Emissions from conventional and electronic waterpipes relative to cigarettes and a heated tobacco product.

Harms associated with the use of smoked tobacco products, including waterpipes, are due to inhalational exposure to toxicants either present in tobacco or formed during the process of combustion. We assessed levels of 37 toxicants in aerosol emissions from conventional waterpipe heated with different charcoals and also with a heat management device (HMD), from the IQOS heated tobacco product (HTP), and the 'OOKA' electronic waterpipe. We also utilised literature data on toxicant yields in 3R4F reference cigarette smoke. When taking use patterns into account, toxicant yields were substantially lower in conventional waterpipe aerosol compared with cigarette smoke. Toxicant yields in electronic waterpipe aerosol were substantially lower than those in conventional waterpipe aerosol, both on a per session basis and when taking typical use patterns into account. Numerous toxicants in conventional waterpipe aerosol were absent in electronic waterpipe aerosol. In summary, during typical use conventional waterpipe emits fewer, and lower levels of, a number of toxicants relative to combustible cigarette smoke. In addition, electronically heating shisha further reduces toxicant levels, and many toxicants are absent in OOKA electronic waterpipe aerosol. These findings have important implications concerning toxicant exposure among waterpipe users, and for understanding how to potentially reduce health risks associated with waterpipe use.