A pesticide with a lower LD50/LC50 value compared with another product indicates what about its toxicity?

• A. It is more poisonous.
• B. It is less poisonous.
• C. It has a higher LD50 value.
• D. It has no toxicity.

Answer: (A)

LD50/LC50 values reflect acute toxicity: the smaller the dose or concentration needed to kill 50% of exposed organisms, the more toxic the substance is. So a pesticide with a lower LD50/LC50 than another is more poisonous because only a small amount is required to reach lethal effects. If the value were higher, the substance would be less toxic since more of it would be needed to reach the same level of mortality. The idea of no toxicity would imply no lethal effect at tested doses, which isn’t what a low LD50/LC50 indicates. For example, a product with 50 mg/kg is far more toxic than one with 500 mg/kg.