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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. LD 50 figures are frequently used as a general indicator of a substance's acute toxicity. A lower LD 50 is indicative of higher toxicity. The term LD 50 is generally attributed to John William Trevan. [2]
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.
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."
The median toxic dose encompasses the category of toxicity that is greater than half maximum effective concentration (ED 50) but less than the median lethal dose (LD 50). However, for some highly potent toxins (ex. lofentanil , botulinum toxin ) the difference between the ED 50 and TD 50 is so minute that the values assigned to them may be ...
Toxicology results may reveal that someone very likely died of fentanyl intoxication, for example, but they won’t show if they had endocarditis or a brain abscess, common conditions in chronic ...
Statistical analysis of dose–response curves may be performed by regression methods such as the probit model or logit model, or other methods such as the Spearman–Kärber method. [5] Empirical models based on nonlinear regression are usually preferred over the use of some transformation of the data that linearizes the dose-response ...
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.