Which term corresponds to the hazard or toxicity assessed by LC50 and LD50?

• A. Hazard & toxicity
• B. Death
• C. Different product's toxicity
• D. Different product's modes of action

Answer: (A)

LC50 and LD50 are acute toxicity metrics that express how toxic a substance is by the concentration or dose needed to kill 50% of a test population within a given time. This directly communicates the hazard potential and intrinsic toxicity of the substance—lower LC50/LD50 values mean higher toxicity. Death is the endpoint used to define the measure, but the idea being tested is the overall hazard or toxicity the substance presents, not the single outcome itself. The other options miss the concept: death describes the result, not the measure; different product toxicity implies a comparison rather than the intrinsic hazard; and modes of action relate to mechanism, not to the toxicity potency captured by LC50/LD50. In short, LC50 and LD50 identify the hazard and toxicity of a substance.