The dosage of liquid agent causing a specifically defined effect in 50 percent of the given population. Within this context, ED50 refers to a percutaneous liquid exposure. Unless otherwise specified, all ED50s are for percutaneous liquid contamination of bare skin. Similarly, the ED05, ED16, ED84, and ED95 are the dosages causing that defined effect in 5 percent, 16 percent, 84 percent, and 95 percent of the given population, respectively.

The dose of a substance that produces a given, defined therapeutic or toxic effect in 50 percent of the exposed population. NOT A 50 PERCENT EFFECT! This is a quantal (yes/no) determination, but it can be applied to graded effects if they are defined in a quantal manner (e.g., the dose of drug necessary to decrease diastolic blood pressure by 10 millimeters ( mm) mercury ( Hg) in 50 percent of the subjects). Under these circumstances, it is imperative that the assumptions and definition of "effect" be stated with the dose.

The median effective dose; the dose that produces the desired effect in 50% of the study population.

(Effective Dose 50) - the amount of material required to produce a specified effect in 50% of an animal population. (See qualification in the definition of LD50).

50 percent effective dose

The dose of a drug that is pharmacologically effective for 50% of the population exposed to the drug or a 50% response in a biological system that is exposed to the drug.

Short for "Effective dose 50"; the dosage of a drug or poison that kills, or stops replication in 50% of the organisms it is tested against. Often applies to does of drug against microorganisms.