Cigarette tar yields in relation to mortality from lung cancer in the cancer prevention study II prospective cohort, 1982-8

Objective To assess the risk of lung cancer in smokers of medium tar filter cigarettes compared with smokers of low tar and very low tar filter cigarettes.Design Analysis of the association between the tar rating of the brand of cigarette smoked in 1982 and mortality from lung cancer over the next six years. Multivariate proportional hazards analyses used to assess hazard ratios, with adjustment for age at enrolment, race, educational level, marital status, blue collar employment, occupational exposure to asbestos, intake of vegetables, citrus fruits, and vitamins, and, in analyses of current and former smokers, for age when they started to smoke and number of cigarettes smoked per day.Setting Cancer prevention study II (CPS-II).Participants 364 239 men and 576 535 women, aged ≥ 30 years, who had either never smoked, were former smokers, or were currently smoking a specific brand of cigarette when they were enrolled in the cancer prevention study.Main outcome measure Death from primary cancer of the lung among participants who had never smoked, former smokers, smokers of very low tar (≤ 7 mg tar/cigarette) filter, low tar (8-14 mg) filter, high tar (≥ 22 mg) non-filter brands and medium tar conventional filter brands (15-21 mg).Results Irrespective of the tar level of their current brand, all current smokers had a far greater risk of lung cancer than people who had stopped smoking or had never smoked. Compared with smokers of medium tar (15-21 mg) filter cigarettes, risk was higher among men and women who smoked high tar (≥ 22 mg) non-filter brands (hazard ratio 1.44, 95% confidence interval 1.20 to 1.73, and 1.64, 1.26 to 2.15, respectively). There was no difference in risk among men who smoked brands rated as very low tar (1.17, 0.95 to 1.45) or low tar (1.02, 0.90 to 1.16) compared with those who smoked medium tar brands. The same was seen for women (0.98, 0.80 to 1.21, and 0.95, 0.82 to 1.11, respectively).Conclusion The increase in lung cancer risk is similar in people who smoke medium tar cigarettes (15-21 mg), low tar cigarettes (8-14 mg), or very low tar cigarettes (≤ 7 mg). Men and women who smoke non-filtered cigarettes with tar ratings ≥ 22 mg have an even higher risk of lung cancer.     

Self-titration by cigarette smokers

An 11-week crossover study was carried out in which 12 subjects smoked high-nicotine (1·84 mg standard yield) and low-nicotine (0·6 mg) cigarettes after an initial period of smoking their usual brands with a medium-nicotine yield (mean 1·4 mg). Plasma and urine nicotine concentrations, carboxyhaemoglobin (COHb) concentration, puffing behaviour, 24-hour cigarette consumption, and butt nicotine content were measured. The changes in plasma nicotine and blood COHb concentrations showed that the smokers compensated for about two-thirds of the difference in standard yields when switched to either high- or low-nicotine cigarettes. Thus, compared with the medium-nicotine brand, the intake of nicotine and carbon monoxide was only about 10% higher when subjects smoked the high-nicotine cigarettes, which had a standard yield 30-40% higher than the medium brands; and only about 15% lower when they smoked the low-nicotine cigarettes, which had a standard yield about 50% lower than the medium brands. But nicotine content and urine nicotine concentrations followed a similar pattern. Changes in puffing behaviour and in 24-hour cigarette consumption were only slight.The results show clear evidence of both upward and downward self-titration of nicotine and carbon monoxide (and tar) intakes when smokers change to cigarettes with standard yields that differ over the range studied.     

Low-tar medium-nicotine cigarettes: a new approach to safer smoking.

The logic of expecting people who cannot stop smoking to switch to cigarettes that have hardly any nicotine is questionable. Tar and nicotine yields of cigarettes available in Britain today correlate 0-93, and further reduction of tar intake is limited by the reluctance of smokers to tolerate similar reductions in nicotine. A new approach would be to aim at lowering tar yields of cigarettes from the present average of 18 mg to around 6 mg but maintaining nicotine yields at around 1-0 to 1-2 mg, which would be acceptable to most smokers. This approach requires that emphasis be placed on tar: nicotine ratios as well as on the absolute yields. These ratios for brands on sale in Britain today average 14-2 and range from 9-6 to 20-8. They provide an additional guide for comparing the relative harmfulness of different brands. For example, 35% of cigarette smokers in Britain smoke either Embassy Filter or Players No 6 Filter; by changing to John Player Carlton King Size they could reduce their tar intake by more than 20% without having to suffer any nicotine deprivation.     

Would a medium-nicotine,low-tar cigarette be less hazardous to health?

Smoking behaviour and exposure to carbon monoxide, nicotine, and tar were studied in 19 middle-tar smokers. All smoked their own brands for three weeks and then switched to either a conventional low-nicotine, low-tar brand (control) or a medium-nicotine, low-tar cigarette for a further three weeks, the order then being reversed. The medium-nicotine, low-tar brand also had a low delivery of carbon monoxide. With the medium-nicotine, low-tar cigarette mouth-level delivery and intake of nicotine was similar to that with the smokers'' usual brands, and significantly greater than with the control low-tar cigarette. Intake of carbon monoxide from the medium-nicotine, low-tar cigarette was significantly less than with either own or control brands. With both low-tar brands mouth-level exposure to tar was reduced relative to smokers'' usual cigarettes. There was no evidence, however, that the reduction in tar exposure was greater with the medium-nicotine brand than with the control low-tar cigarette. Both low tar brands were "''oversmoked" relative to subjects'' usual middle-tar cigarettes. The medium-nicotine, low-tar cigarette was marginally more acceptable than the control brand, and the particular design used in the study resulted in a lower intake of carbon monoxide. In terms of reducing mouth-level exposure to tar, however, the medium-nicotine, low-tar cigarette had no advantage over the control low-tar product. In part this was because of the ratio of tar to nicotine delivery obtained by human smokers was not the same as that obtained by smoking machine.     

Tar yield of cigarettes and risk of acute myocardial infarction. GISSI-EFRIM Investigators.

OBJECTIVE--To analyse the relation between tar and nicotine yield of cigarettes smoked in the recent past and the risk of myocardial infarction. DESIGN--Multicentre case-control study conducted between September 1988 and June 1989. SETTING--Over 80 coronary care units in various Italian regions. SUBJECTS--916 patients with acute myocardial infarction without history of ischaemic heart disease and 1106 controls admitted to hospital for acute conditions not related to known or suspected risk factors for ischaemic heart disease. MAIN OUTCOME MEASURES--Relative risk of myocardial infarction according to type of cigarette smoked adjusted for identified potential confounding factors. Brands of cigarettes classified according to yield of tar and nicotine. RESULTS--Patients with acute myocardial infarction were more often smokers and among smokers they tended to smoke more cigarettes. Compared with non-smokers their estimated relative risks were 3.8, 4.3, 3.2, and 3.7 in the four categories of tar yield (< 10, 10-15, > 15-20, and > 20 mg, respectively). No trend in risk across yields was evident when analysis was restricted to smokers and allowance was made for number of cigarettes. Compared with risks in subjects in the lowest category of tar yield the relative risks were 1.2, 0.8, and 1.0 for the subsequent yields. Compared with risks in non-smokers the relative risks ranged from 9.3 to 12.6 below the age of 50 but no trend was observed with increasing yield. CONCLUSIONS--Changing to cigarettes with a lower tar yield is not an effective means of reducing tobacco related morbidity from myocardial infarction.     

