妊娠作業者・胚・胎児の放射線防護: ICRP勧告の変遷と現在の課題

抄録

In its latest basic recommendations issued in 2007, the International Commission on Radiological Protection (ICRP) recommends that the working conditions of a pregnant worker, after declaration of pregnancy, be such as to ensure that the additional dose to the embryo and fetus would not exceed about 1 mSv during the remainder of the pregnancy, where exposures of the embryo and fetus of pregnant workers are considered and regulated as public exposures. However, it remains unclear, e.g., [1] whether such recommended additional dose of about 1 mSv to the embryo and fetus is the whole body equivalent dose or the effective dose, [2] if the latter, how to compute the effective dose while the currently recommended tissue weighting factors (w_T) do not include the stochastic risks of in utero exposures and while the unavailability of the current epidemiological data sets does not allow computation of detriment for in utero exposures, and [3] whether the embryo and fetus are the public. This paper briefly reviews historical changes in ICRP recommendations on protection of pregnant workers, embryo and fetus, and then discusses pertinent issues behind the 2007 recommendations.