Ok: Carcinogens presence: http://www.ncbi.nlm.nih.gov/m/pubmed/12412839/ ( read the abstract) Estrogen-like activity: http://www.ncbi.nlm.nih.gov/m/pubmed/6296360/ (This is why it shrinks testicles and causes gynecomastia) Physiological brain changes in marijuana users: http://www.ncbi.nlm.nih.gov/m/pubmed/10772599/ (it shrinks your brain... Surprise!!) Psychological events related to cannabis use: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2424288/#!po=0.980392