Yesterday evening, I spent the evening with a friend working for a big tobacco name as a lab researcher. He saw me vaping and flat out told me that it was way worse than an analog, according to tests he had conducted himself.
His argument was that of all e-cigarettes models he tested, none were able to produce consistent temperature of the atomizer. It meant that the nicotine contained in the e-liquid would react differently between two tokes. As such, a "burnt" nicotine molecule would produce cancerous molecules way worse than in an analog. He attributed this behavior to the e-cigarette's inability to control the delivery of e-liquid to the atomizer. When underfed, the atomizer would burn too hot, while when overflown, the atomizer would light up to a lower temperature.
Consequently, he mentioned the inability of an e-cigarette to control the size of the vapor drops: the biggest (low temperature) would get stuck in the throat, while the smallest (burnt) would go as far as the alveolars of the lungs.
Before starting vaping, I have read almost any study I could lay my hands on and none mentioned this in particular. When I confronted my friend with this, he mentioned than even the biggest universities didn't have the testing equipment big tobacco industries had.
His advice to me was: if you must vape, do it without nicotine. If you need your nicotine, light up a fag, it's way less harmful to you.
I have known this friend for a long time and completely trust him. I know that he wouldn't try big tobacco propaganda on me and he looked genuinely worried seeing me vaping. This evening has left me pondering on what he told me. I'd be quite interested to hear your opinion (or first-hand lab knowledge) on this. Is there really cause for concern?