The Drug Update

It's possible that it may be a bit alarmist to even put marijuana in the category of fatal dose at 1000 times normal dose.

The writer in the article seemed to have no really clear idea, other than it must be really, really large.

I still haven't seen any data to supplant what Judge Francis L. Young wrote in his 1988 decision:

"Drugs used in medicine are routinely given what is called an LD-50. The LD-50 rating indicates at what dosage 50% of test animals receiving a drug will die as a result of drug induced toxicity...

At present it is estimated that marijuana's LD-50 is around 1:20,000 or 1:40,000. In layman terms this means in order to induce death, a smoker would have to consume 20,000 to 40,000 times as much marijuana as is contained in one marijuana cigarette.

NIDA-supplied marijuana cigarettes weigh approximately 0.9 grams. A smoker would have to consume nearly 1,500 pounds of marijuana within about 15 minutes to induce a lethal response. In practical terms, marijuana cannot induce a lethal response as a result of drug-related toxicity."

What Pete said, would apply to LSD and psilocybin mushrooms, as well.

Like Pete had commented, while I've heard the 20,000-40,000 LD-50, I haven't been able to find the actual study. Either way, the LD-50 is at least high enough that it is most likely physically impossible to reach the level just by smoking. Can anybody find the publsihed study that finds an Ld-50 of 20,000 to 40,000 though?

I'm looking for the study, but I found this blurb in this ASSESSMENT OF EXPOSURE TO AND HUMAN HEALTH RISK FROM THC AND OTHER CANNABINOIDS IN HEMP FOODS(PDF)

"The physical toxicity of THC is low. Tests to establish a lethal THC dose for monkeys were unsuccessful because the maximum administered dose of 9000 mg/kg body weight did not result in the death of the monkeys (Thompson et al. 1973)."

Got it..

Inhalation, parenteral and oral LD50 values of Δ9-tetrahydrocannabinol in Fischer rats:

The iv LD50 was 36–40 mg/kg, similar to the inhalation dose when the latter was corrected for Δ9-THC losses in the rodent nasal passages

So, 40mg/kg = 2800mg for a 70 kg human, assuming interspecies homogeneity. If you're smoking 5% THC, and assuming 60% retained THC (not all THC from the plant matter makes it into your body), that makes it about 94 gms i.e. 94 joints. Still highly improbable, but quite lower than the 20,000 ratio. Of course, that monkey result above is closer in line with the quoted ratio. So 100 or 20,000? Any volunteers? :)