New ideas, old problems? Heated tobacco products - a systematic review

Heated tobacco products (HTPs) are a form of nicotine delivery intended to provide an alternative to traditional cigarettes. The aim of this systematic review was to present the current state of knowledge on HTPs with an emphasis on the potential impact of HTP use on human health. During the preparation of this systematic review, the literature on HTPs available within Medline/PubMed, EMBASE, CINAHL, ScienceDirect, and Google Scholar was retrieved and examined. In the final review, 97 research papers were included. The authors specifically assessed the construction and operation of HTPs, as well as the chemical composition of HTP tobacco sticks and the generated aerosol, based on evidence from experimental animal and cellular studies, and human-based studies.Heated tobacco products were found to generate lower concentrations of chemical compounds compared to traditional cigarettes, except for water, propylene glycol, glycerol, and acetol. The nicotine levels delivered to the aerosol by HTPs were 70-80% as those of conventional combustion. The results of in vitro and in vivo assessments of HTP aerosols revealed reduced toxicity, but these were mainly based on studies sponsored by the tobacco industry. Independent human-based studies indicated that there was a potentially harmful impact of the active and passive HTP smoking on human health. Currently, a large body of knowledge on HTP exposures and health effects is provided by the tobacco industry (52% of identified studies). Based on the available evidence, HTPs produce lower levels of toxic chemicals, compared to conventional cigarettes, but they are still not risk-free. Int J Occup Med Environ Health. 2019;32(5):595-634.