Declared Pregnancy and Fetal Monitoring for Radiation Workers

 

It is natural to be concerned about the different hazards that can cause harm to a developing embryo/fetus. In a hospital or research setting, one of those hazards is ionizing radiation. It is important to understand the risks of radiation to the unborn child. Presented here is a summary of those risks and the University’s position.

NRC, State, and University Position
The Nuclear Regulatory Commission bases its recommendations and regulations on a conservative theory that implies that any radiation dose results in some effect. The NRC sets their regulations and recommendations to minimize any harmful effect. The annual limit for an occupational worker is set at 5,000 mrem (50 mSv). Because the embryo/fetus is more sensitive to radiation, the dose limits are a fraction of the occupational worker limit and well below the doses at which effects have been obeserved. The dose limit for embryo/fetus is set at 500 mrem (5 mSv) during the entire gestation period.

In order for the lower dose limits to be applied, a worker must declare her pregnancy. A worker must declare her pregnancy voluntarily, in writing, and provide the month and year of conception.

The State of Utah as an agreement state adopts the regulations and recommendations of the NRC.

The University of Utah follows the rules and regulations set forth by the State and the NRC. The lower dose limit can be invoked by providing the Radiological Health Department and the worker’s supervisor with a written declaration of pregnancy (Declaration of Pregnancy PDF) . The worker can “un-declare” her pregnancy and reinstitute the higher occupational annual limit by submitting a written statement to the Radiological Health Department. This declaration dose not automatically mean you will be issued a dosimeter, the issuing of a dosimeter will be made on a case by case basis.

The Radiological Health Department is dedicated to keeping the worker and her unborn child safe from the harmful effects of radiation. The Radiological Health Department will work with an employee to keep radiation doses As Low As Reasonably Achievable (ALARA) so that risks to the embryo/fetus are minimized. Please feel free to contact our office at 581-6141 if you have any questions or concerns.

Fetal Irradiation and Risk
The fetus/embryo has varying radiation sensitivity during the different developmental stages of pregnancy. The most sensitive stage of development is during the first two trimesters.

Childhood Cancer
The increased risk of death of the child from cancer from birth to age ten increases by 0.2 excess deaths per 1,000 children from a dose of 1,000 mrem (10 mSv) in utero.

Malformations
The malformations associated with radiation dose usually express themselves in central nervous system problems. A threshold of 10,000-20,000 mrem (100-200 mSv) has been shown to exist.

Microcephaly (smallness of head) and Mental retardation
Microcephaly and mental retardation excess risk if exposed to 1,000 mrem (10 mSv) is dependent of the stage of development. If this dose is received during weeks 4-7, there is an increased risk of microcephaly of 5 per 1,000 and during weeks 8-11 the risk becomes 9 per 1,000 for the same dose. Additionally, if a dose of 1,000 mrem (10mSv) is received during weeks 8-15, there is an increased risk of mental retardation of 4 per 1,000.

Declaration of Pregnancy Form
Declaration of Pregnancy PDF

Related links
Westside Pregnancy Resource Center
NRC Instruction concerning prenatal radiation exposure PDF
NRC Radiation dose to the embryo fetus PDF
ICRP Pregnancy and Medical Radiation
UC Davis EH&S Pregnancy and Radiation

References
1. National Academy of Sciences. Health Effects of Exposure to Low Levels of Ionizing Radiation: BEIR V. National Academy Press, Washington, D.C., 1990