What is benchmark dose (BMD) and its use in risk assessment?

• A. A dose associated with a specified increase in risk; used to establish reference points for risk estimation.
• B. The lowest dose producing adverse effects in all individuals.
• C. The maximum tolerated dose for a population.
• D. The dose at which risk becomes negligible.

Answer: (A)

Benchmark dose is a dose that corresponds to a predefined increase in adverse response above background, estimated by fitting a dose–response model to the data. In risk assessment, this dose provides a reference point of departure from which safe exposure levels (like a reference dose) are derived. The benchmark response is a chosen level of increased risk (for example, 10% extra cancer risk or a smaller noncancer effect) and the analysis often uses a lower confidence limit (BMDL) to be protective. This approach uses the full dose–response information rather than a single observed effect level, making it more informative for setting limits. It isn’t the lowest dose that causes effects in everyone (that’s a NOAEL/LOAEL concept), nor the maximum tolerated dose, nor the point at which risk becomes negligible.