Publications : Books : Nicotine Addiction in Britain :

6 Regulation of nicotine intake by smokers, and implications for health

*6.1 Titration and compensation
*6.2 Epidemiological evidence on the effects of changes in tar and nicotine yields of cigarettes on disease risk
*6.3 Does the epidemiological evidence support a direct relation between reduction in cigarette yields and disease risk?
*References

6.1 Titration and compensation

The extent to which tobacco users regulate their nicotine intake has important implications both for our understanding of the factors driving smoking behaviour and for attempts to design less toxic smoking products acceptable to smokers. A number of methodologies have been used to examine this issue, including:

  • study of the effects of intravenous nicotine, nicotine chewing gum and nicotine patches on ongoing smoking behaviour1
  • comparison of nicotine intakes among users of different kinds of tobacco products, combustible and non-combustible, which differ markedly in sensory aspects but have in common only nicotine delivery,2,3 and
  • comparison of nicotine intakes from smoking cigarettes with low, medium and high nicotine deliveries.1,4

This research literature has provided abundant evidence for the underlying role of nicotine in smoking behaviour. Because the delivery of both tar and nicotine is highly correlated in cigarette smoke,5 there has been concern about the difficulty of distinguishing effects of tar and of sensory factors from effects of nicotine on smoker compensation. This concern has been largely met by the consistency of findings from observational and experimental studies and from differing tobacco products and routes of delivery. The failure in the market-place of nicotine-free cigarettes delivering substantial levels of tar has also provided powerful indirect evidence.

It is now well established that users of tobacco tend to regulate or titrate their nicotine intake to maintain body levels within a certain range, but there are a number of unanswered questions about the determinants and stability of this range of levels both within and between individuals:

  1. What determines the wide variation in nicotine intake observed between individuals?
  2. To what extent are preferred levels of nicotine intake set by needs intrinsic to the smoker or by the level of nicotine delivery available from the cigarettes smoked in the early stages of uptake of the habit? For example, will smokers who took up smoking in the 1950s, when nominal nicotine deliveries averaged over 2 mg per cigarette, have had their preferred intakes set at a higher level than 1990 novice smokers exposed to cigarettes delivering 1 mg or less?

Definitive answers to most of these questions are still largely lacking. Of particular significance from a public health perspective is the issue of smoker compensation from cigarettes with differing nominal nicotine yields. The process whereby smokers change the way they smoke lower yield cigarettes to compensate for their lower output raises further important questions:

  1. At a given point in time, what is the evidence that, within individual smokers, those smoking brands with higher or lower machine-smoked nicotine yields take in different nicotine doses?
  2. If smokers switch to a cigarette brand with a lower nicotine delivery, to what extent do they increase their intake of nicotine per cigarette to compensate for the reduction in delivery?
  3. What is the evidence that average nicotine intakes in the population have declined over time as cigarette nicotine deliveries have been progressively reduced?

Such questions have been addressed by several types of research study. Naturalistic studies of own brand smoking have examined biochemical measures of smoke intake in groups who have self-selected to smoke brands with differing nominal deliveries. Experimental studies of brand switching (so called forced-switching studies) have looked at the consequences, usually short-term, of changing from usual brand to a lower yielding cigarette (or, less frequently, to a higher yielding brand). In a very few studies, the natural history of brand switching has been examined: that is, subjects have been followed over time, and biochemical measures of intake made before and after spontaneous brand changes. Each type of research design presents particular problems of interpretation, but taken together they provide a consistent picture.

Cross-sectional studies of self-selected own brand smoking

Since the early 1980s, a number of studies have examined smoke intake from own brand smoking, mostly using measures of saliva or plasma cotinine as an indicator of total nicotine intake.6-16 Some studies have looked at particular groups of smokers, such as those attending smokers' clinics,6 while others have been population based.11,16 Studies have also varied in the proportion of subjects smoking ultra-low yielding cigarettes (<0.5 mg nicotine), which remain a rare choice in the general population of smokers. A consistent finding has been that, while nicotine intakes vary greatly between individuals smoking brands of any given delivery, there is relatively little difference in average nicotine intake from brands with differing yields. Some studies have found no differences across the range of yields examined, whilst others have observed a slight, but significant trend to lower intake with lower yields. In yet others, intakes have been flat across a wide range of yields and reduced only in subjects smoking ultra-low brands.

