Many readers reject the opinions of these learned and experienced scientists in favour of their own opinion, which they deem to be much superior, regardless of their education or lack of it. I have come to the opinion that these people are users and no amount of 'proof' would convince them that there is any problem with their habit.
There was an old Christian teacher, one time, who declared, "morality dictates theology". In other words, we construct our image of God and His requirements according to what will allow us to continue with the habits that we enjoy. This is certainly true for some but others diligently seek the truth and eventually find it, even though it comes at some cost.
Pot smokers have a similar standing. They construct the truth to meet their own desires disregarding scientific fact or reality. Paul Simon wrote in his wonderful song, 'The Boxer', "Still a man he hears what he wants to hear, and disregards the rest". This selective hearing has nothing to do with the truth and everything to do with the 'will'.
Our will overpowers our common sense, our ability to hear the truth, and rejects anything that comes with a cost. I'm not talking money here, I'm talking having to give up something - sacrifice. You can only really know the truth when you are willing to sacrifice whatever it is that gets in the way of it. You don't actually have to sacrifice it to know the truth, but you have to be willing to sacrifice it.
Once you know the truth, it is up to you whether you want to continue with your habit. You can play Russian Roulette with your sanity if you so choose, but don't pretend that there is no risk involved - that gun has a bullet in it!