LD50

LD50

The LD50 or Median lethal dose is a standard measure in toxicology that quantifies the dose of a specific substance or radiation that is lethal for 50% of a tested population. This measure is frequently used to compare the relative toxicity of different substances.

Definition and Usage

The LD50 value is expressed in terms of mass of substance administered per unit mass of test subject, typically as milligrams of substance per kilogram of body mass. The LD50 can be determined for any route of entry or administration and is usually given orally.

The LD50 is one of the most common measures of toxicity, but it has been criticized for its lack of accuracy in predicting human toxicity, and for the ethical issues it raises in the use of animals for testing.

Calculation

The LD50 is calculated using statistical methods that estimate the dose that causes death in 50% of the population. This is done by administering the substance to a group of test subjects at varying doses, observing the subjects over a set period of time, and recording the number of subjects that die.

Applications

The LD50 is used in regulatory testing to classify and label substances according to their toxicity. It is also used in the development of new drugs and chemicals, to assess their safety and potential risks.

Criticism

The use of the LD50 has been criticized for its lack of accuracy in predicting human toxicity. It is also criticized for the ethical issues it raises in the use of animals for testing.

See also

• Toxicity
• Dose (biochemistry)
• Toxicology

LD50 Resources
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