Oregon Pesticide Practice Test

Is it true that a pesticide with an oral LD50 of 5 mg/kg is more toxic than a pesticide with an LD50 of 250 mg/kg?

1. True

2. False

3. It depends on the formulation

4. Only for specific pesticides

The correct answer is: True

The correct answer is true because the LD50 value, or lethal dose for 50% of the population, is a standard measure of pesticide toxicity. The lower the LD50 value, the more toxic the substance is considered, as it takes a smaller amount to cause harm or death to half of a test population (often laboratory animals). In this scenario, a pesticide with an oral LD50 of 5 mg/kg indicates that only a small dose is required to achieve lethal effects, making it more toxic compared to a pesticide with an LD50 of 250 mg/kg, which requires a much larger dose to reach the same level of toxicity. Thus, the pesticide with the lower LD50 is indeed more hazardous to organisms when assessing oral toxicity. This understanding of LD50 values is crucial in evaluating pesticide safety and risk, guiding proper handling, application, and regulatory decisions.