ONCE AND FOR ALL: PASSIVE VAPOR IS HARMLESS TO LIVING BEINGS
This is from the Briefing by ASH
Is there a risk to non-users from electronic cigarette vapour?
Although electronic cigarettes do not produce smoke, users exhale a smoke-like vapour which consists largely of water. The level of nicotine present in electronic cigarette vapour is about one tenth of that generated by a cigarette.
Any health risks of secondhand exposure to propylene glycol vapour are likely to be limited to irritation of the throat. One study exposed animals to propylene glycol for 12 to 18 months at doses 50 to 700 times the level the animal could absorb through inhalation.
Compared to animals living in normal room atmosphere, no localised or generalised irritation was found and kidney, liver, spleen and bone marrow were all found to be normal.