Risk of lung cancer among cigarette and pipe smokers in southern China

Synergy of arsenic with smoking in causing cardiovascular disease mortality: A cohort study with 27 follow-up years in China

Background

To explore the patterns of the exposure-response relationship between arsenic exposure and cardiovascular disease (CVD) mortality and investigate the effect of cigarette smoking on the association.

Methods

Seven thousand seven hundred thirty-five tin miners with at least 10 years of arsenic exposure were enrolled since 1992 and followed up for 27 years. Each individual's air arsenic exposure at workplace was calculated by time weighted average arsenic concentration × exposure months. Detailed information on smoking was collected at baseline, and information on smoking status was collected for five consecutive years from 1992 to 1996. Hazard ratio (HR) and 95% confidence interval (CI) for the risk of CVD were estimated using Cox proportional hazards models.

Results

A total of 1,046 CVD deaths occurred in this cohort over 142,287.7 person-years of follow up. We firstly reported that for equal cumulative exposure, participants exposed to higher concentrations over shorter duration had a higher risk of CVD mortality than those exposed to lower concentration over longer duration. The HR and 95% CI were 1.38 (95%CI: 1.03-1.85) in participants exposed to arsenic concentration (45.5-99.5 mg/m³), 1.29 (95%CI: 1.02-1.67) in 99.5-361.0 mg/m³. Further, participants with age at first exposure <18 years had a significantly higher risk of morality from CVD, cerebrovascular and heart diseases than those with ≥18 years. Finally, all synergy indices were greater than 1 (range, 1.11-2.39), indicating that the joint effect of arsenic exposure and cigarette smoking on CVD mortality was greater than the sum of their individual effect.

Conclusions

Exposure to air arsenic at workplace is adversely associated with mortality from CVD, especially among smokers younger than 18 years and smokers.

Quantitative evaluation of radon, tobacco use and lung cancer association in an occupational cohort with 27 follow-up years

BACKGROUND

Occupational radon cohorts provide important information about exposure at residential level, which are difficult to observe prospectively. However, evidence about radon-related lung cancer risks from initial exposure in childhood or interaction between radon and smoking is still limited.

METHODS

A total of 6017 tin miners with at least 10 years of underground radon exposure were enrolled beginning in 1992 and followed for up to 27 years. Lung cancer risks were estimated by modeling total and intensity of radon exposure.

RESULTS

A total of 933 lung cancer cases occurred in this cohort over 89,092 person-years of follow up. Excess relative risk increased by 0.96% per cumulative working level month (WLM). A unique aspect of this population was the early age at first radon exposure for workers. Results showed that lung cancer risk from initial radon exposure in childhood (<13 years old) was greater than risk when first exposure occurred at later ages (13-17, 18-24, and ≥ 25 years old). Moreover, risk declined with years since last exposure and attained age, but increased with age at last exposure. Importantly, these patterns were stable after adjustment for tobacco use or arsenic exposure. For joint effects of radon and other agents, our results support sub-multiplicative as the most likely model for interaction between radon and tobacco use or arsenic exposure.

CONCLUSION

This study highlights the possible importance of radon exposure in childhood in cancer etiology and suggests another potential strategy to mitigate the global lung cancer burden.

Exhalation of alternative tobacco product aerosols differs from cigarette smoke-and may lead to alternative health risks

BACKGROUND

Variation in alternative tobacco product (ATP) constituents, heating potential, and consumer behaviors have made it difficult to characterize their health risks. To date, most toxicity studies of ATPs have used established cigarette endpoints to inform study design. Furthermore, to assess where ATPs fall on the tobacco harm continuum, with cigarettes representing maximum potential risk, studies have tended to compare the relative biological responses to ATPs against those due to cigarettes.

OBJECTIVES

1) To characterize the exhalation profiles of two popular ATPs: electronic cigarettes (e-cigarettes) and hookah waterpipes (hookah) and 2) to determine if ATP exhalation patterns were representative of cigarette exhalation patterns.

METHODS

Exhalation patterns were recorded (mouth only, nose only, or both mouth and nose) among individuals observed in the New York City tri-state area using a recognizable tobacco product (cigarette, e-cigarette, or hookah). Cigarette smokers and e-cigarette vapers were observed on city streets; water-pipe smokers were observed inside Manhattan hookah bars.

RESULTS

E-cigarette vapers practiced exclusive nasal exhalation at far higher rates than did cigarette smokers (19.5% vs 4.9%). Among vapers, e-cigarette device type was also significantly associated with exhalation profile. Overall, cigarette smokers exhaled from their nose approximately half to one-third as often as ATP users (hookah and e-cigarettes, respectively).

CONCLUSIONS

Nasal exhalation of tobacco emissions appears to be a shared characteristic across several types of ATPs. It is therefore plausible that ATP-specific consumer behaviors may foster unique upper respiratory health consequences that have not been observed in smokers. Thus, product-specific behaviors should inform the prioritization of biological endpoints used in studies evaluating ATP toxicity and health effects.

The effects of hookah/waterpipe smoking on general health and the cardiovascular system

Hookah or waterpipe smoking or use is an emerging trend in the US population, especially among the youth. The misperception of hookah being less harmful than cigarettes and the availability of different but "appealing" flavors are considered among the main reasons for this trend. Hookah users however are exposed to many of the same toxic compounds/by-products as cigarette users, but at dramatically higher levels, which might lead to more severe negative health effects. In fact, hookah users are at risks of infections, cancers, lung disease, and other medical conditions. Moreover, because of the overlapping toxicant/chemical profile to conventional cigarettes, hookah smoke effects on the cardiovascular system are thought to be comparable to those of conventional cigarettes. A major source of tobacco addiction is nicotine, whose levels in hookah are extremely variable as they depend on the type of tobacco used. Taken together, in this review of literature, we will provide insights on the negative health effects of hookah in general, with a focus on what is known regarding its impact on the cardiovascular system.

