Very quickly, a great deal of study has gone into looking at the relative harms of different psychoactive substances and pharmaceutical drugs. As I made clear during my remarks, there is broad scientific consensus, and I think people would be way outside that consensus if they were to place cannabis as being more harmful than alcohol and tobacco. Certainly, alcohol and tobacco are much more addictive and toxic.
In terms of cannabis, you're asking if it could be lethal. In terms of the physiologic properties of cannabis and the prevalence of use, those types of reports are almost non-existent in the literature. With confounding factors of poly-substance use and other things, cannabis itself is relatively safe. I agree with the former presenter and have personally seen individuals who have become psychotic from using high-dose cannabis, but that's a transient effect of cannabis intoxication. I've never seen anyone with persistent effects of that. I think it's important to note that alcohol, during intoxication and withdrawal, could make people psychotic.
So relatively, certainly it's much safer.