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).