The Effects of Dietary Supplements on Asthma and Lung Cancer Risk in Smokers and Non-Smokers: A Review of the Literature

Smoking is one of the major global causes of death. Cigarette smoke and secondhand (passive) smoke have been causally related to asthma and lung cancer. Asthma is a potential risk factor for developing lung cancer in both smokers and non-smokers. Prospective studies and randomized control trials (RCTs) of dietary supplements and lung cancer risk in adult smokers and non-smokers have yielded inconsistent results. A few prospective studies have shown that long-term use of high doses of some supplements, such as retinol, β-carotene, B vitamins, and vitamin E, increase lung cancer risk in current and former smokers. Limited evidence from RCTs suggests that vitamin D supplementation is effective in improving lung function and reducing asthma risk in current/former smokers. The relationship between dietary supplements and lung cancer risk has never before been examined in asthmatic smokers and non-smokers. This short review aims to examine the evidence from existing studies for the effects of dietary supplements on asthma/lung cancer risk and mortality in smokers and non-smokers.

Health Effects Reported by Adolescent Water Pipe and/or Cigarette Smokers Compared to Nonsmokers

PURPOSE

The purpose of this study was to determine the prevalence of respiratory and/or physical fitness health problems in adolescent (ages 18-21) water pipe (WP) smokers (with or without cigarette smoking), cigarette-only smokers, and nonsmokers.

METHODS

A comparative four-group study design was used to recruit a non-probability sample of 153 WP smokers only, 103 cigarette smokers only, and 102 cigarette+WP smokers along with 296 nonsmokers. Our hypothesis was that youth who smoked WPs and/or cigarettes would report more respiratory problems and/or poorer physical fitness than those who did not smoke.

RESULTS

The results showed that coughs were significantly associated with smoking in all three of the smoking groups (p < .05). Cigarette-only smokers reported the most adverse outcomes with more wheezing, difficulty breathing, and less ability to exercise without shortness of breath. A dose-response analysis showed similar patterns of adverse health effects for both WP and cigarette smokers. The combined use of both products was not appreciably worse than smoking one product alone. This could be due to cigarette+WP smokers' reporting using less of the respective products when only one product was smoked.

CONCLUSIONS

Even during the adolescent years, WP and/or cigarette smoking youth experienced reportable negative health effects.

The effects of waterpipe tobacco smoking on health outcomes: an updated systematic review and meta-analysis

Background and aims

A systematic review conducted in 2008 found significant associations between waterpipe tobacco smoking and lung cancer, respiratory disease, periodontal disease and low birthweight. Since then, a number of relevant studies have been published. The objective of this study was to update the systematic review on the effects of waterpipe tobacco smoking on health outcomes.

Methods

In May 2015 we electronically searched the following databases with no date restrictions: MEDLINE, EMBASE and the ISI Web of Science using a detailed search strategy with no language restrictions. We also screened the references' lists of the included studies. We included cohort, case-control and cross-sectional studies, and excluded case reports, conference abstracts, editorials and reviews. We excluded studies not conducted in humans, assessing physiological outcomes, not distinguishing waterpipe tobacco smoking from other forms of smoking or not reporting association measures. We assessed risk of bias for each included study and conducted meta-analyses for each of the outcomes of interest.

Results

We identified 50 eligible studies. We found that waterpipe tobacco smoking was significantly associated with: respiratory diseases [COPD; odds ratio (OR) = 3.18, 95% confidence interval CI = 1.25, 8.08; bronchitis OR = 2.37, 95% CI = 1.49, 3.77; passive waterpipe smoking and wheeze OR) = 1.97, 95% CI = 1.28, 3.04]; oral cancer OR = 4.17, 95% CI = 2.53, 6.89; lung cancer OR = 2.12, 95% CI = 1.32, 3.42; low birthweight (OR = 2.39, 95% CI = 1.32, 4.32); metabolic syndrome (OR 1.63-1.95, 95% CI = 1.25, 2.45); cardiovascular disease (OR = 1.67, 95% CI = 1.25, 2.24); and mental health (OR 1.30-2.4, 95% CI = 1.20, 2.80). Waterpipe tobacco smoking was not significantly associated with: oesophageal cancer (OR = 4.14, 95% CI = 0.93, 18.46); worse quality of life scores [standardized mean difference (SMD) = -0.16, 95% CI = -0.66, 0.34]; gastric carcinoma (OR = 2.16, 95% CI = 0.72, 6.47); bladder cancer (OR = 1.25, 95% CI = 0.99, 1.57); prostate cancer (OR = 7.00, 95% CI = 0.90, 56.90); hepatitis C infection (OR = 0.98, 95%0.80, 1.21); periodontal disease (OR = 3.00, 5.00); gastro-oesophageal reflux disease (OR = 1.25, 95% CI = 1.01, 1.56); nasopharyngeal carcinoma (OR = 0.49, 95% CI = 0.20, 1.23); bladder cancer (OR = 1.25, 95% CI = 0.99, 1.57); infertility (OR = 2.50, 95% CI = 1.00, 6.30); and mortality (OR = 1.15, 95% CI = 0.93, 1.43).

Conclusions

There is accumulating evidence about the association of waterpipe tobacco smoking with a growing number of health outcomes.

