Median lethal dose MLD

Median Lethal Dose (MLD)—Dose of radiation required to kill, within a specified period (usually 30 days), 50% of the individuals in a large group of animals or organisms. Also called the LD50, or LD50/30 if for 30 days.. 

Lethal dose A dose of ionizing radiation sufficient to cause death. Median lethal dose (MLD or LD50) is the dose required to kill within a specified period of time (usually 30 days) half of the individuals in a large group or organisms similarly exposed. The LD50/30 for man is 400 to 500 rads (4-5 Gy). 

LD50 = median lethal dose MLD = minimum lethal dose. ... 

Dose is the number one factor in toxic effect determinations. From statistically treated dose-response data, the dose (in mg/kg body weight) killing 50% of the sample population is designated as the median lethal dose (MLD or LD50). However, one should keep in mind that, LD50 values may not accurately reflect the full spectrum of toxicity or hazard all the time, because some chemicals with low acute toxicity may have carcinogenic (or endocrine) effects even at very low doses that produce no evidence of acute toxicity at all. 

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