Comparison of Effect on Tobacco Consumption and Carbon Monoxide Absorption of Changing to High and Low Nicotine Cigarettes

In 10 sedentary workers, smoking as they felt inclined over a five-hour period in the middle of a typical working day, changing to low nicotine cigarettes (<0·3 mg) caused an increase in the number and weight of cigarettes smoked, while changing to high nicotine cigarettes (3·2 mg) caused a decrease (P < 0·01). The average number and weight smoked in five hours for usual, low, and high nicotine brands were respectively 10·6 (6·00 g), 12·5 (6·52 g), and 6·7 (4·19 g). When smoking the usual brand the average blood carboxyhaemoglobin (COHb) increased 1·78% (from 6·38% to 8·16%). But on changing to either high or low nicotine cigarettes the COHb levels instead of increasing, tended to fall (P < 0·01). The average fall of 0·34% while smoking low nicotine cigarettes was due to the low carbon monoxide (CO) yield of these cigarettes, while the fall of 1·04% when smoking high nicotine cigarettes was attributable to reduced consumption. The findings support the view that smoking behaviour is modified to regulate nicotine intake. Besides having low tar and CO yields, the least harmful cigarettes for heavy smokers may be those with a high, rather than low, nicotine yield.     

Respiratory effects of non-tobacco cigarettes.

Data from the Tucson epidemiological study of airways obstructive disease on smoking of non-tobacco cigarettes such as marijuana were analysed to determine the effect of such smoking on respiratory symptoms and pulmonary function. Among adults aged under 40, 14% had smoked non-tobacco cigarettes at some time and 9% were current users. The prevalence of respiratory symptoms was increased in smokers of non-tobacco cigarettes. After tobacco smoking had been controlled for men who smoked non-tobacco cigarettes showed significant decreases in expiratory flow rates at low lung volumes and in the ratio of the forced expiratory volume in one second to the vital capacity. This effect on pulmonary function in male non-tobacco cigarette smokers was greater than the effect of tobacco cigarette smoking. These data suggest that non-tobacco cigarette smoking may be an important risk factor in young adults with respiratory symptoms or evidence of airways obstruction.     

Influence of passive smoking on admissions for respiratory illness in early childhood.

An association was sought between passive smoking and inpatient admissions for respiratory illness in 1058 children born between 1 June and 31 December 1981 and living in the neighborhoods of Nan-Jing Western Road and Yan-An Western Road in Jing-An District, Shanghai. The admission rate for first episodes of respiratory illness was positively correlated with the total daily cigarette consumption of family members during the children''s first 18 months of life. The relative risk of developing a first episode of respiratory illness was 1.80 for children living in families including people who smoked 10 or more cigarettes a day compared with those living in non-smoking families. Multiple logistic regression analysis showed that the effect of passive smoking on inpatient admission for respiratory illness was independent of the child''s birth weight, type of feeding, father''s education, size of the home, and chronic respiratory disease among adults in the family. The adjusted odds ratios compared with the non-smoking group were 1.17 in families smoking 1.9 cigarettes daily and 1.89 in families smoking 10 or more cigarettes daily. These data suggest that exposure to household cigarette smoke of children in early life increases the risk of severe respiratory illness.     

Inhaling and lung cancer: an anomaly explained.

An objective index of inhaling cigarette smoke based on carboxyhaemoglobin concentrations and the carbon monoxide yields of cigarettes was used to investigate possible systematic differences in the extent of inhaling among light and heavy smokers when classified according to their self described inhaling habits. A total of 2108 men who smoked cigarettes were studied. Heavy smokers (20 or more cigarettes a day) had a higher average inhaling index than light smokers (fewer than 20 cigarettes a day) both among those who said that they inhaled and among those who said that they did not. This observation, together with indirect evidence that heavy smokers who inhale deeply may to some extent avoid depositing smoke condensate on their main bronchial epithelium, explains a hitherto unresolved anomaly--namely, that the risk of lung cancer is less among heavy cigarette smokers who say that they inhale than it is among those who say that they do not inhale.     

Carbon monoxide yield of cigarettes and its relation to cardiorespiratory disease.