Assessing the Effect of Waterpipe Smoking on Cancer Outcome - a Systematic Review of Current Evidence

Background: Waterpipe smoking (WPS) is widely believed to be a safe and hazard-free tobacco habit. However, a number of studies have indicated that exposure to several toxicants and carcinogens through WPS is strongly related to serious health hazards. The current paper presents a narrative review on the effects of WPS on cancer outcome. Methods: The addressed focused question was “Is there an association between waterpipe smoking and cancer outcome?” PubMed, Medline, EMBASE, ISI Web of Science and the Cochrane databases were searched until June 2015 using the key words “Waterpipe”, “Hookah”, “Narghileh”, “Shisha”, “Hubbly Bubbly” “cancer” in various combinations. Letters to the Editor, review articles, case-reports and unpublished articles were excluded. Results: A total of 16 studies were included: six on lung cancer, three on oesophageal cancer, two on gastric cancer, two on bladder cancer, and one each on nasopharyngeal, pancreatic and prostate cancers. Our search did not yield any study that evaluated the risk of oral cancer in WPS users. The available evidence showed a significant association of WPS with lung cancer (UOR 6.0, 95% CI 1.78–20.26); however, no association was observed with bladder, nasopharyngeal, pancreatic and prostate cancers. Gastric (OR 3.4, 95% CI 1.7-7.1) and oesophageal cancers (OR 1.85, 95% CI 1.41-2.44) were observed to have weak associations with WPS. Conclusion: Regardless of the limitations, there is sufficient evidence to suggest associations of WPS with cancer, particularly in the lung. Future well-designed studies are required to identify and quantify with confidence all the health effects of this form of smoking.

Cancer risk in waterpipe smokers: a meta-analysis

Objectives

To quantify by meta-analysis the relationship between waterpipe smoking and cancer, including cancer of the head and neck, esophagus, stomach, lung and bladder.

Methods

We performed a systematic literature search to identify relevant studies, scored their quality, used fixed and random-effect models to estimate summary relative risks (SRR), evaluated heterogeneity and publication bias.

Results

We retrieved information from 28 published reports. Considering only highquality studies, waterpipe smoking was associated with increased risk of head and neck cancer (SRR 2.97; 95 % CI 2.26–3.90), esophageal cancer (1.84; 1.42–2.38) and lung cancer (2.22; 1.24–3.97), with no evidence of heterogeneity or publication bias. Increased risk was also observed for stomach and bladder cancer but based mainly on poor-quality studies. For colorectum, liver and for all sites combined risk estimates were elevated, but there were insufficient reports to perform a meta-analysis.

Conclusions

Contrary to the perception of the relative safety of waterpipe smoking, this meta-analysis provides quantitative estimates of its association with cancers of the head and neck, esophagus and lung. The scarcity and limited quality of available reports point out the need for larger carefully designed studies in well-defined populations.

Hookah and Alcohol Use among Young Adult Hookah Smokers: A Mixed Methods Study

OBJECTIVES

Hookah tobacco smoking has grown steadily in popularity among young adults in the United States. Little attention has been given to the relationship between hookah smoking and another behavior that is common among young adults - alcohol use. The purpose of this study was to examine hookah and alcohol use among young adults.

METHODS

Forty young adult hookah smokers (55% female) participated in focus group sessions on hookah use beliefs and a brief survey examining hookah and alcohol use including drinking alcohol before, during, or after smoking hookah.

RESULTS

Quotes from the focus groups indicated that alcohol use may promote hookah use among individuals who have little or no hookah smoking experience. Alcohol use, binge drinking, and alcohol use before, during, and after hookah use were common among the participants regardless of legal drinking age status. Nearly half of the participants preferred to drink alcohol while smoking hookah due to the improved physical and social effects they associated with combining the 2 behaviors.

CONCLUSIONS

For some young adult hookah smokers, alcohol appears to enhance the hookah smoking experience and may play a role in hookah smoking initiation. Future research and interventions should address the association between hookah and alcohol use.

Using the Negative Exponential Model to Describe Changes in Risk of Smoking-Related Diseases following Changes in Exposure to Tobacco

Recently published analyses for four smoking-related diseases show that the declining excess relative risk by time quit is well fitted by the negative exponential model. These analyses estimated the half-life of this excess, that is, the time after quitting when the excess relative risk reaches half that for continuing smokers. We describe extensions of the simple model. One quantifies the decline following an exposure reduction. We show that this extension satisfactorily predicts results from studies investigating the effect of reducing cigarette consumption. It may also be relevant to exposure reductions following product-switching. Another extension predicts changes in excess relative risk occurring following multiple exposure changes over time. Suitable published epidemiological data are unavailable to test this, and we recommend its validity to be investigated using large studies with data recorded on smoking habits at multiple time points in life. The basic formulae described assume that the excess relative risk for a continuing smoker is linearly related to exposure and that the half-life is invariant of age. We describe model adaptations to allow for nonlinear dose-response and for age-dependence of the half-life. The negative exponential model, though relatively simple, appears to have many potential uses in epidemiological research for summarizing variations in risk with exposure changes.

Health effects associated with waterpipe smoking

OBJECTIVE

It is widely held that waterpipe smoking (WPS) is not associated with health hazards. However, several studies have documented the uptake of several toxicants and carcinogens during WPS that is strongly associated with harmful health effects. This paper reviews the literature on the health effects of WPS.

DATA SOURCES

Three databases-PubMed, MEDLINE and EMBASE-were searched until August 2014 for the acute and long-term health effects of WPS using the terms 'waterpipe' and its synonyms (hookah, shisha, goza, narghileh, arghileh and hubble-bubble) in various spellings.

STUDY SELECTION

We included original clinical studies, case reports and systematic reviews and focused on clinical human studies. ∼10% of the identified studies met the selection criteria.

DATA EXTRACTION

Data were abstracted by all three authors and summarised into tables. Abstracted data included study type, results and methodological limitations and were analysed jointly by all three authors.

