Abstract
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.
BACKGROUND
Japanese radiation protection laws and regulations stipulate an effective dose limit of 5 mSv 3 months−1 for female radiation workers of reproductive age. The ICRP recommendations set a limit on the equivalent dose delivered to the abdomen of pregnant women to protect the fetus, as for the general public, during the remaining time of pregnancy after it is known and declared. We have argued for the necessity of the dose restriction for women of reproductive age, which does not exist in the ICRP recommendations, through two questionnaire surveys. One survey involved pregnant women to determine when they became aware of their pregnancy, while the other surveyed female healthcare workers to obtain information about their expectations regarding specific radiation protection measures, including the dose limitation for women, to enable them to safely engage in radiation work. Based on the results of these two surveys (Kato, 2019), we encourage related institutions and society to address the need for the dose limit for women of reproductive age. The two surveys were conducted with the approval of the ‘Tokyo Healthcare University of Health Sciences Ethics Committee on Human Research’ (Approval No. Institution 29-15 and Institution 30-18A, respectively).
SURVEY OF PREGNANT WOMEN
A total of 444 pregnant women (Table 1: first-time mothers, 197; multiparous mothers, 247) who visited six obstetrics and gynaecology hospitals, were asked about the time when they became aware of this pregnancy and the changes in maternal behaviours after pregnancy became apparent. The time when the respondents realised that they were pregnant was distributed between 3.3 and 10.2 weeks, with a mean of 5.2 weeks (±1.1 weeks) of gestational age. Of note, the pregnant woman who noticed her pregnancy the latest (10.2 weeks of gestational age) had a regular menstrual cycle. After finding that they were pregnant, almost all pregnant women made efforts to improve their lifestyles in consideration of fetal effects, such as refraining from taking medication and abstaining from alcohol. We also asked if they would take their x-ray diagnosis, such as dental, chest, and abdomen, that the physician in charge deemed necessary, with four options including ‘yes,’ ‘unsure,’ ‘no,’ and ‘don’t know’. Notably, about 80% of respondents answered that they would not even take an X-ray diagnosis of dental and chest that were not in the irradiation field (Fig. 1).
Opinion on whether to accept X-ray examinations deemed necessary by a physician during pregnancy.
Characteristics of the Pregnant Women who responded to our survey.
A total of 1574 female nurses (1465), physicians (62), and radiology technicians (47) working at six hospitals were asked about radiological protective measures against occupational exposure. The work duration of the female medical staff in the study ranged from less than 1 year to 48 years, with a mean of 9.2 years (±8.6 years). Regarding their past experience in radiological practices, 369 (23.4%) were ‘currently engaged,’ 188 (12.0%) were ‘not currently engaged but had been in the past,’ and 1017 (64.6%) had ‘never been engaged’ (Table 2). A total of 55.1% of nurses, 50.0% of physicians, and 17.8% of radiology technicians had ‘concerns regarding occupational radiation exposure’. Regarding the necessity of the dose limit (5 mSv 3 months−1) for women set by Japanese law, 67.0% said it was necessary, 1.2% said it was not necessary, 17.0% had never thought about it, 13.7% (216 participants) were unsure, and 1.1% (17 participants) did not answer (Fig. 2).
Opinion on the Necessity of Establishing Dose Limits (5 mSv 3 months−1) for female radiation workers by Low.
Characteristics of 1574 responders (1465 Nurses, 62 Physicians, 47 Radiology technicians).
The time when pregnant women themselves became aware of their pregnancy was distributed from 3.3 to 10.2 weeks, with a mean of 5.2 (±1.1) weeks of gestational age, a period of high susceptibility to malformations. Regarding x-ray diagnosis during pregnancy, about 80% of pregnant women answered that they would not even undergo a dental or limb x-ray diagnosis, with little or no possibility of fetal radiation exposure. The medical use of radiation by patients is essentially voluntary and linked to the expectation of direct health benefits of the individual patient (ICRP, 2007), suggesting the need for radiation education for patients to help them make their own decisions regarding which examinations are necessary. Regarding the dose limits for occupational exposure of radiation workers of reproductive age, ensuring that radiation workers have the right to choose whether to focus on radiation protection of the embryo and fetus as a public health concern or on women's right to work is crucial. The effective dose limit of 5 mSv 3 months−1, calculated based on the ICRP recommendation of 100 mSv 5 years−1, was introduced in Japanese radiation protection laws and regulations. Considering the current situation in which many women of reproductive age are concerned about radiation work when they become pregnant, we believe that the establishment of dose limits for women of reproductive age will lead to the safety and security of radiation workers.