These studies are valuable because they demonstrate a reliable tendency for smokers to over-smoke brands with low deliveries and under-smoke those with high nicotine yields, making nominal machine-smoked yields of little or no value in predicting smokers' actual intakes. They establish that a high degree of nicotine compensation is certainly the norm, and indeed do not exclude the possibility that complete compensation is the rule. The observation of lower intakes in ultra-low yield smokers is more consistent with an effect of reduced yield, but this effect could be due to self-selection of lower yielding brands in lighter smokers with lower preferred intakes who do not find the degree of compensatory increased puffing required too aversive.

Forced-switching studies

Most experimental studies of brand switching have been short-term, lasting only a few days or weeks.4 Typically, smokers' intakes of nicotine and other smoke components have been substantially reduced after switching to a lower yielding brand, although not to the extent predicted by the degree of yield reduction.1,17-19 A problem with this type of study is that, although subjects compensate only partially, they also find the low yielding cigarettes unsatisfying. This makes it hazardous to generalise to the real-world situation. It is entirely plausible that, outside the experimental situation, smokers would not persist with cigarettes they found unsatisfying. Data from forced-switching studies, therefore, provide a lower bound for the extent of smoker compensation, but not an upper bound.

Two large switching studies in the UK are unique in that they have randomised large numbers of smokers to lower yielding brands and followed them over a period of six months.20,21 In one study,20 nicotine compensation was essentially complete, while in the other21 it was estimated to be about 80%.

Spontaneous brand switching

Two published studies have followed smokers over time and measured changes in intake of nicotine and other smoke components in relation to spontaneous brand switching. In one study,22 comparable numbers of smokers switched from higher to lower yielding brands, and from lower to higher. Those who switched down had previously been smoking cigarettes with relatively high nicotine yields, while those who switched up had initially smoked low yielding cigarettes (0.42 mg nicotine). In each case measured, intakes of nicotine and carbon monoxide changed in the same direction as the change in nominal yield from the cigarette. However, the reduction in intake observed in smokers who switched to a lower yielding brand was achieved not by a reduction in nicotine intake per cigarette - which in fact remained relatively constant - but by a reduction in the number of cigarettes smoked. The implication, therefore, is that the change to a brand with a lower yield may have been driven by a desire to cut down on smoking in general, in which a change to a lower yield brand was perceived to be helpful but in reality did not contribute to the reduction in intake.

The second study23 investigated the effect of change in brand yield on rate of decline in lung function (measured as FEV1) in men followed over a period of 13 years. Concentrations of nicotine metabolites in the urine were similar over time in all the subjects, whether or not they had switched to a lower tar group, indicating complete compensation of intake.

The overall implication of these studies is therefore that smokers who switch to lower yield brands of cigarette tend to compensate for this change by smoking their cigarettes in a way that provides a greater intake of nicotine. They thus succeed in titrating their body levels to their own internally defined desired range. If this is the case, the question arises whether any realistic benefit in health terms can be achieved, or could reasonably be expected, by encouraging smokers to switch to lower yielding brands.

