Smoking and pulmonary function in five Solomon Island populations.

The relationship between smoking and lung function was examined in a large sample of healthy Solomon Island Melanesians and Polynesians as part of a multidisciplinary study carried out in 1985 and 1986. Comparisons are made between samples of smokers and non-smokers to determine if smoking is associated with a reduction in pulmonary function among males and females between 25 and 75 years of age. The results of this study indicate that cigarette smoking causes significant reductions in the pulmonary function of these populations. In addition, a clear difference in pulmonary function between males and females, as well as a general reduction in female FEV1 values, suggests that cooking smoke inhalation may be operating as a possible risk factor to the pulmonary health of women. Further research is needed to quantify exposure to smoke of both males and females and relate this measure to declines in pulmonary function.     

Alcohol, smoking and body build: obesity as a result of the toxic effect of 'social' alcohol consumption

Previous work showed that obesity in the average human male is not due to increased caloric intake. To test the hypothesis that 'social' ethanol consumption causes obesity by a hepatotoxic mechanism, the relationships between alcohol intake, cigarette smoking, serum gamma-glutamyl transpeptidase (GGT) and body build were investigated in 816 adult patients, 491 males and 325 females. A large part of the Broca index variance could be explained by hepatic damage as reflected by the GGT level. The higher the GGT, the more overweight were the subjects. Hyperinsulinemia may be the pathogenetic link; insulin is the strongest known blocker of lipolysis. Almost the total variation of obesity with GGT, however, occurred in the range of GGT up to 25 U/l, which is usually, but nevertheless erroneously, considered to be the normal range. This effect was independent of sex and age. Normal GGT is below 10 U/l, which is found on average in females aged less than 20 years. Females tolerate less alcohol than males. Although GGT is as high in females as in males around age 30, males drink about three times as much ethanol. For the same GGT the Broca index is significantly higher in females than in males. GGT generally increases with age; maximum GGT is reached in females in the age group 21-40 years (due to the change in drinking habits around 1968), declining thereafter; in males at age 50. Obesity per se is not correlated with a high GGT. In the females there are hormonal factors influencing obesity. Although in the females GGT decreases on average after age 40, obesity increases (due to the decrease in estrogens). After age 50 ethanol tolerance in males decreases: they reduce their alcohol consumption, and yet the GGT remains high. -Cigarette smoking is a factor which independently influences obesity. Although people who smoke tend also to drink more alcohol, smokers are significantly leaner than nonsmokers. On average males smoke about twice as heavily as females; this contributes to the fact that on average males are leaner than females despite their higher alcohol consumption. Due to lower consumption the influence of ethanol and smoking on body build is smaller in females than in males.     

Similarities in Food Cravings and Mood States Between Obese Women and Women Who Smoke Tobacco

The present study assessed food cravings in a cohort of 229 women who differed in smoking history (i.e., never smoker, former smoker, and current smoker) and body weight (i.e., normal weight, overweight, and obese). Each subject completed the Food Craving Inventory (FCI), which measures cravings for sweets, high fats, carbohydrates/starches, and fast‐food fats, and the Profile of Mood States (POMS), which measures psychological distress. Smoking and obesity were independently associated with specific food cravings and mood states. Current smokers craved high fats more frequently than former and never smokers. They also craved starches more frequently and felt more depressed and angry than never smokers, but not former smokers. Whereas cravings for starchy foods and some mood states may be characteristic of women who are likely to smoke, more frequent cravings for fat among smokers is related to smoking per se. Similarly, obese women craved high fats more frequently than nonobese women and depression symptoms were intensified with increasing body weights. We hypothesize that the overlapping neuroendocrine alterations associated with obesity and smoking and the remarkable similarities in food cravings and mood states between women who smoke and women who are obese suggest that common biological mechanisms modulate cravings for fat in these women.     

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).     