Estimates of the carbon monoxide yield of their cigarettes have been obtained for 4910 smokers (68% of all smokers) in the Whitehall study of men aged 40 to 64. In the 10 years after examination 635 men died. When men smoking cigarettes with high carbon monoxide yield were compared with those smoking cigarettes with a low yield, and after adjusting for age, employment grade, amount smoked, and tar yield, the risk of death was 32% lower for coronary heart disease, 49% higher for lung cancer, and 10% lower for total mortality; these differences were not statistically significant. Among men who said that they inhaled the risk of fatal coronary heart disease was 51% lower in the high carbon monoxide group (p less than 0.01), while the risk of lung cancer was 75% higher. These results provide no evidence that a smoker can reduce his risk of death by smoking a brand with a low carbon monoxide yield; he might even increase it. The complex interactions between characteristics of the smoker, smoking behaviour, constituents of tobacco smoke, and health are again demonstrated.     

The epidemiology of white full-term infants with short crown-heel lengths for gestational ages at birth

Fetal growth retardation was diagnosed in 137 (7.8 percent) of 1,757 white full-term infants who had crown-heel lengths below the fifth percentiles for their gestational ages. The incidence of short infants was 121 (11.1 percent) among 1,093 mothers with high-risk pregnancies compared to 16 (2.4 percent) in 664 low-risk mothers (p less than 0.0001). There were four high-risk categories: spontaneous premature rupture of membranes (PROM), fetal conditions, complications of pregnancy, and adverse maternal practices. The incidence of short infants was significantly higher in each of the four high-risk categories than in the low-risk group. There were three other conditions that were present in all pregnancies that were associated with the frequency of short infants: maternal height, socioeconomic status of head of household, and sex of infant. A short maternal height (under 157.7 cm = 62 inches) was significantly associated with an increase in short infants among mothers who smoked cigarettes at any level during pregnancy and among mothers with PROM in combination with other risks, but not in the group of 664 low-risk mothers. Significantly more short girls than short boys were born to mothers who smoked ten or more cigarettes a day throughout pregnancy or who had multiple adverse maternal practices, but no statistically significant differences were noted among mothers who smoked fewer than ten cigarettes per day, among those with PROM as the only risk factor, or among those with medical or obstetrical complications. Moreover, those mothers who were in socioeconomic groups III and IV and had other risk factors had a significantly higher incidence of short infants than did similar mothers in socioeconomic groups I and II.     

Modifying risk of developing lung cancer by changing habits of cigarette smoking.

Data from a hospital based case-control study of lung cancer in Western Europe were used to examine changes in the risk of developing lung cancer after changes in habits of cigarette smoking. Only data for subjects who had smoked regularly at some time in their lives were included. The large size of the study population (7181 patients and 11 006 controls) permitted precise estimates of the effect of giving up smoking. Risks of developing lung cancer for people who had given up smoking 10 or more years before interview were less than half of those for people who continued to smoke. The reduction in risk was seen in men and women and in former smokers of both filter and non-filter cigarettes but varied by duration of smoking habit before giving up. The protective effect of giving up became progressively greater with shorter duration of smoking habit. The risks after not smoking for 10 years for both men and women who had previously smoked for less than 20 years were roughly the same as those for lifelong non-smokers. Reducing the number of cigarettes smoked a day or switching from non-filter to filter cigarettes also lowered the risk of developing lung cancer but not to the extent associated with giving up smoking.     

Mortality in relation to tar yield of cigarettes: a prospective study of four cohorts.

