Passive smoking and lung cancer: current evidence and ongoing studies at the International Agency for Research on Cancer

Meta-Analysis and Systematic Review in Environmental Tobacco Smoke Risk of Female Lung Cancer by Research Type

More than 50% of women worldwide are exposed to Environmental Tobacco Smoke (ETS). The impact of ETS on lung cancer remains unclear. Cohort studies since the late 1990s have provided new evidence of female lung cancer risk due to ETS. The objective of this meta-analysis and systematic review was to analyze the association of ETS with female lung cancer risk from 1997 to 2017, organised based on research design. According to our applied inclusion and exclusion criteria, 41 published studies were included. The relative risk (RR) from the cohort studies or odds ratio (OR) from case-control studies were extracted to calculate the pooled risks based on the type of study. The summary risks of ETS were further explored with the modulators of ETS exposure sources and doses. The pooled risks of lung cancer in non-smoking women exposed to ETS were 1.35 (95% CI: 1.17⁻1.56), 1.17 (95% CI: 0.94⁻1.44), and 1.33 (95% CI: 1.17⁻1.51) for case-control studies, cohort studies, and both types of studies, respectively. The summary RR estimate of the cohort studies was not statistically significant, but the RR increased with increasing doses of ETS exposure (p trend < 0.05). Based on the results of this study, ETS might be an important risk factor of female lung cancer in non-smokers.

Quantification of ETS exposure in hospitality workers who have never smoked

BACKGROUND

Environmental Tobacco Smoke (ETS) was classified as human carcinogen (K1) by the German Research Council in 1998. According to epidemiological studies, the relative risk especially for lung cancer might be twice as high in persons who have never smoked but who are in the highest exposure category, for example hospitality workers. In order to implement these results in the German regulations on occupational illnesses, a valid method is needed to retrospectively assess the cumulative ETS exposure in the hospitality environment.

METHODS

A literature-based review was carried out to locate a method that can be used for the German hospitality sector. Studies assessing ETS exposure using biological markers (for example urinary cotinine, DNA adducts) or questionnaires were excluded. Biological markers are not considered relevant as they assess exposure only over the last hours, weeks or months. Self-reported exposure based on questionnaires also does not seem adequate for medico-legal purposes. Therefore, retrospective exposure assessment should be based on mathematical models to approximate past exposure.

RESULTS

For this purpose a validated model developed by Repace and Lowrey was considered appropriate. It offers the possibility of retrospectively assessing exposure with existing parameters (such as environmental dimensions, average number of smokers, ventilation characteristics and duration of exposure). The relative risk of lung cancer can then be estimated based on the individual cumulative exposure of the worker.

CONCLUSION

In conclusion, having adapted it to the German hospitality sector, an existing mathematical model appears to be capable of approximating the cumulative exposure. However, the level of uncertainty of these approximations has to be taken into account, especially for diseases with a long latency period such as lung cancer.

Lung cancer in never smokers: clinical epidemiology and environmental risk factors

More than 161,000 lung cancer deaths are projected to occur in the United States in 2008. Of these, an estimated 10 to 15% will be caused by factors other than active smoking, corresponding to 16,000 to 24,000 deaths annually. Thus lung cancer in never smokers would rank among the most common causes of cancer mortality in the United States if considered as a separate category. Slightly more than half of the lung cancers caused by factors other than active smoking occur in never smokers. As summarized in the accompanying article, lung cancers that occur in never smokers differ from those that occur in smokers in their molecular profile and response to targeted therapy. These recent laboratory and clinical observations highlight the importance of defining the genetic and environmental factors responsible for the development of lung cancer in never smokers. This article summarizes available data on the clinical epidemiology of lung cancer in never smokers, and several environmental risk factors that population-based research has implicated in the etiology of these cancers. Primary factors closely tied to lung cancer in never smokers include exposure to known and suspected carcinogens including radon, second-hand tobacco smoke, and other indoor air pollutants. Several other exposures have been implicated. However, a large fraction of lung cancers occurring in never smokers cannot be definitively associated with established environmental risk factors, highlighting the need for additional epidemiologic research in this area.