Prevalence of Cigarette Smoking and Associated Factors in a Large Sample of HIV-Positive Patients Receiving Antiretroviral Therapy in Vietnam

BackgroundCigarette smoking presents a salient risk for HIV-positive populations. This study is among the first to examine smoking prevalence, nicotine dependence, and associated factors in a large sample of HIV-positive patients receiving antiretroviral therapy (ART) in Vietnam.MethodsA cross-sectional study of 1133 HIV-positive people was conducted from January to September 2013 at 8 ART clinics in Hanoi (the capital) and Nam Dinh (a rural area). Smoking history and nicotine dependence (Fagerstrom Test of Nicotine Dependence–FTND) were assessed by participant self-report. Logistic regression and Tobit linear regression were performed to identify factors significantly associated with smoking outcomes.ResultsPrevalence of current, former, and never smokers in the sample was 36.1%, 9.5%, and 54.4%, respectively. The current smoking proportion was higher in males (59.7%) than females (2.6%). The mean FTND score was 3.6 (SD = 2.1). Males were more likely to currently smoke than females (OR = 23.4, 95% CI = 11.6–47.3). Individuals with problem drinking (OR = 1.8, 95% CI = 1.1–2.9) and ever drug use (OR = 3.7, 95%CI = 2.5–5.7) were more likely to be current smokers. Older age and currently feeling pain were associated with lower nicotine dependence. Conversely, receiving care in Nam Dinh, greater alcohol consumption, ever drug use, and a longer smoking duration were associated with greater nicotine dependence.ConclusionsGiven the high prevalence of smoking among HIV-positive patients, smoking screening and cessation support should be offered at ART clinics in Vietnam. Risk factors (i.e., substance use) linked with smoking behavior should be considered in prevention programs.     

Smoking as a weight-control strategy among adolescent girls and young women: a reconsideration

Many studies have reported that adolescent girls and young women smoke to control their weight. The majority of these studies are cross-sectional and report on correlational data from quantitative surveys. This article presents data from ethnographic interviews with 60 smokers, interviewed in high school and in follow-up interviews at age 21. Contrary to previous research, this study found little evidence for the sustained use of smoking as a weight-control strategy. In high school, smokers were no more likely than nonsmokers to be trying to lose weight. In the follow-up study, 85 percent of informants replied that they had never smoked as a way to control their weight. One-half of informants at age 21 believed that smoking as a weight-control strategy would be ineffective, while the other one-half had no idea whether it would work or not. Researchers need to exert caution in propagating the idea that smoking is commonly used as a conscious and sustained weight-control strategy among adolescent females and young women.     

Recurrent dieting and smoking among Finnish men and women

Objective: To examine the association of smoking with recurrent dieting and BMI among Finnish adults. Research Methods and Procedures: We used questionnaire data from 1990 on 11,055 subjects from the Finnish Twin Cohort who were 33 to 61 years of age. Multinomial logistic regression analysis was carried out using lifetime dieting as the outcome variable and smoking as the main explanatory variable, adjusted for BMI and age. Twin pairs discordant for dieting and smoking were studied to examine the effect of environmental and genetic factors. Results: Among women, current smokers [odds ratio (OR), 1.09 to 1.41 at different ages] and former smokers (OR, 1.52 to 2.82) were more likely to have dieted recurrently than never smokers. Among men, current smokers were less likely (OR, 0.69; 95% confidence interval, 0.55, 0.87) and former smokers were more likely (OR, 1.30; 95% confidence interval, 1.05, 1.61) to have dieted recurrently at different ages. The differences between the discordant pairs were consistent with this, although not statistically significant. Discussion: Recurrent dieting was associated with former smoking in both sexes and with current smoking in women.     

Maternal and infant demographics and health status: a comparison of black, Caucasian, and Hispanic families

The relationships among ethnicity, demographics, smoking and drinking habits, and maternal and infant health were examined in a sample of 171 low-income and low-risk Black, Caucasian, and Hispanic families. Few ethnic differences in the health status of the mothers and their infants emerged when ethnic differences were directly examined; however, a latent variable analysis indicated that ethnicity was related to smoking and drinking habits such that Caucasian mothers were more likely to smoke and drink. Smoking and drinking, in turn, led to smaller infant size at birth. Demographic differences found in level of income, education, and family composition suggest that low-income families are not necessarily homogeneous.     

Risk Factors for Colorectal Cancer in Patients with Multiple Serrated Polyps: A Cross-Sectional Case Series from Genetics Clinics

Background

Patients with multiple serrated polyps are at an increased risk for developing colorectal cancer (CRC). Recent reports have linked cigarette smoking with the subset of CRC that develops from serrated polyps. The aim of this work therefore was to investigate the association between smoking and the risk of CRC in high-risk genetics clinic patients presenting with multiple serrated polyps.