DATA SYNTHESIS

WPS acutely leads to increased heart rate, blood pressure, impaired pulmonary function and carbon monoxide intoxication. Chronic bronchitis, emphysema and coronary artery disease are serious complications of long-term use. Lung, gastric and oesophageal cancer are associated with WPS as well as periodontal disease, obstetrical complications, osteoporosis and mental health problems.

CONCLUSIONS

Contrary to the widely held misconception, WPS is associated with a variety of adverse short-term and long-term health effects that should reinforce the need for stronger regulation. In addition, this review highlights the limitations of the published work, which is mostly cross-sectional or retrospective. Prospective studies should be undertaken to assess the full spectrum of health effects of WPS, particularly in view of its growing popularity and attractiveness to youth.

Smoky coal, tobacco smoking, and lung cancer risk in Xuanwei, China

OBJECTIVES

Lung cancer rates in Xuanwei are the highest in China. In-home use of smoky coal has been associated with lung cancer risk, and the association of smoking and lung cancer risk strengthened after stove improvement. Here, we explored the differential association of tobacco use and lung cancer risk by the intensity, duration, and type of coal used.

MATERIALS AND METHODS

We conducted a population-based case-control study of 260 male lung cancer cases and 260 age-matched male controls. Odds ratios (OR) and 95% confidence interval (CI) for tobacco use was calculated by conditional logistic regression.

RESULTS

Use of smoky coal was significantly associated with an increased risk of lung cancer, and tobacco use was weakly and non-significantly associated with lung cancer risk. When the association was assessed by coal use, the cigarette-lung cancer risk association was null in hazardous coal users and elevated in less hazardous smoky coal users and non-smoky coal users. The risk of lung cancer per cigarette per day decreased as annual use of coal increased (>0-3 tons: OR: 1.09; 95% CI: 1.03-1.17; >3 tons: OR: 0.99; 95% CI: 0.95-1.03). Among more hazardous coal users, attenuation occurred at even low levels of usage (>0-3 tons: OR: 1.02; 95% CI: 0.91-1.14; >3 tons: OR: 0.94; 95% CI: 0.97-1.03).

CONCLUSION

We found evidence that smoky coal attenuated the tobacco and lung cancer risk association in males that lived in Xuanwei, particularly among users of hazardous coal where even low levels of smoky coal attenuated the association. Our results suggest that the adverse effects of tobacco may become more apparent as China's population continues to switch to cleaner fuels for the home, underscoring the urgent need for smoking cessation in China and elsewhere.

Systematic review with meta-analysis of the epidemiological evidence in the 1900s relating smoking to lung cancer

BACKGROUND

Smoking is a known lung cancer cause, but no detailed quantitative systematic review exists. We summarize evidence for various indices.

METHODS

Papers published before 2000 describing epidemiological studies involving 100+ lung cancer cases were obtained from Medline and other sources. Studies were classified as principal, or subsidiary where cases overlapped with principal studies. Data were extracted on design, exposures, histological types and confounder adjustment. RRs/ORs and 95% CIs were extracted for ever, current and ex smoking of cigarettes, pipes and cigars and indices of cigarette type and dose-response. Meta-analyses and meta-regressions investigated how relationships varied by study and RR characteristics, mainly for outcomes exactly or closely equivalent to all lung cancer, squamous cell carcinoma ("squamous") and adenocarcinoma ("adeno").

RESULTS

287 studies (20 subsidiary) were identified. Although RR estimates were markedly heterogeneous, the meta-analyses demonstrated a relationship of smoking with lung cancer risk, clearly seen for ever smoking (random-effects RR 5.50, CI 5.07-5.96) current smoking (8.43, 7.63-9.31), ex smoking (4.30, 3.93-4.71) and pipe/cigar only smoking (2.92, 2.38-3.57). It was stronger for squamous (current smoking RR 16.91, 13.14-21.76) than adeno (4.21, 3.32-5.34), and evident in both sexes (RRs somewhat higher in males), all continents (RRs highest for North America and lowest for Asia, particularly China), and both study types (RRs higher for prospective studies). Relationships were somewhat stronger in later starting and larger studies. RR estimates were similar in cigarette only and mixed smokers, and similar in smokers of pipes/cigars only, pipes only and cigars only. Exceptionally no increase in adeno risk was seen for pipe/cigar only smokers (0.93, 0.62-1.40). RRs were unrelated to mentholation, and higher for non-filter and handrolled cigarettes. RRs increased with amount smoked, duration, earlier starting age, tar level and fraction smoked and decreased with time quit. Relationships were strongest for small and squamous cell, intermediate for large cell and weakest for adenocarcinoma. Covariate-adjustment little affected RR estimates.

CONCLUSIONS

The association of lung cancer with smoking is strong, evident for all lung cancer types, dose-related and insensitive to covariate-adjustment. This emphasises the causal nature of the relationship. Our results quantify the relationships more precisely than previously.

Laryngeal findings and acoustic changes in hubble-bubble smokers

The purpose of our investigation was to evaluate the laryngeal findings and acoustic changes in hubble-bubble smokers. A total of 42 subjects with history of hubble-bubble smoking were recruited for this study. A corresponding group with a history of cigarette smoking and controls were matched. All subjects underwent laryngeal video-endostroboscopic evaluation and acoustic analysis. In the hubble-bubble smoking group, 61.9% were males. The average age was 30.02 +/- 9.48 years and the average number of years of smoking was 8.09 +/- 6.45 years. Three subjects had dysphonia at the time of examination. The incidence of benign lesions of the vocal folds in the hubble-bubble group was 21.5%, with edema being the most common at 16.7% followed by cyst at 4.8%. The incidence of laryngeal findings was significantly higher in the hubble-bubble group compared to controls. In the cigarette-smoking group, the most common finding was vocal fold cyst in 14.8% followed by polyps in 7.4%, and edema, sulcus vocalis and granuloma. These findings were not significantly different from the hubble-bubble group except for the thick mucus, which was significantly higher in the latter. There were no significant changes in any of the acoustic parameters between hubble-bubble smokers and controls except for the VTI and MPT, which were significantly lower in the hubble-bubble group. In comparison with the cigarette-smoking group, hubble-bubble smokers had significantly higher Fundamental frequency and habitual pitch (p value 0.042 and 0.008, respectively). The laryngeal findings in hubble-bubble smokers are comparable to cigarette smokers. These laryngeal findings are not translated acoustically, as all the acoustic parameters are within normal range compared to controls.

