces that led to a tripartite structure in 1946 have not weakened. However, a growing number of doctors working within the constraints imposed by these damaging divisions are eager for change. The Royal College of General Practitioners has set the lead with its recent emphasis on prevention, and in practical terms the involvement of general practitioners in this field is increasing: for example, the proportion of cervical smears taken by general practitioners in Oxfordshire has increased from 40% to over 70% in the past decade. Similarly the number of community physicians who wish to see community medicine live up to its name is also growing. It was therefore disappointing to read the two recent papers on quality of care published by the Royal College2,3 which fail to include the integration of the skills of population Lee PN, Garfinkel L. Mortality and type of cigarette smoked. J Epidemiol Comm Hlth 1981; 35: 16-22. 20. Higenbottam T, Shipley MJ, Clark TJH, Rose G. Lung function and symptoms of 19.
21. 22. 23. 24.
25. 26.
27. 28.
cigarette smokers related to tar yield and number of cigarettes smoked. Lancet 1980; i: 409-12. Lee PN. Low tar cigarette smoking. Lancet 1980; i: 1365-66. Harnman E. Turning the tables. The Guardian, May 2, 1984: p 11. Harriman E. Tar table ’cheats’ are sued. New Scientist July 21, 1983: 175. Rickert WS, Robinson JC, Young JC, Collishaw NE, Bray DF. A comparison of the the yields of tar, nicotine, and carbon monoxide of 36 brands of Canadian cigarettes tested under three conditions. Prevent Med 1983; 12: 682-94. Rawbone RG Switching to low tar cigarettes: are the tar league tables relevant? Thorax 1984; 39: 657-62. Editorial. Silent prevention Lancet 1979; i: 705-06. Russell MAH Low-tar medium-nicotine cigarettes: A new approach to safer smoking Br Med J 1976; i: 1430-33. Kozlowski LT, Rickert WS, Pope MA, Robinson JC A color-matching technique for monitoring tar/nicotine yields to smokers Am J Publ Hlth 1982; 72: 597-99
Occasional
Survey
IS THERE A FUTURE FOR
LOWER-TAR-YIELD CIGARETTES?
Participants of the Fourth Scarborough Conference on Preventive Medicine*
An international workshop was held to consider whether the policy adopted in to countries encourage the decline in cigarette tar yields many was beneficial. The consensus was that the policy had been beneficial and that tar yields should be further reduced. In addition the yield of other smoke components should be reduced even in the absence of conclusive evidence of their specific toxicity. The lower-tar policy should be monitored to ensure that the concentration of smoke components (or their metabolites) in smokers declines as the yields decline. The public need to be made aware of the uncertainties of the policy with respect to its effects on the risk of diseases other than lung cancer and that the benefits from smoking lower-yield cigarettes are smaller than those derived from avoiding
Summary
cigarettes altogether.
1—Annual consumption of manufactured the USA and UK from 1920 to 1985.
Fig
cigarettes per adult in
(Data for men and women separately are not available for the USA.)
lower-yield policy has been beneficial.’,’ In this paper, which arose from discussions at a meeting in Maine, USA, in 1984, we consider the issues surrounding the advisability ofa lower-tar policy. The conclusion expressed in this paper represents the general view of the group involved but on some issues there were one or two dissensions. the
INTRODUCTION
CIGARETTE
smoking is the most pressing health issue in economically developed countries. Public health policy has been directed at discouraging non-smokers from starting to smoke and encouraging smokers to stop. By the early 1980s in both the US and the UK, cigarette consumption per head had decreased. In the UK it had decreased by about 35% in men from a fairly steady maximum spanning the-period 1940-75 and decreased by about 25% in women from a peak value in 1976. In the US it decreased, in both sexes combined, by about 20% from a peak in 1963. The trends are shown in fig 11,2 (and Tobacco Advisory Council, unpublished). Since the early 1970s, the US and UK authorities have also recommended that people who are unwilling or unable to give up smoking switch to cigarettes of lower tar and nicotine yield, in the expectation that the adverse health effects of smoking could be reduced. 1,3 The policy was never intended to be an alternative to encouraging smokers to give up smoking; nor was it expected that the benefits of smoking lower delivery cigarettes would be as great as those to be derived from stopping smoking altogether. Despite the decline in sales-weighted tar yields in the US and UK (fig 2),1,4 doubt has been expressed about whether *Participants: N. Benowitz, M. Feinleib, C. Feyerabend, L. Garfinkel, R. Greenberg, T. Guarino, J. Haddow (Co-chairman), V. Hawthorne, S. Jones, W. Kannel, D. Kaufman, G. Knight, L. Kozlowski, M. Kunze, J. Luoto, G. Palomaki, N. Pride, G. Rose, M. Russell, R. Stepney (Rapporteur), H. van Vunakis, N. Wald (Co-chairman), J. Wilkenfield, E. Wynder.
