How is risk calculated in relation to pesticides?

• A. Risk = Toxicity x Exposure.
• B. Risk = Toxicity + Exposure.
• C. Risk = Exposure / Toxicity.
• D. Risk = 1 / (Exposure).

Answer: (A)

Understanding pesticide risk starts with recognizing that harm depends on two things: how toxic the chemical is (toxicity) and how much contact people have with it (exposure). In typical risk calculations, you multiply these two factors. Risk rises when either toxicity or exposure increases, and if either is zero, the risk is zero. Other relationships don’t fit how risk behaves: adding toxicity and exposure treats the factors as merely summing harm, which isn’t how the risk from a chemical compounds; dividing exposure by toxicity would imply that higher toxicity reduces risk, which isn’t correct; and taking a reciprocal doesn’t reflect how increasing exposure or increasing toxicity both drive risk up. So the straightforward model is risk = toxicity × exposure.