Pesticides from class '2 moderately hazardous' have LD50 for the rat (oral) in which range?

• A. 5-50 mg/kg BW
• B. Over 500 mg/kg BW
• C. 50-500 mg/kg BW
• D. 0.5-5 mg/kg BW

Answer: (C)

Understanding how acute toxicity is categorized helps here. LD50 is the dose that kills 50% of test animals; the smaller the LD50, the more toxic the substance. Pesticides labeled as moderately hazardous occupy a middle tier: they are more toxic than the least hazardous substances but not as deadly as the most toxic ones. So their rat oral LD50 sits in the middle of the toxicity spectrum. That’s why this option best fits the description. If a substance had a very low LD50, it would be in a higher hazard category, and if its LD50 were very high, it would be considered less hazardous.