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In toxicology, the median lethal dose, LD 50 (abbreviation for "lethal dose, 50%"), LC 50 (lethal concentration, 50%) or LCt 50 is a toxic unit that measures the lethal dose of a given substance. [1] The value of LD 50 for a substance is the dose required to kill half the members of a tested population after a specified test duration.
The system is based on LD50 determination in rats, thus an oral solid agent with an LD50 at 5 mg or less/kg bodyweight is Class Ia, at 5–50 mg/kg is Class Ib, LD50 at 50–2000 mg/kg is Class II, and at LD50 at the concentration more than 2000 mg/kg is classified as Class III. Values may differ for liquid oral agents and dermal agents. [1]
In toxicology, the lethal dose (LD) is an indication of the lethal toxicity of a given substance or type of radiation.Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilogram of subject body weight) at which a given percentage of subjects will die.
If the result of a study is a toxic effect that does not result in death, it is classified as this form of toxicity. [2] Toxic effects can be defined differently, sometimes considering the therapeutic effect of a substance to be toxic (such as with chemotherapeutics) which can lead to confusion and contention regarding a substance's TD 50 ...
It is calculated using the LD50 or LC50. [1] The Occupational Safety and Health Administration (OSHA) regulation (1910.134(b)) defines the term as "an atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual's ability to escape from a dangerous atmosphere."
Dermal LD50 Up to and including 200 mg/kg From 200 to 2000 mg/kg From 2000 to 20,000 mg/kg Greater than 20,000 mg/kg Eye Effects
However, the nature of animal studies also limits the applicability of experimental results in the human population and its significance in evaluating potential risk of certain substances. [5] In toxicology, there are some other safety factors including LD50, LC50 and EC50.
The fixed-dose procedure (FDP), proposed in 1992 by the British Toxicology Society, is a method to assess a substance's acute oral toxicity. [1] [2]In comparison to the older LD 50 test developed in 1927, this procedure produces similar results while using fewer animals and causing less pain and suffering. [3]