Dose Equivalent to an Embryo/Fetus

Section 340 Section 340.280  Dose Equivalent to an Embryo/Fetus a)         Except as otherwise provided in subsections (d) and (e) of this Section, the licensee or registrant shall ensure that the dose equivalent to an embryo/fetus during the entire pregnancy, due to occupational exposure of a declared pregnant woman, does not exceed 5 mSv (0.5 rem).  (For recordkeeping requirements, see Section 340.1160(d) of this Part.) b)         The dose equivalent to an embryo/fetus shall be taken as the sum of: 1)         The deep dose equivalent to the declared pregnant woman during the entire pregnancy; and 2)         The dose equivalent to the embryo/fetus from radionuclides in the embryo/fetus and radionuclides in the declared pregnant woman during the entire pregnancy. c)         The licensee or registrant shall make efforts to avoid substantial variation above a uniform monthly exposure rate to a declared pregnant woman so as to satisfy the limit in subsection (a) of this Section. AGENCY NOTE:  The National Council on Radiation Protection and Measurements report entitled "Recommendations on Limits for Exposure to Ionizing Radiation", NCRP 91, published June 1, 1987, recommends that no more than 0.5 mSv (0.05 rem) of the allowed dose to the embryo/fetus be received during any one month during a declared pregnancy. d)         If the declared pregnant woman has not notified the licensee or registrant of the estimated date of conception, the licensee or registrant shall ensure that the dose equivalent to an embryo/fetus, as specified in subsection (b) of this Section, due to occupational exposure of the declared pregnant woman does not exceed 0.5 mSv (0.05 rem) per month, during the remainder of the pregnancy.  If after initially declaring her pregnancy, a declared pregnant woman advises the licensee or registrant of the estimated date of conception, the dose limits specified in subsections (a) and (e) of this Section shall apply. AGENCY NOTE:  The Agency encourages licensees and registrants to explain to declared pregnant workers that providing an estimated date of conception will enable the licensee or registrant to more accurately assess the radiation dose equivalent to the embryo/fetus and assist the licensee or registrant in determining appropriate precautions to be taken for the remainder of the pregnancy. e)         If by the time the woman informs the licensee or registrant of the estimated date of conception the dose equivalent to the embryo/fetus has exceeded 4.5 mSv (0.45 rem), the licensee or registrant shall be deemed to be in compliance with subsection (a) of this Section if the additional dose equivalent to the embryo/fetus as specified in subsection (b) of this Section does not exceed 0.5 mSv (0.05 rem) during the remainder of the pregnancy.