1. Hope-Simpson RE. The nature of herpes zoster: hypothesis. Proc R Soc Med 1965; 58: 9-20. 2 Thomas M, Robertson
A
long
term
study
and
a new
WJ Dermal transmission of virus as a cause of shingles. Lancet 1971,ii: 1349-50. 3. Berlin BS, Campbell T. Hospital-acquired herpes zoster following exposure to chickenpox JAMA 1970, 211: 1831-33. 4. Morens DM, Bregman DJ, West M, et al. An outbreak of varicella-zoster virus infection among cancer patients Ann Intern Med 1980; 93: 414-19. 5. Ederer F, Myers MH, Mantel N. A statistical problem in space and time: Do leukemia cases come in clusters? Biometrics 1964; 20: 626-36. 6 Weller TH. Varicella and herpes zoster. N Engl JMed 1983; 309: 1362-68.
HAVE LOWER-YIELD CIGARETTES BEEN OF
HELP SO FAR?
Lung Cancer The carcinogenic activity of tobacco smoke seems to reside in the tar,7 so it is reasonable to expect that cigarettes yielding less tar will be less likely to cause lung cancer. However, the relation may not be straightforward. One cause of uncertainty involves "compensatory" smoking-the tendency of smokers to increase the amount of smoke inhaled from a cigarette of lower tar yield and, to a lesser extent, to increase the number of cigarettes smoked. Several studies in which the intake of carbon monoxide or nicotine have been used as an indirect of tar exposure have found that the estimated reduction in tar intake is only about half of what might be expected from the difference in cigarette tar yields.8-11 Prospective epidemiological studies12-14 of lung cancer show, on average, an approximate 20% reduction in risk associated with lower-tar (or filter) cigarettes compared with higher tar (or plain)-a difference that is very much what would be expected from the intake studies. Most lung cancers still occur in filter cigarette smokers who have switched from plain cigarettes, so the full effects of filter cigarettes have not yet been seen. One case-control study that has looked at lifelong filter smokers suggests that the reduction in risk may be between 30 and 40%.15 Secular trends in lung cancer mortality and cigarette consumption in Britain indicate that the lower risk of lung cancer in smokers of lower tar compared with high-tar measure
CAC, Brown WK, Clarke A, et al Herpes zoster in general practice JR Coll Gen Pract 1975; 25: 29-32. 8. Cradock-Watson JE, Ridehalgh MKS, Bourne MS. Specific immunoglobulin responses after varicella and herpes zoster J Hyg (Camb) 1979; 82: 319-36. 9. Weller TH. Varicella and herpes zoster. N Engl J Med 1983; 309: 1434-40. 10. Arvin AM, Koropchak CM, Witter AE. Immunologic evidence of reinfection with varicella zoster virus. J Infect Dis 1983; 148: 200-05. 1 1. Gershon AA, Steinberg SP, Gelb L. Clinical reinfection with varicella-zoster virus. J Infect Dis 1984; 149: 137-42. 12. Gershon AA, Steinberg SP. Cell-mediated immunity to varicella-zoster virus measured by virus inactivation. Mechanism and blocking of the reaction by specific antibody Infect Immun 1979, 25: 164-69 7. Ross
1112 increased threefold in cigarette smokers, was unrelated to nicotine or carbon monoxide yield. Therefore, apart from one study (the largest),12 reductions in tar and nicotine yields have been found to have essentially no effect on the risk of coronary heart disease. Chronic Obstructive Lung Disease
Chronic obstructive lung disease has not been extensively studied in relation to tar yields and, though the smoke components responsible for it are unknown, interest has extended to oxides of nitrogen as a possible cause. Several cigarette brands yielding lower amounts of tar and nicotine have relatively high deliveries of nitric oxide and other gases (unpublished results, UK Laboratory of Government Chemist). The evidence that lower-tar cigarettes confer a health advantage rests mainly on results from only two prospective studies. The American Cancer Society Study" found an association between lower-tar-yield cigarettes and a (non-significant) reduction in deaths due to emphysema. The Whitehall Study reported that lower-tar smokers produced less phlegm2° and had a slightly higher FEV 121 than smokers of the same number of high-tar cigarettes. DOUBTS ON THE FUTURE OF THE LOWER-YIELD POLICY
Year
Fig
2-Sales-weighted
from 1968
to
tar
and nicotine
yields
in the UK and USA
1984.
