Assessment of polycyclic aromatic hydrocarbons, carbon monoxide, nicotine, metal contents and particle size distribution of mainstream Shisha smoke

There is a widespread but unsubstantiated belief that the practice of smoking shisha products is relatively safe, which has led to resurgence in its use. This study aimed to characterise the mainstream smoke composition of three popular smoking products for shisha:, two that contain tobacco and one herbal, a tobacco-free product. A smoking machine was used to generate mainstream smoke from shisha in a series of controlled experiments using the three shisha smoking products. Each smoking session lasted 30 minutes and used 10g shisha product. The mainstream smoke was sampled and analysed for selected metals, nicotine, carbon monoxide (CO) and selected polycyclic aromatic hydrocarbons (PAHs). The particle size distribution of the shisha smoke was also determined. Levels for most metals in the mainstream smoke were found to be lower, or close to, the limit of detection (LOD) for all three smoking products. The main exceptions were copper (total yield of 1.3 and 2.3μg for the two tobacco-containing mixtures and 1.7μg for the herbal tobacco-free product) and zinc (yield ranged from 1.1μg for a tobacco-containing mixture to 2.1μg for the herbal product). Nicotine yields for the two tobacco-containing mixtures averaged 316 and 339μg per smoking session. PAHs were detected for all three shisha products, although yields for PAHs were generally less than the LOD of <0.02μg; the highest levels were observed for acenaphthene with the herbal tobacco-free product (total yield 17.3μg). CO levels in the mainstream smoke ranged from 800 to 1000ppm, suggesting a typical CO yield of 30mg per smoking session. The mass median aerodynamic diameter of the mainstream smoke ranged from 100-150nm. Results from this study appear to be different compared to other published studies, which could be owing to a number of factors such as shisha product type, smoking behaviour and measurement methods.