Which statement best describes LD50?

Which statement best describes LD50?

• A. Dose that kills all animals
• B. A measure of dermal exposure
• C. Dose killing 50% of animals
• D. The lethal dose for 50% of humans

Answer: (C)

LD50 is the median lethal dose used in acute toxicity testing. It represents the amount of a substance, given in a specific way (such as oral or dermal) per unit of body weight, that would kill 50% of the animals in a test population. This makes it a comparative measure of toxicity, where a lower LD50 indicates greater acute toxicity under the tested conditions. It’s not the dose that kills all animals (that would be LD100). It isn’t a general measure of dermal exposure, since the LD50 value needs to be tied to a specific exposure route. It also isn’t a universal lethal dose for humans; LD50 values are determined in animals and can vary by species, strain, sex, age, and route of exposure, so they’re used as an approximate indicator rather than a precise human dose.

LD50 is the median lethal dose used in acute toxicity testing. It represents the amount of a substance, given in a specific way (such as oral or dermal) per unit of body weight, that would kill 50% of the animals in a test population. This makes it a comparative measure of toxicity, where a lower LD50 indicates greater acute toxicity under the tested conditions. It’s not the dose that kills all animals (that would be LD100). It isn’t a general measure of dermal exposure, since the LD50 value needs to be tied to a specific exposure route. It also isn’t a universal lethal dose for humans; LD50 values are determined in animals and can vary by species, strain, sex, age, and route of exposure, so they’re used as an approximate indicator rather than a precise human dose.