Methods and Findings

We identified 151 Caucasian individuals with multiple serrated polyps including at least 5 outside the rectum, and classified patients into non-smokers, current or former smokers at the time of initial diagnosis of polyposis. Cases were individuals with multiple serrated polyps who presented with CRC. Controls were individuals with multiple serrated polyps and no CRC. Multivariate logistic regression was performed to estimate associations between smoking and CRC with adjustment for age at first presentation, sex and co-existing traditional adenomas, a feature that has been consistently linked with CRC risk in patients with multiple serrated polyps. CRC was present in 56 (37%) individuals at presentation. Patients with at least one adenoma were 4 times more likely to present with CRC compared with patients without adenomas (OR = 4.09; 95%CI 1.27 to 13.14; P = 0.02). For females, the odds of CRC decreased by 90% in current smokers as compared to never smokers (OR = 0.10; 95%CI 0.02 to 0.47; P = 0.004) after adjusting for age and adenomas. For males, there was no relationship between current smoking and CRC. There was no statistical evidence of an association between former smoking and CRC for both sexes.

Conclusion

A decreased odds for CRC was identified in females with multiple serrated polyps who currently smoke, independent of age and the presence of a traditional adenoma. Investigations into the biological basis for these observations could lead to non-smoking-related therapies being developed to decrease the risk of CRC and colectomy in these patients.     

Maternal smoking in pregnancy and sex differences in perinatal death between boys and girls

The sex difference in perinatal mortality in developed countries is largely unexplained. The current study evaluated the differences in the impact of maternal smoking during pregnancy on the risk of perinatal death between males and females. The analysis involved 11,469 and 9,404 newborns derived from two population-based birth cohorts in Northern Finland, for 1966 and 1985-86, respectively. The perinatal mortality rate was 23 per thousand in the 1966 cohort and 9 per thousand in the 1985-86 cohort. The rate ratio (RR) for mortality for males over females is 1.15 and 1.60 in the two cohorts, respectively. Among children whose mothers smoked during pregnancy, the RR was 2.2 (95% CI 1.0, 4.7) for the former cohort and 4.8 (95% CI 1.5, 15.2) for the later cohort; and among the children whose mothers did not smoke the corresponding RR was 1.2 (95% CI 0.9, 1.6) and 1.1 (95% CI 0.6, 1.9). Maternal smoking during pregnancy could be an important determinant accounting for the excess perinatal death for males over females. Our results encourage evaluation of the findings among other populations.     

Twin concordance for a binary trait. II. Nested analysis of ever-smoking and ex-smoking traits and unnested analysis of a "committed-smoking" trait

Twin concordance rates for a binary trait can provide information about causes of trait variation. However, if trait prevalence varies with age (or birth cohort) or between the sexes, trait concordance rates will be artificially inflated because of the matching within pairs of twins. Our previous paper showed how to minimize the effects of such confounding by using logistic regression to model trait prevalence as a function of age and sex and that the binary correlation coefficient was useful as a measure of concordance that can be adjusted for trait prevalence. This method is extended here to allow for nested analyses and is applied to the smoking habits of a sample of 3,807 pairs of adult twins. For monozygotic (MZ) twins, the correlation coefficients for the binary trait of "ever-smoking" (males: .50 +/- .04; females: .60 +/- .02) were significantly greater than for dizygotic (DZ) twins (males: .37 +/- .05; females: .31 +/- .04; unlike-sex pairs: .21 +/- .03). For "giving-up smoking," given that both twins were previously smokers, the correlations for MZ twins (males: .37 +/- .07; females: .29 +/- .05) were also greater than for DZ twins (males: .11 +/- .09; females: .26 +/- .08; unlike-sex pairs: .13 +/- .06), although the difference was not statistically significant for females. Current smokers who had been smoking for at least 10 years were arbitrarily defined as "committed-smokers." The binary trait of "committed-smoking" was more strongly correlated in MZ twins (males: .41 +/- .06; females: .41 +/- .04) than in DZ twins (males: .22 +/- .08; females: .18 +/- .05; unlike-sex pairs: .16 +/- .05). These observations suggest that as well as depending on socially determined environmental factors, smoking behavior is influenced by genetic factors and/or by environmental factors unique to the MZ twin environment, which are of particular importance as determinants of "committed-smoking." There is a need for further research to investigate the personal characteristics of "committed-smokers" and to seek intervention strategies that are more suited to the needs of individual smokers.     

