Smokers Of Low Tar Cigarettes Research Articles

Control of tobacco-related disease.

As ways of discouraging tobacco consumption, the effects of increases in price and in quantitative information may have been under-emphasized. To decrease the hazards of tobacco, switches from cigarettes to pipes, cigars or 'smokeless' tobacco may be useful, as may a reduction in cigarette tar delivery. Indeed, the spread of existing tar level reductions from capitalist to socialist countries might prevent tens of thousands of lung cancer deaths each year in the early decades of the next century, and (perhaps by attempts to engineer cigarettes so that smokers of lower tar cigarettes are less likely to 'compensate' by taking more smoke) it should eventually also be possible to change cigarettes so as also to reduce their effects on heart and lung disease. Changes in consumption and in composition of tobacco products are complementary, not competing, strategies. If both are pursued effectively, then although the life expectancy of old people may not be much improved, the proportion of adults who die before reaching old age will decrease substantially.

Tar yield and risk of acute myocardial infarction: pooled analysis from three case-control studies

Controversial information is available with reference to the role of type or yield of cigarettes on the risk of cardiovascular disease. We considered the issue in a combined dataset of three case-control studies of acute myocardial infarction conducted in Italy between 1983 and 2003. Cases were 1990 subjects with a first episode of non-fatal acute myocardial infarction, and controls were 2521 patients in hospital for acute diseases unrelated to smoking or other recognized risk factors for myocardial infarction. The odds ratio and the corresponding 95% confidence interval (CI) were derived by unconditional multiple logistic regression models, including terms for age, sex, and several major risk factors for myocardial infarction. As compared to never smokers, the multivariate odds ratio was 2.70 (95% CI 2.01-3.63) for smokers of low tar cigarettes (<10 mg), 3.06 (95% CI 2.53-3.70) for intermediate (10-19 mg) and 3.14 (95% CI 2.12-4.64) for high tar yield (> or =20 mg). After further allowance for duration of smoking and number of cigarettes per day, as compared to low tar yield cigarettes, the odds ratio was 1.14 (95% CI 0.85-1.53) for intermediate, and 1.28 (95% CI 0.81-2.02) for high tar yield. Our study confirms that no substantial reduction in acute myocardial infarction risk resulted from the decrease of cigarette tar yield.

Review Article Fifty Years' Experience of Reduced-Tar Cigarettes: What Do We Know About Their Health Effects?

Since the 1950s, cigarettes sold in the United States have undergone a progressive modification, including the addition of filters and a reduction in the average machine-measured tar and nicotine yield per cigarette by over 60%. These, and other, temporal changes in manufactured cigarettes, coupled with the complexity of smoking behavior, make it difficult to assess the impact of the newer cigarettes on health. Recently, some researchers have suggested that the newer products, marketed as being less harmful, may in fact provide no benefit compared to the older, higher tar cigarettes. The primary purpose of this review is to critically evaluate the available epidemiologic evidence on the health effects of low-tar cigarettes. This body of data provides the only means of assessing the effects of long-term exposure to these products, as they are actually used. After identifying important methodological problems confronting research in this area, studies of lung cancer, coronary heart disease, chronic obstructive pulmonary disease, and total mortality are examined in terms of their strengths and weaknesses and their results. Thirty-five studies of lung cancer are suggestive that smokers of low tar cigarettes have a lower risk (by 20-30%) compared to smokers of higher tar cigarettes. Only a minority of studies of heart disease provide evidence of a reduction in risk, on the order of 10%. Studies concerning chronic obstructive pulmonary disease (COPD) are inconsistent, but the majority suggest decreased risk in smokers of lower tar cigarettes. Finally, studies that included total mortality indicate with a high degree of consistency that the total death rate is reduced in smokers of lower tar cigarettes, on the order of 10-20%. Because of the multiplicity of factors involved in smoking behavior, including compensation for reduced nicotine, and the modest magnitude of the apparent reduction in risk, the relative benefits of low tar cigarettes remain uncertain. Additional analyses of existing data sets could further clarify the impact of low-tar cigarettes.

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.

