publications

Elevated toxicant yields with narghile waterpipes smoked using a plastic hose
Food and Chemical Toxicology, December 2007, http://dx.doi.org/10.1016/j.fct.2007.12.007
R. Saleh and A. Shihadeh

Abstract–The effect of hose permeability on toxicant yields for the narghile waterpipe is investigated with special reference to the recent adoption of plastic as a hose construction material. Measurements of air infiltration rates for 23 leather and plastic hoses representing 11 types commonly available in Beirut, Lebanon were made, revealing that while leather hoses allowed significant outside air infiltration during a puff – constituting up to 32% of the puff volume – plastic hoses were found to be air-tight, indicating that the smoke reaching the waterpipe user can be considerably more concentrated when delivered via a plastic hose. Total particulate matter (TPM), nicotine and carbon monoxide (CO) yields were compared when a waterpipe was machine smoked using a highly permeable leather and an air-tight plastic hose. It was found that the plastic hose resulted in similar yields of nicotine, but more than double the CO yielded with the highly permeable leather hose. Thus, even if narghile smokers titrate for nicotine intake, the use of a plastic hose will likely greatly increase exposure to CO, a major causative agent in cardiovascular disease.

Measurement of 16 polycyclic aromatic hydrocarbons in narghile waterpipe tobacco smoke
Food and Chemical Toxicology, In press, December 2007
E. Sepetdjian, A. Shihadeh, and N. Saliba

Abstract–An analytical method for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in the mainstream of narghile smoke is presented. The smoke was generated using a digital waterpipe smoking machine connected to the mouthpiece of a narghile that was loaded with 10 g of a popular flavored tobacco and kept alight with quick-light charcoal briquettes that are commonly used for this purpose. A standard smoking regimen consisting of 171 puffs of 530 ml volume and 2.6 s duration spaced 17 s apart was used, and the smoke condensates were collected on glass fiber filters. PAHs were extracted with toluene assisted by sonication. For purification, the extract was passed through a silica cartridge and eluted with hexane. The eluent was preconcentrated, reconstituted in acetonitrile, and analyzed using a GC-MS-SICP method. The method showed good selectivity, repeatability, accuracy and sensitivity. The limit of detection ranged from 15 and 96 ng for benzo[a]pyrene and indeno[123-cd]pyrene, respectively. It was found that a single narghile smoking session delivers approximately 50 times the quantities of carcinogenic 4-and 5-membered ring PAHs as a single 1R4F cigarette smoked using the FTC protocol. The pattern of PAH concentrations suggested that formation pathways differ from those of the cigarette, possibly reflecting the differing combustion conditions of the two smoking devices.

Comparison of trip average in-vehicle and exterior CO determinations by continuous and grab sampling using an electrochemical sensing method
Atmospheric Environment, Volume 41, Issue 28, 2007
L. Abi Esber, M. El-Fadel, A. Shihadeh

Abstract–In air quality monitoring studies, continuous sampling is capable of reflecting real time variation of gas levels, however, with a margin of uncertainty related to the response time of the sensor and to the speed of concentration fluctuation. In contrast, grab sampling allows the determination of average gas concentration over the whole sampling period eliminating thus the uncertainties associated with the continuous method. As studies of in-vehicle carbon monoxide (CO) exposure often show rapidly fluctuating CO levels and are increasingly using the continuous electrochemical sensing method, the present activity aims at validating the suitability of the latter method for this monitoring task. For this purpose, an electrochemical CO sensing monitor was used to continuously monitor CO level inside and outside of a vehicle moving in an urban area, and to analyze the content of concomitantly taken grab samples. Trip-average CO levels measured using the two testing methods were compared. For CO levels higher than the instrument detection limit (1 ppm), the observed percent difference between continuous and grab sampling results varied within a fairly acceptable range (0.6–15.4%). The regression of continuous sampling data against grab sampling data revealed an average error of 6.9%, indicating the suitability of the continuous electrochemical method for monitoring in-vehicle and exterior average CO concentration under typical urban traffic conditions.

In situ carbon monoxide, “tar,” and topography measurements for 20 narghile waterpipe smokers in natural settings using a novel smoke sampling device
M. Katurji and A. Shihadeh
13th Annual Meeting of the SRNT, Austin, Tx, February 2007

