From this article:In conclusion, E-cig exposure results in immunomodulatory effects that are similar to those observed after exposure to cigarette smoke. Since bacterial and viral exacerbations are major drivers of COPD disease progression, this study raises a concern that COPD patients who switch from cigarettes to E-cigs may not observe substantial improvement in their disease progression. Furthermore, popularity of E-cigs among teenagers is rapidly rising, which may lead to an emerging threat to public health with regards to recurrent bacterial or viral infections. Despite the common perception that E-cigs are safe, this study clearly demonstrates that E-cig use, even for relatively brief periods, may have significant consequences to respiratory health in an animal model; and hence, E-cigs need to be tested more rigorously, especially in susceptible populations.
From the Verge: David Peyton, a chemist at Portland State University who was not involved with the study, tells The Verge. "Critically, I would like to see this group follow up with no-nicotine e-cigarette fluid, I would like to see no flavoring at all, I would like to see ... the glycerine alone, and see what effects those have."
Though Peyton sees no problems with the study's protocols, its limited scope means that it's a starting point for a lot more research. "As a scientist there are a whole host of question that this study opens up."
And I agree. There are many different variables at play here, but the most important takeaway is that there appears to be some immunosuppressive effect from this ecig vapor. People are going to argue that it's so much better than cigarettes for you, and that's completely true. It's a great smoking cessation device, if you plan on actually quitting eventually. Many people switch to ecigs only to go on to be addicted to using ecigs. While that's ultimately much better for them than cigarettes, it's not better than using nothing at all.
Another problem is that there is a substantial rise in people simply starting with ecigs because they enjoy the flavoring or "cool factor." For ecigarette companies, this is great. For the consumer, not so much.
This is an actual, peer reviewed mouse model which is more definitive than in vitro models that have been done in the past. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0116861