6.2 Epidemiological evidence on the effects of changes in tar and nicotine yields of cigarettes on disease risk

The manufactured cigarette of today is a very different product from that on sale 40 years ago. The filter tip became widespread in the 1950s, and standard length cigarettes have been successively replaced by king size and super kings. Changes in tobacco processing technology have included the widespread use of both reconstituted tobacco sheet and expanded tobacco, as well as additives of various kinds. Machine-smoked estimates of tar and nicotine yields, using methods such as the US Federal Trade Commission (FTC) protocol (see Section 8.2), have declined continuously and substantially from over 30 mg tar and 2.5 mg nicotine to about 11 mg tar and 1 mg nicotine. In the UK, these continuing yield reductions were the subject of a series of voluntary agreements between the tobacco industry and government, now superseded by regulation at the European level.24 It is important to note, however, that the yield reductions have not been due primarily to changes in the underlying tobacco content (indeed, the nicotine content of the tobacco in ultra-low yielding brands may actually be higher than that of high yielding brands), but have been achieved principally by the introduction of filter ventilation holes to dilute the smoke inhaled from the cigarette with a variable amount of air.25 This results in a reduction in machine-smoked tar and nicotine yields measured by the FTC or similar protocols, but can be readily defeated by a smoker seeking higher intakes. As discussed above, there is overwhelming evidence that, in practice, smokers achieve higher intakes from lower yielding brands than those predicted from machine smoking.

Lowering tar and nicotine yields has been the main plank of product modification policies aimed at reducing the health risks of cigarettes. The question that arises, particularly in view of compensatory smoking for reduced nicotine, is whether lowered yields have produced a net benefit to public health. The answer must take into account not only any reduction of smoking related disease resulting from lowered yields, but also any possible adverse effects attributable to the adoption of low yield brands as opposed to giving up smoking completely.26,27

The relation between cigarette yield and lung cancer risk

A number of epidemiological studies, both case-control and prospective, have examined the relationship of the tar and nicotine yield of the brand of cigarette smoked with the risk of lung cancer. In some studies, smokers of filter cigarettes have been compared with those smoking regular untipped brands,28-31 while in others an attempt has been made to categorise smokers by the specific tar yield of their brands.32,33 Findings have consistently pointed to a lowering of risk in smokers of filter by comparison with untipped cigarettes, and with lower compared with higher tar yield. The relative risk in smokers of non-filter compared to filter cigarettes has ranged from 1.3 to 2.3 in different studies.34 Tang et al33 estimated that the relative mortality from lung cancer for a 15 mg decrease in tar yield per cigarette was 0.75. Stellman and Garfinkel32 concluded that the excess lung cancer risk for current smokers was directly proportional to the estimated total milligrams of tar consumed daily (standardised mortality ratio 100 + 1.731 ´ mg of tar per day). Reviewing this literature in 1986,34 Stellman noted that most smokers at that time had almost invariably smoked untipped cigarettes before switching to lower yielding filter brands, and argued that in future cohorts of smokers, who would be exposed to cigarettes of much lower yield for much greater proportions of their lives, the associated risks would decline even further.

An analysis which considered time trends in lung cancer death rates in British smokers over the period in which cigarette yields were declining rapidly came to a similarly optimistic conclusion.35 Lung cancer death rates in men aged 35-44 declined by over 50% over the 25 years to 1983. Since changes in cigarette smoking prevalence could account for only a small proportion of this, it was inferred that the most likely cause of the decrease was the change in tar yields. On this basis, Peto concluded that the introduction of cigarette tar level reduction in countries where tar levels remain high might ultimately avoid about half of all cigarette-induced lung cancer.35 More recent data from the USA, however, do not support this interpretation. Results from the American Cancer Society's (ACS) second major cohort CPS2, conducted in the 1980s, suggest that there has been no reduction in lung cancer risk relative to the earlier CPS1 baseline assessment in 1959. Rates of lung cancer in men aged under 55 were in fact somewhat higher in the more recent cohort, despite reductions in the tar yield of cigarettes in both the USA and the UK.36 It is therefore not clear whether the trend in British lung cancer data is indeed attributable to the change in cigarette tar yields.

Cigarette yields and other cancers

The pattern of findings for cancers other than lung cancer (including oesophageal, larynx and bladder cancers) is more consistent, with studies tending to demonstrate an association between the use of filter or lower yield brands and a lower risk of disease.34,37-39

Heart disease. Data from the ACS prospective study which was begun in 1959 showed that deaths from coronary heart disease rose consistently with yield of cigarette smoked.40 Parish et al41 reported that rates of non-fatal myocardial infarction were slightly (10%) higher in medium tar than low tar cigarette smokers, but noted the difficulty of making adequate adjustment in their data for confounding by socio-economic factors.

