Evaluation of the Tobacco heating System 2.2. Part 3: Influence of the tobacco blend on the formation of harmful and potentially harmful constituents of the Tobacco heating System 2.2 aerosol

Introduction:
This article evaluates the impact of different tobacco blends on the formation of harmful and potentially harmful constituents (hPhCs) in the aerosol produced by the Tobacco heating System 2.2 (ThS2.2). The study aims to identify the clustering of hPhCs in the aerosols from different tobacco plug blends and to determine which tobacco types/tobacco blend compositions would result in the largest reductions of the yields of hPhCs in the mainstream aerosol.

Key Points:

* The study used 19 different tobaccos, which were blended and formed into tobacco sticks to produce different sensory perceptions when used in the ThS2.2.
* The tobacco stick was constructed by sequentially assembling the tobacco plug wrapped in paper over-wrap, a hollow acetate tube wrapped in paper over-wrap, a polymer-film filter wrapped in paper over-wrap, and a mouthpiece filter wrapped in paper over-wrap.
* The tobacco sticks were made of cast leaf containing the tobaccos and tobacco blends, humectants, and flavorings.
* The hPhCs in ThS2.2 aerosol produced by each type of tobacco were determined by performing tests using samples of each single tobacco, but the air-cured tobaccos aC1, aC2, aC4, and aC5 could not be tested because it was not possible to use these tobaccos to form cast leaf suitable for manufacturing tobacco plugs.
* The impact of blending beyond the typical usage level of different tobacco types was investigated using blends containing up to 40% of single grades of air-cured tobaccos, up to 40% of fire-cured tobacco, and up to 20% of filler tobacco.
* The selected tobaccos were homogenized and ground, then blended as required. Cast leaf was then formed from each blend, and tobacco plugs were produced from the different cast leaf materials.
* The compositions of the monitor blend (FR1) and the 43 different tobacco blends that were used (BL1 eBL43) are listed in Table 2.

Main Message:
The study found that the blend composition had minimal effects on the yields of most hPhCs in the aerosol. however, blends containing high proportions of nitrogen-rich tobacco, such as air-cured and some Oriental tobaccos, produced higher acetamide, acrylamide, ammonia, and nitrogen oxide yields than other blends. Most hPhCs were found to be released mainly through the distillation of hPhCs present in the tobacco plug or after being produced in simple thermal reactions. Therefore, the hPhC concentrations in the ThS2.2 aerosol may be further minimized by limiting the use of flue- and fire-cured tobaccos, which may be contaminated by hPhCs during the curing process, and carefully selecting nitrogen-rich tobaccos with low concentrations of endogenous hPhCs for use in the tobacco plug blend.

Schaller, Jean-Pierre, Johannes P.M. Pijnenburg, anu ajithkumar, and anthony R. Tricker. “Evaluation of the Tobacco heating System 2.2. Part 3: Influence of the Tobacco Blend on the Formation of harmful and Potentially harmful Constituents of the Tobacco heating System 2.2 aerosol.” Regulatory Toxicology and Pharmacology 81 (November 2016): S48–58. https://doi.org/10.1016/j.yrtph.2016.10.016.