I see zero percent chance of actual science doing this. "Harmless" is way too high of a standard to prove. I could see something along lines of "minimal harm" or "negligible" but then adversaries will take the slightest of the slightest and blow it up into "great cause for concern." Or similar to what was done with secondhand smoke.
This is why e-cig use has been and will be lumped in with smoking restrictions in many municipalities, cities, states and countries...
