Lethal concentration fifty.

The concentration of an active ingredient in air which is expected to cause death in 50% of the test animals so treated. A means of expressing the toxicity of a compound present in air as dust, mist, gas or vapor. It is generally expressed as micrograms per liter as a dust or mist, but in the case of gas vapor, as parts per million (ppm).

In a dose-response relationship, the LC50 is the concentration of chemical that is expected to produce death in 50% of the organisms that are exposed to that concentration. [compare to EC50

The concentration of a chemical(s) in air (inhalation toxicity) or water (aquatic toxicity) that will kill 50% of the organisms in a specific test situation.

The concentration in air that causes death of 50% of the test animals: The test animal and the test conditions should be specified; the value is expressed in mg/liter, mg/m3, or ppm. The higher the number, the lower the toxicity.

Lethal concentration in 50% of animals tested.

Lethal concentration that will kill 50 percent of the test animals within a specified time. See LD50.

Lethal concentration 50. The median concentration of an airborne material expected to kill 50% of a group of test animals. Expressed as: Parts of a material per million parts of air (ppm); micrograms per liter of air ( ug/L); or milligrams of material per cubic meter of air (mg/m3).

A calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.

the concentration of a material in air which causes death in 50% of a group of test animals. The material is inhaled over a set period of time, usually 4 hrs. LC stands for lethal concentration.

means a concentration of a substance (usually in air) that is estimated to produce death in 50 per cent of a population of experimental animals on inhalation for a short period of time.

(Lethal Concentration): A measure of a pesticide's acute toxicity by concentration. It is the concentration of a chemical at which 50% of the test group dies. It is a time dependent value (i.e., the length of the test may vary) and may be an observed value or, more frequently, one calculated by interpolation or extrapolation. In birds, currently, groups of young test animals are exposed continuously to graded doses of a chemical in their food for a 5 day period. They are then put on clean feed and observed for at least three more days. The avian LC50 is then expressed as parts per million (ppm) or milligrams of chemical per kilogram of feed. See LD50 and toxicity test.

Median Lethal Concentration: Statistically estimated concentration that is expected to be lethal to 50% of a group of organisms tested. Death may be defined by the mortality, intoxification, and population effect groups. TLms and TL50s with death as the measured endpoint are reported as LC50. LOEC Lowest observed effect concentration: The lowest concentration of a material used in a toxicity test that has a statistically significant adverse effect on the exposed population of test organisms compared to the controls. When derived from a life cycle or partial life cycle test, it is numerically the same as the upper limit of the MATC. Also called lowest observed adverse effect level (LOAEL).

concentration in air killing 50% of experimental animals

Lethal Concentration” of a substance suspended in the air or dispersed in water.

Lethal Concentration 50%; the concentration of a material in air which on the basis of laboratory tests, is expected to cause 50% mortality in a group of test animals when administered as a single exposure

(lethal concentration, 50 percent): The toxicant or effluent concentration that would cause death in 50% of the test organisms (EPA, 2000). The concentration is calculated from the data set using statistical or graphical models. The lower the LC50, the more toxic the chemical or effluent sample. Other LC values, e.g. the LC90 or LC5 may also be calculated to determine concentrations causing more or less mortality to the population. Note: The LC value must always be associated with the duration of exposure. Thus a 48-h LC50, 96-h LC50, etc. is calculated.

See Lethal Concentration50.

Lethal Concentration 50%. The concentration that causes the deaths of 1/2 of the animals exposed to a toxicant for a specified time, expressed as vol./vol. (ppm, %), or mass/volume (mg/L).

The concentration of a substance that produces death in 50 per cent of a population of experimental organisms within a specified period. It is usually expressed as milligrams per litre (mg/L) or milligrams per kilogram (mg/kg) as a concentration in food, water or air.

Median Lethal Concentration in a Bioassay

See LETHAL CONCENTRATION 50.

a measure of acute, inhalation toxicity representing a lethal con- centration for 50% of exposed test animals

the concentration of a chemical which kills 50% of a sample population. This measure is generally used when exposure to a chemical is through the animal breathing it in, while the LD50 is the measure generally used when exposure is by swallowing, through skin contact, or by injection. (See also LD50).

Lethal concentration of a substance killing 50 percent of an exposed organisms at a specific time interval. Also referred to as the median lethal concentration (MLC).

LC50 Lethal Concentration of a toxicant that will kill 50 percent of the test population. A common measure of acute toxicity.

The concentration of a contaminant that is lethal to half the organisms in a bioassay.

lethal concentration of a substance in air that will kill 50% of test animals when inhaled over a period of time, usually one hour.

the theoretical lethal concentration for 50 per cent of a group of animals

The statistically derived median lethal concentration, it is the concentration of a test material that can be expected to cause 50% mortality in a group of test animals for a given duration. Usually associated with an exposure duration, e.g. 4-hour LC50.

the concentration of a material in air that will kill 50 per cent of a group of test animals with a single exposure (usually 1 to 4 hours). The LC50 is expressed as parts of material per million parts of air, by volume (ppm) for gases and vapors, or as micrograms of material per liter of air (g/l) or miligrams of material per cubic meter of air (mg/m3) for dusts and mists, as well as for gases and vapors.

Lethal concentration 50%; a measure of acute toxicity. The concentration of a substance in air expected to kill half of a group of test animals exposed for a specified period.

The concentration of a chemical in air or water which is expected to cause death in 50 percent of test animals living in the air or water.

Lethal concentration 50, median lethal concentration. The concentration of a material in air that on the basis of laboratory tests (respiratory route) is expected to kill 50% of a group of test animals when administered as a single exposure in a specific time period.