Polycyclic aromatic hydrocarbons, carbon monoxide, “tar”, and nicotine in the mainstream smoke aerosol of the narghile water pipe

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Abstract

A smoking machine protocol and yields for “tar”, nicotine, PAH, and CO are presented for the standard 171-puff steady periodic smoking regimen proposed by Shihadeh et al. [Shihadeh, A., Azar, S., Antonios, C., Haddad, A., 2004b. Towards a topographical model of narghile water-pipe café smoking: A pilot study in a high socioeconomic status neighborhood of Beirut, Lebanon. Pharmacology Biochemistry and Behavior 79(1), 75]. Results show that smokers are likely exposed to more “tar” and nicotine than previously thought, and that pyronsynthesized PAH are present in the “tar” despite the low temperatures characteristic of the tobacco in narghile smoking. With a smoking regimen consisting of 171 puffs each of 0.53 l volume and 2.6 s duration with a 17 s interpuff interval, the following results were obtained for a single smoking session of 10 g of mo’assel tobacco paste with 1.5 quick-lighting charcoal disks applied to the narghile head: 2.94 mg nicotine, 802 mg “tar”, 145 mg CO, and relative to the smoke of a single cigarette, greater quantities of chrysene, phenanthrene, and fluoranthene. Anthracene and pyrene were also identified but not quantified. The results indicate that narghile smoke likely contains an abundance of several of the chemicals thought to be causal factors in the elevated incidence of cancer, cardiovascular disease and addiction in cigarette smokers.

Introduction

Studies on the chemical composition, toxicity, and carcinogenicity of cigarette smoke generated using a smoking machine are widely used to predict and understand health effects of smoking, and to compare effects of varied tobacco blends, delivery methods, and puffing behavior. They complement in-vivo and epidemiological studies of smoking and have contributed significantly to a better understanding of cigarette smoke toxicity and carcinogenicity (Hoffmann et al., 2001) and to generating the evidence needed for anti-tobacco policies and action. More than 4800 compounds, including 69 carcinogens, have been identified in cigarette smoking machine studies that span a period of more than 40 years (Hoffmann et al., 2001). In contrast, we have been able to locate only four studies (Rakower and Fatal, 1962, Hoffman et al., 1963, Sajid et al., 1993, Shihadeh, 2003) of the chemistry of narghile smoke in the open English-language literature, in which a comparatively small range of chemical compounds were investigated. In none of these studies are CO or PAH, two major toxic agents in tobacco smoke, quantified using relevant narghile smoking parameters.

This relative paucity in research on narghile smoke chemistry cannot be attributed to the insignificance of the topic. The narghile water-pipe is prevalent in Southwest Asia and North Africa, and in recent years has shown a sharp rise in popularity particularly among young people (Chaaya et al., 2004). National and local surveys in Kuwait (Memon et al., 2000), Egypt (Mohamed et al., 2003), Syria (Maziak et al, 2004), and Lebanon (Shediac-Rizkallah et al., 2002, Jabbour, 2003) have found that 20–70%, and 22–43% of the sampled populations has ever smoked or currently smokes the narghile, respectively. Anecdotal evidence in the form of newspaper reports (e.g. McNicoll, 2002; Landphair, 2003, Edds, 2003, Gangloff, 2004) and “hookah bar” advertisements in college papers and on the internet suggest that water-pipe smoking is catching on in North America and Europe as well.

With a dearth of scientific studies, researchers, public health officials, and the general public have had little data to assess the potential hazards of water-pipe smoking. Even so, a widespread perception among smokers, and even physicians (Kandela, 1997), is that the water through which the smoke bubbles filters the toxic components, rendering the practice considerably less harmful than cigarette smoking.

While it is tempting to do so because of the sheer volume of available cigarette smoke data, the water-pipe is so different from the cigarette that data on smoke composition and toxicity cannot be extrapolated from the later to the former. Apart from the obvious differences in smoke delivery, involving long passages and a water bubbler in the case of the narghile, the smoke aerosol generation process is also considerably different. Whereas the cigarette involves a self-sustaining combustion of roughly 1 g of dried and shredded tobacco in several puffs with volumes on the order of tens of ml, the argileh utilizes an external heat source (charcoal) to largely devolatalize typically 10–20 g of heavily flavored and hydrated tobacco paste (in the case of mo’assel tobacco; see Shihadeh (2003) for a description of narghile components and typology) with puff volumes an order of magnitude greater and with characteristic tobacco temperatures several hundreds of degrees Celsius lower. Thus there is a need for developing research methods and smoke composition data specific to the narghile water-pipe.

Our previous work (Shihadeh, 2003) on the mainstream narghile smoke chemistry showed that it contains significant amounts of “tar” and nicotine, and that even for the same total smoked volume, the results varied considerably depending on the machine puffing regimen used. We also found that while the “tar” of a single narghile smoking session was startlingly high, typically two orders of magnitude greater than that produced from a single cigarette, it was likely to have a different composition due to the much lower temperature of the tobacco in the narghile. We anticipated therefore that the proportion of pyrosynthesized 4- and 5-ring PAHs responsible for much of the carcinogenicity of “tar” should be considerably lower than for cigarettes. It was also found that approximately 5 g of charcoal were consumed in the course of a single smoking session, suggesting the possibility of large quantities of carbon monoxide being delivered to the smoker.

The current study follows up on these issues. The objectives were to (1) provide new data for “tar” and nicotine using an updated, and considerably more intense, puffing model which was derived from precise smoking topography measurements of 52 smokers in the field, (2) quantify the amount of CO delivered to the smoker, and (3) quantify PAH in the particulate phase so as to allow an informed interpretation of the high quantities of “tar” with respect to carcinogenic PAH compounds.

Section snippets

Smoking machine

A first-generation digitally programmable smoking machine was developed for this study (see Fig. 1). The programmable inputs to the smoking machine include puff duration, flow rate, interpuff interval, and total number of puffs. The smoking machine relies on a high-flow vacuum pump which is modulated by an electronic proportional control valve. The control valve signal is generated using feedback control provided by a PC-based data acquisition and control (DAQ) system. The feedback is provided

TPM and tobacco consumed

The average TPM for the 32 replicate smoking sessions was 1.38 ± 0.26 g (mean ± standard deviation), while the average tobacco consumed was 4.7 ± 0.4 g. The wide range of tobacco consumed for the 32 replicate sessions probably reflects inherent variability in hand-packing the tobacco mixture in the narghile head, as well as differences in the burning history of the charcoal disk caused by the varying degrees of coal fracture, disintegration, and migration on the head which resulted from its “drumming”

Discussion

Using a smoking model based on detailed smoking topography field measurements, new data have been generated on the composition of smoke from a narghile loaded with 10 g of mo’assel tobacco mixture, and fueled with 1.5 quick-lighting charcoal disks applied in such a manner as to give realistic aerosol production rates and tobacco burn fractions. As expected, the updated smoking model, which prescribes a more intensive smoking regimen than used in our earlier study, resulted in significantly

Acknowledgments

The authors acknowledge Carol Sukhn, Sana’ Fayad, and Osan Nashalian of the Core Environment Laboratory at the American University of Beirut for carrying out the GC-MS and HPLC analyses. The authors also acknowledge the role of Sima Azar in developing the smoking machine and Nour El Lababidi and Ahmad Dahrouj in helping execute the smoking machine study. This work was funded by the University Research Board at the American University of Beirut, and by the Research for International Tobacco

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