Evaluation of the Tobacco Heating System 2.2. Part 2: Chemical composition, genotoxicity, cytotoxicity, and physical properties of the aerosol

Abstract

The chemical composition, in vitro genotoxicity, and cytotoxicity of the mainstream aerosol from the Tobacco Heating System 2.2 (THS2.2) were compared with those of the mainstream smoke from the 3R4F reference cigarette. In contrast to the 3R4F, the tobacco plug in the THS2.2 is not burnt. The low operating temperature of THS2.2 caused distinct shifts in the aerosol composition compared with 3R4F. This resulted in a reduction of more than 90% for the majority of the analyzed harmful and potentially harmful constituents (HPHCs), while the mass median aerodynamic diameter of the aerosol remained similar. A reduction of about 90% was also observed when comparing the cytotoxicity determined by the neutral red uptake assay and the mutagenic potency in the mouse lymphoma assay. The THS2.2 aerosol was not mutagenic in the Ames assay. The chemical composition of the THS2.2 aerosol was also evaluated under extreme climatic and puffing conditions. When generating the THS2.2 aerosol under "desert" or "tropical" conditions, the generation of HPHCs was not significantly modified. When using puffing regimens that were more intense than the standard Health Canada Intense (HCI) machine-smoking conditions, the HPHC yields remained lower than when smoking the 3R4F reference cigarette with the HCI regimen.

Levels of selected analytes in the emissions of “heat not burn” tobacco products that are relevant to assess human health risks

“…Similar to the carbonyl compounds, the emissions of the volatile and semi-volatile compounds benzene, 1,3-butadiene, isoprene, styrene, and toluene were with a reduction of 97 to over 99% markedly lower when compared to combustible cigarettes (Table 1). The range of values found is again similar to the manufacturer’s data (Schaller et al 2016). To address consistency of nicotine and TPM release during the smoking procedure, the 12 puffs of the smoking protocol were divided into four intervals of three puffs each and analyzed separately.…”

“…Total particulate matter (TPM) was comparable to the manufacturer’s findings and higher than TPM from some combustible cigarettes. The yields of the carbonyl compounds formaldehyde, acetaldehyde, acrolein, and crotonaldehyde were, with a reduction of 80–96%, considerably lower when compared to combustible cigarettes (Table 1) and comparable to the published emissions observed by the manufacturer (Schaller et al 2016). Similar to the carbonyl compounds, the emissions of the volatile and semi-volatile compounds benzene, 1,3-butadiene, isoprene, styrene, and toluene were with a reduction of 97 to over 99% markedly lower when compared to combustible cigarettes (Table 1).…”

“…We displayed the lowest and the highest yields per analyte that could stem from different brands and calculated the corresponding reductions of our findings as averages of both stick variants. The levels of nicotine in this study were lower compared to the data provided by the manufacturer (Schaller et al 2016) and also lower but still in the same range compared to the conventional cigarettes (Counts et al 2005). Total particulate matter (TPM) was comparable to the manufacturer’s findings and higher than TPM from some combustible cigarettes.…”

“…The manufacturer has stated that the yield of harmful and potentially harmful constituents (HPHC) is reduced by about 90% compared to the 3R4F reference cigarette. Importantly, a reduction of more than 95% was reported for major carcinogens, including benzene and 1,3-butadiene, when emissions were generated using the Health Canada Intense smoking regimen (Schaller et al 2016). …”

iQOS: evidence of pyrolysis and release of a toxicant from plastic

“…Pyrolysis of tobacco is an endothermic reaction which occurs at temperatures between 200°C and 600°C, during which the majority of volatile and semivolatile components of cigarette smoke are formed 21 22. Although the Philip Morris study indicated that the aerosol produced by iQOS devices reduce the amount of chemicals found on the Food and Drug Administration’s Harmful and Potentially Harmful Constituents list by limiting tobacco pyrolysis,5 our study, showing charring, in conjunction with a study by Auer et al , which confirmed the presence of volatile organic compounds, polycyclic aromatic hydrocarbons, carbon dioxide and nitric oxide,23 contradict the claim that tobacco pyrolysis is minimised in iQOS. Although iQOS operates at temperatures less than 350°C, this does not negate the formation of volatile and semivolatile harmful constituents of tobacco smoke, which tend to have boiling points that range from 70°C to 300°C 21 22…”