An <i>in vitro</i> estimation of pH of mainstream smoke from smoked tobacco products using a custom fabricated smoking device – A pilot study

Objectives: External factors, namely, nutrition, microorganisms, temperature, and cigarette use, have an impact on the oral pH. This influence is counteracted by saliva, which maintains the pH within the range of 6.2–7.6. One aspect contributing to this balance is tobacco preferences, which are influenced by delivery methods and popularity, ultimately leading to pH alterations. The aim of this study was to determine and compare the pH levels of the mainstream smoke emitted from three smoked tobacco products; beedis, filtered cigarettes, and unfiltered cigarettes. Material and Methods: The study comprises of three groups of 25 samples each: unfiltered and filtered cigarettes and beedis. A custom-fabricated apparatus was developed to estimate the mainstream smoke pH. The device consists of a disposable plastic container with two holes on top for flexible plastic tubing. One tubing end goes into distilled water while the other attaches to the heated tobacco product (HTP), directing smoke into the water. A 5 mL disposable syringe simulates inhalation, creating negative pressure in the water. The pH of the collected smoke was measured with a digital pH meter. The mainstream smoke was standardized using the international organization for standardization and federal trade commission cigarette filter test method smoking regimens, with one puff per minute, 35 mL volume over 2 s, to a defined butt length. Results: The study revealed that filtered and unfiltered cigarettes had lower pH levels than beedis, with acidic pH for cigarettes (unfiltered – 6.286, filtered – 6.057) and alkaline pH for beedis (7.253). Conclusion: According to the study, the pH of mainstream smoke from HTPs deviates from the physiological range of the oral cavity. Continuous exposure of saliva to this smoke not only interacts synergistically with carcinogens in these products but it is also one of the techniques employed by manufacturers for increasing absorption into the bloodstream.