OK, I admit it, I'm a science nerd. I should be, I spent long enough staring at test tubes, chromatography results and burns on my fingers to earn the badge.
When I see someone trying to twist simple scientific FACT that really pushes my nerd alert and puts everything they say from there on in question.
So, I hear you say, what's this got to do with Vaping? Propanediol. Yes, I know, you've probably never heard of it. Or rather them...
Propanediol isn't one chemical, it's a group of isomers or chemicals with the same number of carbon, hydrogen etc, but plugged together in a different shape.
One of the Propanediol (or PDO) family you know quite well. 1,2-Propanediol is commonly known as Propylene Glycol.
There are two other members, 1,3-Propanediol (Trimethylene Glycol, TMG) and 2,2-Propanediol (dimethylmethanediol). 1,2-PDO and 1,3-PDO are both glycols, 2,2-PDO is a geminal diol.
PG and TMG are pretty similar in properties and there is some suggestion that TMG may be kinder to the skin and less drying than PG. But that's not proven. And like PG the makers of TMG don't recommend it for use in vaping although it's GRAS. Not because it's dangerous, no, because they can't prove it isn't and don't want to get sued to hell.
Neither one of PG or TMG have been shown to be healthier or safer than each other. Period.
Both PG and TMG can be and are made from one of three sources; Petroleum, Glycerol, Vegetable feedstock. The vegetable process uses genetically modified bacteria (normally E.Coli or similar) to ferment the feedstock which produces the glycol to be extracted. Greener than the first two sources in terms of pollution and energy usage, but GM bacteria (GMM) would scare the ass off 99% of green fans.
So if someone says "ooh, we don't use PG, we use glycol","ooh, we don't use PG, we use propanediol" or "our glycol is naturally sourced" you can now safely kick them in the ass and point out they failed at science. And probably most other forms of thinking......