The effects of waterpipe tobacco smoking on health outcomes: a systematic review

BACKGROUND

There is a need for a comprehensive and critical review of the literature to inform scientific debates about the public health effects of waterpipe smoking. The objective of this study was therefore to systematically review the medical literature for the effects of waterpipe tobacco smoking on health outcomes.

METHODS

We conducted a systematic review using the Cochrane Collaboration methodology for conducting systematic reviews. We rated the quality of evidence for each outcome using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology.

RESULTS

Twenty-four studies were eligible for this review. Based on the available evidence, waterpipe tobacco smoking was significantly associated with lung cancer [odds ratio (OR) = 2.12; 95% confidence interval (CI) 1.32-3.42], respiratory illness (OR = 2.3; 95% CI 1.1-5.1), low birth-weight (OR = 2.12; 95% CI 1.08-4.18) and periodontal disease (OR = 3-5). It was not significantly associated with bladder cancer (OR = 0.8; 95% CI 0.2-4.0), nasopharyngeal cancer (OR = 0.49; 95% CI 0.20-1.23), oesophageal cancer (OR = 1.85; 95% CI 0.95-3.58), oral dysplasia (OR = 8.33; 95% CI 0.78-9.47) or infertility (OR = 2.5; 95% CI 1.0-6.3) but the CIs did not exclude important associations. Smoking waterpipe in groups was not significantly associated with hepatitis C infection (OR = 0.98; 95% CI 0.80-1.21). The quality of evidence for the different outcomes varied from very low to low.

CONCLUSION

Waterpipe tobacco smoking is possibly associated with a number of deleterious health outcomes. There is a need for high-quality studies to identify and quantify with confidence all the health effects of this form of smoking.

A critique of recent hypotheses on oral (and lung) cancer induced by water pipe (hookah, shisha, narghile) tobacco smoking

The medical hypothesis that the mainstream smoke (the one inhaled by the user) from "water pipes" (mainly: shisha, hookah, narghile) causes oral cancer is certainly acceptable. However, most of the recent reviews on this issue, including an attempt to develop an hypothesis for hookah carcinogenesis, have not cited key references of the world available literature which, so far, generally do not support such an hypothesis. Besides, the proposal is biased since it is apparently an adaptation of the cigarette model whereas cigarette and hookah smokes are, chemically to start with, completely different. Furthermore, all water pipes, despite their striking varieties and the consequences on the chemical processes, are, according to the same cancer-hypothesis, considered as one. The reason is the use, in the cited mainstream literature, of a nominalism ("waterpipe", often in one word) which does not allow any distinction between devices. This critical article suggests to take into account all the peculiar characteristics into consideration in order to come up with another (or several other) carcinogenesis model(s). "Firmly believ[ing] that water pipe smoking can provoke lung cancer as well as oral cancer", based on what may be seen as a rather reductionist view of the issue, is not enough.

Variation in lung cancer risk by smoky coal subtype in Xuanwei, China

Lung cancer rates in Xuanwei County have been among the highest in China for both males and females and have been causally associated with exposure to indoor smoky (bituminous) coal emissions that contain very high levels of polycyclic aromatic hydrocarbons. There are numerous coal mines across the County. Although lung cancer risk is strongly associated with the use of smoky coal as a whole, variation in risk by smoky coal subtype has not been characterized as yet. We conducted a population-based case-control study of 498 lung cancer cases and 498 controls, individually matched to case subjects on age (+/-2 years) and sex to examine risk by coal subtype. Odds ratios (ORs) and 95% confidence intervals (CIs) for coal subtype were calculated by conditional logistic regression, adjusting for potential confounders. Overall, smoky coal use was positively and statistically significantly associated with lung cancer risk, when compared with the use of smokeless coal or wood (OR = 7.7, 95% CI = 4.5-13.3). Furthermore, there was a marked heterogeneity in risk estimates for specific subtypes of smoky coal (test for heterogeneity: p = 5.17 x 10(-10)). Estimates were highest for coal of the Laibin (OR = 24.8, 95% CI = 12.4-49.6) and Longtan (OR = 11.6, 95% CI = 5.0-27.2) coal types and lower for coal from other subtypes. These findings strongly suggest that in Xuanwei and elsewhere, the carcinogenic potential of coal combustion products can exhibit substantial local variation by specific coal source.

