Mar Vista Animal Medical Center

3850 Grand View Blvd.
Los Angeles, CA 90066


What is LD 50?


"LD50" stands for "lethal dose to 50% of a population." Typically lethal doses are expressed as oral (toxin taken by mouth) or by dermal (toxin placed on the skin). LD50's are usually determined with lab animal species such as rats, mice, and rabbits, but occasionally information is available for dogs. LD50's are expressed in milligrams of ingredient per kilogram of animal body weight (i.e. mg/kg) and provides a way to compare the toxicity of different substances. The higher the LD50, the less toxic a substance is. Some of the materials reviewed here are so safe that LD50 has not been determined and we can only say that it is greater than a certain amount tested. The highest numbers represent the safest numbers.