Overdosing on Cannabis Would Require a Superhuman Effort

I've just been reading a report about cannabis on the 'Schaffer Library of Drug Policy' entitled:
Acute Effects of Marihuana.

This report contains some excellent information on various effects of cannabis. It covers a wide variety of subjects, including physical effects on body organs, cognitive effects, social effects and sections that explain psychosis episodes etc. I highly recommend it to anyone who wants to know more about what they are smoking or eating. Here is a small sample of what's covered.

Overdosing

You've probably heard of stories about how much it would take to overdose on THC. Stories like "You'd have to eat a pound to OD" etc. Well, here are some figures from the report, based on research conducted around 1971 using two synthetic THC chemicals and an extract of THC from marijuana. The studies were conducted on rats, dogs and monkeys. These resulting figures gave them an estimate of how much a 70kg(154lb) human would need to take to match the doses administered to the animals:

The non-fatal consumption of 3000 mg/kg A THC by the dog and monkey would be comparable to a 154-pound human eating approximately 46 pounds (21 kilograms) of 1%-marihuana or 10 pounds of 5% hashish at one time. In addition, 92 mg/kg THC intravenously produced no fatalities in monkeys. These doses would be comparable to a 154-pound human smoking at one time almost three pounds (1.28 kg) of 1%-marihuana or 250,000 times the usual smoked dose and over a million times the minimal effective dose assuming 50% destruction of the THC by smoking.

In other words, it would be impossible for humans to ingest enough cannabis by eating or smoking to kill themselves with a THC overdose.

Deaths From THC

I've never heard of nor read, up until I read this report, of any THC related deaths. However, there appears to be some anecdotal reports of deaths from overdosing, but not in the standard sense (links added by Indica Man):

There is no conclusive evidence that short-term marihuana use alone directly results in any physical damage to man. A few scattered fatalities associated with marihuana use are occasionally reported. Most are from 19th century Indian experiences with large oral doses of charas (Deakin, 1880; Bouquet, 1951; Ewens, 1904, Walton, 1938; Indian Hemp Drugs, 1893). Brill et al. (1970) and Smith (1968) have noted that there have not been any reliable reports of human fatalities attributable purely to marihuana, although very high doses have been administered by users.

A frequently cited recent report from Belgium by Heyndrickx et al. (1970) describes an essentially negative pathological and toxicological study of a 23-year-old man found dead in the presence of marihuana, and hashish. A cannabinoid was detected in his urine. However, this finding in no way inculpates marihuana as the responsible agent. There are many possible causes of sudden death which are not toxins and do not produce observable pathology; e.g. anaphylactic reactions, insulin shock, cardiac arhythmias, etc.

A case report (Nahas, 1971) of an attempted suicide by smoking hashish, recently in France is even more anecdotal. An individual was reported to have smoked consecutively ten pipes of hashish containing approximately 200 mg of Delta 9 THC each before losing consciousness. But recovery occurred after supportive treatment.

Another case report (Hughes et al., 1970) relates severe diabetic coma with ketoacidosis after the ingestion of huge amounts of marihuana by a mental patient. However, it appears that the pronounced vomiting secondary to the marihuana ingestion caused a severe electrolyte imbalance and alkalosis. Possibly a vulnerable glucose-regulating system responded to the severe stress inappropriately. Retrospectively, there was no history of diabetes noted previously but this was not confirmed or ruled out by lab tests prior to the episode.

Several case reports (Henderson and Pugsley, 1968 King and Cowen, 1970; King et al., 1970; Lundberg et al., 1971; Gary and Keylon, 1970) noted acute severe, physiological disturbances and acute collapse (shock, chills and fever) subsequent to intravenous injection of suspensions of marihuana. These symptoms may have been due to an allergic reaction to injected foreign plant material, to a bacteremia and/or to the injection of insoluble particles which are filtered by the organs. The symptoms may be considered a complication of the mode of use, rather than results of the drug.

Go on, take the time to check this report out. It'll be time well spent.