Meta-analysis of studies of passive smoking and lung cancer: effects of study type and continent

BACKGROUND

To calculate a pooled estimate of relative risk (RR) of lung cancer associated with exposure to passive smoking in never smoking women exposed to smoking spouses. This study is an updated meta-analysis that also assesses the differences between estimated risks according to continent and study type using meta-regression.

METHODS

From a total of 101 primary studies, 55 studies are included in this meta-analysis, of which, 7 are cohort studies, 25 population-based case-control and 23 non-population-based case-control studies. Twenty previously published meta-analyses are also reviewed. Fixed and random effect models and meta-regression are used to obtain pooled estimates of RR and P-value functions are used to demonstrate consistency of results.

RESULTS

The pooled RR for never-smoking women exposed to passive smoking from spouses is 1.27 (95% CI 1.17-1.37). The RR for North America is 1.15 (95% CI 1.03-1.28), Asia, 1.31 (95% CI 1.16-1.48) and Europe, 1.31 (1.24-1.52). Sequential cumulative meta-analysis shows no trend. There is no strong evidence of publication bias.

CONCLUSIONS

The abundance of evidence, consistency of finding across continent and study type, dose-response relationship and biological plausibility, overwhelmingly support the existence of a causal relationship between passive smoking and lung cancer.

Passive smoking and lung cancer: a cumulative meta-analysis

OBJECTIVE

To review the epidemiological evidence for the association between passive smoking and lung cancer.

METHOD

Primary studies and meta-analyses examining the relationship between passive smoking and lung cancer were identified through a computerised literature search of Medline and Embase, secondary references, and experts in the field of passive smoking. Primary studies meeting the inclusion criteria were meta-analysed.

RESULTS

From 1981 to the end of 1999 there have been 76 primary epidemiological studies of passive smoking and lung cancer, and 20 meta-analyses. There were 43 primary studies that met the inclusion criteria for this meta-analysis; more studies than previous assessments. The pooled relative risk (RR) for never-smoking women exposed to environmental tobacco smoke (ETS) from spouses, compared with unexposed never-smoking women was 1.29 (95% CI 1.17-1.43). Sequential cumulative meta-analysed results for each year from 1981 were calculated: since 1992 the RR has been greater than 1.25. For Western industrialised countries the RR for never-smoking women exposed to ETS compared with unexposed never-smoking women, was 1.21 (95% CI 1.10-1.33). Previously published international spousal meta-analyses have all produced statistically significant RRs greater than 1.17.

CONCLUSIONS

The abundance of evidence in this paper, and the consistency of findings across domestic and workplace primary studies, dosimetric extrapolations and meta-analyses, clearly indicates that non-smokers exposed to ETS are at increased risk of lung cancer.

IMPLICATIONS

The recommended public health policy is for a total ban on smoking in enclosed public places and work sites.

Genetic analysis of families with nonsmoking lung cancer probands

As part of a genetic epidemiologic study of lung cancer among nonsmokers, we investigated the role of genetic predisposition in familial aggregation. Cases were identified from the Metropolitan Detroit Cancer Surveillance System. Information on lung cancer occurrence, smoking habits (active or passive), and chronic respiratory diseases in first-degree relatives was obtained for 257 nonsmoking lung cancer probands (71 males, 186 females) diagnosed at ages 40-84 years. Among the 2,021 first-degree relatives, 24 (2.6%) males and 10 (1.1%) females were reported as having lung cancer. The occurrence of lung cancer among smoking and nonsmoking relatives was 4.5% and 1.1% in males and 2.8% and 0.4% in females, respectively. To evaluate the role of a putative Mendelian gene (one locus, two alleles) in the presence of other risk factors, we performed complex segregation analyses on the data using two different regressive model approaches [Segregation Analysis of a Discrete Trait Under a Class A Regressive Logistic Model, V4.0 (REGD) and Segregation Analysis of a Truncated Trait, V2.0, Model 1(REGTL)] as implemented in the Statistical Analysis for Genetic Epidemiology (SAGE) program. Using either approach, an environmental model best explained the observed lung cancer aggregation in families ascertained through nonsmoking probands. Based on our final model, only 0.04% of this population had a very high risk and 4.2% had a moderate risk of lung cancer. The rest of the population had virtually no risk of lung cancer during their lifetime unless they have multiple risk factors. Among the high-risk individuals without any risk factor under study, the estimated risks at ages 40, 60, and 80 years in males were 16.7%, 83.6%, and 95.4%, and in females were 14.0%, 72.2%, and 88.0%, respectively. Among at-moderate-risk smokers the estimated risks at the same age and gender groups were essentially the same as in the high-risk nonsmokers. Our results suggest that the pattern of lung cancer occurrence in families of nonsmoking lung cancer patients differs from that in families of smoking lung cancer patients. Despite the profound effect of smoking on the risk of lung cancer, other environmental and/or genetic risk factors need to be identified.