cigarettes observed in epidemiological studies is not the result of self-selection. Male per head cigarette consumption changed only slightly between 1946 and 1975 (fig 1), but tar levels per cigarette decreased substantially, beginning in 1965 (fig 2). In the next few years the incidence of lung cancer began to decrease in younger men.16 Since then, a similar trend has become apparent for older men as well. During the same period, while tar yields decreased, cigarette consumption per head increased among women, and no reduction in female lung cancer mortality occurred.
Coronary Heart Disease The component of cigarette smoke that is responsible for the excess risk of coronary heart disease is not known, though nicotine and carbon monoxide are suspect. The nicotine and carbon monoxide yields of lower yielding cigarettes have, on 4 average, been reduced by less than their tar yields.4 Therefore, compensatory smoking results in an intake of nicotine and carbon monoxide which is not much less than that of smokers of higher yielding brands. On the assumption that coronary heart disease is due to nicotine, carbon monoxide, or a smoke constituent closely related to either, the disease is thus unlikely to be materially reduced by smoking currently available cigarettes with lower nicotine or carbon monoxide yields. Recent epidemiological observations indicate that the risk of coronary heart disease is not greatly affected by the yield of the cigarette. The American Cancer Society Study suggested a small decrease in coronary heart disease mortality among smokers of relatively low tar or nicotine cigarettes compared with smokers of higher yields.12 In the Framingham study, however, filter cigarette smokers had a greater risk of coronary heart disease than smokers of non-filter cigarettes. 17 Data from the Whitehall Study14 were inconclusive, and the West of Scotland Study’3 found no significant difference in coronary heart disease mortality between smokers of plain and filter cigarettes. A recent study from Boston’8 showed clearly that the risk of non-fatal myocardial infarction, while
The wisdom of advocating further reductions in cigarette yield has been challenged on three main grounds. We present the argument and the response in each
case.
Diminishing Returns and Possibility of Encouraging Smoking The reductions in male lung cancer risk observed so far in the UK and US are largely attributable to the switch from non-filter to filter cigarettes during the 1950s and 1960s. There is
direct evidence that the beneficial effects which the reduction in yield from around 35 mg to around 18 mg tar will also be found when yields fall from the present average of 15 mg to 10 mg or below. More research on the effects of smoking modern lower-tar cigarettes is needed. Compensation might increase with further reductions in yield, leading to diminishing returns in disease prevention. If this were true and if the lower-tar policy were to encourage people to start smoking or discourage smokers from giving up the habit, the balance could be tipped against the lower-tar policy. On a larger scale, by appearing to legitimise the habit, the lower-tar policy may also militate against government efforts to encourage the avoidance of smoking. The importance of compensatory smoking should not be overemphasised. Even if further reductions in tar yields produce proportionately less benefit, any benefit would be worthwhile. Concerns that a lower-tar policy will encourage smoking do not seem to be well grounded and tar-reduction programmes may actually help people to give up smoking. In both the US and the UK, which have active tar-reduction programmes, there have been notable reductions in general smoking rates and cigarette consumption. In the American Cancer Society Survey, people who had switched to lower-tar cigarettes at the start of the study were more likely to have become ex-smokers by the end, irrespective of the number of no
accompanied
cigarettes originally smoked.
Possibility that Cigarette Engineering Might Increase Risk of Disease
Changes in cigarette design might increase the risk of chronic obstructive lung disease or cardiovascular disease by increasing the concentration of harmful smoke components
1113
other than those specifically being reduced and possibly also bv increasing the extent of inhalation. However, although it is possible that certain toxic smoke components may be increased in cigarettes with otherwise lower yields, there is at present no satisfactory evidence that lower-tar cigarettes materially increase the risk of cardiovascular or chronic obstructive lung disease in comparison with current higher tar brands.
