Index | Site Map | FAQ | Facility Info | Reading Rm | New | Help | Glossary | Contact Us

The entries for selected radionuclides and chemical forms in the tables in this appendix have been calculated from the modeling presented in Revision 1 to NUREG/CR-5631 (Ref. C1). It has been assumed that 1 Ci of activity is introduced into the maternal transfer compartment (blood). Pregnancy is assumed to begin at the time of fertilization, roughly 2 weeks after menses, and gestation is considered to consist of nine 30-day months.

Radiation dose rates were calculated from the initial fraction that was present after a single administration at the start of each of these months or on the assumed final day (day 270) of gestation. Monthly doses were determined by integrating under the curve relating the fraction of the activity in the embryo/fetus at the start of each month after administration and the fraction at the beginning of the subsequent month of gestation. Monthly doses are shown for the inclusive periods, expressed in days. Doses to the embryo/fetus from radionuclides in maternal organs were calculated; when appropriate, these are included to provide total radiation absorbed doses. The tabulated values of cumulated doses were determined as the sum of the monthly doses.

As noted in Revision 1 to NUREG/CR-5631 (Ref. C1), ICRP Publication 30 (Ref. C2) employs a metabolic model in which a fraction of activity in the first transfer compartment (blood) often is assumed to go immediately to excretion. Because of the minuscule mass of the embryo/fetus immediately following fertilization, for some materials the biokinetic model thus predicts that there would be negligible initial activity in the embryo after administration at that time, and that there would be minimal activity at later times. As a consequence, the dose rate and doses also would be negligible, which is indicated by N in the table. For these nuclides, an approximation of the cumulative dose for an intake occurring during the first 30 days should be made based on a time-weighted average of the 31-day intake data. The cumulative dose from an intake in the first 30 days of pregnancy may be estimated by multiplying the 31-day cumulated dose value by the ratio of the days-to-date in the first month to a 30-day period. For example, assuming a maternal intake of ¹⁴C resulting in a 1 µCi blood uptake on the 20th day of the pregnancy, the gestation dose should be determined by multiplying the cumulative dose from an intake at day 31 (i.e., Table C3, Cumulated Dose column, 1.89E-04 rads) by the ratio of 20 days to 30 days (i.e., 20 divided by 30).

Table C1
Radiation Doses to the Embryo/Fetus from 1 μCi of ³H, as Tritiated Water, Introduced into the Maternal Transfer Compartment (Blood)

Table C2
Radiation Doses to the Embryo/Fetus from 1 µCi of ³H, as a Hexose or Amino Acid, Introduced into the Maternal Transfer Compartment (Blood)

Table C3
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹⁴C, as a Bicarbonate, Hexose, Amino Acid, Introduced into the Maternal Transfer Compartment (Blood)

Table C4
Radiation Doses to the Embryo/Fetus from 1 µCi of ⁵⁷Co, Introduced into the Maternal Transfer Compartment (Blood)

Table C5
Radiation Doses to the Embryo/Fetus from 1 µCi of ⁵⁸Co, Introduced into the Maternal Transfer Compartment (Blood)

Table C6
Radiation Doses to the Embryo/Fetus from 1 µCi of ⁶⁰Co, Introduced into the Maternal Transfer Compartment (Blood)

Table C7
Radiation Doses to the Embryo/Fetus from 1 µCi of ⁵⁷Co, as Vitamin B-12, Introduced into the Maternal Transfer Compartment (Blood)

Table C8
Radiation Doses to the Embryo/Fetus from 1 µCi of ⁶⁰Co, as Vitamin B-12, Introduced into the Maternal Transfer Compartment (Blood)

Table C9
Radiation Doses to the Embryo/Fetus from 1 µCi of ⁸⁹Sr Introduced into the Maternal Transfer Compartment (Blood)

Table C10
Radiation Doses to the Embryo/Fetus from 1 µCi of ⁹⁰Sr (in Equilibrium with ⁹⁰Y) Introduced into the Maternal Transfer Compartment (Blood)

Table C11
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹⁰⁶Ru (in Equilibrium with ¹⁰⁶Rh) Introduced into the Maternal Transfer Compartment (Blood)

Table C12
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹²⁵I Introduced into the Maternal Transfer Compartment (Blood)

Table C13
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹³¹I Introduced into the Maternal Transfer Compartment (Blood)

Table C14
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹³²I Introduced into the Maternal Transfer Compartment (Blood)

Table C15
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹³³I Introduced into the Maternal Transfer Compartment (Blood)

Table C16
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹³⁴I Introduced into the Maternal Transfer Compartment (Blood)

Table C17
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹³⁵I Introduced into the Maternal Transfer Compartment (Blood)

Table C18
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹³⁴Cs Introduced into the Maternal Transfer Compartment (Blood)

Table C19
Radiation Doses to the Embryo/Fetus from 1 µCi of ¹³⁷Cs Introduced into the Maternal Transfer Compartment (Blood)

Table C20
Radiation Doses to the Embryo/Fetus from 1 µCi of ²³³U Introduced into the Maternal Transfer Compartment (Blood)

Table C21
Radiation Doses to the Embryo/Fetus from 1 µCi of ²³⁴U Introduced into the Maternal Transfer Compartment (Blood)

Table C22
Radiation Doses to the Embryo/Fetus from 1 µCi of ²³⁵U Introduced into the Maternal Transfer Compartment (Blood)

Table C23
Radiation Doses to the Embryo/Fetus from 1 µCi of ²³⁸U Introduced into the Maternal Transfer Compartment (Blood)

Table C24
Radiation Doses to the Embryo/Fetus from 1 µCi of ²³⁸Pu Introduced into the Maternal Transfer Compartment (Blood)

Table C25
Radiation Doses to the Embryo/Fetus from 1 µCi of ²³⁹Pu Introduced into the Maternal Transfer Compartment (Blood)

Table C26
Radiation Doses to the Embryo/Fetus from 1 µCi of ²⁴¹Am Introduced into the Maternal Transfer Compartment (Blood)

*N indicates that the metabolic pattern is such that the dose rates and doses would be negligible throughout gestation when activity is administered immediately after fertilization. Approximations of doses resulting from administration during the first month are described on page C-1.

REFERENCES

C1. M. R. Sikov et al., "Contribution of Maternal Radionuclide Burdens to Prenatal Radiation Dose--Interim Recommendations," NUREG/CR-5631, Revision 1 (PNL-7445), U.S. Nuclear Regulatory Commission, March 1992.

C2. International Commission on Radiological Protection, "Limits for Intakes of Radionuclides by Workers," ICRP No. 30, Parts 1 through 4, including supplements, Annals of the ICRP, Volume 2, No. 3/4, Pergamon Press Inc., 1979.