Which sequence correctly lists the basic steps in a human health risk assessment for environmental pollutants?

• A. Hazard identification; Dose–response assessment; Exposure assessment; Risk characterization.
• B. Exposure assessment; Hazard identification; Dose–response; Risk characterization.
• C. Risk characterization; Hazard identification; Exposure assessment; Dose–response.
• D. Hazard identification; Exposure assessment; Dose–response; Risk characterization; uncertainty analysis.

Answer: (A)

Understanding how a human health risk assessment is organized helps you see why this order makes sense: identify what could cause harm, quantify how risk changes with dose, estimate how much exposure people actually have, then combine everything to describe overall risk and its uncertainties. The best sequence follows hazards identification first, then dose–response assessment, then exposure assessment, and finally risk characterization. Hazard identification is foundational—you need to know what substances and effects are of concern before you can judge how bad they can be. The dose–response step explains how adverse effects relate to the amount of substance, giving a link between dose and harm that informs how to interpret exposure data. Once you know the dose–response relationship, you estimate exposure to translate real-world contact into a dose that can be evaluated in relation to that relationship. Finally, risk characterization brings it all together to describe the overall risk and discuss uncertainties. Starting with exposure misses the needed hazard context, placing risk characterization first assumes everything else is already done, and swapping dose–response and exposure disrupts the logical flow from how toxicity changes with dose to how much exposure actually occurs.