" Effect Concentration 50% " or concentration having 50% of effect compared to control

The EC50 represents the plasma concentration/AUC required for obtaining 50 percent of the maximum effect in vivo.

In a dose-response relationship showing sublethal effects, the EC50 is the concentration that produces a level of effect = 50% of the maximum effect.  For example, the EC50 may be the concentration that causes a particular behavioral effect in 50% of the organisms that are tested. [compare to LC50

See median effective concentration.

Effective concentration; the dosage at which the desired response is present for 50 percent of the population.

The molar concentration of an agonist, which produces 50% of the maximum possible response for that agonist.

The median effective concentration of a material dissolved in water that is expected to affect 50% of a group of test animals.

The concentration of test substance in dilution water that is calculated to effect 50 percent of a test population during continuous exposure over a specified period of time.

Exposure concentration of a material which has a defined effect upon 50 percent of the test population.

The median effective concentration (ppm or ppb) of the toxicant in the environment (usually water) that produces a designated effect in 50 percent of the test organisms exposed.

The term EC50 represents the concentration of a compound where 50% of its maximal effect is observed.