Radiation Protection Dosimetry Vol. 112, No. 4 © Oxford University Press 2004; all rights reserved
Can tissue weighting factors be established for the embryo and fetus?
Institute for Science and Ethics, University of Duisburg-Essen, Auf dem Sutan 12, 45239 Essen, Germany
Corresponding author: streffer.essen{at}t-online.de
For the calculation of effective dose (E), tissue weighting factors (wT) are needed to represent the varying radiosensitivity of the tissues in the human body with respect to the induction of stochastic effects. The wT-values have been determined by the International Commission on Radiological Protection according to the stochastic detriment of human populations during their postnatal life. This study discusses whether these wT-values can also be used for the embryo/fetus. For this purpose, the epidemiological data and some results from animal experiments on carcinogenesis after prenatal radiation exposures have been reviewed. Most human data have been obtained from studies of childhood cancers (<19 y of age) after exposures during prenatal development. These tumours differ from those observed later in life after radiation exposures of children and adults. From animal data and more recent results from the atomic bomb survivors, it appears that not only childhood cancers but also cancers occurring during adulthood would have to be considered for the determination of possible wT-values after prenatal irradiation. From the present data it is concluded that sufficient data for defining wT-values following exposure of the embryo/fetus are not available at present.