While a great deal remains unknown about the long-term health effects of e-cigarette smoking, two recently published medical research studies are shedding more light on the subject. Two specific risks have been identified: heart disease and childhood asthma.

The first study was published in the March 2017 Journal of the American Medical Association Cardiology. The study involved 42 subjects, 23 of whom were e-cigarette users. Researchers found that those who habitually used e-cigarettes suffered from oxidative stress (an impaired ability of the body to ward off cell-damaging free radicals) and elevated levels of adrenaline in the heart muscle. Oxidative stress has long been associated with heart disease, while high levels of coronary adrenaline can cause rapid heartbeat and hypertension – two risk factors for heart attack.

Although the evidence is compelling, lead author Dr. Holly Middlekauff warns that the results show only an association between e-cigarette use and heart disease risk factors – not necessarily cause and effect. However, they do indicate that, contrary to industry claims, e-cigarettes are not necessarily a “safer” alternative to combustible tobacco cigarettes.

She says, “The results were a bit surprising because it is widely believed that e-cigarettes are less harmful than tobacco cigarettes…Instead, we found the same types of abnormalities in our e-cigarette users that are reported in tobacco cigarette users, and these abnormalities are associated with increased cardiac risk. The key finding from our study is that e-cigarettes have real, adverse physiologic effects that have been associated with heart disease.”

Dr. Middlekauf acknowledges that “…most studies show that carcinogens are present at much lower levels in e-cigarettes compared to tobacco cigarettes,” but adds that “We do not know if a tobacco cigarette smoker is better off switching to e-cigarettes.” In order to learn more about these health dangers, the research team has begun comparing the effects of e-cigarettes to those from tobacco. In the meantime, she advises that “if you don’t already smoke tobacco cigarettes, don’t start using e-cigarettes – they are not harmless.”

Another study from Australia published just this week found an association between e-cigarette use by pregnant women and reduced lung function as well as an elevated risk for allergic asthma for her child. Lead researcher Dr. Pawan Sharma warns that their findings “show that e-cigarette use during pregnancy should not be considered safe.” The study, which involved the use of laboratory mice and human lung cells, was conducted at the University of Technology in Sydney. The findings are in line with an earlier study that found the use of e-cigarettes during pregnancy to pose risks to the fetus’ neurological development.