In lab mice, exposure to e-cigarette vapors for two weeks produced markers of blood nicotine comparable to those seen in people who smoke cigarettes and e-cigarettes. E-cigarette vapors also “produced mild effects on the lungs, including inflammation and protein damage,” notes Thomas Sussan of the Johns Hopkins Bloomberg School of Public Health, lead author of the study, published February 4 in PLOS ONE.
Inhaling free radicals, biologically harmful molecular fragments, may be responsible for the inflammation. Sussan’s group found that each vaping puff contains 700 billion free radicals, which ultimately triggered “a significant increase in oxidative stress.”
After two weeks of vaping, some mice were exposed to Streptococcus bacteria or influenza viruses. Compared with nonvaping mice, these mice were far less able to resist infection. Many became sick, and some even died from flu. No mice that had been breathing clean air died from their flu exposures.
Vaping’s impacts may trace to nicotine, Sussan’s group posits. However, the liquid solvent used to deliver nicotine in each e-cigarette puff also can be toxic to lungs. So even nicotine-free vaping might prove harmful, the authors conclude.