El de 50 (dose for Islam) means the amount of deadly, etc. the phrase is from a certain amount of a toxin that, if a number of laboratory animals used for be used, on average, 50% of them.

the amount of El, 50, the larger is the toxicity of the substance is less. El de 50 based on mg / kg body weight of the animal used to determine the degree of toxicity is expressed. For example, El, 50 malathion, etc. of 3000 mg per kg body weight. Test el de 50 by Jay. W. (J. W. Trevan) in 1927 devised.