Abstract -This study reports in situ measurements of CO and “tar” intake of 20 narghile waterpipe smokers in Beirut cafés and homes using a novel real-time smoke sampling/topography instrument. Whenever a smoker draws a puff, approximately 2% the smoke is proportionally sampled from a special mouthpiece by a computer-controlled miniature pump. The sample passes through a particulate trap and into a Teflon bag for off-line chemical analysis. The instrument has been validated by attaching it to a laboratory waterpipe smoking machine and comparing mainstream and sampled smoke composition. By sampling the smoke as it is generated by real smokers in their natural settings, difficulties associated with reproducing smoker idiosyncrasies in laboratory smoking machine studies are avoided. Using this instrument, a pilot study was conducted in two cafés (n = 11 participants, 10 men, mean age = 27), and homes (n = 9 participants, 5 men, mean age = 24) in Beirut, Lebanon. The objectives of this study were to measure toxicant intake and smoker topography of waterpipe tobacco (ma’assel) smokers in their natural settings, and to compare these to previous toxicant yield data derived using a laboratory smoking machine. Results showed that smokers inhaled 111.4±0.11 milligrams CO (mean±standard error) and 350±120 milligrams “tar”. Mean smoking time, puff duration, interpuff interval, number of puffs, puff volume, and total inhaled smoke volume were 48±1.6 minutes, 2.8±0.06 seconds, 15.2±0.59 seconds, 178±9.4 puffs, 0.59±0.02 liters, and 95.6±4.7 liters, respectively. Inhaled CO and “tar” increased monotonically with smoked volumes (R-square of 0.58 and 0.64), with an average slope of 1.2 and 3.7 milligrams/liter respectively. These data are comparable to previous smoking machine study data, and confirm that - contrary to the widespread perception that the water bubbler renders the smoke safe for consumption - CO and “tar” intakes by narghile waterpipe smokers during a single use session are many times greater than those associated with a single cigarette.

Effect of smoke CO concentration and overall puff duration on CO boost in waterpipe smokers: direct evidence linking toxicant exposure and uptake
A. Shihadeh, S. Rustom, M. Katurji, W. Maziak, T. Eissenberg, K. Ward
World Conference on Tobacco OR Health, Washington DC, July 2006

Abstract -Despite its long history and widespread use, only recently have methods begun to be developed for studying waterpipe smoke chemistry. Using a “best estimate” waterpipe machine smoking method, a recent study found that a single smoking session yields staggering quantities of carbon monoxide. Given the tentative stage of waterpipe testing methods, the current study objectives were: 1) to validate whether the current machine smoking laboratory protocol (Shihadeh and Saleh, 2005) yields realistic levels of smoke CO, and 2) to determine whether smoke CO concentration indicates CO uptake by smokers, and how this depends on smoking topography parameters. A novel instrument was developed to simultaneously measure smoking topography and sample the inhaled smoke. It was attached to the waterpipes of 14 volunteers in a clinic in Aleppo, Syria. Participants were free to prepare and smoke a waterpipe using any method they choose. At the end of a smoking session, the sampled smoke was analyzed for CO concentration. Expired air CO was measured before and after each waterpipe use session to determine CO boost. CO boost in smokers ranged from 2-53 ppm (median boost = 13 ppm). The data showed that the higher the smoke CO concentration and the longer the overall puff duration, the greater the CO boost. This can be regarded as definitive evidence that users absorb the CO present in waterpipe smoke in a dose dependent manner. We also found that the smoking machine method results in a smoke CO concentration consistent with that of in vivo smokers.

Waterpipe tobacco smoking: health effects, research needs, and recommended action by regulators Advisory Note by the WHO Study Group on Tobacco Product Regulation, 2005 Tobacco smoking using a waterpipe: product, prevalence, chemistry/toxicology, pharmacological effects, and health hazards A monograph prepared for The WHO Study Group on Tobacco Product Regulation [document]

Polycyclic aromatic hydrocarbons, carbon monoxide, “tar”, and nicotine in the mainstream smoke aerosol of the narghile water pipe
Food and Chemical Toxicology, Volume 43, Issue 5, May 2005
Shihadeh, A. and Saleh, R.

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 (2004).  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.

Size distribution dynamics of a hygroscopic aerosol flowing through an isothermal wall tube with coupled heat and mass transfer: modeling and experimental validation [poster]
Poster presentation at the 24th Annual AAAR Conference, Austin, Tx, October 2005
Alan Shihadeh* and Rawad Saleh

Abstract - We present an experimental and computational study of a volatile continuum regime polydisperse aerosol flowing through a constant wall temperature tube. Following Finlay and Stapleton (1995) a Lagrangian numerical method for simulating 2-way coupled heat and mass transfer between the aerosol droplets, bulk phase, and tube wall was developed to predict hygroscopic growth or shrinkage. The aerosol particle size distribution is discretized using a moving grid in which each bin is characterized by a single particle volume that is allowed to change in accordance with the coupled heat/mass transfer model. Wall heat and mass transfer is approached using a boundary layer formulation. Computations are compared to experimental data generated with a nebulized saline solution flowing through a heated constant wall temperature tube. The initial size distribution of the nebulized saline particles is determined using the residual method with a QCM cascade impactor. The evolution of the bulk temperature of the aerosol as it travels through the tube is measured for a variety of flow conditions and saline concentrations, and is compared to predictions from the 2-way coupled model. By using bulk-phase temperature as the primary diagnostic, a number of practical difficulties – which have thus far hindered presentation of experimental data for this fundamental problem – associated with analyzing a volatile aerosol are avoided. The experimental setup and data are presented which can be used to validate computational models of flowing hygroscopic aerosols, including Finlay and Stapleton’s 2-way model which has been used to predict hygroscopic particle growth for lung deposition calculations of inhaled aerosols.

