The terrible truth about cannabis: Expert's devastating 20-year study finally demolishes claims that smoking pot is harmless
One in six teenagers who regularly smoke the drug become dependent
It doubles risk of developing psychotic disorders, including schizophrenia
Heavy use in adolescence appears to impair intellectual development
Driving after smoking cannabis doubles risk of having a car crash
Study's author said: 'If cannabis is not addictive then neither is heroin'
The drug is currently legal in two states - Washington and Colorado
A further 21 states have allowed it to be used for medicinal purposes
Obama said earlier this year cannabis is not as dangerous as alcohol
more
http://www.dailymail.co.uk/news/article-2783111/The-terrible-truth-cannabis-Expert-s-devastating-20-year-study-finally-demolishes-claims-smoking-pot-harmless.html