Chronic obstructive pulmonary disease. A review of data from cross-sectional and prospective studies indicated that smoking low yield cigarettes leads to lower phlegm, reduced cough and less shortness of breath, but found no evidence for an effect on mortality.40 As stated above, the rate of decline in lung function among smokers followed up for 13 years from 1971-1983 was similar in those who switched to lower yielding brands and those whose tar group did not change.23

6.3 Does the epidemiological evidence support a direct relation between reduction in cigarette yields and disease risk?

Despite the general epidemiological consensus, reinforced by the conclusions of an international workshop,42 that lowered tar yields result in lowered risks of smoking related disease, there are good reasons for questioning whether the observed associations are truly causal rather than the result of uncontrolled confounding.

First amongst these concerns is the uncertainty whether smokers of cigarettes of differing tar yields at a given point in time have substantially different tar exposures, or whether, within individuals, changes over time in nominal tar yields of the brands smoked actually result in lowered tar exposure. There is also the difficulty of assigning any individual to a particular tar category on the basis of brand smoked at one point in time when that individual will have a previous history of smoking higher yielding brands, and may indeed smoke lower yielding cigarettes in the future.

The most important concern is the difficulty of controlling adequately for factors which influence both choice of cigarette brand, and consequently yield, and the risk of smoking related disease. Principal among these is socio-economic status, which is strongly associated with brand choice, with poorer smokers being much more likely to choose higher yielding brands.43,44 There is also strong emerging evidence that poor smokers have higher nicotine intakes than affluent smokers at any level of cigarette consumption, and hence would be expected to be more at risk of smoking related disease.45 While most available studies have adjusted for age and sex, it is acknowledged that few have been able to examine other potential biases in subject selection or to control for differences in socio-economic status between smokers of cigarettes with different yields.34
The difficulty of drawing firm conclusions from comparisons between self-selected groups smoking lower or higher yielding brands can be illustrated by the Bross and Gibson study.28 These authors used a case-control design to examine lung cancer risk in men who, at assessment in the early 1960s, smoked either filter or regular untipped cigarettes, and found a relative risk of 1.7 in those smoking the latter. Filter cigarettes became widely available only in the 1950s, so it can be inferred that for the great majority of their smoking careers the filter smokers would have smoked higher yielding plain brands. Moreover, since the median date of switching to filters in the USA was 1964,46 those who switched before this date would have been among the group of early innovators. Such a group would be expected to differ from others in many respects, including socio-economic status, education and awareness of health risks, and even level of nicotine dependence43 - characteristics that would also relate to risk of smoking related disease. These considerations indicate that it would be premature and unwise to interpret the association of modestly lowered risk of lung cancer, other cancers or heart disease in self-selected groups smoking filter or low tar cigarettes as causally related to lowered tar yields.

Observed lowered age-specific risks of lung cancer over time in a population (after adjusting appropriately for any changes in smoking prevalence) might be regarded as providing stronger evidence for an effect of yield reduction on risk, but here again there are problems. The fact that the secular reduction in age-specific lung cancer risk observed in the UK has not been replicated in the USA,36 where cigarette tar yields have also reduced, suggests that other factors may be responsible. Declines in disease risk over time can also be plausibly explained by other factors, such as the reduction in tar-to-nicotine ratio in smoke that has accompanied the shift towards lower yielding brands.24,47 This implies that, even with complete nicotine compensation, smokers would be exposed to somewhat less tar in the 1980s and 1990s than in the 1950s and 1960s. Changes in risk over time could also be due to qualitative changes in the carcinogenicity of tar, if alterations in tobacco processing technology resulted in tar which on a gram-per-gram basis was less carcinogenic. Data on this question are largely lacking from recent years, although there is evidence that smoke from cigarettes made from reconstituted tobacco sheet may be less carcinogenic.48