Exposure to environmental tobacco smoke and risk of lung cancer in non-smoking women from Moscow, Russia

The association between exposure to ETS and the risk of lung cancer in life-time non-smoking women was investigated by means of a hospital based case-control study in Moscow, Russia. The main importance of our study is that it was conducted on a population with a specific smoking pattern from which no information is available on health effects of ETS. A total of 189 incident cases of histologically confirmed lung cancer were identified in 2 principal cancer treatment hospitals in Moscow. A total of 358 female oncology patients from the same hospitals were selected as controls. The controls matched by the hospitals to the cases were similarly restricted to never-smokers. Women diagnosed with cancer of the upper respiratory organs were ineligible for selection as controls. Personal interviews of cases and controls were conducted in the hospital wards, using a closed-form structured questionnaire. An elevated risk of lung cancer was observed in women whose husbands smoked. The odds ratio (OR) adjusted by age and education for husband's smoking was 1.53 (95% CI, 1.06-2.21). Smoking by other members of the family, by colleague's, or by fathers in the women's childhood do not affect the risk of lung cancer. The risk is higher for women whose husbands smoke "papirosy" (OR 2.12; 95% CI, 1.32-3.40), a special Russian type of cigarettes with a long mouthpiece, and usually very high levels of tar (> 30 mg/cig) and nicotine (> 1.8 mg/cig). Our study suggests that the association between exposure to ETS of the spouse and risk of lung cancer in non-smoking women is somewhat stronger for squamous-cell carcinoma (OR, 1.94; 95% CI, 0.99-3.81) than for adenocarcinoma (OR, 1.52; 95% CI, 0.96-2.39).

Epithelial, possibly precancerous, lesions of the lung in relation to smoking, passive smoking, and socio-demographic variables

We have undertaken an autopsy-based study to evaluate the etiologic importance of active and passive smoking, as well as socio-demographic variables, in the development of pathologic precursors of lung cancer. Lung specimens were taken at autopsy from 531 persons who had died within four hours from a cause other than respiratory or cancer in Athens (Greece) or the surrounding area. Specimens were examined blindly for basal cell hyperplasia, squamous cell metaplasia, cell atypia and mucous cell metaplasia, i.e., pathological entities considered as epithelial, possibly precancerous, lesions (EPPL). Interviews were conducted with next of kin of the deceased. Suitable autopsy specimens as well as completed interviews were eventually available for 275 subjects. EPPL score was regressed on the available independent variables. EPPL score was higher among active smokers than among nonsmokers, while ex-smokers occupied an intermediate position. Conditional on smoking habits, EPPL score was higher among women than among men and higher among manual than among non-manual workers, in agreement with the corresponding patterns with respect to lung cancer. Nonsmoking women married to ever smokers had significantly higher EPPL score than those married to never smokers. The overall findings of this study suggest that EPPL is a valuable indicator of lung cancer risk and that exposure to environmental tobacco smoke is associated with higher EPPL levels and therefore with higher lung cancer risk.

