That's not how this works. If it were, what evidence do you have that air conditioning, air fresheners, cell phones, car exhaust, flouridated drinking water, energy drinks, staring at computer screens, caramel color, etc. are NOT harmful? Keep in mind that all of these environmental agents started becoming prevalent around the same time that various cancers seemed to explode among the population.
A zero harm requirement is impossible to meet. There are studies showing that the amount of compounds found in second hand vapor are so low they are at times only detectable, not measurable.
Yes, I imagine it is. If you want to make health claims about a product, positive or negative, you need to be able to back that up with science. Especially if your claims are being used as the basis for legislation. Otherwise I could say that the plastic used in water bottles causes cancer, we need to restrict the use of plastic water bottles, and by the way, I own a company that makes reusable metal canteens if you're interested.
I don't mean to be rude, but you don't seem to understand the following concept...
The dose makes the poison.
There is no way in hell that second-hand diketones from vaping will ever harm anyone.
Not now, not tomorrow, and not next Thursday.
Reading the statements from so many vapers who think they are experts in toxicology explains why most the public want to regulate vaping.