It's a fog machine folks. A personal, food grade, flavoured fog machine. The fluid contains propylene glycol, vegetable glycerin, artificial flavour and possibly nicotine. Any suggestion that we don't know what is in them is false, the health effects of vaporized propylene glycol and vegetable glycerin are well studied and widely regarded as harmless. Any nasty incidental chemicals that come from boiling the flavour and the nicotine are found in such small amounts they are considered harmless. Perhaps with some horrible cheap versions, or mis-use nasty chemicals could appear but those are anomalous to the bulk of the data. More data is good, but we do know beyond the shadow of a doubt that inhaling burning tobacco will kill you.
There is no science behind their position. What is happening here is a disruptive technology is posed to save millions and millions of lives and health care dollars, and reduce millions in tax revenue. Juice makers tend to be small and artisanal or huge and chinese. Mainstream tobacco has had little to do with it, but it wants that money and is concerned with how quickly the tides are changing. Many governments depend on that tax revenue. They don't want us to spend $15 a month on it, they want us to spend $15 a day. They're used to milking addicts. I mean, they're addicts after all...
On a personal note, I was a heavy smoker who tried everything possible to quit. I chewed nicotine gum for 2 years in an effort to quit. Patches, drugs, cold turkey, nothing kept me quit. Now...well I prefer vaping to smoking. On the rare occasion I've smoked a cigarette since I started has only reinforced that smoking sucks. I started with strong fluid but reduced it without any problems. I can smell, I can taste, I don't stink or cough. My health has obviously improved.
So sure, regulate labeling and over 18 for nicotine juice just as most vendors are self regulating now. Kids aren't dumb, and any teenager who is going to get an e-smoke to "look cool" is just as likely to use a real smoke to do so. I'm not sure the "milkshake" flavour is really a draw for them. Looking cool and doing something counterculture...well, that's hot. They know (just like we do) that nicotine is addictive so if we offer them juice without nicotine, they won't care. They'll lie if they have to, use fancy machinery and eventually tire of the fad, and perhaps we will divert an entire generation...or perhaps we'll find it's an excellent method of all manners of drug delivery, 'cause we're human and all and the kids aren't dumb.
However it turns out, at this point and given what we know, all logic screams we should not be making folks who are addicted to nicotine turn back to a more harmful methods of delivery. The FDA, Health Canada, WHO and the like should continue to research and see what happens but should butt out of any restrictions.