Effects of type of smoking (pipe, cigars or cigarettes) on biological indices of tobacco exposure and toxicity

Although all forms of smoking are harmful, smoking pipes or cigars is associated with lower exposure to the lethal products of tobacco products and lower levels of morbidity and mortality than smoking cigarettes. Cytochrome P-450-1A (CYP1A) is a major pathway activating carcinogens from tobacco smoke. Our primary aim was to compare CYP1A2 activity in individuals smoking pipes or cigars only, cigarettes only and in non-smokers. We studied 30 smokers of pipes or cigars only, 28 smokers of cigarettes only, and 30 non-smokers male subjects matched for age. CYP1A2 activity was assessed as the caffeine metabolic ratio in plasma. One-day urine collection was used for determining exposure to products of tobacco metabolism. Nitrosamine and benzo[a]pyrene DNA adducts were measured in lymphocytes. CYP1A2 activity was greater (p<0.0001) in cigarette smokers (median: 0.61; interquartile range: 0.52-0.76) than in pipe or cigar smokers (0.27; 0.21-0.37) and non-smokers (0.34; 0.25-0.42) who did not differ significantly. Urinary cotinine and 1-hydroxypyrene levels were higher in cigarette smokers than in pipe or cigar smokers and higher in the later than in non-smokers. DNA adducts levels were significantly lower in pipe or cigar smokers than in cigarette smokers. In multivariate analysis, cigarette smoking was the only independent predictor of CYP1A2 activity (p<0.0001) and of 1-hydroxypyrene excretion in urine (p=0.0012). In this study, pipe or cigar smoking was associated with lower exposure to products of tobacco metabolism than cigarette smoking and to an absence of CYP1A2 induction. Cigarette smoking was the only independent predictor of CYP1A2 activity in smokers. However, inhalation behaviour, rather than the type of tobacco smoked, may be the key factor linked to the extent of tobacco exposure and CYP1A2 induction. Our results provide a reasonable explanation for the results of epidemiological studies showing pipe or cigar smoking to present fewer health hazards than cigarette smoking.

The role of public policies in reducing smoking and deaths caused by smoking in Vietnam: Results from the Vietnam tobacco policy simulation model

A simulation model is developed for Vietnam to project smoking prevalence and associated premature mortality. The model examines independently and as a package the effects of five types of tobacco control policies: tax increases, clean air laws, mass media campaigns, advertising bans, and youth access policies. Predictions suggest that the largest reductions in smoking rates will result from implementing a comprehensive tobacco control policy package. Significant inroads may be achieved through tax increases. A media campaign along with programs to publicize and enforce clean air laws, advertising bans and youth access laws would further reduce smoking rates. Tobacco control policies have the potential to make large dents in smoking rates, which in turn could lead to many lives saved. In the absence of these measures, deaths from smoking will increase. The model also helps to identify information gaps pertinent both to modeling and policy-making.

Are waterpipe users interested in quitting?

Waterpipe smoking has increased dramatically worldwide in recent years, with an estimated 100 million daily users. Research on this traditional Middle Eastern tobacco use method is in its infancy, and little is known about users' cessation-related attitudes and experiences. A random sample of 268 narghile (waterpipe) smokers (40% female; mean age = 30 years; range = 18-68) was obtained from cafes and restaurants in Aleppo, Syria. The majority of users (86.5%) believed they could quit using waterpipes at any time, but that belief was inversely related to perceived dependence, with only 48.7% of those who thought they were "very hooked" believing they could quit. Interest in quitting was expressed by 28.4% of subjects, with the majority (89.2%) reporting health concerns as a primary reason, and 59.2% having made an unsuccessful quit attempt in the past year. In a logistic regression model, independent predictors of interest in quitting included being married, having smoked for fewer years, not increasing the frequency of smoking over time, and having family members who do not smoke a waterpipe and disapprove of its use. Results indicate that a sizable percentage of waterpipe users express interest in quitting and have tried unsuccessfully in the past to quit. Waterpipe use needs to be considered in developing effective tobacco use cessation programs in the Middle East.

Tobacco smoking using a waterpipe: a re-emerging strain in a global epidemic

CONTEXT

The global tobacco epidemic may kill 10 million people annually in the next 20-30 years, with 70% of these deaths occurring in developing countries. Current research, treatment, and policy efforts focus on cigarettes, while many people in developing regions (Asia, Indian subcontinent, Eastern Mediterranean) smoke tobacco using waterpipes. Waterpipes are increasing in popularity, and more must be learned about them so that we can understand their effects on public health, curtail their spread, and help their users quit.

OBJECTIVE

To conduct a comprehensive review regarding global waterpipe use, in order to identify current knowledge, guide scientific research, and promote public policy.

DATA SOURCES

A Medline search using as keywords "waterpipe", "narghile", "arghile", "shisha", "hookah", "goza", "hubble bubble" and variant spellings (for example, "hooka"; "hukka") was conducted. Resources compiled recently by members of GLOBALink were used.

STUDY SELECTION

Every identified published study related to waterpipe use was included.

DATA SYNTHESIS

Research regarding waterpipe epidemiology and health effects is limited; no published studies address treatment efforts. Waterpipe use is increasing globally, particularly in the Eastern Mediterranean Region, where perceptions regarding health effects and traditional values may facilitate use among women and children. Waterpipe smoke contains harmful constituents and there is preliminary evidence linking waterpipe smoking to a variety of life threatening conditions, including pulmonary disease, coronary heart disease, and pregnancy related complications.

CONCLUSIONS

More scientific documentation and careful analysis is required before the spread of waterpipe use and its health effects can be understood, and empirically guided treatment and public policy strategies can be implemented.

Tobacco initiation, cessation, and change: evidence from Vietnam

Studies of the impact of tobacco prices on decisions to initiate and quit smoking have, to date, largely been restricted to developed countries. Such analyses, when set in developing countries, are complicated by the availability of a wide range of tobacco products that are nicotine substitutes for cigarettes. This study, which uses data from two rounds of the Vietnam Living Standards Survey in 1992-1993 and 1997-1998, finds evidence of substitution among tobacco products in response to changes in relative prices and points to the need for comprehensive tobacco-control strategies that are not restricted to cigarettes alone. We find that higher cigarette prices may not necessarily encourage quitting and may only divert cigarette smokers to rustic tobacco, which is potentially as harmful to human health as cigarettes.