Thus, whilst it is possible that changes in cigarette yields can translate into some degree of health benefit, the effects of titration and compensation by smokers mean that any reduction in health risk achieved with low yield cigarettes is unlikely to be proportionately related to the magnitude of the nicotine yield reduction. If there is a health benefit to be accrued from smoking low rather than high yield cigarettes, this is likely to arise from reductions in tar-to-nicotine ratios rather than from changes in absolute levels of either constituent alone. There is in fact no strong evidence that actual tar exposures (as opposed to tar yields) have come down at all since the 1960s. As tobacco industry scientists speculated in an internal memorandum dating from 1984:

Consumers may have been obtaining 14-16 mg PMWNF [particulate matter water and nicotine free - a technical term for tar] (and normal equivalent nicotine delivery) for a very long time, i.e. compensating down to 16 mg when cigarettes delivered 25 mg and compensating up if they are now smoking a 13 mg … The discussion was based on example using PMWNF but it is accepted that nicotine is both the driving force and the signal [as impact] for compensation in human smoking behaviour'.49

While the tobacco industry has long understood the implications of smoker compensation, there is clear evidence that smokers misunderstand published machine-smoked yields and derive false health reassurance from them,27 as may have been intended by tobacco companies.50 There are therefore reasonable grounds for concern that low tar cigarettes offer smokers an apparently healthier option while providing little if any true benefit. In so far as low yield cigarettes may discourage smokers who would otherwise have given up smoking completely from doing so, they may indeed be counterproductive in terms of public health.27

