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Schlagwörter:
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Zusammenfassung:
The natural 226Ra activity in human foetal bone ash remains constant from the fourth to the tenth month of pregnancy. The 226Ra content is equal to that determined in the bone ash of adults, found to be 1.3 * 10−14 c/g of bone ash. An analogous identity in the 226Ra content of soft tissue of foetuses and adults has also been found. For both embryonic and adult tissues the specific activity is 1 * 10−16 c/g of fresh tissue. From comparison of the specific values of the 226Ra content in bone and soft tissue it may be derived that the major portion of the 226Ra content of the foetus is in the skeleton. Therefore the specific 226Ra activity of ashed total foetuses is of the same order of magnitude as the value in foetal bones. The 226Ra activity of placental tissue is about 2 * 10−16 c/g of fresh tissue. The discrimination factor between the placenta and the foetal bones, and the placental transfer of 226Ra are discussed. The specific radium level of both the placenta and the embryonic tissue proved to be comparable. In consequence the placenta does not act as a barrier for the natural 226Ra content, that is to say there seems to be no discrimination in the passage of this radionuclide.
