Which LD50 value indicates the least toxic substance among the options 10 mg/kg, 100 mg/kg, 250 mg/kg, 600 mg/kg?

Which LD50 value indicates the least toxic substance among the options 10 mg/kg, 100 mg/kg, 250 mg/kg, 600 mg/kg?

• A. 10 mg/kg
• B. 100 mg/kg
• C. 250 mg/kg
• D. 600 mg/kg

Answer: (D)

The key idea is that LD50 is a measure of acute toxicity where a higher value means the substance is less toxic. LD50 is the dose required to kill 50% of a test population; if you need a larger dose to reach that point, the substance is less dangerous in acute exposure. Among the options, 600 mg/kg is the largest LD50, so it requires the biggest amount to be lethal to half the population, making it the least toxic. The smaller LD50 values (10, 100, 250 mg/kg) indicate higher toxicity because far smaller doses can be lethal. So, the least toxic substance corresponds to the highest LD50 value, which is 600 mg/kg.

The key idea is that LD50 is a measure of acute toxicity where a higher value means the substance is less toxic. LD50 is the dose required to kill 50% of a test population; if you need a larger dose to reach that point, the substance is less dangerous in acute exposure.

Among the options, 600 mg/kg is the largest LD50, so it requires the biggest amount to be lethal to half the population, making it the least toxic. The smaller LD50 values (10, 100, 250 mg/kg) indicate higher toxicity because far smaller doses can be lethal.

So, the least toxic substance corresponds to the highest LD50 value, which is 600 mg/kg.