Assessing the comparability of toxic emissions reduction from heated tobacco aerosols relative to cigarette smoke: a scientific approach to bridging datasets

Heated tobacco products (HTPs) offer a reduced risk potential by avoiding combustion, thereby lowering toxic emissions. This study evaluated 34 heated tobacco stick (HTS) variants, each with different tobacco blends, using two heating devices to assess the comparability of 51 toxic emission reductions compared to combustible cigarette smoke. Aerosols and 1R6F reference cigarette smoke were generated under standardized conditions, and droplet or particle size distributions were measured. Toxic emission levels were analyzed using a proposed statistical approach to determine comparability. In vitro toxicological evaluation was performed using mutagenicity, genotoxicity, and cytotoxicity assays. Additionally, published data on Biomarkers of Exposure (BoE) were reviewed to assess whether reduced emissions corresponded to reduced human exposure at the category level. Overall, HTS emissions were reduced by 93.57% compared to cigarette smoke, with consistent reductions across blends and devices. HTS aerosols consistently showed significantly reduced in vitro biological activity compared to cigarette smoke, with reductions observed across all HTS types, devices, and sample phases, even at higher concentrations than those used for cigarette samples. Toxic emissions data from other HTP technologies in published literature were also reviewed, showing comparable reduced levels leading to consistent reductions in BoE. These findings suggest that the heat-not-burn principle provides substantial exposure reduction independent of product-specific attributes. The study supports the bridging of aerosol chemistry and toxicological datasets, and leveraging published BoE results across the HTP category, to streamline product assessments.