References

  1. Russell MAH. Nicotine and the self-regulation of smoke intake. In: Wald N, Froggatt P (eds). Nicotine, smoking and the low tar programme. Oxford: Oxford University Press, 1989: 151-69.
  2. Holm H, Jarvis MJ, Russell MAH, Feyerabend C. Nicotine intake and dependence in Swedish snuff takers. Psychopharmacology 1992; 108: 507-11.
  3. Russell MAH, Jarvis MJ, Devitt G, Feyerabend C. Nicotine intake by snuff users. Br Med J 1981; 283: 814-7.
  4. Benowitz NL. Dosimetric studies of compensatory cigarette smoking. In: Wald N, Froggatt P (eds). Nicotine, smoking and the low tar programme. Oxford: Oxford University Press, 1989: 133-50.
  5. Hasenfratz M, Baldinger B, Battig K. Nicotine or tar titration in cigarette smoking behavior? Psychopharmacology 1993; 112: 253-8.
  6. Russell MA, Jarvis M, Iyer R, Feyerabend C. Relation of nicotine yield of cigarettes to blood nicotine concentrations in smokers. Br Med J 1980; 280: 972-6.
  7. Russell MA, Jarvis MJ, Feyerabend C, Saloojee Y. Reduction of tar, nicotine and carbon monoxide intake in low tar smokers. J Epidemiol Community Health 1986; 40: 80-5.
  8. Benowitz NL, Hall SM, Herning RI, Jacob P, et al. Smokers of low-yield cigarettes do not consume less nicotine. N Engl J Med 1983; 309: 139-42.
  9. Benowitz NL, Jacob P 3d, Yu L, Talcott R, et al. Reduced tar, nicotine, and carbon monoxide exposure while smoking ultralow- but not low-yield cigarettes. JAMA 1986; 256: 241-6.
  10. Wald NJ, Boreham J, Bailey A. Relative intakes of tar, nicotine, and carbon monoxide from cigarettes of different yields. Thorax 1984; 39: 361-4.
  11. Woodward M, Tunstall Pedoe H. Self-titration of nicotine: evidence from the Scottish Heart Health Study. Addiction 1993; 88: 821-30.
  12. Woodward M, Tunstall Pedoe H. Do smokers of lower tar cigarettes consume lower amounts of smoke components? Results from the Scottish Heart Health Study. Br J Addict 1992; 87: 921-8.
  13. Gori GB, Lynch CJ. Analytical cigarette yields as predictors of smoke bioavailability. Regulatory Toxicol Pharmacol 1985; 5: 314-26.
  14. Byrd GD, Davis RA, Caldwell WS, Robinson JH, deBethizy JD. A further study of FTC yield and nicotine absorption in smokers. Psychopharmacology 1998; 139: 291-9.
  15. Maron DJ, Fortmann SP. Nicotine yield and measures of cigarette smoke exposure in a large population: are lower-yield cigarettes safer? Am J Pub Health 1987; 77: 546-9.
  16. Coultas DB, Stidley CA, Samet JM. Cigarette yields of tar and nicotine and markers of exposure to tobacco smoke. Am Rev Respir Dis 1993; 148: 435-40.
  17. Russell MAH, Sutton SR, Iyer R, Feyerabend C, Vesey CJ. Long-term switching to low-tar low-nicotine cigarettes. Br J Addict 1982; 77: 145-58.
  18. Guyatt AR, Kirkham AJ, Mariner DC, Baldry AG, Cumming G. Long-term effects of switching to cigarettes with lower tar and nicotine yields. Psychopharmacology 1989; 99: 80-6.
  19. Stephen A, Frost C, Thompson S, Wald N. Estimating the extent of compensatory smoking. In: Wald N, Froggatt P (eds). Nicotine, smoking and the low tar programme. Oxford: Oxford University Press, 1989: 100-15.
  20. Peach H, Hayward DM, Shah D, Ellard GA. A double-blind randomized controlled trial of the effect of a low- versus a middle-tar cigarette on respiratory symptoms - a feasibility study. IARC Sci Publ 1986; 74: 251-63.
  21. Frost C, Fullerton FM, Stephen AM, Stone R, et al. The tar reduction study: randomised trial of the effect of cigarette tar yield reduction on compensatory smoking. Thorax 1995; 50: 1038-43.
  22. Lynch CJ, Benowitz NL. Spontaneous cigarette brand switching: consequences for nicotine and carbon monoxide exposure. Am J Pub Health 1987; 77: 1191-4.
  23. Peach H, Hayward DM, Ellard DR, Morris RW, Shah D. Phlegm production and lung function among cigarette smokers changing tar groups during the 1970s. J Epidemiol Community Health 1986; 40: 110-6.
  24. Waller RE, Froggatt P. Product modification. Br Med Bull 1996; 52: 193-205.
  25. Kozlowski LT, Mehta NY, Sweeney CT, Schwartz SS, et al. Filter ventilation and nicotine content of cigarettes from Canada, the United Kingdom, and the United States. Tob Control 1998; 7: 369-75.
  26. Gray N. Low-tar cigarettes: bane or benefit. Cancer Detect Prev 1987; 10: 187-92.
  27. National Cancer Institute Expert Committee. The FTC cigarette test method for determining tar, nicotine and carbon monoxide yields of US cigarettes. NIH Publication No. 96-4028. Smoking and Tobacco Control Monograph No. 7. Washington, DC: NCI, 1996.