Association between exclusive pipe smoking and mortality from cancer and other diseases

BACKGROUND

Although many studies have examined the adverse health effects of pipe smoking combined with other forms of tobacco use, few have included large numbers of exclusive pipe smokers. The prevalence of pipe smoking has declined since the 1960s, yet usage is still common regionally, especially among older populations.

METHODS

Using Cox proportional hazards models, we examined the association between pipe smoking and mortality from tobacco-related cancers and other diseases in a cohort of U.S. men enrolled in the Cancer Prevention Study II, an American Cancer Society prospective study. The cohort of 138 307 men included those who reported, in their 1982 enrollment questionnaire, exclusive current or former use of pipes (n = 15,263 men) or never use of any tobacco product (n = 123,044 men). Analyses were based on 23 589 men who died during 18 years of follow-up.

RESULTS

Current pipe smoking, compared with never use of tobacco, was associated with an increased risk of death from cancers of the lung (relative risk [RR] = 5.00, 95% confidence interval [CI] = 4.16 to 6.01), oropharynx (RR = 3.90, 95% CI = 2.15 to 7.08), esophagus (RR = 2.44, 95% CI = 1.51 to 3.95), colorectum (RR = 1.41, 95% CI = 1.15 to 1.73), pancreas (RR = 1.61, 95% CI = 1.24 to 2.09), and larynx (RR = 13.1, 95% CI = 5.2 to 33.1), and from coronary heart disease (RR = 1.30, 95% CI = 1.18 to 1.43), cerebrovascular disease (RR = 1.27, 95% CI = 1.09 to 1.48), and chronic obstructive pulmonary disease (RR = 2.98, 95% CI = 2.17 to 4.11). These risks were generally smaller than those associated with cigarette smoking and similar to or larger than those associated with cigar smoking. Relative risks of lung cancer showed statistically significant increases with number of pipes smoked per day, years of smoking, and depth of inhalation and decreases with years since quitting.

CONCLUSION

Results from this large prospective study suggest that pipe smoking confers a risk of tobacco-associated disease similar to cigar smoking.

Tobacco use and cancer causation: association by tumour type

In the second part of our review we describe the association between tobacco use and risk of specific cancer types. There is evidence for an established association of tobacco use with cancer of the lung and larynx, head and neck, bladder, oesophagus, pancreas, stomach and kidney. In contrast, endometrial cancer is less common in women who smoke cigarettes. There are some data suggesting that tobacco use increases the risk for myeloid leukaemia, squamous cell sinonasal cancer, liver cancer, cervical cancer, colorectal cancer after an extended latency, childhood cancers and cancer of the gall bladder, adrenal gland and small intestine. Other forms of cancer, including breast, ovarian and prostate cancer, are unlikely to be linked to tobacco use.

Household stove improvement and risk of lung cancer in Xuanwei, China

BACKGROUND

Lung cancer rates in rural Xuanwei County, Yunnan Province, are among the highest in China. Residents traditionally burned "smoky" coal in unvented indoor firepits that generated very high levels of air pollution. Since the 1970s, most residents have changed from firepits to stoves with chimneys. This study assessed whether lung cancer incidence decreased after this stove improvement.

METHODS

A cohort of 21 232 farmers, born from 1917 through 1951, was followed retrospectively from 1976 through 1992. All subjects were users of smoky coal who had been born into homes with unvented firepits. During their lifetime, 17 184 subjects (80.9%) changed permanently to stoves with chimneys. A hospital record search detected 1384 cases of lung cancer (6.5%) during follow-up. Associations of stove improvement with lung cancer incidence were analyzed with product-limit plots and multivariable Cox models. In 1995, indoor concentrations of airborne particles and benzo[a]pyrene were compared in Xuanwei homes during smoky coal burning in stoves with chimneys and in unvented stoves or firepits.

RESULTS

A long-term reduction in lung cancer incidence was noted after stove improvement. In Cox models, risk ratios (RRs) for lung cancer after stove improvement were 0.59 (95% confidence interval [CI] = 0.49 to 0.71) in men and 0.54 (95% CI = 0.44 to 0.65) in women (for both, P<.001). Incidence reduction became unequivocal about 10 years after stove improvement. Levels of indoor air pollution during burning with chimneys were less than 35% of levels during unvented burning.

CONCLUSION

Changing from unvented to vented stoves appears to benefit the health of people in China and may do so in other developing countries as well.

Analysis of a historical cohort of Chinese tin miners with arsenic, radon, cigarette smoke, and pipe smoke exposures using the biologically based two-stage clonal expansion model

Hazelton, W. D., Luebeck, E. G., Heidenreich, W. F. and Moolgavkar, S. H. Analysis of a Historical Cohort of Chinese Tin Miners with Arsenic, Radon, Cigarette Smoke, and Pipe Smoke Exposures Using the Biologically Based Two-Stage Clonal Expansion Model. Radiat. Res. 156, 78-94 (2001).The two-stage clonal expansion model is used to analyze lung cancer mortality in a cohort of Yunnan tin miners based on individual histories with multiple exposures to arsenic, radon, cigarette smoke, and pipe smoke. Advances in methodology include the use of nested dose-response models for the parameters of the two-stage clonal expansion model, calculation of attributable risks for all exposure combinations, use of both a fixed lag and a gamma distribution to represent the time between generation of the first malignant cell and death from lung cancer, and scaling of biological parameters allowed by parameter identifiability. The cohort consists of 12,011 males working for the Yunnan Tin Corporation, with complete exposure records, who were initially surveyed in 1976 and followed through 1988. Tobacco and arsenic dominate the attributable risk for lung cancer. Of 842 lung cancer deaths, 21.4% are attributable to tobacco alone, 19.7% to a combination of tobacco and arsenic, 15.8% to arsenic alone, 11% to a combination of arsenic and radon, 9.2% to a combination of tobacco and radon, 8.7% to combination of arsenic, tobacco and radon, 5.5% to radon alone, and 8.7% to background. The models indicate that arsenic, radon and tobacco increase cell division, death and malignant conversion of initiated cells, but with significant differences in net cell proliferation rates in response to the different exposures. Smoking a bamboo water pipe or a Chinese long-stem pipe appears to confer less risk than cigarette use, given equivalent tobacco consumption.

