The Effect of E-Cigarette Aerosol Emissions on Respiratory Health: A Narrative Review

Summary of Study

Bottom Line: This review of e-cigarette (EC) health effects furthers the consensus that ECs are significantly safer than cigarettes. The clinical evidence confirms that ECs are unlikely to raise significant health concerns for the respiratory tract under normal conditions of use. Studies that find otherwise are often flawed. Promoting further access to ECs may offer an opportunity to reduce or prevent some of the otherwise inevitable burden of respiratory morbidity and mortality caused by tobacco smoking.

Some regulators and health professionals have raised concerns that the respirable aerosols generated by ECs contain several constituents of potential toxicological and biological relevance to respiratory health. Many of these studies have faulty methodological quality and accuracy of their interpretation. Some findings must be questioned because in some studies the dosing was substantially higher than for weight-adjusted daily doses in humans.

There is potential for EC misinformation from poorly designed and largely misinterpreted experimental studies. As for the majority of existing observational and epidemiological studies, preclinical (i.e. in vitro systems and animal models) and clinical models can be also uninformative or even misleading due to problems with methodology and interpretation of these studies.

It is urgent to address common mistakes and to develop robust and realistic methodological recommendations in order to adequately assess the impact of EC use on human health under normal condition of use.

It is paramount to improve research methods, data quality and interpretation of study findings:

  • In relation to experimental in vitro and animal models, exposure studies must be representative of human inhalation exposure to e-cigarette aerosols under normal condition of use and include relevant controls.
  • In relation to human behavioral/market research, it is important to develop and standardize new questionnaires for improved assessments of dependence on e-cigarettes, patterns and frequency of use, as well as device characteristics.
  • In relation to clinical and epidemiological studies, it is mandatory to include as comparison groups individuals who continue to smoke, those who try to quit with other evidence-based tobacco cessation treatments, and those who are not users of tobacco products, including e-cigarettes.

EC users and smokers considering ECs have the right to be informed about the relative risks of EC use, and to be made aware that findings of studies published by the media are not always reliable.

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