Link between cannabis and mortality is still not established: “A recent editorial in this journal implied that as many as 30 000 deaths in Britain every year might be caused by smoking cannabis. The authors reasoned that since the prevalence of smoking cannabis is about one quarter that of smoking tobacco the number of deaths attributable to smoking cannabis might be about one quarter of the number attributed to tobacco cigarettes (about 120 000). The idea that the use of cannabis increases mortality is worthy of closer examination. How do we assess this issue?” British Medical Journal editorial