Lung cancer and environmental tobacco smoke in a non-industrial area of China

We report results from a population-based case-control study of lung cancer and environmental tobacco smoke (ETS) among never-smokers conducted in 2 rural prefectures of China, including 200 female and 33 male lung cancer cases, and 407 female and 114 male controls, matched on age, sex and prefecture of current residence. The odds ratio (OR) for ever-exposed to ETS was 1.19 (95% CI 0.7-2.0), with a significant trend (p<0.05) with increasing exposure. ORs were 1.00, 1.04, 1.13 and 1.51 for non-exposed, <10, 10-19 and >/=20 pack-years of ETS exposure, respectively. Excess risks were limited to ETS exposures in childhood (</=18 years of age). The OR for ever-exposed to ETS in childhood, adjusting for ETS exposure in adulthood, was 1. 52 (95% CI 1.1-2.2), with a significant trend (p<0.01) with increasing pack-years of childhood exposure, 1.00, 1.43, 1.81 and 2. 95, respectively. After adjustment for ETS in childhood, there was no excess risk from adult ETS exposure. The OR for ever-exposed to ETS in adulthood was 0.90 (95% CI 0.-1.4). These results were not affected by adjustment for type of residential dwelling, type or amount of fuel used, perceived indoor smokiness, or measures of socioeconomic status, or omitting next-of-kin respondents.

Risk factors and early detection of lung cancer in a cohort of Chinese tin miners

PURPOSE

To examine risk factors and establish a biologic specimen and data bank for the study of early markers of lung cancer.

METHODS

We designed a dynamic cohort using an ongoing lung cancer screening program among radon- and arsenic-exposed tin miners in Yunnan China. Through the first four years of the study, 8,346 miners aged 40 years and older with over 10 years of occupational exposure have been enrolled, risk factors have been assessed, annual sputum and chest radiographs have been obtained, and numerous biologic specimens have been collected.

RESULTS

A total of 243 new lung cancer cases have been identified through 1995. Radon and arsenic exposures are the predominant risk factors, but lung cancer risk is also associated with chronic bronchitis and silicosis, as well as a number of exposure to tobacco smoke, including early age of first use, duration, and cumulative exposure. Tumor and sputum samples are being examined for early markers of lung cancer.

CONCLUSION

A cohort of occupationally-exposed tin miners with an extensive biologic specimen repository has been successfully established to simultaneously study the etiology and early detection of lung cancer.

Radon exposure in residences and lung cancer among women: combined analysis of three studies

Lung cancer risk in relation to indoor radon was examined in three case-control studies in Stockholm (Sweden), New Jersey (United States), and Shenyang (People's Republic of China). Year-long measurements of radon gas were made in current and past homes of 966 women who developed lung cancer and of 1,158 control women, included in the combined analysis. Nearly 14 percent of the participants were estimated to have a time-weighted, mean, radon concentration in their homes of more than 4 pCi/l (150 Bq/m3) during the period from five to 35 years prior to the date of lung cancer diagnosis (or comparable date for controls). There was a tendency for risk to increase with increasing levels of radon in NJ and Stockholm, but the trends for individual studies and overall were not statistically significant. The estimates of the excess relative risk for indoor exposure per pCi/l were 0.18 (95 percent [CI] = -0.04-0.70) in NJ, 0.06 (CI = -0.05-0.34) in Stockholm, and -0.02 (CI = -infinity-0.03) for Shenyang; these estimates did not differ significantly from each other. The overall excess RR per pCi/l was 0.00 (CI = -0.05-0.07); the confidence limits were sufficiently broad, however, that the overall estimate was still compatible with extrapolations of risks from miners. Cigarette smoking was the predominant cause of lung cancer with the RR significantly elevated in all studies. Within smoking categories, the trend in risk with increasing mean radon concentration was inconsistent. Analyses of data from several studies are complicated by the possibility that there may exist important differences in study bases which might affect results, and which may be controlled only partially through adjustment procedures. Future efforts to combine various residential studies will need to be attentive to the intrinsic limitations of studies to detect low levels of risk as well as the unique uncertainties associated with estimating, accurately, cumulative exposure to indoor radon.

Variation in smoking-related lung cancer risk factors by cell type among men in Argentina: a case-control study

A high mortality rate for lung cancer (62.7 per 100,000) is found in Rosario, Argentina. To investigate the reasons for this high rate, a case-control study was carried out among 215 male cases with histologically confirmed lung cancer and 433 hospitalized controls for conditions unrelated to tobacco consumption. Odds ratios (OR) of squamous cell (SQ), adenocarcinoma (AD), and small cell (SM) carcinoma of the lung associated with different characteristics of the smoking habit were quantified. Ninety-eight percent of the cases had smoked regularly. Smokers were significantly younger at diagnosis than ex-smokers (P < 0.0001), a pattern consistent for all cell types. The ORs for the heaviest cf the lowest consumption categories were 15.3 for SQ, 11.6 for AD, and 11.6 for all lung cancer (P < 0.0001). Risks associated with the use of unfiltered cigarettes were three to five times higher than those for filtered cigarettes, depending on cell types. For ex-smokers, risks after 10 years of nonsmoking were about 12 times lower than those of current smokers (P < 0.001). To halt further increases in lung cancer, preventive measures in Argentina should be directed primarily towards smoking control.