Mr-Pirk, I don't think the overall message about marijuana was wrong per se or created a particular loss of credibility. Most young people are going to doubt what an older person says out of sheer ignorance and basic stuck on stupid mentality simply because they are young, it hasn't happened to them and therefore they must know it all.
There is a bridge in my patrol area that kids jump off of. During the summer, it's about 40-60 feet above the water. Kids tell me bridge jumping isn't dangerous. I tell them about the submerged rocks underneath the water and how the water level shifts up and down due to the amount of water being released from dams upstream. They tell me they haven't hit one yet. I ask them if they are planning on relaying the message through some spirit medium after they hit the rock and die. They repeat that they haven't hit the rock yet.
I have people tell me that marijuana isn't dangerous either. I point out babies who are born to parents who use marijuana and ask why those babies are fussier, have attention deficit disorders and other ailments. Then I ask why studies on marijuana confirm possible birth defects and higher levels of tar and nicotine than cigarettes. I also point out from personal experience on the job that I have seen a significant # of people who use marijuana do move on to other drugs. People then tell me that marijuana isn't dangerous and doesn't lead to using other drugs. And their # 1 reason why they believe so.......is that it hasn't happened to them personally. YET!!!!
Some other people have already pointed out how cigarettes and alcohol also harm the body. The simple fact is that ingesting harmful substances into your body is not a good idea and eventually those harmful substances
can cause you health problems. Pick your poison and take your chances but don't make such a foolish argument that anybody who reads even a few health studies can see right through. We all make our choices and then we need to live (or die) from the consequences.
p.s. I do not recommend the bridge jumping.