3.27 Health effects of smoking tobacco in other forms

Last updated: March 2015
Suggested citation:Bellew, B, Greenhalgh, EM & Winstanley, MH. 3.27 Health effects of smoking tobacco in other forms. In Scollo, MM and Winstanley, MH [editors]. Tobacco in Australia: Facts and issues. Melbourne: Cancer Council Victoria; 2015. Available from http://www.tobaccoinaustralia.org.au/3-27-health-effects-of-smoking-tobacco-in-other-fo


Data from the 2013 National Drug Strategy Household Survey show that while the vast majority of Australian smokers (89%) use manufactured cigarettes, a variety of other tobacco products are also used either regularly or occasionally, either in conjunction with use of cigarettes or exclusively. About one-third (33%) of smokers report any use of roll-your-own, and about ten percent (10.4%) report use of cigarillos or  cigars. Fewer than 2% report use of pipe tobacco.1 Unbranded tobacco (also known as chop-chop) is roughly processed loose tobacco that has been grown, distributed and sold without government intervention or taxation.2 In 2013, of smokers aged 14 years or older about one-third had seen or heard of unbranded loose tobacco. The proportion of smokers who had ever smoked and smoked unbranded loose tobacco at the time of the survey declined between 2010 and 2013 (from 24.0% down to 16.5%, and from 4.9% down to 3.6%, respectively). The overall proportion of smokers using it regularly remained low at 0.8%.1

Smoking tobacco by means of a waterpipe (using a system by which smoke passes through water prior to inhalation) is widespread in other parts of the world3-5 and is also practised in Australia. One study reporting prevalence of 11% among Arab-speaking adults).6 Data from the National Drug Strategy Household Survey indicates that 2.4% of all Australians aged over 14 years, and 6.7% of current smokers, had used a waterpipe in the year prior to the survey. Usage was much higher among young adults (18-24 years) who were also current smokers, at 17%.7 For more information on the extent to which tobacco products other than manufactured cigarettes are used in Australia, see Chapter 1, Section 1.11.

3.27.1 Manufactured loose tobacco

Manufactured loose tobacco, hand-rolled into cigarette paper and smoked with or without a filter, causes the same range of diseases as smoking manufactured cigarettes. Variations in quantity of tobacco used per cigarette and filtration make measurements of individual exposure more difficult to assess, but the directly comparable exposure to harmful constituents and method of consumption means that smokers of these products have at least an equivalent risk of developing disease as do smokers of conventional cigarettes. Several decades of research on the health effects of tobacco use have enabled comparisons between products with and without filters, and with high and low nicotine and tar yields. Overall, neither has the incidence of lung cancer varied with tobacco product used, nor have other health benefits become apparent.8

3.27.2 Unbranded loose tobacco ('chop-chop')

Chop-chop is used by some as an alternative to other manufactured tobaccos due to its comparative affordability, and common misapprehensions that it is less harmful to health since it is apparently more 'natural' and 'unadulterated,' not having been processed in the usual way.9-11 Research has shown that some batches of chop-chop contain bulking agents such as twigs, raw cotton and grass clippings. Fungal (mould) spores have also been detected. Fungal spores are of particular health concern since they give rise to mycotoxins, including aflotoxin, a known carcinogen. Inhalation of and contact with fungi and their mycotoxins can cause a range of adverse responses in the liver, kidneys and skin, and cause illnesses including allergic reactions, chronic bronchitis, asthma and lung diseases.12 Australian chop-chop users report significantly worse health than smokers of licit tobacco. In a recent study in which a comparison with licit-only tobacco smokers was undertaken, current users of chop-chop had significantly greater odds of reporting below-average social functioning (OR 1.61; 95% CI, 1.06–2.44), measurable disability (OR 1.95; 95% CI, 1.08–3.51), below-average mental health (OR 1.61; 95% CI, 1.22–2.13) and above-average bodily pain (OR 1.40; 95% CI, 1.06–1.85).13

