Firstly, +1 for flattery - though the great thing about chemistry (and science in general, for that matter) is that there’s always plenty more to learn, so even as a chemistry teacher I still wouldn’t call myself an expert!
To be clear, the fact that the e-liquids used in e-cigarettes still aren’t regulated means that there’s no catch-all list of ingredients or effects - these will vary from brand to brand. However, there are a few common inclusions.
Propylene glycol (below) is used to draw in moisture/water vapour. It’s an FDA approved food additive considered safe for oral intake, and causes the visible fume during exhalation. However, some research has shown that inhalation can cause respiratory irritations in some.
Glycerin (below) is an alternative used in combination or instead of propylene glycol. It’s considered by the FDA to be safe.
Obviously nicotine being present is a given; however, research has also found small amounts of nitrosamines, carcinogenic compounds found in tobacco and tobacco smoke, in several different e-liquids. In another study, two types of nitrosamines were detected in 9 out of 12 e-liquid brands. It is worth noting that this study also clarified that the levels of these toxicants were 9-450 times lower than in normal cigarette smoke.
Regulation for e-cigarettes as medicinal products is expected to come into force in 2016 - this regulation will be designed to ensure the chemical composition is known, and will improve the variable quality of different brands currently available.
Hope that answers your question!
by Daniel Griswold