After studying the harm reduction offered by e-cigarettes in 2015, three years later, the UK Department of Health undertook a study on heated tobacco products. After consulting all the available scientific literature on this subject at the time, he found that the results of the various works had to be treated with caution, especially because only 20 of the 843 studies identified had followed the scientific peer validation process. Of those 20 studies, 12 were funded by the tobacco industry itself.
A few days ago, a new study was done on the subject. Conducted by the Institut français du cancer (INCa) and the Institut français de recherche en santé publique (IResP), it aimed to compare the chemical composition and toxicological effects of heated tobacco products, electronic cigarette vapour and traditional cigarette smoke.
The methodology of their survey:
The materials used for the experiment are:
IQOS, like a heated tobacco product. In the following graphs, it is referred to as http (Heated Tobacco Product), for heated tobacco products.
A common model of electronic cigarette equipped with a resistance of 2.6 ohms used at a power of 4.6 W, and a box operating with a resistance of 0.5 ohms at 18W and 30W, the powers recommended by the manufacturer according to the resistors used.
A classic tobacco cigarette.
To perform the experiment, the same smoker (Vitrocell® VC1) was used for the different types of products. The profile has been set to "intense", which corresponds to a 55 ml burst that lasts 2 seconds every 30 seconds. This profile allows you to smoke a cigarette completely in 10 puffs and finish an IQOS stick in 12 inhalations. Regular vapers also participated in the study to vape under the same conditions as the smoking machine and confirmed the “lack of dry blows and sufficient steam production”.
Each sample was repeated 4 times. Non-sampled measurements were also performed as recommended by the protocol for this type of study.
Research focused on the identification and quantification of carbonylated compounds and polycyclic aromatic hydrocarbons (PAHs). These two groups of molecules are among the main compounds released during the combustion of tobacco and contribute “significantly” to the carcinogenic effects of tobacco smoke, as the authors point out.
As the study authors state, “15 compounds were quantified at concentrations 2 to 15 times higher in cigarette smoke than in HTP aerosols.” Hexanal was the only compound measured at a higher level of PH emissions (22.1 ng/puff) than in 3R4F tobacco smoke (10.4 ng/puff), and benzaldehyde was produced in almost equal quantities by PH and cigarette.
However, the researchers also noted that all carbonylated compounds were measured in much lower quantities in the vapours of the various test conditions of the electronic cigarette than in tobacco products, with the exception of m-tolualdehyde and 2,5-Dimethylamine, which has only been detected in the Modbox aerosols, at low and high power.
Regarding these compounds, the scientists note that a puff of IQOS (35 μg/puff) produces 84.7% less carbonyl compounds than a puff of cigarette smoke (230 μg/puff). These results are consistent with previous studies, some of which were conducted by the manufacturer of IQOS, cigarette manufacturer Philip Morris International (PMI). However, the scientists note that “several harmful carbonyls have still been measured in the HTP aerosol, such as acetaldehyde and formaldehyde, which are carcinogenic compounds.”
Vaping produced at least 98.5% less of these compounds than IQOS. For the researchers, their production is the result of the thermal degradation of glycerol and propylene glycol contained in e-liquids. However, these compounds were “several times less” than emissions of QSIs or tobacco cigarettes.
The researchers came to the following conclusion:
Overall, our data shows that at normal vaporization temperatures, carbonyl levels in e-cigarette emissions are only a small fraction of the levels inhaled by tobacco users.”
Similar to carbonyl compounds, researchers noted that 21 compounds were “significantly lower” in IQOS emissions than in cigarette smoke, between 2 and 276 times lower, and were also “even lower” in e-cigarette aerosols.
Simply put, IQOS emitted 96.2% less PAHs than tobacco cigarettes, and vaping between 64.9% and 78.2% less than IQOS.
For the researchers, these results for vaping are explained, in particular, because these electronic liquids are “free of tobacco ingredients that contain the precursors to PAHs.”
In their conclusions, the researchers note that as part of efforts to reduce tobacco damage, in which smokers should ideally be able to freely choose between a variety of alternatives to smoking, new tobacco products (such as PH) and e-cigarettes seemed to have the potential for a promising new offering.
However, they say it is “fundamental” for smokers to know and compare the health risks of these various emerging options to determine which product to choose to quit.
They state that the heated tobacco product studied “releases slightly less nicotine and much lower amounts of carbonyl compounds and PAHs than tobacco cigarettes.”
However, they also note that “HTP emissions still contain carcinogens (e.g., formaldehyde, acetaldehyde, benzo[a]pyrene) and the amounts of carbonyles and PAHs are much higher than in e-cigarette vapours.”
Therefore, although IQOS has “reduced cytotoxicity” compared to cigarette smoke, it remains “higher” than in vaping.
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