Researchers in Sweden have found a correlation between heavy pot use and shortened life spans. Examining data from over 45,000 Swedish men between the years of 1970 and 2011, researchers discovered that the harmful effects of smoking marijuana — such as cancer, lung and heart disease — were more likely to have developed in subjects who claimed heavy use during their teenage years. A previous study of the same group showed no link between marijuana use and death, but given that the new study covered a longer period (of roughly 42 years), the effects became more pronounced. The study also noted that the risk of death from accidental injury or suicide among the group also rose in accordance with their level of marijuana use as teens.
Read more here.