To assess the effects of cigarette smoking on the incidence of non-fatal myocardial infarction, and to compare tar in different types of manufactured cigarettes. In the early 1990s responses to a postal questionnaire were obtained from 13,926 survivors of myocardial infarction (cases) recently discharged from hospitals in the United Kingdom and 32,389 of their relatives (controls). Blood had been obtained from cases soon after admission for the index myocardial infarction and was also sought from the controls. 4923 cases and 6880 controls were current smokers of manufactured cigarettes with known tar yields. Almost all tar yields were 7-9 or 12-15 mg/cigarette (mean 7.5 mg for low tar (< 10 mg) and 13.3 for medium tar (> or = 10 mg). The cited risk ratios were standardised for age and sex and compared myocardial infarction rates in current cigarette smokers with those in non-smokers who had not smoked cigarettes regularly in the past 10 years. At ages 30-49 the rates of myocardial infarction in smokers were about five times those in non-smokers (as defined); at ages 50-59 they were three times those in non-smokers, and even at ages 60-79 they were twice as great as in non-smokers (risk ratio 6.3, 4.7, 3.1, 2.5, and 1.9 at 30-39, 40-49, 50-59, 60-69, 70-79 respectively; each 2P < 0.00001). After standardisation for age, sex, and amount smoked, the rate of non-fatal myocardial infarction was 10.4% (SD 5.4) higher in medium tar than in low tar cigarette smokers (2P = 0.06). This percentage was not significantly greater at ages 30-59 (16.6% (7.1)) than at 60-79 (1.0% (8.5)). In both age ranges the difference in risk between cigarette smokers and non-smokers was much larger than the difference between one type of cigarette and another (risk ratio 3.39 and 3.95 at ages 30-59 for smokers of similar numbers of low and of medium tar cigarettes, and risk ratio 2.35 and 2.37 at ages 60-79). Most possible confounding factors that could be tested for were similar in low and medium tar users, with no significant differences in blood lipid or albumin concentrations. The present study indicates that the imminent change of tar yields in the European Union to comply with an upper limit of 12 mg/cigarette will not increase (and may somewhat decrease) the incidence of myocardial infarction, unless they indirectly help perpetuate tobacco use. Even low tar cigarettes still greatly increase rates of myocardial infarction, however, especially among people in their 30s, 40s, and 50s, and far more risk is avoided by not smoking than by changing from one type of cigarette to another.

How the steady-state cotinine concentration in cigarette smokers is directly related to nicotine intake.

The relationship between nicotine intake and steady-state cotinine concentration was studied in a sample of 125 subjects who smoked their usual brands of cigarettes. Nicotine and tar yield of cigarettes was determined with a smoking machine, under standardized conditions. Blood was drawn about 8 hours after the last cigarette was smoked and serum cotinine was measured by high performance liquid chromatography. Cotinine levels ranged from 11 to 400 ng/ml, and nicotine daily intake ranged from 1 to 33 mg/day. Regression analysis and the correlation coefficient, r = 0.919, significant at p less than 0.0001, showed that steady-state cotinine level was linearly and directly related to daily available nicotine, with an increase in correlation coefficient directly related to the increase in tar and nicotine yield. From the findings we also conclude that smokers of low-tar cigarettes do not tend to compensate for lower yields of nicotine.

Lung cancer risk is proportional to cigarette tar yield: Evidence from a prospective study

The age-adjusted risk for lung cancer among over 120,000 male current cigarette smokers in the American Cancer Society's 1959–1972 prospective study was analyzed according to tar yield and quantity smoked per day. At each quantity level, the risk increased with increasing tar yield, and at each tar level, the risk increased with numbers of cigarettes smoked daily. The risks in smokers of cigarettes with the lowest yields, however, far exceeded those of former smokers and nonsmokers. The excess lung cancer risk for current smokers was directly proportional to the estimated total milligrams of tar consumed daily: SMR = 100 + 1.731 × milligrams tar per day. Tar yields today are much lower than they were at the time of this study and presage an eventual reduction (but not elimination) of lung cancer risk for those who continue to smoke cigarettes, especially among lifetime smokers of low-tar cigarettes.

Respiratory symptoms and low tar cigarette smoking--a longitudinal study on young people.

Longitudinal data on the effect of low tar cigarette smoking on respiratory symptoms was collected from a sample of Finnish young people born in 1966, by mailed questionnaires in 1979, 1983 and 1985. Cough was 3 to 6 times more common than expected after starting smoking low tar brands (1-10 mg tar). The increase in cough was the same as with those who started middle tar cigarette smoking (11-18 mg). Before starting smoking, the low tar cigarette smokers did not report more symptoms than the middle tar or nonsmokers. After a few years smoking cough and phlegm were 2 to 3 times more common in the low tar cigarette smokers than in the non-smokers but on the same level as in the middle tar cigarette smokers. Tar yield was not a significant predictor of symptoms in logistic regression analysis.

