Galactic cosmic radiation exposure of pregnant flight crewmembers

Background: In recommending the occupational dose limit of ionizing radiati on for pregnant women, the International Commission on Radiological Protect ion apparently assumes that the dose to the conceptus from ionizing radiati on exposure is about half the dose at the surface of the mother's abdomen. Methods: To test this assumption with respect to galactic cosmic radiation, calculations were made using FAA computer program CARI-LF2, which calculat es equivalent doses from galactic cosmic rays at selected depths in soft ti ssue at any specified location in the atmosphere or an user-entered flight profiles. Results:The calculations showed that the equivalent dose of galac tic radiation was almost the same at all depths. Conclusions: Thus the assu mption of considerable shielding of the conceptus being provided by the wom an's body is not correct with respect to galactic cosmic radiation, the pri ncipal type of radiation to which aircrews are exposed. The effective dose as calculated with FAA computer program CARI-5E, which calculates effective dose in an anthropomorphic phantom at any specified location in the atmosp here or-on user-entered flight profiles, was found to be a good estimate of the equivalent dose at the depth of the conceptus.