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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]
Dermal Toxicity: LD 50 for acute dermal toxicity means that dose of the material which, administered by continuous contact for 24 hours with the shaved intact skin (avoiding abrading) of an albino rabbit, causes death within 14 days in half of the animals tested. The number of animals tested must be sufficient to give statistically valid ...
Many gases have toxic properties, which are often assessed using the LC 50 (median lethal concentration) measure. In the United States, many of these gases have been assigned an NFPA 704 health rating of 4 (may be fatal) or 3 (may cause serious or permanent injury), and/or exposure limits (TLV, TWA/PEL, STEL, or REL) determined by the ACGIH professional association.
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.
Toxic substances – Substances with an LD 50 value ≤ 300 mg/kg (oral) or ≤ 1000 mg/kg (dermal) or an LC 50 value ≤ 4000 ml/m 3 (inhalation of dusts or mists) e.g. nearly everything that contains cyanide groups
Acute toxicity includes five GHS categories from which the appropriate elements relevant to transport, consumer, worker and environment protection can be selected. Substances are assigned to one of the five toxicity categories on the basis of LD 50 (oral, dermal) or LC 50 (inhalation).
Because individuals typically have different levels of response to the same dose of a toxic substance, a population-level measure of toxicity is often used which relates the probabilities of an outcome for a given individual in a population. One such measure is the LD 50. When such data does not exist, estimates are made by comparison to known ...