Urinary thioethers in low tar cigarette smokers

The urinary elimination of thioethers has been studied according to the smoking habit in 52 subjects. Urinary thioethers (UT) increase with the number of cigarettes and this is specially noteworthy in individualised studies. As a contribution to clarify the relevance of smoking ‘low tar’ cigarettes, we performed a comparative study in six volunteers. Each subject smoked four types of cigarettes, namely brown normal-tar; brown low-tar; blond normal-tar; and blond low-tar, during one week for each type. UT were collected daily in the whole study. The statistical analysis revealed there are no differences despite the type of cigarettes. Probably the subject compensates the lower content of tar and nicotine by smoking each cigarette with more intensity, since the number of cigarettes/day remained constant for each subject. These results reveal the uncertainty of the claimed ‘healthiness’ of low tar and nicotine cigarettes.

Increased risk of respiratory symptoms in young smokers of low tar cigarettes.

The effect of cigarettes yielding less than 10 mg tar was investigated in a representative sample (n = 4729) of 16 and 18 year old Finns. The rate of response was 80%. Cough and phlegm were significantly increased in young people smoking low tar cigarettes. When more than nine cigarettes were smoked daily respiratory symptoms were 2.4-6.2 times more prevalent among those who smoked low tar cigarettes than among those who never smoked. No differences were found between the smokers of low tar and medium tar cigarettes (yielding tar 10-18 mg). These data disagree with the hypothesis that the new low tar brands of cigarettes are less likely to cause respiratory symptoms than the old medium tar brands.

Urinary excretion of thioethers among low-tar and medium-tar cigarette smokers.

The urinary excretion of thioethers was studied among smokers of medium-tar cigarettes (16.3 mg/cig.) and low-tar cigarettes (5.4 mg/cig.). The test persons (26 smokers and 11 nonsmokers) were healthy young men in the military service. The smokers had an increased excretion of thioethers into the urine (P = 0.002 with Mann-Whitney U-test) when compared with the nonsmokers. No differences in the amount of urinary thioethers were detected between the low-tar and medium-tar cigarette smokers. The smokers (varying from 2.0 to 8.5 mmol/mol creatinine) had more individual variation than the nonsmokers (varying from 1.5 to 4.5 mmol/mol creatinine). Furthermore, the individual variation in the group of low-tar cigarette smokers did not markedly differ from the individual variation of medium-tar cigarette smokers.

Relationship between cigarette yields, puffing patterns, and smoke intake: evidence for tar compensation?

The relationship between cigarette yields (of nicotine, tar, and carbon monoxide), puffing patterns, and smoke intake was studied by determining puffing patterns and measuring blood concentrations of nicotine and carboxy-haemoglobin (COHb) in a sample of 55 smokers smoking their usual brand of cigarette. Regression analyses showed that the total volume of smoke puffed from a cigarette was a more important determinant of peak blood nicotine concentration than the nicotine or tar yield of the cigarette, its length, or the reported number of cigarettes smoked on the test day. There was evidence of compensation for a lower tar yield over and above any compensation for nicotine. When nicotine yield was controlled for, smokers of lower-tar cigarettes not only puffed more smoke from their cigarettes than smokers of higher-tar cigarettes but they also had higher plasma nicotine concentrations, suggesting that they were compensating for the reduced delivery of tar by puffing and inhaling a greater volume of smoke. The results based on the COHb concentrations were consistent with this interpretation. If an adequate intake of tar proves to be one of the main motives for smoking, then developing a cigarette that is acceptable to smokers and also less harmful to their health will be much more difficult.

Effect of cigarette tar content and smoking habits on respiratory symptoms in women.

Standardized respiratory disease questionnaires (ATS-DLD-78) were administered to 5,686 adult women. Risk factors were evaluated by logistic analysis that adjusted for multiple potential confounding factors. Among current smokers, the number of cigarettes smoked per day was consistently the strongest risk factor for chronic cough, chronic phlegm, wheeze, and dyspnea. The odds ratios for these symptoms in a smoker of 25 or more cigarettes per day relative to a smoker of 1--14 cigarettes per day were 4.74, 4.21, 2.05, and 3.71, respectively. Ex-smokers showed risks between those of current and never smokers. Cigarette tar content was a significant independent risk factor for chronic cough (p = 0.005) and of borderline significance for chronic phlegm (p = 0.077). High tar cigarette smokers in this population (average, 22 mg) had an odds ratio of 2.01 for chronic cough and 1.59 for chronic phlegm relative to low tar cigarette smokers (average, 7 mg). The effect of cigarette tar was linear and independent of cigarettes smoked per day. Smoke inhalation was a significant risk factor for chronic cough (p = 0.029) and for chronic phlegm (p = 0.038). Tar content and smoke inhalation were not significant risk factors for wheeze or dyspnea. Cigarette particulate content (tar) appears to be causally linked to cough and phlegm production., but the association of cigarette smoking and symptoms of wheeze and dyspnea may be more strongly related to the vapor phase of cigarette smoke.