3.27.3 Cigar smoking

Cigar smoke is at least as toxic and carcinogenic as cigarette smoke and possibly more so. Cigars contain more tobacco per stick than cigarettes, take longer to smoke, and produce higher concentrations of a number of noxious compounds including carbon monoxide, nitrogen oxides, carcinogenic N-nitrosamines and ammonia.14 A recent systematic review found that cigar smoking carries many of the same health risks as cigarette smoking. Mortality risks from cigar smoking vary by number of cigars per day and inhalation level, but can be as high as or exceed those of cigarette smoking. Specifically, primary cigar smoking (current, exclusive cigar smoking with no history of previous cigarette or pipe smoking) was associated with all cause-mortality, oral cancer, esophageal cancer, pancreatic cancer, laryngeal cancer, lung cancer, coronary heart disease (CHD), and aortic aneurysm. Strong dose- response relationships were observed between the number of cigars smoked per day and inhalation level, and oral, esophageal, laryngeal, and lung cancers. Among primary cigar smokers who reported that they did not inhale, relative mortality risk was still highly elevated for oral, esophageal, and laryngeal cancers..15 A 2010 European longitudinal study involving more than 100,000 men found that, compared to never smokers, the risk of cancers of the lung, upper aerodigestive tract and bladder combined was more than doubled (HR 2.2; 95% CI, 1.3–3.8) for exclusive cigar smokers. Effects were stronger in current than in ex-smokers and in inhalers than in non-inhalers. For ever-smokers of both cigarettes and cigars there was more than a five-fold increase in the risk of these cancers (HR 5.7; 95% CI, 4.4–7.3) making the risk elevation as high as that among exclusive cigarette smokers.16 A case–control study focusing only on lung cancer found a five-fold increase in risk for smoking cigars only compared to never smokers (OR 5.6; 95% CI, 2.9–10.6)17 consistent with estimates from earlier research.18 Other research has shown that cigar-only smokers had a 60% increased risk of pancreatic cancer compared with those who had never used tobacco (OR 1.6; 95% CI, 1.2– 2.3), the risk with increasing according to the amount of cigar smoked per day (OR 1.82 for ≥10 grams of tobacco),19 which is broadly consistent with risk estimates from a 2008 meta-analytic review.20

Smoke drifting from the burning tip of a lit cigar contains most of the same toxic and carcinogenic compounds as cigarette smoke, and because they are larger, cigars generate smoke for a longer period of time–as long as 90 minutes for a single large cigar. This is a health concern for those constantly exposed to an indoor environment affected by cigar smoke;14 some researchers have concluded that high passive exposure to smoke from cigars and pipes may be associated with lung cancer risk.17 Cigar use has increased in popularity in the US, prompting concern among some tobacco control organisations21; in Australia the proportion of smokers using cigars and pipes alone rose from an estimated 1.2% in 2004 to 1.6% in 2010.22, 23 See Chapter 1, Section 1.11 and Chapter 10, Section 10.6 for further discussion.

3.27.4 Pipe smoking

Longitudinal research conducted in Norway has reported that pipe smoking is not safer than cigarette smoking. The study followed a cohort of more than 16 000 men for up to 13 years. Between pipe and cigarette smokers, no or only minor differences were found in mortality from any cause and the specified smoking-related diseases.24 Pipe smoking is associated with decreased lung function and increased odds of airflow obstruction, even in participants who had never smoked cigarettes;25 it is associated with a significantly higher risk of dying from COPD, cerebrovascular disease and cardiovascular disease. Compared to never smokers, exclusive pipe smokers are estimated to have a three-fold increase in risk (HR 3.0; 95% CI, 2.1–4.5) for cancers of lung, upper aerodigestive tract and bladder combined, 16 and an eight-fold in the risk (OR 8.7; 95% CI, 4.0–18.9) of all upper digestive tract cancers (including a 12-fold risk for oral and seven-fold risk for pharyngeal cancer). Pipe smokers who are also heavy alcohol drinkers have a massive 38-fold increased risk of these cancers (OR 38.8; 95% CI, 13.6–110.9) as compared to never smokers and light drinkers, strongly suggesting that pipe smoking and heavy alcohol drinking may interact in a way that greatly increases the risks.26

As with cigarette smoking, the risk of developing tobacco-caused disease varies in a dose–response relationship, disease risk increasing with the amount smoked, the depth to which it is inhaled and the duration of smoking. For most disease entities, the relative risk of developing tobacco-related disease declines with quitting, increased length of time of cessation and younger age at quitting.27

Disease patterns differ from those observed in cigarette smokers because pipe smokers tend to inhale the smoke less deeply, taking up nicotine through the mucous membranes lining of the mouth instead of predominantly via the lungs. Some earlier studies suggested the possibility of some harm reduction benefits in switching from cigarette to pipe smoking.16 It was suggested that the magnitude of the extra risk was smaller if people had switched to cigars or pipes only (i.e. quit cigarettes) and had not compensated with greater smoking intensity. However it should be noted that recent research has found that men who switched from cigarettes only to pipe only had a risk that was not significantly different from the risk in sustained smokers of cigarettes only,24 so that the overall main conclusion about pipe smoking is that it is very hazardous and is certainly not a safe alternative to cigarette smoking.

