We look at the different studies being published, and assess the study design, the methods, the test products, and the scientific approach. Because it's all important to understanding the results.
The easiest way to look at this question about the toxicity of the Tobacco Heating System (THS) aerosol is to look at the FDA conclusions based on our scientific dossier. The FDA received all of our toxicological studies. These studies looked at the complete aerosol that is generated by THS. This aerosol includes the propylene glycol and the glycerin. In the end, the FDA concluded that overall, there was a lower toxic potential for THS despite the fact that there may be increases in some of the chemicals.
These two specific compounds, which are used to form the aerosol in e-cigarettes and THS, have been very well studied. It is important that these are of the appropriate chemical grade, and that any heating that takes place of these compounds is controlled. So, an e-cigarettes using a high-power setting, could heat the e-liquid at quite high temperatures, which could generate compounds like glycidol, which is a known toxin. But the levels of these compounds are extremely low in devices that are operating properly. So, it's unlikely that this is a major issue for THS and we would direct people to have a look at the recent review by UK Committee on Toxicity, where they reviewed e-cigarettes.