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 now 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 Tetrahydrocannabinol (active ingredient found in Cannabis): 3000 mg/kg in dogs and monkeys.
- LD50 of batrachotoxin: estimated at 1 to 2 µg/kg in humans.
- LD50 of Polonium 210: estimated at 10 (inhaled) to 50 (ingested) nanograms in humans makes this one of the most toxic substances known. One gram in theory could poison 100 million people of which 50 million would die.
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- "Allergan Receives FDA Approval for First-of-Its-Kind, Fully in vitro, Cell-Based Assay for BOTOX® and BOTOX® Cosmetic (onabotulinumtoxinA)". Source: Allergan, Inc. News Provided by Acquire Media. Page last updated 24 June 2011. http://agn.client.shareholder.com/releasedetail.cfm?ReleaseID=587234. Retrieved 2011-06-26.
- "In U.S., Few Alternatives To Testing On Animals". Washington Post. Page last updated 12 April 2008. http://www.washingtonpost.com/wp-dyn/content/article/2008/04/11/AR2008041103733.html. Retrieved 2011-06-26.
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