3.27.5 Waterpipe smoking

Using a waterpipe to smoke tobacco is not a safe alternative to cigarette smoking.28 Secondhand smoke from waterpipe tobacco use produces a similar level of air pollutants as cigarettes, and poses a serious health risk to those exposed.5,28,29 Names for waterpipe vary and include 'narghile', 'arghile', 'shisha', 'goza', 'hubble bubble' and 'hookah'.30 Waterpipe smoking use spread through the Middle East and Asia, and waterpipes were widely used in Turkey during the Ottoman Empire (15th century), Iran, Lebanon, Syria, Jordan, Greece, India, Pakistan, Palestine, Egypt and Saudi Arabia. As people immigrated to Europe from India, Pakistan, Northern Africa and the Middle East, hookahs and hookah cafes began appearing in European cities. Today, hookah bars and cafés are popular in many parts of Britain, France, Spain, Russia, India, Asia and throughout the Middle East and are growing in popularity in the US,3 with some estimates that about one billion people worldwide are waterpipe users.31

Waterpipe apparatus varies widely in design, but the method of use requires the heating with burning charcoal of moist tobacco (usually sweetened and flavoured) to produce smoke, which is passed through water before being inhaled via a mouthpiece on the end of a hose.4,5 Electronically heated systems have also been developed in recent years, but the effects of these on smokers and the environment have not been well-studied.32 Waterpipe smoking usually occurs in a social setting with a number of participants seated around the waterpipe, taking it in turns to inhale.  The availability of pre-moistened, shaped and flavoured tobacco made especially for waterpipe use (‘Maassel’) since the 1990s is likely to have contributed to a resurgence in waterpipe smoking in the Eastern Mediterranean Region, and its increased popularity.5,33 At least in some cultures, women and girls are more likely to use a waterpipe than to use other forms of tobacco, and it is popular among younger smokers. Because the smoke passes through a reservoir of water, waterpipe smoking may erroneously34 be perceived as being less lethal than other methods of tobacco use.5,30,35 Although the moist smoke produced by waterpipe smoking may be more palatable than cigarette smoke,4 many of the harmful gases and chemicals found in cigarette smoke are present in equal or even greater amounts in waterpipe smoke, including carbon monoxide, nicotine and heavy metals.5 Waterpipe smokers are typically exposed to smoke over a longer period than cigarette smokers, a session lasting somewhere between 45 minutes to an hour, but some sessions may continue for many hours.4 Although waterpipe smokers do not usually smoke as frequently as do cigarette smokers,35.36 it has been estimated that during a typical session, a waterpipe smoker inhales more than 100 times the volume of smoke produced by smoking a single cigarette.28 

A systematic review was conducted by Akl and colleagues to examine the effects of waterpipe tobacco smoking on health outcomes. While the quality of available studies was poor, the researchers found that waterpipe smoking of tobacco was significantly associated with a doubling, respectively, in the risks of lung cancer (OR 2.12; 95% CI, 1.32– 3.42), respiratory illness (OR 2.3; 95% CI, 1.1– 5.1), low birthweight (OR 2.12; 95% CI, 1.08– 4.18), and at least a trebling in the risk of periodontal disease (OR = 3–5).37

Another recent systematic review and meta-analysis of six cross-sectional studies was conducted to examine the effects of waterpipe tobacco smoking on lung function compared with no smoking.

Despite methodological limitations in the reviewed studies, the authors were able to conclude that waterpipe smoking of tobacco negatively affects lung function, may be as harmful as cigarette smoking and is likely to be a cause of COPD.6 Research into the acute effects of waterpipe smoking on the cardiorespiratory system has been reported. Forty-five similarly sized volunteers (including 30 men) were studied after a single 30-minute domestic open-air group-smoking session of waterpipe smoking. Carboxyhaemoglobin levels were significantly raised post-waterpipe smoking, especially in women. Three of 45 subjects demonstrated carboxyhaemoglobin concentrations varying between 20% and 26%, high enough levels for consideration of inpatient treatment in susceptible individuals. Blood pressure, heart rate, and respiratory rate were all significantly increased post-waterpipe smoking. The authors concluded that one session of waterpipe smoking causes acute biologic changes that might result in marked health problems.38

