False!

Yes it's true that marijuana comes from a plant, but so does tobacco (and cocaine and heroin). In fact, marijuana actually contains 5x more toxins than tobacco, it's certainly not a 'safe' alternative to smoking cigarettes.

Another thing to keep in mind is that vaporizers do not eliminate toxins found in marijuana, although, they have been shown to reduce the carbon monoxide levels emitted; using a vaporizer is not a harmless way to ingest marijuana, as a significant amount of carbon monoxide and other toxins still enter your body.