DISTRICT OF COLUMBIA: You may have read this week that a new “20-year research study” on marijuana use “finally demolishes claims that smoking marijuana is harmless,” and has found that it “makes you stupid,” that “smoking marijuana over the long-term can develop cancer” [SIC], and that marijuana is “as addictive as heroin.” At least, that’s what you’d conclude if you’d read most media coverage of the study. But if you’d actually read the study yourself (which I highly recommend!), you’d likely walk away with very different conclusions.
The paper in question is a review of 20 years of existing research into the health effects of marijuana use. By design, it doesn’t tell us anything we don’t already know. The focus is almost exclusively on the effects of long-term heavy (daily or near-daily) marijuana use: “this paper deals with the adverse effects of cannabis smoking, especially the adverse health effects of regular, typically daily, cannabis smoking,” the author, Wayne Hall, a drug adviser to the World Health Organization, writes.
Setting aside the alarmist accounts of the study in many media outlets, here’s what Hall actually found:
You can’t OD from marijuana
“The estimated fatal dose [of THC, the primary active compound in marijuana] in humans derived from animal studies is between 15 and 70 grams. This is a far greater amount of cannabis that even a very heavy cannabis user could use in a day,” Hall writes. The average joint contains about a half a gram of marijuana, and the average potency of seized marijuana in 2013 was 12.58 percent, which means there are about 0.06 grams of THC in the average joint, which means that somebody would need to smoke somewhere between 238 and 1,113 joints in a day – or at least 10 joints an hour, for 24 hours straight – before overdose could become a realistic concern.