Possibility that Tar-tables May Mislead Smokers It has been argued that compensatory smoking defeats the purpose of Government tables of tar yields, based as they are on a standard set of machine-smoking variables.22 Tar-tables may mislead smokers and reduce the credibility of the lowertar strategy. Furthermore, it is possible for manufacturers to "cheat the machine". One brand of cigarette, in particular (the US brand ’Barclay’, which uses the ’Actron’ filter) represents a special case of a general problem of blockage of the ventilation holes of cigarettes with ventilated filters. These cigarettes have holes in the side of the filter tip which allow smoke drawn through the cigarette to be diluted. ’Barclay’is alleged to occupy a lower rank in the tar-table than is appropriate." Its filter has ventilation channels which are typically crushed and blocked iri the normal course of smoking by lips and fingers, but are not obstructed during machine smoking. With ventilated cigarettes that do not have these channels, hole blocking is thought to be a sporadic rather than a systematic consequence of normal smoking. Canadian and British data24,25 and the results of unpublished studies by the UK Government Chemist largely counter the argument that the tar-tables mislead smokers. Altering the machine-smoking conditions does not materially affect the ranking of different brands. As intended, the figures are therefore fair indications of relative yields, although they do not reflect the absolute yields to the smoker. Undoubtedly, attempts should be made to prevent particular brands from having an unreasonable advantage under conditions of machine smoking. For example, the grip with which the cigarettes are held in the machine could be made to simulate’ more closely that produced by human lips-for instance, the gripping device could be elliptical instead of circular, but efforts have to be made to ensure that there is no leak. THE WAY FORWARD
Continue the Lower-tar Approach while Reducing Yield of Other Noxious Agents
Despite uncertainties about the medical effects of reducing yield further, there is insufficient reason to abandon the policy altogether. It needs to be modified, though. More emphasis needs to be given to the reduction of carbon monoxide yields and those of other noxious agents. Control of tar yields, albeit by "voluntary agreements" between the Government and the tobacco industry, are already in force in tar
the UK, and similar controls could be instituted for other specified smoke components. Yield reductions could also be encouraged by taxing higher-yielding brands more heavily. This policy was followed in the UK26 but was unfortunately withdrawn, despite successful reductions in the sale of cigarettes with tar yields over 20 mg. The tobacco industry has complied with the lower-tar policy in the US and the UK. It has recently also curtailed exports of high-tar cigarettes to developing countries. The mdustry, however, may be less enthusiastic about price controls or the control of the yield of other noxious agents, on the grounds that evidence of toxicity for a specific smoke
Fig 3-Diagram by smoking.
which smokers
can
gauge their
intensity of
Middle circle indicates the staining of a cigarette butt with standard smoking procedure; left circle represents relative "under-smoking" and right circle relative "over-smoking". (Supplied by L. Kozlowski.) .
component should be provided before the yield of that component is restricted. At first sight, this seems reasonable. However, the chances of showing that any single component of tobacco smoke is responsible for a particular disease is small, not because the component is harmless, but because the studies required are difficult, if not impossible, to carry out. Cigarette smoke inhaled into the lungs is one of the most toxic environmental hazards in general life, but the exact chemicals responsible and their modes of action remain largely unknown. In the face of these difficulties it is unreasonable to demand evidence of toxicity for individual chemicals before preventive action is taken. To do so would be like resisting demands for clean drinking water until the precise microorganisms responsible for disease were known. It is sensible public health policy to focus attention on broad components of tobacco smoke for which there is general evidence of toxicity, such as tar, while at the same time ensuring that the concentration of other components likely to be harmful are reduced as well. A gradual reduction in the concentration of components such as carbon monoxide and oxides of nitrogen, based on knowledge of their biological effects; is more likely to change mortality and morbidity for the better than for the worse. Publicising the reduction in yields other than tar (preferably on the packet as well as in separate tables) will draw attention to the risk of diseases other than lung cancer, such as coronary heart disease, which are caused by cigarette smoking.