A comparison of the demographic,lifestyle, and sexual behaviour characteristics of virgin and non-virgin adolescents

Demographic, life-style, and sexual behavior characteristics of a random cluster sample of virgin (n = 605) and nonvirgin (n = 321) students recruited from three high schools in Toronto, Ontario (Canada) in 1994 were compared. The mean age at first intercourse among nonvirgins was 13.76 years for males and 14.8 years for females. 19% of virgins reported engaging in noncoital sexual behavior. 74% of virgin males and 89% of virgin females did not expect to have sexual intercourse in the next 12 months. The following sociodemographic variables were significantly associated with being a virgin: being in grades 9-11, female gender, Asian ethnicity, attendance at a religious school, and doing 14 or more hours of homework a week. In terms of life-style factors, nonvirgins were significantly more likely than virgins to have been involved in a serious relationship in the past year, to have engaged in masturbation of or by a partner, to report oral sex, to do 5 hours or less of homework a week, to drink heavily, drink and drive, and smoke daily. There were no significant differences between groups in terms of their levels of happiness and satisfaction with life. Overall, these findings indicate that sexual intercourse while in high school forms part of a life-style characterized by high-risk behaviors.     

Water-pipe smoking and metabolic syndrome: a population-based study

Water-pipe (WP) smoking has significantly increased in the last decade worldwide. Compelling evidence suggests that the toxicants in WP smoke are similar to that of cigarette smoke. The WP smoking in a single session could have acute harmful health effects even worse than cigarette smoking. However, there is no evidence as such on long term WP smoking and its impact on chronic health conditions particularly cardiovascular and metabolic conditions. Therefore, we conducted this study to investigate the relationship between WP smoking and metabolic syndrome (MetS). This was a cross-sectional study carried out in Punjab province of Pakistan using the baseline data of a population-based study - Urban Rural Chronic Diseases Study (URCDS). Information was collected by trained nurses regarding the socio-demographic profile, lifestyle factors including WP smoking, current and past illnesses. A blood sample was obtained for measurement of complete blood count, lipid profile and fasting glucose level. MetS was ascertained by using the International Diabetic Federation's criteria. We carried out multiple logistic regressions to investigate the association between WP smoking and MetS. Final sample included 2,032 individuals - of those 325 (16.0%) were current WP smokers. Age adjusted-prevalence of MetS was significantly higher among current WP smokers (33.1%) compared with non-smokers (14.8%). Water-pipe smokers were three times more likely to have MetS (OR 3.21, 95% CI 2.38-4.33) compared with non-smokers after adjustment for age, sex and social class. WP smokers were significantly more likely to have hypertriglyceridemia (OR 1.63, 95% CI 1.25-2.10), hyperglycaemia (OR 1.82, 95% CI 1.37-2.41), Hypertension (OR 1.95, 95% CI 1.51-2.51) and abdominal obesity (OR 1.93, 95% CI 1.52-2.45). However, there were no significant differences in HDL level between WP smokers and non-smokers. This study suggests that WP smoking has a significant positive (harmful) relationship with MetS and its components.     

Study of smoking habits in hospital and attitudes of medical staff towards smoking.

Most hospital policies place little or no restriction on patients'' smoking in hospital. In this study patients were surveyed to determine if they smoked and if their doctors advised or ordered them to stop smoking in hospital. As well, the smoking habits and attitudes towards smoking of the medical staff and other hospital workers were explored. Of 741 patients 37% were smokers, and those who responded fully to a questionnaire 86% continued to smoke in hospital. Patients who were advised or ordered not to smoke (59%) were no more likely to stop smoking than those who were not so advised or ordered. Physicians were less likely to smoke than other hospital staff, and those who did smoke were much more likely not to smoke while in the hospital. Physicians appear to have a reasonable appreciation of the health hazards of smoking, and almost two thirds are in favour of stricter restrictions on patients'' smoking in hospital. The ineffectiveness of their efforts is primarily due to hospital policies that are not in keeping with physicians'' standards of practice and with established knowledge of the deleterious effects of smoking on health.     

