Thursday, May 7, 2009

Lesson One: What is a Lethal Dose
The amount it would take to kill a human being is referred to as the "lethal dose" represented by LD followed by 50 or even 100. For example, LD50 refers to how much of a substance it would take to kill 50% of a sample population. LD100 refers to 100% lethal dose, that is, the minimum it would take to kill an entire population.

The way a lethal dose depends on the weight of the person. The general formula is the weight of the person in kilograms (2.2lbs = 1kg) multiplied by the toxic dose per kilogram. For example, the toxic dose of Tylenol (or acetaminophen) is 150mg/kg. A 200-pound person would need to ingest approximately 28 extra strength (500mg) Tylenol pills to reach his personal lethal dose.

What other "common" chemicals are toxic to humans and in what doses?
Water is a common chemical, right? The ld50 of water is 9mL/kg or about 9 liters of water. That's about 2 to 3 gallons of water straight, to cause a toxic reaction.

How possible is that?
Ask Leah Betts, Micheal J. Schindler, little 4yo Cassandra Killpack, 3yo Rosita Gonzalez, Walter Jennings, Matthew Carrington, Jennifer Strange, Jacqueline Henson, and Anna Wood. Or, maybe you should ask their families because all of those people died from water toxicity.

But, wait a minute. This is about the...
Lethal Dose of Marijuana
So, how much marijuana can one smoke to cause death?
Well sorry folks. If you were interested in dying from marijuana use, it simply won't happen. While there are numerous deaths from Tylenol ingestion and even from something as "simple" as drinking too much water, there are NO deaths from smoking marijuana.
"In summary, enormous doses of Delta 9 THC, All THC and concentrated marihuana extract ingested by mouth were unable to produce death or organ pathology in large mammals but did produce fatalities in smaller rodents due to profound central nervous system depression." [link]
In other words, the researchers couldn't give large mammals (that's kind of like us) enough marijuana to kill them no matter how much they tried. In fact, the LD50 of marijuana is so difficult to ascertain that discussions of LD50 occur hypothetically. That means, researchers are guessing how much marijuana it would take to kill a person.
"Firstly, it is important to realize that marijuana is a substance which can objectively be considered harmless. According to Lester Greenspoon, M.D., former associate professor of psychiatry at the Harvard Medical School, the hypothetical lethal dose of marijuana is 40,000 times the psychoactive dose. The lethal dose of alcohol, a legal drug, is 4 to 10 times the psychoactive dose. The figure for marijuana is hypothetical in that is has only been shown to be true in rats; there are no records of lethal marijuana overdose in humans anywhere." [link]
So, who's willing to ingest 40,000 times the psychoactive dose of marijuana? The psychoactive dose for marijuana is about a 1g joint. That's 40,000 grams or 1400 ounces or 90 pounds of marijuana all within 15 minutes. I'd like to try but I think I can only smoke about 3 to 5 joints in 15 minutes if I rush it. Something tells me I'll be really hungry and/or asleep which may seem like death. Don't wake me up though. The pink bunnies are my friends.
CLASS DISMISSED..
See you tomorrow, alive and well as long as you don't drink too much water while you don't take too much Tylenol.

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