Occupational Radiation Exposure Limits for Employees Who Are Pregnant or Breast-Feeding
Background
Exposure of the embryo/fetus to ionizing radiation carries a risk of causing certain adverse health effects such as cancer and developmental abnormalities. Accordingly, the National Council on Radiation Protection and Measurement (NCRP) has recommended that the total dose equivalent to the embryo/fetus from occupational exposure of the expectant mother not exceed 500 mRem (NCRP Report No. 53), and that once the pregnancy is known, exposure of the embryo/fetus not exceed 50 mRem in any month (NCRP No. 91). The Nuclear Regulatory Commission (NRC) requires (in 10 CFR 20.1208) that the dose to an embryo/fetus during the entire pregnancy, due to occupational exposure of a declared pregnant woman, not exceed 500 mRem, and that substantial variations in a uniform monthly exposure rate to satisfy this limit be avoided. The dose to the embryo/fetus is taken as the sum of the external deep dose equivalent to the pregnant woman and the dose from radionuclides incorporated in the embryo/fetus and pregnant woman.
In support of the NCRP recommendations and NRC regulations, the University of Pittsburgh's Radiation Safety Committee has instituted the following policy and guidelines for occupational radiation exposure of employees who are pregnant or breast-feeding.
Policy
The dose to an embryo/fetus during the entire pregnancy, due to occupational exposure of a declared pregnant woman, will be limited to 500 mRem. Substantial variations in a uniform monthly exposure rate should be avoided. Limits of exposure to the general population will be applied to a nursing infant. Work restrictions may be required in order to meet the intent of this policy.
Procedure
A radiation worker who becomes pregnant should notify her department head or supervisor and the Radiation Safety Office (RSO) as early as possible. If the employee chooses not to declare the pregnancy to the RSO, additional controls and monitoring for her radiation exposure cannot be implemented.
Declaration of pregnancy is voluntary and involves the completion of a written declaration that is submitted to the Radiation Safety Office.
Upon notification of pregnancy, the RSO will provide instruction as applicable, on the risks of radiation exposure to the embryo/fetus of the worker. The RSO will also evaluate the employee's radiation work environment, past exposure history, and potential for future exposure. Based on this information, the RSO may make recommendations or impose restrictions regarding the employee's duties involving occupational radiation exposure. This review and evaluation will be documented, signed by the employee, the employee's department head or supervisor, and the Radiation Safety Officer, and filed in the RSO.
The pregnant employee may continue working in those areas and job duties where it is unlikely that her external and internal radiation exposures will exceed the total and monthly limits to the embryo/fetus, with proper attention to safe radiation practices. A pregnant employee will be restricted from those areas and job duties where there is potential for a significant radiation dose to the embryo/fetus from either an external or internal exposure. Examples of these types of situations are, but not limited to: administration of radiopharmaceutical therapy or manual brachytherapy, caring for patients administered radiopharmaceutical therapy or brachytherapy, or working in a laboratory where radio-iodine in a volatile form is being used.
Appropriate radiation monitoring will be provided if it is likely that the embryo/fetus might receive an external dose of more than 50 mRem during the entire pregnancy. Bioassay will be required to monitor internal exposures for workers handling unsealed sources of radioactive material, if it is likely that an intake of a radionuclide would exceed 1 percent of an Annual Limit on Intake (ALI) during the entire period of gestation. Records of the dose to the embryo/fetus will be maintained with the mother's radiation dose records.
Once the total effective dose to the embryo/fetus of the declared pregnant woman exceeds 400 mRem, she will be restricted from any further work involving occupational radiation exposure for the remainder of the pregnancy.
An employee who has declared that she is breast-feeding may be restricted from those areas and job duties where unsealed sources of volatile radioactive materials are used. Bioassay may be required to monitor internal exposures of nursing workers handling unsealed sources of radioactive material. Recommendations will be made, based on the bioassay results, to assure that the nursing infant does not receive an annual committed effective dose equivalent of more than 100 mRem.