Introduction

Although cigarettes are the most common type of tobacco smoking worldwide, the centuries-old habit of narghile use has witnessed a resurrection not only in the Middle East, but also in other culturally-different parts of the world. There exist different types of narghile pipes with variation in material, size and shape. In the main, narghile pipes consist of a body, a bowl and a tube (Fig. 1). The body is made of glass or steel, is shaped like a decanter and is filled with water. The bowl is positioned within the body and is the site where tobacco is placed before being covered with a conical cap to protect the flame from extinction when smoked in an open space. The tube, being one or several, conveys the tobacco smoke from the bowl to the mouth.1 To smoke the narghile, tumbac (moistened raw tobacco) is covered with burning charcoal and placed on a tray on top of the pipe which, in turn, is connected to a glass bottle of water.2 On sucking, tobacco is drawn through the water and into the oral cavity either to be inhaled or blown away. More recent variations on this theme include the use of tobacco flavoured with molasses. This mixture is called tobamel (tobacco plus 'mel' for 'honey' in Latin) or mu'essel ('honeyed', in Arabic).3

Figure 1: A typical narghile pipe
figure 1

A typical narghile pipe

A number of synonyms have been used to describe narghile including water pipe, hookah, shisha, hubble bubble, argileh, sheesha, nargila, nargileh, mada'a and goza. In the present review, we shall refer only to the word narghile.

Narghile smoking has been practised for many centuries in Asia and Africa and the habit remains extremely popular today. The practice has a particularly high prevalence in the Middle East and some would argue that it has reached epidemic proportions.4,5,6,7

Interestingly, narghile smoking in the Middle East is more prevalent than cigarettes in both males and females,8 and it is thought that it may either precede the use of cigarettes, or be a substitute for cigarettes, because of cost savings.9 The habit appears to be common in females because they are currently being targeted as potential narghile users with advertising that emphasises the benefits of independence, stylishness, weight control, sophistication and power.5 In recent years, however, narghile smoking has become more common in western countries such as the UK and USA,7,9,10,11,12,13,14,15,16 a trend that most probably reflects the influx of immigrants to these countries together with globalisation.

Adverse health effects

Narghile smoking has a variety of adverse health effects. Aldehyde compounds found in narghile smoke are known to be toxic, carcinogenic and hazardous.17 By contrast to cigarette smoking, one session of narghile smoking is thought to release greater amounts of formaldehyde, acetaldehyde, acrolein propionaldehyde and methacrolein.17

Systemically, narghile smoking is associated with decreased pulmonary function leading to increased risk of chronic obstructive airway disease.18,19 Further, there have been reports of an association with certain types of cancer including bronchogenic carcinoma,20 oesophageal carcinoma,21 bladder cancer22 and pancreatic cancer.23

Significantly few studies have reported the effects of narghile smoking in the oral cavity.24 The habit is known to promote periodontal bone loss,25 and increase the possibility of acute osteitis (dry socket) after exodontias.26,27 Interestingly, no studies have reported an association between narghile smoking and oral candidiasis despite there being a positive correlation between tobacco smoking in general and increased oral carriage of Candida species.28,29,30,31 The association between narghile smoking and oral leukoplakia is tenuous at best and where it has been reported, there are obvious co-factors such as cigarette smoking and betel quid chewing that are present.32

Narghile and oral cancer

Oral squamous cell carcinoma (OSCC) is a world health problem and accounts for some 250,000 new cases each year worldwide, with the Indian subcontinent accounting for one third of the global burden. The 5-year survival for patients with OSCC is approximately 50% - a statistic that has changed little over the past 40 years.33 Primarily, the disease occurs in males in their sixth and seventh decades,34 but the demographics are changing, particularly in Europe, such that it is increasingly common in a younger cohort of patients.35,36,37,38 Between 1990 and 1999, the incidence of OSCC increased in males of all ages from 6.5 to 8.3 per 100,000 and in females from 2.6 to 3.6 per 100,000.39 Current thinking suggests that the increase in incidence of OSCC reflects changes in the pattern of exposure to certain risk factors.

OSCC is associated with many risk factors including tobacco and alcohol use, viral and candidal infections, immune suppression, genetic susceptibility, occupational hazards, dental health, diet and socioeconomic status.40 Primarily, however, the disease is associated with tobacco and alcohol,40,41 which act together in a synergistic way.42

Tobacco use occurs in many different forms. Smoking is the most common method of tobacco intake and occurs via the use of cigarettes, cigars, pipes, kreteks, bidis, and narghile. The habit of pipe smoking is becoming less common,43 but cigar smoking is increasingly popular and it is cautionary to note that cigars contain significantly higher concentrations of toxic and carcinogenic compounds than cigarettes.44 Bidis are small, brown, hand-rolled tobacco cigarettes rolled in tendu or temburni leaves and usually tied with a string at one end; they are primarily used in India and South East Asia.43 Kreteks are cigarettes with a blend of tobacco and cloves/oil of cloves; they contain approximately 60% tobacco and 40% ground clove buds and have a distinctive scent.43,45

The risks of smoking tobacco, however, are significantly compounded by 'reverse' smoking whereby the lighted end of a cigarette is placed within the oral cavity, a habit that is popular in South America.40

Smokeless tobacco (ST) refers to tobacco that is typically consumed orally but is not burned and includes chewing cut tobacco leaves, betel quids (tobacco, areca nut, lime and spices wrapped in the leaf of the betel vine), snus and snuff (moist ground tobacco).43

Non-combusted tobacco products are thought to carry lower disease risks compared with combusted tobacco products,46 but this is obviously dependent on the level of tobacco intake and the presence of other risk factors. Invariably, chewing tobacco leads to OSCC at the site where the tobacco is in contact with the oral mucosa (buccal sulcus and buccal mucosa) and contrasts with OSCC in smokers which is predominantly localised to the floor of the mouth, lateral border of the tongue and lingual aspect of the lower alveolus. A few cases of OSCC have been reported in users of narghile.47 It is thought that the development of oral cancers in narghile smokers is attributed to exposure to carcinogenic chemicals (described above), mechanical trauma (irritation by the bamboo or plastic tubes used in the mouth piece), the heat generated from the smoke and chronic infection that would be associated with the use of one narghile by several individuals.47 The link between narghile smoking and OSCC is interesting because there is a popular belief that the filtration of the tobacco smoke through water removes potential carcinogens. However, while water filtration removes water soluble aldehydes, it has little or no effect in removing the water insoluble constituents of tar. Current data show that there are greater concentrations of tar and its constituents in narghile smoke than cigarette smoke.48,49 Recent studies have shown that as little as three narghile smoking sessions exposes individuals to large quantities of carcinogenic polycyclic aromatic hydrocarbons,50 and a single narghile smoking session is equivalent to the formaldehyde released from 17 cigarettes and acetaldehyde from five cigarettes.17 Furthermore, narghile smokers appear to have a greater lifetime exposure to tobacco than ordinary smokers; for example, in Iran the average age to start cigarette smoking compared to narghile smoking is 14.5 ± 2.4 years versus 11.2 ± 1.5 years, respectively.51

Conclusion

In this review, we describe the adverse effects of narghile smoking. This is a growing habit particularly in the Middle East and is likely to have adverse consequences to western countries. Unfortunately, neither the oral side effects of the habit or the relationship of the practice to OSCC are well documented and warrant further study. We suggest that both medical and dental personnel should be alerted as to the potential dangers of the habit and appropriate preventative measures are introduced at government level to limit the consequences of this practice.