Biokinetics and internal dose from selected radionuclides to the human fetus

For radioisotopes of the elements iodine, iron, caesium and strontium applied in medicine or playing a role in the emissions from nuclear facilities, a comparative assessment of fetal and maternal radiation exposures after the incorporation of iodine 131, iron 59, caesium 137 and strontium 90 is presented. In spite of the differences in regard to the physical properties, the distribution and retention in the organism, for the four radionuclides considered the following commonly applying conclusions may be drawn: - the activity concentrations in the relevant fetal tissues (iodine:thyroid, iron:liver, caesium:total body, strontium:bone) may be higher than those in the respective maternal tissues; the half-lives in the respective tissues are virtually shorter in the fetus due to the higher turnover-rate, as compared to those of the mother; the absorbed fraction of the energy emitted is lower in the fetal organs due to their much smaller dimensions, as compared to the respective organs of the mother