The epidemiology of lung cancer: review of risk factors and Spanish data

Lung cancer is the main form of cancer among men both in Spain and in the rest of europe. However, Spanish incidence rates are among the lowest of the European registries, especially for women. In this country, lung cancer mortality increased much more rapidly for men than for women between the fifties and the eighties. This increase was larger for lung cancer than for any other site. The trend of incidence, in Spain as well as in the greatest part of the world, is entirely explained by tobacco consumption, which remains the major risk factor for lung cancer. Occupational radon and asbestos exposures are other important but less extended determinants of lung cancer. Genetic factors could also play a role in the occurrence of the disease. On the other side, a high consumption of fruit and vegetables is protective, but, so far, no single dietary component has been found to be preventive. In this article, we review the major risk factors of lung cancer with an emphasis on Spanish and European data.

At least one in seven cases of cancer is caused by smoking. Global estimates for 1985

Tobacco smoking is accepted as a major cause of cancers of the lung, larynx, oral cavity and pharynx, oesophagus, pancreas, kidney and bladder. The proportions of these cancers that are due to smoking were estimated for the year 1985 for 24 areas of the world. Fifteen percent--1.1 million new cases per year--of all cancer cases are attributed to cigarette smoking, 25% in men and 4% in women. In developed countries, the tobacco burden is estimated at 16% of all annual incident cases. In developing countries, the corresponding figure is 10%. In total, 85% of the 676,000 cases of lung cancer in men are attributable to tobacco smoking. The highest attributable fractions (AF: 90-93%) are estimated in areas where the habit of cigarette smoking in men has been longest established: North America, Europe, Australia/New Zealand and the former USSR. Among the other 6 cancer sites considered in this analysis, those with the largest fractions of tobacco-related cases are the larynx, mouth and pharynx (excluding nasopharynx) and oesophagus. In regions where males have smoked for several decades, 30 to 40% of all cancers in this sex are attributable to tobacco. Unless tobacco-control efforts in developing countries are strengthened, the massive rise in cigarette consumption over the last few decades will produce a comparable rise in cancer in these countries within the next 20 to 30 years.

Indices of morbidity and control of asthma in adult patients exposed to environmental tobacco smoke

The study was undertaken to compare the indices of morbidity and control of asthma in 100 adult patients exposed to environmental tobacco smoke (ETS) inhalation (group 2), with 100 asthmatics not exposed (group 1). Exposure was established from the history of smoking by the patient's spouse and other close contacts. Asthma control and morbidity were assessed during their follow-up visits in the chest outpatient clinic by inquiring into the emergency department (ED) visits, hospitalization, acute episodes, requirement of parenteral drugs at home, corticosteroids, and maintenance bronchodilators in the preceding 1-year period. Index per patient was also calculated. Lung function was recorded by the measurement of forced expiratory flows on the same day of the follow-up visit. The mean age and disease duration were comparable, but the expiratory flows were lower in the patients exposed to ETS. More patients in group 2 required daily bronchodilators (66 percent) and intermittent corticosteroids (56 percent). The number of ED visits, acute episodes, and parenteral bronchodilators per patient were significantly more (p < 0.01) in group 2 patients. Similarly, the number of weeks of absence from work and of corticosteroid requirement were more (p < 0.01) in the ETS-exposed patients. We conclude that the control of asthma is poor and morbidity greater in adult patients with asthma exposed to ETS at home and/or at work.

Cancer incidence among waitresses in Norway

Previous studies have found high risk of cancers of the upper aerogastric tract, liver, and lung among waiters. Since approximately 75 percent of those working in the restaurant business in Norway are women, we have analyzed cancer incidence in a cohort of waitresses, to determine whether they have the same high cancer-risk as their male colleagues. The cohort consisted of 5,314 waitresses organized in the Restaurant Workers' Union between 1932 and 1978. The follow-up period was from 1959 to 1991. The standardized incidence ratio (SIR) for all causes of cancer was 1.0 (95 percent confidence interval [CI] = 0.9-1.1), based on 430 observed cases. Cancers of the tongue, mouth, pharynx, larynx, esophagus, and liver were grouped together as alcohol-associated cancers. SIR for these cancers combined was 1.1 (CI = 0.5-2.2). For lung cancer, SIR was 2.3 (CI = 1.6-3.1). Cervical cancer was also more frequent than expected, and breast cancer less frequent than expected. The larger excess of lung cancer and cervical cancer appeared in the sub-cohort working in restaurants with a license to serve alcohol. No excess risk of alcohol-associated cancers could be detected in this cohort of Norwegian waitresses. A longer follow-up period will be necessary to evaluate possible consequences of an increased alcohol consumption among younger waitresses. Waitresses in Norway are, like their male colleagues, at high risk for lung cancer.

