Answer to Question #4959 Submitted to "Ask the Experts"

Category: Radiation Workers — Pregnant Workers

The following question was answered by an expert in the appropriate field:

I am a nuclear medicine technician in my fifth week of pregnancy. My whole-body exposure for one month was 189 mrem. How bad can that be for the fetus?

At the radiation dose you describe, there would be no expected biological effect for the fetus. The National Council on Radiation Protection & Measurements, 1977, said that the risk of abnormality is negligible at 5,000 mrad or less when compared to other risks of pregnancy, and the risk of malformations is significantly increased above natural levels only at doses above 15,000 mrad (for our purposes, you can consider an mrem and an mrad the same).

Although the radiation dose level is not a particular concern for the fetus, you need to contact your organization's radiation safety officer (RSO). You need to do this because:

The regulatory gestational radiation dose limit to a declared pregnant worker is 500 mrem and you are on track to exceed this.
Nuclear Regulatory Commission regulations and some Agreement State regulations state that average exposure to a declared pregnant worker should be maintained, if possible, to 50 mrem/month.
The dose you mention, 189 mrem, seems a bit high for a nuclear medicine technologist to receive in a month so your RSO should review your exposure history to determine ways you can minimize your dose. The average whole-body radiation dose for a nuclear medical technician is 400-600 mrem/year (National Council on Radiation Protection & Measurements Report 124).

Kelly Classic
Certified Medical Health Physicist

Answer posted on November 4, 2005. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.