Agreed, I also take issue with "Safer than cigarettes"; we know a lot more about cigarettes/tobacco than e-cigarettes. It's true that cigarettes have a large buffet of unsafe chemicals, but it's clear that e-cigarettes have widely varied chemicals from brand to brand with little transparency as to what they are. I feel it's more appropriate to say "Safer than cigarettes, we think". The Popcorn Lung situation comes to mind. Buyer/user beware.

but I don't put any of those things inside my body if I'm simply walking behind you on the sidewalk while you consume them.

That's not a distinction the parent commenter made.

You put a whole lot of crap in your body walking down American streets, unless you think all those cars are crapping out rainbows and sunshine from the exhaust pipe.

Agreed, "proven safe" would fail even with water, which is toxic to humans above certain quantities.

What about "generally recognized as safe", which is a category I think most foods fall into unless evidence directly to the contrary surfaces?

Sugar is generally recognised as unsafe, addictive and unhealthy. Tens of millions of people suffer from it.

You're not speaking the same language as your parent commenter. "Generally Recognized As Safe" (GRAS) is an FDA designation, and not a literal phrase. High Fructose Corn Syrup, for example, is GRAS.

And yet, we need it to survive.