Hi Katy,
I think your question is a very valid one. I didn't start vaping till a few weeks ago; however my man has been vaping for quite a while longer and of course, the ever sceptic in me, proceeded to do a fair bit of research. The links that were shared are well known articles and I'd recommend reading them.
My main concern wasn't the vegetable glycerine but more the polyethylene glycols thus I concentrated most of my research on that.
In my research I stumbled upon a wikipedia entry that listed an LD50 mention in the hazard section when dosed in 30ml/kg on rats:
PEG 400 - Wikipedia, the free encyclopedia
The PEG400/PG has been used in the pharmaceutical industry for years; although the 30ml/kg tests in rats resulted in an LD50, it was administered undiluted. A second medical report made very clear to me that there is no imminent cause for concern
Elsevier
A small excerpt which speaks volumes: "The Kd of polyethylene glycol 414 between hexane and water was 0.000015, indicating that there are only 1.5 parts of polyethylene glycol 414 in hexane for 100,000 parts of polyethylene glycol 414 in water."
The studies about the effects long term that I have been able to track down in the local medical library were, to say the least, inconclusive since virtually none address the inhaling of PG in vapor form.
I am a sceptical nerd and have done extensive research (and bored you probably with some incomprehensible terms) and have not found any indication of "vaping" being more harmful than drinking a soda per day.
To address possible flavor issues; I'd suggest only purchasing flavors mixed with natural flavor extracts.
Besides the nicotine the ingredients used in e-liquids are more common in our daily food intake than we realise.
Good luck in your vaping endeavors and I hope I have been able to assist you a bit in decreasing your worries with my limitless nerdness
Edited addition:
In my enthusiastic banter I forgot to address your concern for the coils and wicks; I cannot say much about the disposable cartridges but there is a lot of choice when it comes to creating your own custom set up.
Wicks can be created from a wide variety of materials; including (but not limited to) natural cotton, the coils are made out of regular metal wire, not unlike the heating coils used on the bottom of a water heater/boiler that heats our water, and/or contains our water that we use for daily consumption (think coffee makers, tea machines, etc.).
All in all, as has been mentioned by various other vaping enthusiasts; put all the denominators against the ingredients of a cigarette and you are pretty much down to a no brainer IMO.
Cheers
