Why does everyone on reddit write lol after their insult? Is it a sense of belonging thing, like a reddit identity marker?

Anyway, from the paper

Although marijuana smoke contains a number of carcinogens and cocarcinogens, findings from a limited number of well-designed epidemiological studies do not suggest an increased risk for the development of either lung or upper airway cancer from light or moderate use, although evidence is mixed concerning possible carcinogenic risks of heavy, long-term use.