After a comprehensive investigation of e-cigarettes based on 800 studies, the National Academies of Sciences, Engineering, and Medicine concluded that their use may lead youth to start smoking and adults to stop smoking.
While exposure to nicotine from e-cigarettes is variable, there was substantial evidence that nicotine intake from e-cigarettes among experienced adult users can be comparable to that from cigarettes. There was also conclusive evidence that in addition to nicotine, most e-cigarettes contain and emit numerous potentially toxic substances. But except for nicotine, exposure to potentially toxic substances from e-cigarettes seemed significantly lower compared with cigarettes.
Substituting e-cigarettes for conventional cigarettes reduces users’ exposure to many toxicants and carcinogens and reduces short-term adverse health outcomes in several organ-systems, but causes increased coughing and wheezing in adolescents and an increase in asthma exacerbations.
Links with other diseases require more study.