Accumulating evidence of the health effects associated with waterpipe smoking now makes a compelling case that there are serious risks for those exposed, that is in no way a safe alternative to cigarette smoking and that its spread among young people represents a global problem.39 Associations with lung cancer, respiratory illness, low birthweight, periodontal disease,37 impaired lung function,6 and acute cardiorespiratory effects40 have been noted. There is evidence that waterpipe smoke contains many of the same toxicants as cigarette smoke, including those that cause cardiovascular disease (e.g. carbon monoxide), lung disease (e.g. volatile aldehydes), cancer (e.g. polycyclic aromatic hydrocarbons) and dependence (i.e. nicotine).41 Waterpipe smoking is an efficient means of delivering toxicants to the smoker; for example, recent research reveals that, relative to a single cigarette, a single waterpipe session exposes the smoker to 3–9 times the carbon monoxide and 1.7 times the nicotine.42 WPS is associated with features of dependence, such as drug-seeking behaviour, inability to quit despite repeated attempts, and abstinence-induced withdrawal that is suppressed by subsequent waterpipe use.43 Sharing the waterpipe, a popular practice among youth worldwide, can be associated with infectious disease risks, such as tuberculosis.44,45 Waterpipe smoking-related emissions can harm non-smokers; for example, studies have shown that waterpipe smoking generates high levels of toxicants/carcinogens (e.g. volatile organic compounds, polycyclic aromatic hydrocarbons, metals, carbon monoxide and particulate matter) in the surrounding air, putting non-smokers at risk.46,47 Finally, evidence suggests that waterpipe smoking can undermine tobacco control, because it can be used as a replacement for cigarettes among quitters or serves as a gateway to cigarette initiation.44

3.27.6 Kreteks

Kreteks are cigarettes that contain a combination of cloves and clove oil, tobacco and other additives. Originating in Indonesia, where they account for about 90% of the market,27 a small number of brands are currently imported into Australia.

Although kreteks are smaller than typical cigarettes, they can deliver similar levels of nicotine and carbon monoxide to smokers.28 Gas chromatographic analysis of kreteks has revealed high levels of eugenol, anethole and coumarin compounds. The authors of one such study noted that compounds such as eugenol are known to be hazardous to humans when inhaled in high concentrations, and pose significant health concerns. The researchers concluded that usage of such compounds in smoking products, particularly at high levels, should be discouraged pending the availability of detailed toxicity information.29 Another analysis found that the levels of these compounds found in kreteks are significantly higher than those typically found in commercial cigarette brands.30 Long-term research on the health effects of smoking kreteks is scant, but it can be reasonably assumed that they pose at least the same dangers to health as conventional cigarettes. Popular use of these cigarettes in the US commenced in about 1980; by the mid-1980s warnings had begun to appear in the literature, notably so when 13 cases of severe illness with clove cigarette smoking were reported to the Centers for Disease Control and the California Department of Health Services; the clinical characteristics of these cases included haemorrhagic pulmonary oedema, pneumonia, bronchitis and hemoptysis (spitting up or coughing up of blood).31

Research from Indonesia has shown that regular kretek smokers have 13‒20 times the risk of abnormal lung function than non-smokers.32 Kretek use is associated with a higher risk of acute lung injury, particularly in susceptible individuals such as those with asthma or respiratory infections.33 There is also evidence that clove cigarettes are linked with greatly increased risk of dental disease. In a longitudinal study of more than 1000 male bus drivers in Jakarta, 27% of those who had smoked for 10 years or less had dental caries. This proportion increased to 79.6% among those smoking for 11–15 years and rose to 89.3% among those smoking for more than 15 years. People who smoked 7–12 cigarettes a day were more than twice as likely (RR 2.66, p<0.0001) to develop dental caries compared to those smoking 0–6 cigarettes a day. Those categorised as smoking either 13–18 cigarettes a day (RR 3.19, p<0.0001]) or more than 18 cigarettes a day (RR 2.96, p<0.0001) were three times more likely to do so.34

As previously noted, cloves contain a substance called eugenol, which when inhaled has the characteristics of a local anaesthetic. In the past this attribute has lent kreteks a reputation as soothing for sore throats and asthma,27 but in fact it can reduce the gag reflex, leading to pulmonary aspiration (when substances such as food or drink enter the lungs).33 The American Medical Association reviewed the medical evidence concerning clove cigarettes in 1988 and reached the following conclusions:
(i) clove cigarettes are tobacco products; therefore they possess all the harms associated with smoking tobacco cigarettes; and
(ii) inhaling clove cigarette smoke has been associated with severe lung injury in a few susceptible persons. People with asthma or with a throat or lung infection in its early stages may have an increased risk of harm from inhaling clove cigarette smoke.33

Kreteks are used by 2.4% of high school and 1.2% of middle school students in the US.35 Consumption patterns in Australia are not known.