OBJECTIVE--To investigate relation between tar yield of manufactured cigarettes and mortality from smoking related diseases. DESIGN--Prospective epidemiological study of four cohorts of men studied between 1967 and 1982. SETTING--Combined data from British United Provident Association (BUPA) study (London), Whitehall study (London), Paisley-Renfrew study (Scotland), and United Kingdom heart disease prevention project (England and Wales). SUBJECTS--Of the 56,255 men aged over 35 who were included in the studies, 2742 deaths occurred among 12,400 smokers. Average follow up was 13 years. MAIN OUTCOME MEASURES--Relative mortality from smoking related diseases according to tar yields of cigarettes smoked. RESULTS--Age adjusted mortality from smoking related diseases in smokers of filter cigarettes was 9% lower (95% confidence interval 1% to 17%) than in smokers related diseases consistently decreased with decreasing tar yield. Relative mortality in cigarette smokers for a 15 mg decrease in tar yield per cigarette was 0.75 (0.52 to 1.09) for lung cancer, 0.77 (0.61 to 0.97) for coronary heart disease, 0.86 (0.50 to 1.50) for stroke, 0.78 (0.40 to 1.48) for chronic obstructive lung diseases, 0.78 (0.65 to 0.93) for these smoking related diseases combined, and 0.77 (0.65 to 0.90) for all smoking related diseases. CONCLUSION--About a quarter of deaths from lung cancer, coronary heart disease, and possibly other smoking related diseases would have been avoided by lowering tar yield from 30 mg per cigarette to 15 mg. Reducing cigarette tar yields in Britain has had a modest effect in reducing smoking related mortality.     

Respiratory symptoms in Manitoba farmers: association with grain and hay handling.

Of a random sample of farmers in two crop districts of Manitoba mailed a respiratory questionnaire in 1976, 833 (82% of those currently farming in the area) replied. More than half were grain farmers and nearly half had never smoked cigarettes. The prevalence of chronic cough and phlegm production, wheezing and exertional dyspnea was positively related to the amount of smoking but was also higher than expected in nonsmokers. Acute dyspnea, sometimes of delayed onset and accompanied by fever, was most commonly related to handling old grain and was reported by 44% of the farmers. Current smokers were more susceptible than nonsmokers to this type of dyspnea. Farmers with history of acute dyspnea while handling grain were more likely to wear masks, but the overall rate of mask wearing, even among those at highest risk, was low.     

Smoker's face: an underrated clinical sign?

In a prospective survey of patients attending a general medical outpatient clinic roughly half the current cigarette smokers who had smoked for 10 years or more were identified, using defined criteria, by their facial features alone. These facial features, designated "smoker''s face," were present in three (8%) of those who had smoked cigarettes for 10 years or more in the past and in none of the non-smokers. The association of smoker''s face with current smoking that had continued for 10 years or more was significant (p less than 0.001) and remained after the patient''s age, social class, exposure to sunlight, recent change of weight, and estimated lifetime consumption of cigarettes were controlled for. Smoker''s face may be a helpful indicator in antismoking campaigns.     

Delay and probability discounting as related to different stages of adolescent smoking and non-smoking

This study examined relations between different patterns of adolescent cigarette smoking and discounting of monetary rewards due to delay (delay discounting) and probabilistic uncertainty (probability discounting). The study also examined the relation between smoking and the number of peer friends who smoke and level of parent education. Participants were 55 adolescents (28 females) between 14 and 16 years of age who were categorized according to the following patterns of smoking behavior: "never smokers" (n=19; 10 females) who had not tried even one cigarette; "triers" (n=17; 9 females) who had recently tried cigarettes for the first time; and "current smokers" (n=19; 9 females) who smoked a minimum of one cigarette every week for at least 6 months prior to data collection. It was hypothesized that current smokers would discount more than those who had never smoked. No specific hypotheses were made for participants only trying cigarettes. Unexpectedly, results indicated no differences in discounting between the current smokers and never smokers. However, the trier group discounted probabilistic rewards significantly more than the never- and current-smoker groups. Also, triers and current smokers both reported having more friends who smoked than never smokers, and fathers of never smokers had significantly more education than fathers of either triers or current smokers. These results suggest that impulsive discounting may be more related to adolescents trying cigarettes than to their becoming regular smokers, whereas number of peer friends who smoke and parent level of education seem to differentiate between those who have smoked to some extent (triers and current smokers) and those who have not even tried cigarettes (never 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.     