  28. Bross ID, Gibson R. Risks of lung cancer in smokers who switch to filter cigarettes. Am J Pub Health Nations Health 1968; 58: 1396-403.
  29. Wynder EL, Mabuchi K, Beattie EJ Jr. The epidemiology of lung cancer. Recent trends. JAMA 1970; 213: 2221-8.
  30. Wynder EL, Stellman SD. Impact of long-term filter cigarette usage on lung and larynx cancer risk: a case-control study. J Natl Cancer Inst 1979; 62: 471-7.
  31. Lubin JH, Blot WJ, Berrino F, Flamant R, et al. Patterns of lung cancer risk according to type of cigarette smoked. Int J Cancer 1984; 33: 569-76.
  32. Stellman SD, Garfinkel L. Lung cancer risk is proportional to cigarette tar yield: evidence from a prospective study. Prev Med 1989; 18: 518-25.
  33. Tang JL, Morris JK, Wald NJ, Hole D, et al. Mortality in relation to tar yield of cigarettes: a prospective study of four cohorts. Br Med J 1995; 311: 1530-3.
  34. Stellman SD. Cigarette yield and cancer risk: evidence from case-control and prospective studies. IARC Sci Publ 1986; 74: 197-209.
  35. Peto R. Overview of cancer time-trend studies in relation to changes in cigarette manufacture. In: Zaridze DG, Peto R (eds). Tobacco: a major international health hazard. IARC Scientific Publication No. 74. Lyon: IARC, 1986: 211-6.
  36. Thun MJ, Day-Lally CA, Calle EE, Flanders WD, Heath CW. Excess mortality among cigarette smokers: changes in a 20-year interval. Am J Pub Health 1995; 85: 1223-30.
  37. La Vecchia C, Liati P, Decarli A, Negrello I, Franceschi S. Tar yields of cigarettes and the risk of oesophageal cancer. Int J Cancer 1986; 38: 381-5.
  38. La Vecchia C, Bidoli E, Barra S, D'Avanzo B, et al. Type of cigarettes and cancers of the upper digestive and respiratory tract. Cancer Causes Control 1990; 1: 69-74.
  39. Lopez Abente G, Gonzalez CA, Errezola M, Escolar A, et al. Tobacco smoke inhalation pattern, tobacco type, and bladder cancer in Spain. Am J Epidemiol 1991; 134: 830-9.
  40. Stellman SD. Influence of cigarette yield on risk of coronary heart disease and chronic obstructive pulmonary disease. IARC Sci Publ 1986; 74: 237-49.
  41. Parish S, Collins R, Peto R, Youngman L, et al. Cigarette smoking, tar yields, and non-fatal myocardial infarction: 14,000 cases and 32,000 controls in the United Kingdom. The International Studies of Infarct Survival (ISIS) Collaborators. Br Med J 1995; 311: 471-7.
  42. Participants of the Fourth Scarborough Conference on Preventive Medicine. Is there a future for lower-tar-yield cigarettes? Lancet 1985; ii: 1111-4.
  43. Wynder EL, Goodman MT, Hoffmann D. Demographic aspects of the low-yield cigarette: considerations in the evaluation of health risk. J Natl Cancer Inst 1984; 72: 817-22.
  44. Jarvis MJ, Marsh A, Matheson J. Factors influencing choice of low-tar cigarettes. In: Wald N, Froggatt P (eds). Nicotine, smoking and the low tar programme. Oxford: Oxford University Press, 1989: 220-8.
  45. Jarvis MJ, Wardle J. Social patterning of health behaviours: the case of cigarette smoking. In: Marmot M, Wilkinson R (eds). Social determinants of health. Oxford: Oxford University Press, 1999: 240-55.
  46. Stellman SD, Garfinkel L. Smoking habits and tar levels in a new American Cancer Society prospective study of 1.2 million men and women. J Natl Cancer Inst 1986; 76: 1057-63.
  47. Jarvis MJ, Russell MAH. Sales-weighted tar, nicotine and carbon monoxide yields of U.K. cigarettes: 1985. Br J Addict 1986; 81: 579-81.
  48. Gori GB, Bock FG. A safe cigarette? Banbury Report 3. Cold Spring Harbor: Cold Spring Harbor Laboratory, 1980.
  49. British American Tobacco. Proceedings of the smoking behaviour-marketing conference July 9th-12th 1984. Minnesota Trial exhibit 13,431.
  50. Hurt RD, Robertson CR. Prying open the door to the tobacco industry's secrets about nicotine: the Minnesota Tobacco Trial. JAMA 1998; 280: 1173-81.50

Contents

Contributors, Foreword and Key Points
1  Tobacco smoking in Britain: an overview
2 Physical and pharmacological effects of nicotine
3 Psychological effects of nicotine and smoking in man
4 Is nicotine a drug of addiction?
5 The natural history of smoking: the smoker's career
6 Regulation of nicotine intake for smokers, and implications for health
7 The management of nicotine addiction
8 Regulatory approaches to tobacco products in Britain
9 Summary and recommendations

This page last updated on May 4, 2001