E-cigarettes compromise the immune system in the lungs and generate some of the same potentially dangerous chemicals found in traditional nicotine cigarettes, says a team of researchers including an Indian-origin scientist.
"Our findings suggest that e-cigarettes are not neutral in terms of the effects on the lungs," said senior author Shyam Biswal, professor at the Johns Hopkins Bloomberg School of Public Health in the US.
E-cigarettes are an emerging public health concern, as they gain popularity among current and former smokers as well as those who have never smoked, including teenagers.
The perception that e-cigarettes pose little health risk is so entrenched that some smokers, including those with chronic obstructive pulmonary disease (COPD), are switching from cigarettes to e-cigarettes, the researchers noted.
"We have observed that they increase the susceptibility to respiratory infections in the mouse models," Biswal noted.
For the study, researchers divided the mice into two groups: one was exposed to e-cigarette vapour in an inhalation chamber in amounts that approximated actual human e-cigarette inhalation for two weeks, while the other group was just exposed to air.
The mice exposed to e-cigarette vapour were significantly more likely to develop compromised immune responses to both the viral and the bacterial infections, the researchers found.
As part of their study, the researchers also determined that e-cigarette vapour contains "free radicals," known toxins found in cigarette smoke and air pollution.
Free radicals are highly reactive agents that can damage DNA or other molecules within cells, resulting in cell death.
The findings appeared in the journal PLOS ONE.