E-cigarette exposure was found to impair immune responses in mouse model and researchers suggested that e-cigarettes may not be as safe as previously believed.
In a study with mice, Johns Hopkins Bloomberg School of Public Health researchers have found that e-cigarettes compromise the immune system in the lungs and generate some of the same potentially dangerous chemicals found in traditional nicotine cigarettes.
Senior author Shyam Biswal said that their findings suggest that e-cigarettes are not neutral in terms of the effects on the lungs and they have observed that they increase the susceptibility to respiratory infections in the mouse models. This warrants further study in susceptible individuals, such as chronic obstructive pulmonary disease (COPD) patients who have switched from cigarettes to e-cigarettes or to new users of e-cigarettes who may have never used cigarettes.
Lead author Thomas Sussan said that e-cigarette vapor alone produced mild effects on the lungs, including inflammation and protein damage, but when this exposure was followed by a bacterial or viral infection, the harmful effects of e-cigarette exposure became even more pronounced. The e-cigarette exposure inhibited the ability of mice to clear the bacteria from their lungs, and the viral infection led to increased weight loss and death indicative of an impaired immune response.
As part of their study, the researchers also determined that e-cigarette vapor 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. Cigarette smoke contains 1014 free radicals per puff.
Sussan added that they were surprised by how high that number was, considering that e-cigarettes do not produce combustion products. Granted, it's 100 times lower than cigarette smoke, but it's still a high number of free radicals that can potentially damage cells.
The findings are published in the journal PLOS ONE.