== POV tag == 

 I've tagged the article with POV now. There are several unresolved threads relating content already here on the talk-page, and still more content is added to the article that relies on a single review. The changes to the lede, relating to this, such as a sentence such as: 
 :The e-cigarette aerosol delivers nicotine, ultrafine particles, other toxic chemicals, and carcinogens.[1] There is a poor relationship between labeled and existing nicotine content, as well as differing levels of other chemicals and toxicants in the e-liquid and aerosol.[1] 
 Is putting significant weight on something that i haven't seen other reviews do, and seem to indicate that some editors simply want to describe this topic as negatively as possible.