Smoking habits and cadmium intake in Turkey

Tobacco was estimated to account over 4 million annual deaths in 1998 and deaths attributable to tobacco usage will rise to 8.4 million in 2020 (http://tobacco.who.int/en/advocacy/wntdzoola.html.) In Turkey, 74% of the males and 29% of the females are smoking, and each year, 150,000 deaths are associated with cigaret smoking. There are 4700 chemical compounds in cigaret smoke, including 43 carcinogens. Cadmium (Cd) is only one of these harmful chemicals in the cigaret. The level of cadmium in whole blood is a reliable index of extent of recent metal uptake. In this study, cadmium concentrations in fasting whole-blood samples, from 119 healthy subjects (58 males and 61 females), ranging in age from 17 to 77 yr, who were not occupationally exposed to cadmium were measured by graphite furnace atomic absorption spectrometry, which is the most widely used technique for the measurement of cadmium concentrations in the whole blood. The blood cadmium concentration of nonsmokers, ex-smokers, and smokers were compared. The blood cadmium concentration of female smokers were found to be highest (mean: 2.62±0.72; median: 0.90 ng/mL Cd) and that of nonsmokers lowest (mean: 0.67±0.57; median: 0.44 ng/mL Cd). For smokers, an analysis of smoking history exhibited significant correlations between the number of daily cigarets smoked and the blood cadmium concentration (r=0.54, p=0.001) and years of smoking and blood cadmium concentration (r=0.51, p<0.001). Cadmium intake from cigaret smoking was found to be higher that the intake from air and diet.     

Reducing harm from tobacco smoke exposure during pregnancy

In addition to the health risks that maternal tobacco smoke exposure in pregnancy poses to women, this is a cause of substantial fetal morbidity and mortality. In pregnancy, maternal tobacco smoke exposure can arise because women either smoke or are passively exposed to environmental tobacco smoke as a consequence of other's smoking. This article discusses the scope for clinicians to help reduce both types of tobacco smoke exposure in pregnancy, with a specific focus on available and effective interventions for smoking cessation by pregnant women. Behavioral support with smoking cessation is the only intervention that has been proven to encourage smoking cessation in pregnancy and reduces smoking rates in late pregnancy by 6 to 7%. There are physiological reasons to suspect that nicotine replacement therapy (NRT) will be less or (in)effective for smoking cessation in pregnancy when compared with its use by nonpregnant smokers. However, there are also strong theoretical reasons to suspect that NRT is likely to be safer than continued smoking in pregnancy. Consequently, this article reviews evidence for the safety and effectiveness of NRT when used for smoking cessation in pregnancy and recommendations concerning the use of NRT in pregnancy are presented.     

Maternal smoking in pregnancy and sex differences in perinatal death between boys and girls

Abstract

The sex difference in perinatal mortality in developed countries is largely unexplained. The current study evaluated the differences in the impact of maternal smoking during pregnancy on the risk of perinatal death between males and females. The analysis involved 11,469 and 9,404 newborns derived from two population‐based birth cohorts in Northern Finland, for 1966 and 1985–86, respectively. The perinatal mortality rate was 23 per thousand in the 1966 cohort and 9 per thousand in the 1985–86 cohort. The rate ratio (RR) for mortality for males over females is 1.15 and 1.60 in the two cohorts, respectively. Among children whose mothers smoked during pregnancy, the RR was 2.2 (95% CI 1.0, 4.7) for the former cohort and 4.8 (95% CI 1.5, 15.2) for the later cohort; and among the children whose mothers did not smoke the corresponding RR was 1.2 (95% CI 0.9, 1.6) and 1.1 (95% CI 0.6, 1.9). Maternal smoking during pregnancy could be an important determinant accounting for the excess perinatal death for males over females. Our results encourage evaluation of the findings among other populations.     

Systematic review of the epidemiological evidence comparing lung cancer risk in smokers of mentholated and unmentholated cigarettes

Background

US mentholated cigarette sales have increased considerably over 50 years. Preference for mentholated cigarettes is markedly higher in Black people. While menthol itself is not genotoxic or carcinogenic, its acute respiratory effects might affect inhalation of cigarette smoke. This possibility seems consistent with the higher lung cancer risk in Black men, despite Black people smoking less and starting smoking later than White people. Despite experimental data suggesting similar carcinogenicity of mentholated and non-mentholated cigarettes, the lack of convincing evidence that mentholation increases puffing, inhalation or smoke uptake, and the similarity of lung cancer rates in Black and White females, a review of cigarette mentholation and lung cancer is timely given current regulatory interest in the topic.

Methods

Epidemiological studies comparing lung cancer risk in mentholated and non-mentholated cigarette smokers were identified from MedLine and other sources. Study details were extracted and strengths and weaknesses assessed. Relative risk estimates were extracted, or derived, for ever mentholated use and for long-term use, overall and by gender, race, and current/ever smoking, and meta-analyses conducted.

