Shisha smoking, nickel and chromium levels in Tunisia

Abstract

In a recent study published in this journal, the authors credit researchers from the US–Syrian Centre for Tobacco Studies for stating that “the medical hypothesis that the mainstream smoke, the one inhaled by the user, from water pipes (mainly: shisha, hookah, narghile) causes oral cancer is certainly acceptable (Rastam et al. 2010)” (Khlifi et al. 2013). If, on the one hand and for one decade now, the shisha (hookah, narghile) issue had not been the subject of a global confusion of concepts and methods never witnessed before nor elsewhere in the biomedical field (Chaouachi 2013), this would not have any great importance. However and on the other hand, the above sentence is unfortunately the one that heralds a critical article exposing a series of serious errors in relation to shisha smoking and oral cancer hypotheses, to be found in the very US–Syrian paper cited by the Tunisian team (Chaouachi and Sajid 2010). The Tunisian study found high levels of chromium and nickel blood levels among subjects when compared to controls. One explanation is that all subjects were residents of the Sfax region, known for the environmental impact of its industrial activity which includes an important phosphate treatment plant. However, the control for other risk factors (smoking in particular) is quite interesting as one particular popular form of the latter, shisha, could be suspected for being a source of heavy metals. Such a hypothesis is interesting because, since the early mid-1990s, shisha users have begun to use, in Tunisia in particular, stainless metal bowls (top of the pipe locally named “ra’s” for “head” or “keskes” for “sieve” because of its holes) and aluminium tin foil (cookware type) over it. The function of the latter is that of a thermal screen (temperatures inside the bowl barely exceeding 200 °C) between the glowing charcoal at the top of the bowl and the smoking product inside it, thus offering a chemistry of smoke completely different from that generated by the much higher temperatures at the tip of a cigarette (900 °C). As in the case of the easily avoidable risk of CO poisoning in ill-ventilated places, public health recommendations based on the above assumption were issued in this respect as early as 2004 (Chaouachi 2005). However, there are still potential confusion factors regarding the shisha smokers themselves. The questionnaire used in the Tunisian study could be usefully enhanced. If the item about subjects’ preferred flavours does not appear of great importance, the following questions, by contrast, seem essential: