The name LD50 is an abbreviation for "Lethal Dose, 50%" or median lethal dose. It is the amount of the substance required (usually per body weight) to kill 50% of the test population.
The test was created by J.W. Trevan in 1927 but has been phased out. The U.S. Food and Drug Administration has begun to approve non-animal alternatives to LD50, in response to research cruelty concerns and the lack of validity/sensitivity of animal tests as they relate to humans.
- Oral LD50 of grain alcohol: 10.6 g/kg in young rats, 7.06 g/kg in aged rats.
- Oral LD50 of nicotine: 50 mg/kg in rats.
- Oral LD50 of Table Salt: 3000 mg/kg in rats 
- LD50 of Delta-9-tetrahydrocannabinol (THC) (active ingredient found in Cannabis): Fischer rat, oral 1,270 mg/kg
- LD50 of smoked and inhaled Cannabis or Marijuana: Unknown. At present it is estimated that marijuana's therapeutic index is around 1:20,000 or 1:40,000 (the "1" in the prior estimate is based on an "effective dose" of the .9 grams contained in NIDA-supplied marijuana cigarettes, although the potency of Cannabis changes based on the genetics of the source plant) placing its LD50 around at least 18,000g.
- What is an LD50 and LC50
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- Alcohol Chemistry
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- "Safety (MSDS) data for sodium chloride". Archived from the original on 2007-10-30. Retrieved 2007-01-15.
- Inhalation, parenteral and oral LD50 values of Δ9-tetrahydrocannabinol in Fischer rats
- What is the lethal dose of marijuana?