After reading through this thread, while it was long, I'm glad it happened. It's made me do more thinking and more research just to put the questions raised to rest in my own mind. Several folks have done the same - great finds btw!
If I had any doubts before about the safety of vaping, they have all been alleviated because of this thread. Thank you all for that
This little bit I grabbed during my 'evidence and common sense' search and sums up my thoughts on the matter precisely. I think the discussion is over, but wanted to just add my two cents anyway...
Vaping using VG and PG ingredients are generally regarded as safe (GRAS). They've all been tested and approved so thoroughly that there is no need to regulate them. Even the anti-freeze, propylene glycol, is certified safe for human consumption. That's why it replaced the old, toxic to kitties and puppies, ethylene glycol. The flavourings are the only ingredients where even halfway credible doubt could be sown, since it's been pointed out they haven't been tested specifically for inhalation. But consider, that objection has never been raised before vaping came along, yet flavouring agents have always been used in products that could be inhaled - medically approved inhalers, air fresheners, perfumes & grooming products, everything that makes a bakery smell so wonderful, frying bacon is supposedly carcinogenic now and puts oily particulates in the air (OMG lipid pneumonia!). Face it, lungs are actually pretty hardy organs, as long as you lay off the carcinogens, toxins and solid particulates - all present in smoke and completely absent in vapour.