Results

Eight generally good quality studies were identified, with valid cases and controls, and appropriate adjustment for age, gender, race and smoking. The studies afforded good power to detect possible effects. However, only one study presented results by histological type, none adjusted for occupation or diet, and some provided no results by length of mentholated cigarette use. The data do not suggest any effect of mentholation on lung cancer risk. Adjusted relative risk estimates for ever use vary from 0.81 to 1.12, giving a combined estimate of 0.93 (95% confidence interval 0.84-1.02, n = 8), with no increase in males (1.01, 0.84-1.22, n = 5), females (0.80, 0.67-0.95, n = 5), White people (0.87, 0.75-1.03, n = 4) or Black people (0.90, 0.73-1.10, n = 4). Estimates for current and ever smokers are similar. The combined estimate for long-term use (0.95, 0.80-1.13, n = 4) again suggests no effect of mentholation.

Conclusion

Higher lung cancer rates in Black males cannot be due to their greater preference for mentholated cigarettes. While some study weaknesses exist, the epidemiological evidence is consistent with mentholation having no effect on the lung carcinogenicity of cigarettes.     

Environmental tobacco smoke and tobacco related mortality in a prospective study of Californians, 1960-98

Objective To measure the relation between environmental tobacco smoke, as estimated by smoking in spouses, and long term mortality from tobacco related disease.Design Prospective cohort study covering 39 years.Setting Adult population of California, United States.Participants 118 094 adults enrolled in late 1959 in the American Cancer Society cancer prevention study (CPS I), who were followed until 1998. Particular focus is on the 35 561 never smokers who had a spouse in the study with known smoking habits.Main outcome measures Relative risks and 95% confidence intervals for deaths from coronary heart disease, lung cancer, and chronic obstructive pulmonary disease related to smoking in spouses and active cigarette smoking.Results For participants followed from 1960 until 1998 the age adjusted relative risk (95% confidence interval) for never smokers married to ever smokers compared with never smokers married to never smokers was 0.94 (0.85 to 1.05) for coronary heart disease, 0.75 (0.42 to 1.35) for lung cancer, and 1.27 (0.78 to 2.08) for chronic obstructive pulmonary disease among 9619 men, and 1.01 (0.94 to 1.08), 0.99 (0.72 to 1.37), and 1.13 (0.80 to 1.58), respectively, among 25 942 women. No significant associations were found for current or former exposure to environmental tobacco smoke before or after adjusting for seven confounders and before or after excluding participants with pre-existing disease. No significant associations were found during the shorter follow up periods of 1960-5, 1966-72, 1973-85, and 1973-98.Conclusions The results do not support a causal relation between environmental tobacco smoke and tobacco related mortality, although they do not rule out a small effect. The association between exposure to environmental tobacco smoke and coronary heart disease and lung cancer may be considerably weaker than generally believed.     

Prospective study of effect of switching from cigarettes to pipes or cigars on mortality from three smoking related diseases.

OBJECTIVE: To estimate the extent to which cigarette smokers who switch to cigars or pipes alter their risk of dying of three-smoking related diseases-lung cancer, ischaemic heart disease, and chronic obstructive lung disease. DESIGN: A prospective study of 21520 men aged 35-64 years when recruited in 1975-82 with detailed history of smoking and measurement of carboxyhaemoglobin. MAIN OUTCOME MEASURES: Notification of deaths (to 1993) classified by cause. RESULTS: Pipe and cigar smokers who had switched from cigarettes over 20 years before entry to the study smoked less tobacco than cigarette smokers (8.1 g/day v 20 g/day), but they had the same consumption as pipe and cigar smokers who had never smoked cigarettes (8.1 g) and had higher carboxyhaemoglobin saturations (1.2% v 1.0%, P < 0.001), indicating that they inhaled tobacco smoke to a greater extent. They had a 51% higher risk of dying of the three smoking related diseases than pipe or cigar smokers who had never smoked cigarettes (relative risk 1.51; 95% confidence interval 0.96 to 2.38), a 68% higher risk than lifelong non-smokers (1.68; 1.16 to 2.45), a 57% higher risk than former cigarette smokers who gave up smoking over 20 years before entry (1.57; 1.04 to 2.38), and a 46% lower risk than continuing cigarette smokers (0.54; 0.38 to 0.77). CONCLUSION: Cigarette smokers who have difficulty in giving up smoking altogether are better off changing to cigars or pipes than continuing to smoke cigarettes. Much of the effect is due to the reduction in the quantity of tobacco smoked, and some is due to inhaling less. Men who switch do not, however, achieve the lower risk of pipe and cigar smokers who have never smoked cigarettes. All pipe and cigar smokers have a greater risk of lung cancer than lifelong non-smokers or former smokers.