3.27.7 Bidis (beedis, beedies, biris)

For information about bidis, see section 3.32.3

Relevant news and research

For recent news items and research on this topic, click here.(Last updated July 2020)


1. Australian Institute of Health and Welfare. 2010 National Drug Strategy Household Survey: survey report. Drug statistics series no. 25, AIHW cat. no. PHE 145. Canberra: AIHW, 2011. Available from: http://www.aihw.gov.au/publication-detail/?id=32212254712&libID=32212254712&tab=2

2. Auditor-General. Administration of tobacco excise. Audit report no. 55, 2001-02 Performance Audit. Canberra: Australian National Audit Office, Commonwealth of Australia, 2002. Available from: http://www.anao.gov.au/uploads/documents/2001-02_Audit_Report_55.pdf

3. American Lung Association. Tobacco Policy Trend Alert. An emerging deadly trend: waterpipe tobacco use. Washington DC: ALA, 2007. Available from: http://www.lungusa2.org/embargo/slati/Trendalert_Waterpipes.pdf

4. Knishkowy B and Amitai Y. Water-pipe (narghile) smoking: an emerging health risk behaviour. Pediatrics 2005;116(1):113-19. Available from: http://pediatrics.aappublications.org/cgi/reprint/116/1/e113.pdf

5. Maziak W, Ward KD, Afifi Soweid RA and Eissenberg T. Tobacco smoking using a waterpipe: a re-emerging strain in a global epidemic. Tobacco Control 2004;13(4):327–33. Available from: http://tc.bmjjournals.com/cgi/content/abstract/13/4/327

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7. Australian Institute of Health and Welfare. National Drug Strategy Household Survey, 2013 [computer file], 2015, Australian Data Archive, The Australian National University: Canberra.

8. US Department of Health and Human Services. The health consequences of smoking: a report of the Surgeon General. Atlanta, Georgia: US Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2004. Available from: http://www.cdc.gov/tobacco/data_statistics/sgr/index.htm

9. Aitken C, Fry TR, Grahlmann L and Masters T. Health perceptions of home-grown tobacco (chop-chop) smokers. Nicotine & Tobacco Research 2008;10(3):413-6. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18324558

10. Bittoun R. 'Chop chop' tobacco smoking [Letter]. Medical Journal of Australia 2002;177(2):686-7. Available from: http://www.mja.com.au/public/issues/177_11_021202/bittoun_021202.pdf

11. Lindorff K. Tobacco–time for action. National Aboriginal and Torres Strait Islander Tobacco Control Project. Final report. Canberra: National Aboriginal Community Controlled Health Organisation, 2002. Available from: http://www.weftweb.net/naccho/Files/NACCHO_Tobacco_report.pdf

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15.    Chang CM, Corey CG, Rostron BL, and Apelberg BJ. Systematic review of cigar smoking and all cause and smoking related mortality. BMC Public Health, 2015; 15(1):390. Available from: http://www.biomedcentral.com/1471-2458/15/390

16. McCormack V, Agudo A, Dahm C, Overvad K, Olsen A, Tjonneland A, et al. Cigar and pipe smoking and cancer risk in the European prospective investigation into cancer and nutrition. International Journal of Cancer 2010;127(10):2402–11. Available from: http://onlinelibrary.wiley.com/doi/10.1002/ijc.25252/pdf

17. Boffetta P, Nyberg F, Agudo A, Benhamou E, Jockel K, Kreuzer M, et al. Risk of lung cancer from exposure to environmental tobacco smoke from cigars, cigarillos and pipes. International Journal of Cancer 1999;83(6):805-6. Available from: http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-0215(19991210)83:6%3C805::AID-IJC18%3E3.0.CO;2-I/pdf

18. Higgins IT, Mahan CM and Wynder EL. Lung cancer among cigar and pipe smokers. Preventive Medicine 1988;17(1):116-28. Available from: http://www.ncbi.nlm.nih.gov/pubmed/3362797