Incidence of cancer among male waiters and cooks: two Norwegian cohorts

Previous occupational survey studies have identified 'waiter' and 'cook' as possible high risk occupations for cancer. However, few cohort studies have been performed among persons in the restaurant business, and we therefore have analyzed cancer incidence in two cohorts of Norwegian waiters and cooks. The cohorts consisted of skilled male workers, 1,463 waiters and 2,582 cooks, who received their craft certificate between 1958 and 1983. The cohorts were followed from 1959 through 1991. The standardized incidence ratio (SIR) for all causes of cancer was 1.4 (95 percent confidence interval [CI] = 1.2-1.7] for waiters, and 1.1 (CI = 0.9-1.4) for cooks. Cancers of the tongue, mouth, pharynx, larynx, esophagus, and liver were grouped together as alcohol-associated cancers. SIR for these cancers combined was 5.1 (CI = 3.4-7.4) for waiters and 4.2 (CI = 2.2-7.2) for cooks. For lung cancer, SIR was 2.0 (CI = 1.3-2.9) for waiters and 0.7 (CI = 0.2-1.7) for cooks. For alcohol-associated cancers, the analysis carried out according to number of years since first employment showed a larger number of cases than expected for both occupations in all time-periods. The excess of lung cancer cases among waiters appeared after 30 years or more of employment. The study shows that waiters and cooks are at high risk of cancers associated with alcohol consumption, and that waiters, in addition, show high rates for lung cancer. The hypothesis of an occupational lung-cancer risk in cooks was not supported by this study.

Environmental tobacco smoke and the risk of cancer in adults

The apparent effect of environmental tobacco smoke (ETS) exposure on cancer risk has become an important social and political issue. The risk of cancer in non-smokers is often the main reason for prohibiting or restricting smoking in public places. A number of epidemiological studies have shown an association between ETS exposure and lung cancer. However, the strength of this association has still to be estimated. Only a few studies have reported on ETS and cancer from sites other than the lung in adults. No definite conclusions can be drawn at present from a critical review of the epidemiological evidence, but the suggestion of an association is present for sinonasal cancer, while bladder cancer does not seem to be associated to ETS exposure. Positive studies are available for cancers from other sites, including the breast, the uterine cervix and the brain, but these are difficult to interpret.

Urban-rural variation in cancer incidence in Denmark 1943-1987

Urban and rural cancer incidence in Denmark in 1943-1987 was analysed. A consistent urban excess was found for all sites combined for individuals of each sex, irrespective of age at diagnosis. The capital:rural incidence ratio was 1.42 for men and 1.25 for women, and these ratios were not affected to any great extent using another definition of urban areas. Urban:rural ratios were highest for cancers of the respiratory, urinary and upper digestive tracts. The differences cannot be explained by tobacco and alcohol consumption alone. Other risk factors linked to urbanisation may contribute importantly to the "urban factor", and analytical studies of data at an individual level are required to establish their relative importance. Our findings contradict the generally accepted view that there is no urban-rural difference in cancer incidence in the relatively small, homogeneous population of Denmark.

Passive smoking and sister-chromatid exchanges in lymphocytes

The object of this study was to determine whether exposure to environmental tobacco smoke is associated with DNA damage reflected by the frequency of sister-chromatid exchange (SCE) in lymphocytes. Within a cross-sectional design, 106 male non-smoking adults, employees of two administrative companies, were divided on the basis of self-reported exposure into high and low passive smoking groups. The high exposed subjects (passive smokers, n = 50) lived with smokers, worked with smokers and were exposed to tobacco smoke for an average of 70 h/week. The low exposed non-smokers (n = 56) were exposed for an average of 5 h/week. Plasma cotinine levels for the passive smokers ranged between 0.4 and 9.0 ng/ml (median 1.4 ng/ml), and for the low exposed group between 0.0 and 1.9 ng/ml (median 0.4 ng/ml) (p less than 0.0001; Mann-Whitney test). No difference was observed between the two groups in the frequency of SCEs in lymphocytes: 4.66 +/- 0.05 for passive smokers and 4.68 +/- 0.04 for low exposed non-smokers (mean +/- SEM) (p = 0.80; t-test). Reclassification of subjects on the basis of plasma cotinine levels did not change the results substantially. These results are in accordance with observations that the increase in cancer risk due to passive smoking is small in comparison with the increase due to active smoking. The SCE test may be too insensitive to be useful for the evaluation of possible cytogenetic effects related to passive smoking.

