In toxicology, how is dose defined?

• A. Dose equals concentration x intake
• B. Dose equals exposure duration
• C. Dose equals frequency of exposure
• D. Dose equals route of exposure

Answer: (A)

The main idea is that dose is the amount of chemical that actually enters the body. It is determined by how concentrated the contaminant is in the exposure medium and how much of that medium is taken in. In practice, multiplying the concentration (how much chemical per unit of medium) by the intake (how much medium is consumed or inhaled) gives the total amount reaching the body, often then scaled by body weight to yield mg/kg. This is why dose is best described as concentration times intake—the other factors like how long you’re exposed, how often, or the route of exposure influence how much is absorbed and delivered, but they are not the dose by themselves.