A closed-loop control “playback” smoking machine for generating mainstream smoke aerosols
J. Aerosol Medicine, Volume 19, Issue 2, 2006
Shihadeh, A. and Azar, S.

Abstract - A first generation smoking machine capable of reading and replicating detailed puffing behavior from recorded smoking topography data is presented. Unlike standard smoking machines, which model human puffing behavior as a steady periodic waveform with a fixed puff frequency, volume, and duration, this novel machine generates a mainstream smoke aerosol by automatically "playing-back" puff topography recordings. Because combustion chemistry is highly non-linear, representing real smoking behavior with a smoothed periodic waveform may result in a tobacco smoke aerosol with a significantly different chemical composition and physical properties than that generated by a smoker.  The machine presented here utilizes a rapid closed-loop control algorithm coded in Labview® to generate smoke aerosols for toxicological assessment and inhalation studies. To illustrate its use, dry particulate matter and carbon monoxide yields generated using the playback and equivalent periodic puffing regimens are compared for a single smoking session by a 26 year old male narghile water-pipe smoker.  It was found that the periodic puffing regimen yielded 20% less CO than the played-back smoking session, indicating that steady periodic smoking regimens, which are widely used in tobacco smoke research, may not produce realistic smoke aerosols.

Investigation of mainstream smoke aerosol of the argileh water pipe
Food and Chemical Toxicology, Volume 41, Issue 1, January 2003
Alan Shihadeh

Abstract - A first-generation smoking machine and protocol have been developed in order to study the mainstream smoke aerosol and elucidate thermal-fluid processes of the argileh water pipe. Results using a common mo'assel tobacco mixture show that, contrary to popular perceptions, the mainstream smoke contains significant amounts of nicotine, ''tar'' and heavy metals. With a standard smoking protocol of 100 puffs of 3 s duration spaced at 30-s intervals, the following results were obtained in a single smoking session: 2.25 mg nicotine, 242 mg nicotine-free dry particulate matter (NFDPM), and relative to the smoke of a single cigarette, high levels of arsenic, chromium and lead. It was found that increasing puff frequency increased the NFDPM but had little effect on nicotine delivery, while removing the water from the bowl increased by several-fold the nicotine, but had little effect on NFDPM. It was also found that the charcoal disk heat source contributed less than 2% of total particulate matter (TPM), and that characteristic temperatures of the tobacco varied from 450 deg C nearest the heat source to 50 deg C furthest away, indicating that the NFDPM is likely a result of devolatilization rather than chemical reaction, and will thus differ significantly in composition from that of cigarette smoke.

New Research: Narghile Smokers Exposed to Dangerous Chemicals [english] [arabic]
Press Release, February 2003

Two new studies conducted by researchers at the American University of Beirut and St. Joseph University in Beirut show that narghile smoke contains significant quantities of the same chemicals which make cigarette smoke harmful. The findings contradict the commonly held belief that the water of the narghile water pipe renders the smoke harmless

Towards a topographical model of argileh water-pipe café smoking [english]
Pharmacology, Biochemistry and Behavior, Vol 79/1, September 2004
Alan Shihadeh, Sima Azar, Charbel Antonios, Antoine Haddad

Abstract–A pilot study of argileh water-pipe smokers in a café in the Hamra neighborhood of Beirut, Lebanon was conducted in order to develop a preliminary model of argileh water-pipe smoking behavior for use in laboratory smoking machine studies. The model is based on data gathered from smoking sessions of 30 minutes or longer duration from 52 smoker volunteers using a differential pressure puff topography instrument developed for the pulsating, high-flow water-pipe, as well as anonymous visual observations of 56 smokers in the same café. Results showed that the “average” water pipe smoking session consists of 171 530 ml puffs of 2.6 s duration at a frequency of 2.8 p/min. The results indicated that previous toxicological assessment of argileh smoke that assumed a smoking session consisting of 100 300 ml puffs probably underestimated the amount of “tar” and nicotine produced in a single smoking session.

A portable, low-resistance puff topography instrument for pulsating, high flow smoking devices
Behavior Research Methods, Instruments, & Computers, Volume 37, Issue 1, 2005
Alan Shihadeh, Charbel Antonios, Sima Azar

Abstract– A smoking topography instrument appropriate for pulsating high flow rate smoking devices such as the argileh water pipe has been developed and tested. Instrument precision and repeatability was determined using a digitally controlled smoking machine, and the added draw resistance due to the topography instrument was measured over the range of expected puff flow rates. The maximum error in any topography variable was found to be less than 5%. The instrument was successfully demonstrated in a pilot field study of 30 volunteer argileh smokers. The pilot study yielded an average smoker puff volume, duration, and interpuff interval of 0.53 l, 2.47 s, 16.28 s, respectively.