Implement Biochemical Epidemiological Monitoring The continuation of the lower-tar policy and its possible extension to other noxious agents in cigarette smoke needs to be monitored. There are practical difficulties in doing this with disease or death as end-points. An alternative and more manageable approach is to measure exposure to smoke components directly, by the use of biochemical markers such as cotinine and carbon monoxide in blood. The application of such "biochemical epidemiological" techniques may help predict changes in mortality and morbidity without having to wait for the full pathological effects. Investigate Compensatory Smoking A medium-nicotine low-tar cigarette has been proposed as one which might reduce the extent to which smoke from a cigarette is inhaled.27 The effect of nicotine yield (and other features of a cigarette, such as its draw resistance) on the extent of compensation in the general population needs further investigation. The public health position on whether nicotine yields should be maintained can then be clarified. Increase Awareness
of Possible Dangers of Compensatory
Smoking At the same time as the lower yield approach is pursued, governments should make smokers more aware of the reality and potential risks of compensatory smoking. Kozlowski28
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has suggested that cigarette packets might contain a simple illustration (fig 3) showing the extent to which the end of a filter is stained by smoking. Darker,staining would suggest oversmoking relative to the machine and so provide a guide to the absolute yield being obtained, and how it can be reduced.
Point of View COMMUNITY GENERAL PRACTITIONER DAVID MANT
CONCLUSION
There is a future for lower-tar yield cigarettes, but the aim should be to reduce the yield of other smoke components as well as of tar. Biochemical monitoring of the concentration of smoke components (or their metabolites) in smokers can ensure that exposure is on average reduced even if this reduction is less than would be expected from the reduction in machine-smoked yields on account of human compensatory smoking. The public needs to be made aware of the uncertainties of the policy, particularly those arising from compensatory smoking, and also that the benefits of smoking lower-yield cigarettes can only be small compared with those of avoiding the smoking habit altogether. The lower-yield approach is but one facet of a general strategy aimed at reducing the extent of disease caused by smoking in societies in which some people will continue to smoke regardless of the adverse long-term consequences to their health. This paper arose from papers and discussion at the Fourth Scarborough Conference on Preventive Medicine held in September, 1984, in Scarborough, Maine, USA. The meeting was sponsored and supported financially by the American Cancer Society, Maine Division, Esther G. Dachslager Fund, and the American Heart Association, Maine Affiliate Inc. We thank the Tobacco Advisory Council, the Laboratory of the GovernChemist, the US Office of Smoking and Health, and Stephanie Kiryluk for helping to provide certain data referred to in the paper. ment
Correspondence Environmental Bartholomew’s
should be addressed to N. J. W., Department of and Preventive Medicine, Medical College of St Hospital, Charterhouse Square, London ECIM 6BQ. REFERENCES
smoking: A report of the surgeon general. US Department of Health and Human Services, Public Health Service, Office of Smoking and Health, 1981. 2. Lee PN, ed. Statistics of smoking in the United Kingdom, research paper I. 7th ed. London. Tobacco Research Council, 1976. 3. Third Report of the Independent Scientific Committee on Smoking and health. Chairman: Peter Froggatt. London: HM Stationery Office, 1983: 11. 4. Wald NJ, Doll R, Copeland G. Trends in tar, nicotine, and carbon monoxide yields of UK cigarettes manufactured since 1934. Br Med J 1982; 282: 763-65. 5. Prevention of coronary heart disease: report of a WHO expert committee. WHO Tech Rep Ser, 678. Geneva: World Health Organisation, 1982: 27. 6. Gerstein DR, Levison PK, eds. Reduced tar and nicotine cigarettes: smoking behavior and health. Washington DC: National Academy Press, 1982: 5. 7. Wynder EL, Hoffman D. Tobacco and tobacco smoke: studies in experimental carcinogenesis. New York: Academic Press, 1967. 529. 8. Wald NJ, Idle M, Boreham J, Bailey A. Inhaling habits among smokers of different types of cigarette. Thorax 1980; 35: 925-28. 9. Ashton H, Stepney R, Thompson JW. Self-titration by cigarette smokers. Br Med J 1979; ii: 357-60. 10. Russell MAH, Sutton SR, Iyer R, Feyerabend C, Vesey CJ. Long term switching to low-tar low nicotine cigarettes. Br J Addict 1982; 77: 145-48. 