Dose limits to protect maternal and fetal health: Legislation in Japan

Japanese radiation protection laws and regulations stipulate an effective dose limit of 5 mSv 3 months^-1 for female radiation workers of reproductive age, with a focus on protecting the fetus as the general public. To maintain this unique Japanese dose limit, we conducted two questionnaire surveys to determine when pregnant women become aware of their pregnancy (444 participants) and to obtain information about expectations regarding radiation protection practices among female healthcare staff (1574 participants). Pregnant women became aware of their pregnancy at 5.2 weeks (±1.1 weeks) of gestational age, a time of high sensitivity with respect to embryonic deaths and malformations. Regarding the necessity of the effective dose limit (5 mSv 3 months^-1) set by Japanese law for women, only 1.2% of the respondents deem it not 'necessary'. The effective dose limit of 5 mSv 3 months^-1 for radiation workers of reproductive age is an important criterion for female workers to engage in radiation work safely and securely. We considered this value is in line with the ethical foundation of the ICRP's basic protection policy and protection system and is reasonable in terms of radiation control practices.