Can anyone PROVE that marijuana is harmful if used through a butane free vaporizer?

In this situation there would be no smoke that would release harmful carcinogens into the lungs and no harmful chemicals from flame or chemical lighters. Marijuana is well known in the medical field to relieve symtpons of Alzheimers,glaucoma,depression, and chronic pain. It would be a wise decision for the government to p out butane free vaporizers to medical marijuana users in my opinion so that no harmful carcinogens would be released during the inhaling of the marijuana. Please answer this question seriously. To the marijuana protesters - please concentrate your efforts on baning tobacco instead. Afterall, it was a german who wanted to make marijuana illegal while promoting the sales of tobacco and beer. Some of the brightest doctors are of course GERMANS! If marijuana would be made legal, oh how doctors would lose so much money. That is to say, of course the german doctors want you to drink beer and smoke - you'll be seeing them and paying them more often.