11. Stepney R. Would a medium-nicotine, low-tar cigarette be less hazardous to health? Br Med J 1981; 283: 1292-96. 12. Hammond EC, Garfinkel L, Seidman H, Lew EA "Tar" and nicotine content of cigarette smoke in relation to death rates. Env Res 1976; 12: 263-74. 13. Hawthorne VM, Fry JS. Smoking and health the association between smoking behaviour, total mortality, and cardiorespiratory disease in West Central Scotland. J Epidemiol Comm Hlth 1978; 32: 260-66. 14. Higgenbottam T, Shipley MS, Rose G. Cigarettes, lung cancer, and coronary heart disease: the effects of inhalation and tar yield.] J Epidemiol Comm Hlth 1982; 36: 113-17. 15 Lubin JH, Blot WJ, Berrino F, et al Patterns of lung cancer according to type of cigarette smoked. Int J Cancer 1984, 33: 569-76. 16. Wald NJ. Smoking. In Vessey MP, Gray MJA, eds. Cancer risks and prevention. Oxford: Oxford University Press, 1985 44-67. 17. Castelli WP, Dawber TR, Feinleib M, Garrison RJ, McNamara PM, Kannel WB. The filter cigarette and coronary heart disease: the Framingham study. Lancet 1981; ii: 109-13. 18. Kaufman DW, Helmrich SP, Rosenberg L, Miettinen OS, Shapiro S Nicotine and carbon monoxide content of cigarette smoke and the risk of myocardial infarction in young men. N Engl J Med 1983; 308: 410-13. 1. The health consequences of
PETER ANDERSON
Oxfordshire Health Authority, Manor House, Headley Way, Oxford OX3 9DZ The attainment of quality in general practice entails explicit recognition of the public-health content of primary care. General practitioners should accept responsibility for auditing the state of the practice health, monitoring and controlling environmental disease, planning local services, auditing the effectiveness of preventive programmes, and evaluating the population effects of medical intervention. This requires specific training in the skills of population medicine, reallocation of scarce resources, and cooperation with existing public-health doctors. Eventual integration of community medicine and general practice is desirable.
Summary
INTRODUCTION
"The world needs a new kind of doctor, one who combines clinical skills with the skills of population medicine." This exhortation by Hartl applies not only to general practice but to all areas of medicine. It is ironic that this dichotomy exists in the United Kingdom, which boasts a population-based system of primary care, an expertise in population medicine which is unrivalled in Europe, and a National "Health" Service. The divisions in the structure of the health service which have led to a community-medicine specialty without access to the community and a primary-health-care system without responsibility for the community’s health is not an evolutionary accident. Some of the political forces that led to a tripartite structure in 1946 have not weakened. However, a growing number of doctors working within the constraints imposed by these damaging divisions are eager for change. The Royal College of General Practitioners has set the lead with its recent emphasis on prevention, and in practical terms the involvement of general practitioners in this field is increasing: for example, the proportion of cervical smears taken by general practitioners in Oxfordshire has increased from 40% to over 70% in the past decade. Similarly the number of community physicians who wish to see community medicine live up to its name is also growing. It was therefore disappointing to read the two recent papers on quality of care published by the Royal College2,3 which fail to include the integration of the skills of population Lee PN, Garfinkel L. Mortality and type of cigarette smoked. J Epidemiol Comm Hlth 1981; 35: 16-22. 20. Higenbottam T, Shipley MJ, Clark TJH, Rose G. Lung function and symptoms of 19.
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cigarette smokers related to tar yield and number of cigarettes smoked. Lancet 1980; i: 409-12. Lee PN. Low tar cigarette smoking. Lancet 1980; i: 1365-66. Harnman E. Turning the tables. The Guardian, May 2, 1984: p 11. Harriman E. Tar table ’cheats’ are sued. New Scientist July 21, 1983: 175. Rickert WS, Robinson JC, Young JC, Collishaw NE, Bray DF. A comparison of the the yields of tar, nicotine, and carbon monoxide of 36 brands of Canadian cigarettes tested under three conditions. Prevent Med 1983; 12: 682-94. Rawbone RG Switching to low tar cigarettes: are the tar league tables relevant? Thorax 1984; 39: 657-62. Editorial. Silent prevention Lancet 1979; i: 705-06. Russell MAH Low-tar medium-nicotine cigarettes: A new approach to safer smoking Br Med J 1976; i: 1430-33. Kozlowski LT, Rickert WS, Pope MA, Robinson JC A color-matching technique for monitoring tar/nicotine yields to smokers Am J Publ Hlth 1982; 72: 597-99