Asthma from childhood at age 21: the patient and his disease.

Information was obtained from 336 21-year-olds who had begun wheezing before the age of 7 about their knowledge of asthma and its effect on their current life style. Two-thirds of the subjects were still symptomatic. A control group of 62 subjects was available for comparison. Knowledge about asthma was poor, particularly among those with less troublesome symptoms. Half of those with frequent episodic asthma and one-third with persistent asthma did not regard excess use of bronchodilator aerosols as potentially dangerous. Over three-quarters of those with persistent asthma were not receiving adequate treatment. One-third of third of those with persistent asthma were missing substantial time from work because of respiratory illness, and a similar proportion were restricting sporting activities. The incidence of smoking was disturbingly high in all asthma groups. The higher the number of cigarettes ever smoked and the higher the current tobacco consumption the less satisfactory was the progress of asthma. Both cigarette smoking and severity of asthma contributed to chronic production of sputum. Children and teenagers with asthma should be educated to seek more appropriate medical help and thereby reduce morbidity.     

Carbon monoxide yields of cigarettes and their relation to nicotine yield and type of filter.

Carbon monoxide (CO) yields of 11 popular brands of British cigarette, two types of cigarette containing tobacco-substitute, and one brand of cigar were measured under standardized conditions. Yields of the conventional cigarettes ranged from 5.0 to 20.2 mg per cigarette (1.3 to 4.7% by volume). The cigar yielded 81.7 mg (10.0%) CO and the two semi-synthetic cigarettes 17.2 (4.2%) and 28.2 mg (6.2%) CO. Puff-by-puff analysis showed an increase in CO concentration as a cigarette is smoked. In brands with nicotine yields over 1.0 mg no relationship was apparent between nicotine yield and CO yield, and the filters of cigarettes in this category did not appear to reduce the CO yield. In the low nicotine cigarettes with ventilated filters there appeared to be some correlation between nicotine yield and CO yield, and these filters were highly effective in reducing CO yield, owing mainly to the ventilation. We suggest that official publication of CO yields might motivate manufacturers to produce cigarettes with lower yields.     

A Simple and Rapid Method for Standard Preparation of Gas Phase Extract of Cigarette Smoke

Cigarette smoke consists of tar and gas phase: the latter is toxicologically important because it can pass through lung alveolar epithelium to enter the circulation. Here we attempt to establish a standard method for preparation of gas phase extract of cigarette smoke (CSE). CSE was prepared by continuously sucking cigarette smoke through a Cambridge filter to remove tar, followed by bubbling it into phosphate-buffered saline (PBS). An increase in dry weight of the filter was defined as tar weight. Characteristically, concentrations of CSEs were represented as virtual tar concentrations, assuming that tar on the filter was dissolved in PBS. CSEs prepared from smaller numbers of cigarettes (original tar concentrations ≤15 mg/ml) showed similar concentration-response curves for cytotoxicity versus virtual tar concentrations, but with CSEs from larger numbers (tar ≥20 mg/ml), the curves were shifted rightward. Accordingly, the cytotoxic activity was detected in PBS of the second reservoir downstream of the first one with larger numbers of cigarettes. CSEs prepared from various cigarette brands showed comparable concentration-response curves for cytotoxicity. Two types of CSEs prepared by continuous and puff smoking protocols were similar regarding concentration-response curves for cytotoxicity, pharmacology of their cytotoxicity, and concentrations of cytotoxic compounds. These data show that concentrations of CSEs expressed by virtual tar concentrations can be a reference value to normalize their cytotoxicity, irrespective of numbers of combusted cigarettes, cigarette brands and smoking protocols, if original tar concentrations are ≤15 mg/ml.