Heated Tobacco Products: A Review of Current Knowledge and Initial Assessments

Abstract

The health risks of tobacco smoking have been documented in numerous studies and smoking rates have declined in developed countries over the last 50 years. Today, we know that cigarette smoking is the major cause of preventable deaths due to tobacco smoke induced diseases. As a consequence of an increased awareness of smoking-related health risks, heated tobacco products (HTPs) are marketed as reduced toxicant alternatives to conventional tobacco products. Manufacturers claim that levels of toxicants and hazardous compounds are significantly reduced, implying that inhalation of the modified aerosol is less harmful compared to conventional cigarettes. In this manuscript, previous assessments of HTPs are briefly summarized, including a short discussion on challenges with the adaption of standard analytical methods used for tobacco smoke. The reliability of analytical data is important for risk assessment approaches that are based on reduced toxicant exposure. In order to assess a putative reduction of health risks, an integrated study design is required that should include clinical studies and epidemiology data. One manufacturer applied for a classification as a Modified Risk Tobacco Product (MRTP) in the United States, based on extensive toxicological studies that have also been published. However, data are not yet sufficient for a reliable assessment or recognition of putatively reduced health risks. Challenges regarding a classification in Europe are also discussed briefly in this review.

Keywords: emissions; harm reduction; heated tobacco products; risk assessment; tobacco smoke.

Figure 1

Temperature zones in a combustible cigarette (A) in comparison to different Heated Tobacco Products (B).

Figure 2

Schematic overview of required data and studies to facilitate risk assessments of tobacco products. Epidemiological data are most conclusive but can usually only be used retrospectively. Therefore, risk assessments rely on models that consider emissions, pre-clinical and clinical studies. Meanwhile numerous studies on smoke chemistry and in vitro toxicology have been published by industry and independent researchers. In contrast, in vivo and clinical studies are far more complex. No sufficient independent data are available.