Health Physics Questions and Answers - Question 138
Question 138: Although it is extremely unlikely, long-lived residual radioactive material in the body of a female worker from her previous employment could deliver a dose exceeding the limit to a subsequently conceived embryo / fetus. For example, a former DOE worker who had been involved in an accident could have a large americium or plutonium body burden. 10 CFR 20.1208 makes no special provision for this eventuality. What action would the NRC expect the licensee to take?
Answer: The answer to this question is provided in Regulatory Guide 8.36, "Radiation Dose to the Embryo / Fetus," which indicates that if monitoring of a declared pregnant woman is required, the existing body burden must be included in determining the embryo / fetus dose. If the licensee determines that the dose to the embryo / fetus has exceeded 0.5 rem, or is within 0.05 rem of the dose limit by the time the woman declares her pregnancy, the licensee may allow the embryo / fetus to receive an additional 0.05 rem during the remainder of her pregnancy. If the prior body burden alone caused a dose to the embryo / fetus in excess of the limit, that dose should be recorded, but the NRC would not take enforcement actions for this "overexposure" provided that the licensee does not allow the embryo / fetus to receive more than 0.05 rem after the woman has declared her pregnancy. See the answer to the related Question 120. That answer states that the intent of 10 CFR 20.1208 (d) is that the licensee should not be in violation of the limit for the embryo / fetus as a result of doses received by the embryo / fetus before the woman declared her pregnancy or doses received as a result of intakes before that declaration was made.
(Reference: 10 CFR 20.1208)