The carrier liquid might be the same thing as theater haze, but theater haze doesn't contain nicotine (which has known health risks even without combustion products), doesn't contain flavorings that are only tested for food use (and the example of "popcorn lung" from diacetyl shows that inhaling flavorings directly is not the same as using them in food), and is inhaled in much lower concentrations. E-cigs are safer than smoking, but to call them "harmless" is a strong claim that requires evidence.