Which statement about LC50 is incorrect?

Which statement about LC50 is incorrect?

• A. It is a measure of the dose that kills 50% of test organisms
• B. A lower LC50 indicates greater toxicity
• C. It is used to describe acute toxicity
• D. It measures the time to death in 50% of subjects

Answer: (D)

LC50 is the concentration of a chemical in the exposure medium that kills 50% of the test organisms within a defined period. It describes acute toxicity by linking a concentration to a mortality outcome after a set exposure time, so a smaller LC50 means higher toxicity because less chemical is needed to reach 50% mortality. It does not measure how long it takes for death to occur; that would be described by a time-to-death metric such as LT50. So the statement about measuring time to death is the one that’s not correct. Remember, LC50 focuses on concentration, whereas LD50 concerns dose per organism.

LC50 is the concentration of a chemical in the exposure medium that kills 50% of the test organisms within a defined period. It describes acute toxicity by linking a concentration to a mortality outcome after a set exposure time, so a smaller LC50 means higher toxicity because less chemical is needed to reach 50% mortality. It does not measure how long it takes for death to occur; that would be described by a time-to-death metric such as LT50. So the statement about measuring time to death is the one that’s not correct. Remember, LC50 focuses on concentration, whereas LD50 concerns dose per organism.