19. Bertuccio P, La Vecchia C, Silverman D, Petersen G, Bracci P, Negri E, et al. Cigar and pipe smoking, smokeless tobacco use and pancreatic cancer: an analysis from the International Pancreatic Cancer Case-Control Consortium (PanC4). Annals of Oncology 2011;22(6):1420-6. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21245160

20. Iodice S, Gandini S, Maisonneuve P and Lowenfels AB. Tobacco and the risk of pancreatic cancer: a review and meta-analysis. Langenbecks Arch Surg 2008;393(4):535-45. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18193270

21. Campaign for Tobacco-Free Kids. The rise of cigars and cigar-smoking harms. Factsheet. Washington, DC: CTFK, 2011. Available from: http://www.tobaccofreekids.org/research/factsheets/pdf/0333.pdf

22. Australian Institute of Health and Welfare. National Drug Strategy Household Survey, 2004, computer file, Editor. Canberra: Australian Social Science Data Archive, The Australian National University, 2005.

23. Australian Institute of Health and Welfare. 2010 National Drug Strategy Household Survey: survey report. Drug statistics series no. 25, AIHW cat. no. PHE 145.Canberra: AIHW, 2011. Available from: http://www.aihw.gov.au/publication-detail/?id=32212254712&libID=32212254712&tab=2

24. Tverdal A and Bjartveit K. Health consequences of pipe versus cigarette smoking. Tobacco Control 2011;20(2):123-30. Available from: http://tobaccocontrol.bmj.com/content/20/2/123.abstract

25. Rodriguez J, Jiang R, Johnson W, MacKenzie B, Smith L and Barr R. The association of pipe and cigar use with cotinine levels, lung function, and airflow obstruction: a cross-sectional study. Annals of Internal Medicine 2010;152(4):201–10. Available from: http://www.annals.org/content/152/4/201.long

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30. Maziak W, Ward KD and Eissenberg T. Interventions for waterpipe smoking cessation. Cochrane Database of Systematic Reviews 2007(4) Available from: http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD005549/frame.html

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35. Asfar T, Ward K, Eissenberg T and Maziak W. Comparison of patterns of use, beliefs, and attitudes related to waterpipe between beginning and established smokers. BMC Public Health 2005;5(19):doi:10.1186/1471-2458-5-19. Available from: http://www.biomedcentral.com/1471-2458/5/19

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37. Akl E, Gaddam S, Gunukula S, Honeine R, Jaoude P and Irani J. The effects of waterpipe tobacco smoking on health outcomes: a systematic review. International Journal of Epidemiology 2010;39(3):834–57. Available from: http://ije.oxfordjournals.org/cgi/content/full/39/3/834?view=long&pmid=20207606

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41. Shihadeh A and Saleh R. Polycyclic aromatic hydrocarbons, carbon monoxide, 'tar', and nicotine in the mainstream smoke aerosol of the narghile water pipe. Food and Chemistry Toxicology 2005;43(5):655-61. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15778004

42. Eissenberg T and Shihadeh A. Waterpipe tobacco and cigarette smoking: direct comparison of toxicant exposure. American Journal of Preventive Medicine 2009;37(6):518–23. Available from: http://www.ajpm-online.net/article/PIIS0749379709005832/fulltext

43. Maziak W, Rastam S, Ibrahim I, Ward KD, Shihadeh A and Eissenberg T. CO exposure, puff topography, and subjective effects in waterpipe tobacco smokers. Nicotine & Tobacco Research 2009;11(7):806-11. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19420278

44. Steentoft J, Wittendorf J and Andersen JR. Tuberculosis and water pipes as source of infection. Ugeskrift for Laeger 2006;168(9):904-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16513054

45. Munckhof W, Konstantinos A, Wamsley M, Mortlock M and Gilpin C. A cluster of tuberculosis associated with use of a marijuana water pipe. International Journal of Tuberculosis and Lung Disease 2003;7(9):860-5. Available from: http://www.ncbi.nlm.nih.gov/pubmed/12971670

46. Fromme H, Dietrich S, Heitmann D, Dressel H, Diemer J, Schulz T, et al. Indoor air contamination during a waterpipe (narghile) smoking session. Food and Chemistry Toxicology 2009;47(7):1636-41. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19394392

47. Saade G, Seidenberg AB, Rees VW, Otrock Z and Connolly GN. Indoor secondhand tobacco smoke emission levels in six Lebanese cities. Tobacco Control 2010;19(2):138-42. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20378588

48. Maziak W. The waterpipe: time for action. Addiction 2008;103(11):1763-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18778388