You know, I got my tent in a ringer by starting a thread about possibile PG dangers when I was on another vape forum. I posted a link to two MSDS listings that were on a vendor's site...well this guy DW (moderator) insisted that I was a spammer and that the MSDS and the safe handling instructions are different (they are combined into the MSDS at the hospital where I work, I am in a respiratory related field). Being that I was new to message boards and vaping I didn't realize that I had to spell out everything for this jerk. Anyway it's all academic, the warnings said that you should only use PG in well ventilated areas. I also posted a link to show how PG is used in hospitals (in pediatrics) and then this moderator seemed to think that I actually believe that neonates vape, and insisted that my links were idiotic...ok. What the article showed was that the neonatal body adjusts to the extra lactic acid caused by PG exposure and there is no damage.
PG is a touchy subject for some and despite what this moderator insisted, It has NOT been proven safe. So I decided to use myself as a test subject. I have chronic asthma/allergies and I am a former 4 pack per day smoker with some vocal problems (I'm also a singer)...quit for 11 years, relapsed, lost the voice, quit again, switched to strong cigars so I did not have to inhale. Still some minor throat irritation. Started vaping. Strangely enough, when I vape straight PG it does seem to irritate my trachea...but for some reason it also clears my throat and that damn chronic phlegm in my larynx seems to disappear! OK it has not been proven safe...or unsafe for that matter. We are essentially the pioneers of this new habit. I only know that PG is not considered a carcinogen. I will take my chances as long as I am feeling good.