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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.
Highly Toxic: a gas that has a LC 50 in air of 200 ppm or less. [2] NFPA 704: Materials that, under emergency conditions, can cause serious or permanent injury are given a Health Hazard rating of 3. Their acute inhalation toxicity corresponds to those vapors or gases having LC 50 values greater than 1,000 ppm but less than or equal to 3,000 ppm ...
The term incipient lethal level is used to describe a LC 50 value that is independent of time. [8] A comparable measurement is LCt 50, which relates to lethal dosage from exposure, where C is concentration and t is time. It is often expressed in terms of mg-min/m 3. LCt 50 is the dose that will
The half dollar, sometimes referred to as the half for short or 50-cent piece, is a United States coin worth 50 cents, or one half of a dollar.In both size and weight, it is the largest circulating coin currently minted in the United States, [1] being 1.205 inches (30.61 millimeters) in diameter and 0.085 in (2.16 mm) in thickness, and is twice the weight of the quarter.
IC 50 values are typically expressed as molar concentration. IC 50 is commonly used as a measure of antagonist drug potency in pharmacological research. IC 50 is comparable to other measures of potency, such as EC 50 for excitatory drugs. EC 50 represents the dose or plasma concentration required for obtaining 50% of a maximum effect in vivo. [1]
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The constants listed here are known values of physical constants expressed in SI units; that is, physical quantities that are generally believed to be universal in nature and thus are independent of the unit system in which they are measured. Many of these are redundant, in the sense that they obey a known relationship with other physical ...
The term "potency" refers to the EC 50 value. The lower the EC 50, the less the concentration of a drug is required to produce 50% of maximum effect and the higher the potency. The EC 10 and EC 90 concentrations to induce 10% and 90% maximal responses are defined similarly. There is a wide range of EC 50 values of drugs; they are typically