Heat-Not-Burn Tobacco Products: The Devil in Disguise or a Considerable Risk Reduction?

Background: Heat-not-burn (HNB) tobacco products are not burnt but instead are inserted into a tobacco-heating system, which heats the tobacco at temperatures below that required to initiate combustion. This mechanism potentially results in significantly reduced concentrations of heat-generated toxicants in the inhalable aerosol.Method: The margin of exposure (MOE) approach was applied for quantitative risk assessment. The MOE is defined as the ratio between the toxicological threshold and the estimated human intake of the same compound. The higher the MOE, the lower the risk of a compound.Findings: The MOEs were increased by factors of 3 to 415 for the most toxic compounds in tobacco smoke, comparing use of HNB with smoking conventional tobacco products. The combined MOE for all compounds was increased 23-fold, excluding nicotine, or 10-fold including nicotine. Thus, the overall risk for cumulative toxic effects was markedly lower for HNB products.Conclusions: HNB tobacco reduced the risk of exposure to 9 out of the 20 most toxic compounds in tobacco beyond an MOE threshold of 10,000. While our results show that use of HNB products leads to a considerable risk reduction compared to conventional tobacco, the products cannot be considered completely “risk-free” due to risk of exposure to the remaining toxicants with MOE below the threshold.