Define dose and dose rate in toxicology terms, and how they relate to exposure assessment.

• A. Dose is the surface area of exposure, dose rate is the color of the chemical.
• B. Dose is the amount of chemical contact with the body; dose rate is the amount per unit time; IH uses exposure duration and concentration to estimate dose.
• C. Dose rate is distance from source; Dose is time exposed.
• D. Dose refers to the lethal amount; dose rate to the speed of release.

Answer: (B)

In toxicology, dose is the amount of chemical that actually contacts or enters the body, and dose rate is the amount delivered per unit time. When doing exposure assessment, industrial hygienists estimate how much chemical reaches the body by using the exposure concentration and the duration of exposure, then applying the appropriate intake rate for the route (inhalation or dermal) and often normalizing by body weight to express it as mg/kg. This connection between external conditions (concentration and time) and the internal dose is what ties exposure to potential toxic effects. The other ideas—like surface area, color, distance from the source, or merely the duration without rate—don’t define dose or dose rate, and terms about lethal amounts or speed of release describe different concepts (toxicity endpoints and release kinetics) rather than the dose itself.