alcohol, it found that the ratio was about ten to one--in other words, if a couple of shots of vodka are enough to make you tipsy, twenty shots might kill you, if you can keep them down. Cocaine, it found, was slightly safer, with a ratio of fifteen to one. LSD has a ratio of 1,000 to one, whereas marijuana is safest of all: it is impossible to die of overdose, as far as anyone can tell. Even with the edibles, there is no evidence that one can die of overdose--you simply have a stronger and longer-lasting effect than you may have wanted. For heroin, the ratio between an effective dose and a deadly one is just six to one. Given that batches vary dramatically in their purity, each shot is a game of Russian roulette.