Re: propylene glycol plus some flavourings ?
« There were stories last year of e-cig liquids containing Diacetyl. It's an artificial flavouring added to 'butter' popcorn and is safe to eat. Inhaling it however will seriously mess up your lungs. »
Smoking has never been associated, directly or indirectly, with diacetyl-induced pathologies. And yet tobacco smoke contains way more diacetyl than even the worst eliquids.
So while I agree with you that eliquid flavourings should be regulated in order to avoid dangerous chemicals (including diacetyl), let's be honest and stop the paranoia: it's highly unlikely that the levels of diacetyl present in some shoddy eliquids have any measurable effect at all.