Indoor sources of mutagenic aerosol particulate matter: smoking, cooking and incense burning

The emission of aerosol particles and their mutagenic activity as well as the emission of some gaseous pollutants has been studied experimentally in order to compare the emission from some indoor pyrolysis processes. Cigarette (tobacco and herbal) smoking, incense and mosquito-coil burning and frying of experimental lean minced pork emitted particulate matter. Their extracts were mutagenic in the Ames Salmonella test with TA98 and activation as well as, with a higher response, in a microsuspension test with the same strain and activation condition. The response of the particles from the smoking and burning processes varied from 3000 to 50,000 revertants per gram of smoked or burnt material in the conventional Salmonella test and from 50,000 to 350,000 revertants per gram in the microsuspension assay. The frying of lean minced pork gave an airborne emission of about 53 and 560 revertants per gram of fried pork, respectively, in the 2 assays. The frying of some common food items following cookbook recipes also emitted mutagenic aerosol particles but the emitted activity was less than that in the pork experiment. Carbon monoxide, isoprene and benzene were present in the emissions from the smoking and burning processes but were not detectable in the frying fumes. The results suggest that incense and mosquito-coil burning can cause indoor air pollution akin to that from cigarette smoking. Indoor air pollution from cooking requires further study.

Indoor air pollution: an edifice complex

The collision of escalating technological sophistication and surging environmental awareness has caused the reexamination of many societal paradigms. Horror stories about lethal chemical exposures involving isolated cases of ignorance, carelessness or greed have caused the public to demand constant vigilance to prevent exposure to potentially hazardous substances. Accordingly, much time and resource has been expanded by the U.S. government and citizens to abate and prevent air and water pollution. While these efforts have met with measurable success, there is increasing public concern about a new generation of pollution-related human illness in office, home and transportation environments. New instances of Sick Building Syndrome or Building Related Illness are reported daily by the popular press. Human health effects such as cancer, infectious disease, allergy and irritation have been ascribed to indoor air pollution. The clinical aspects of indoor air pollution are often discounted by consulting engineers and industrial hygienists involved in indoor air quality. Physicians and clinically-trained scientists have received a "Macedonian call" to sift clinical relevance from the emotional aspects of indoor air quality problems. Point sources of pollutants, associated human health effects, and problem solving approaches associated with indoor air pollution are described. Regulatory and litigational aspects of indoor air pollution are also discussed.

Adjusting for misselection using subsampling in epidemiological studies

In epidemiological research it is sometimes necessary to conduct a case-control study in a part of the population which is not exposed to certain risk factors. Such a study design may be useful to investigate the risk related to a weak carcinogen in presence of other strong risk factors. It may happen that some individuals are wrongly included in the study group due to misreporting of the true exposure status. This misselection may cause biased odds ratio estimates of the factors of interest. It is therefore recommended that an evaluation study to validate the selection procedure is undertaken. We propose a two-stage sample design, consisting of a case-control study and a validation study in a subsample. Misselection rates in cases and control for different exposure groups may be estimated in the subsample and used to correct the odds ratio estimation from the first stage. It is shown how the total sample size should be attributed to the case-control sample and to the second-stage sample in order to give an unbiased estimate with minimal variance. The allocation is shown to be dependent on a number of parameters which is illustrated numerically and graphically. Efficiency considerations are also addressed.

