What is a bioassay and when is it required?

• A. A measurement of radioactive material within the body or excreta to estimate internal dose; required when there is potential for inhalation/ingestion or intake above threshold levels
• B. A blood pressure check
• C. A measure of external exposure from outside the body
• D. A survey instrument calibration process

Answer: (A)

Bioassay means measuring radioactive material that may be inside the body or in bodily excreta to estimate the internal dose a worker has received from intake. It is required when there is potential for internal contamination that could exceed predefined threshold levels, such as when inhalation, ingestion, or wound contamination is possible. The results support internal dosimetry to determine the committed effective dose, guide medical follow-up if needed, and ensure regulatory dose limits and safety standards are met. This differs from measuring external exposure with dosimeters or survey meters and from instrument calibration, which are not about detecting internal radioactive material.