Answer to Question #110 Submitted to "Ask the Experts"
Category: Policy, Guidelines, and Regulations — Guidance Documents
The following question was answered by an expert in the appropriate field:
Q
What is the origin of release criteria for personnel who have potential contamination on their skin?
A
Release criteria for personnel contamination of the skin, or clothing, is intended to meet the following goals or requirements for occupational workers (i.e., this is not applicable for release criteria, for example, for patients who have received diagnostic or therapeutic administration of radio-pharmaceuticals):
- It must be low enough to ensure exposure limits are not approached for the contaminated individual, or any individual coming in close proximity or contact with the contaminated person.
- It must be low enough to ensure subsequent ingestion or inhalation of the radioactive material coming off the contaminated individual cannot result in an intake of any radiological significance.
- It must be high enough to allow for detection using readily available and standard radiation survey instrumentation.
- It should be at a level that serves as an indicator that good contamination control practices in the workplace may have failed in order for the contamination to have occurred.
The most limiting condition of these goals or requirements is, invariably, number 3; that is, the capability of survey instrumentation to detect contamination drives the release criteria. The levels at which standard survey instruments (for example, a Geiger-Muller tube "frisker" and meter, or portal monitoring systems) are well below the levels that would give any concern for subsequent exposure. However, the detection of unexpected personnel contamination should be taken seriously by radiation protection personnel because it may be an indicator that some aspect of contamination control procedures failed with a potential for greater consequences later if the cause is not found and corrected. In addition, any contamination detected above the release criteria should be removed, using reasonable efforts and techniques, even if it doesn't pose an exposure hazard. This is part of the philosophy to keep exposures As Low As Reasonably Achievable (ALARA). However, care should be taken not to use cleaning techniques on the skin that may injure the skin for contamination levels that are above the release criteria but low enough to not cause a concern for the exposure.
Keith H. Dinger, CHP
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