Passive smoking and diet in the etiology of lung cancer among non-smokers

A case-control study was undertaken in Athens to explore the role of passive smoking and diet in the causation of lung cancer, by histologic type, in non-smoking women. Among 160 women with lung cancer admitted to one of seven major hospitals in Greater Athens between 1987 and 1989, 154 were interviewed in person; of those interviewed, 91 were life-long non-smokers. Among 160 identified controls with fractures or other orthopedic conditions, 145 were interviewed in person; of those interviewed, 120 were life-long non-smokers. Marriage of a non-smoking woman to a smoker was associated with a relative risk for lung cancer of 2.1 (95% confidence interval [CI] 1.1-4.1); number of cigarettes smoked daily by the husband and years of exposure to husband's smoking were positively, but not significantly, related to lung cancer risk. There was no evidence of any association with exposure to smoking of other household members, and the association with exposure to passive smoking at work was small and not statistically significant. Dietary data collected through a semi-quantitative food-frequency questionnaire indicated that high consumption of fruits was inversely related to the risk of lung cancer (the relative risk between extreme quartiles was 0.27 (CI 0.10-0.74)). Neither vegetables nor any other food group had an additional protective effect; furthermore, the apparent protective effect of vegetables was not due to carotenoid vitamin A content and was only partly explained in terms of vitamin C. The associations of lung cancer risk with passive smoking and reduced fruit intake were independent and did not confound each other.(ABSTRACT TRUNCATED AT 250 WORDS)

32P-postlabelling analysis of DNA adducts in monocytes of smokers and passive smokers

In a controlled study, ten male volunteers were subjected to different smoking and passive smoking conditions. After 60 h of strictly controlled nonsmoking, five smokers were exposed to mainstream smoke only, while five nonsmokers were exposed to the gas phase of environmental tobacco smoke (ETS). In a second experiment smokers were mainstream and ETS exposed, while nonsmokers were exposed to complete ETS. Blood was drawn before and after smoking and DNA adducts were analysed from blood monocytes by the 32P-postlabelling assay, using the nuclease P1 enhancement method. We detected DNA adducts in monocytes of all probands. These adducts unrelated to smoking showed interindividual differences but only minor intraindividual changes in four samples of the same donor. After smoking interindividually variable additional adducts were visible in active smokers only. These smoking-related adducts had disappeared after 40 h of nonsmoking and reappeared again in three out of five smokers after the second smoking period. We conclude that smoking causes an interindividually variable pattern of DNA adducts in active smokers. These adducts disappear in less than 2 d, owing to the fast turnover of monocytes in the intravascular system. The effects described could not be observed in heavily exposed passive smokers.

The effect of involuntary smoking on the occurrence of chronic obstructive pulmonary disease

One hundred and three ever-married women with newly diagnosed Chronic Obstructive Pulmonary Disease (COPD), who have never smoked, and 179 ever-married women who were visiting friends or relatives at the same hospital during the same period and have never smoked, were interviewed regarding the smoking habits of their husbands. There was statistically marginally significant difference between the COPD cases and the controls with respect to their husband's smoking habits. The association was irregular with respect to daily number of cigarettes smoked but there was a smooth dose response curve with respect to life long total number of cigarettes smoked, with women whose husband smoked more than 300 thousand cigarettes having a relative risk of 1.8 (90% confidence interval of 0.9-3.6) compared to women whose husband has never smoked. These findings, and converging related evidence, indicate that exposure to environmental tobacco smoke may be a risk factor for the development of COPD.

Environmental tobacco smoke: overview of chemical composition and genotoxic components

Tobacco smoke contains numerous compounds emitted as gases and condensed tar particles. The sidestream smoke emissions, which constitute the major part of environmental tobacco smoke (ETS), are generally larger than the mainstream smoke emissions. Many of the organic compounds, belonging to a variety of chemical classes, are known to be genotoxic and carcinogenic. These include the known constituents, alkenes, nitrosamines, aromatic and heterocyclic hydrocarbons and amines. Emission of sidestream smoke in indoor environments with relatively low ventilation rates can result in pollutant concentrations above those generally encountered in ambient air in urban areas. The chemical characteristics of ETS thus support the indications that exposure to ETS can be causally associated with the induction of several types of cancer.