In 2011, for occupational exposure in planned exposure situations, the International Commission on Radiological Protection (ICRP) recommended an equivalent dose limit for the lens of the eye of 20 mSv/year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv. Japanese regulatory authorities started discussions on the dose limit to the lens in 2017. In April 2021, new regulations related to the dose limit to the lens will take effect. Employers should comply new related regulations and optimize radiation protection. On June 30, 2020, the second day of the 53rd Annual Meeting of the Japan Health Physics Society (Web conference), the live symposium entitled “Symposium for Radiation Protection of the Lens of the Eye (Webinar)” was held. In this symposium, new guidelines for the lens dose monitoring and for the safety management of medical staff were introduced. In addition, the current status and issues in the nuclear, medical and individual monitoring fields were reported and discussed. In this paper, we reconsidered the presentations of this symposium and discussed radiation protection on the lens of the eye in the future.
Long-term biological irradiation experiments require considerable materials and time until to obtain analytical results. Thus, if the results that might be obtained can be predicted when designing an experiment, that information is very useful to those who will perform the experiment. However, there has not been any simulator that can accurately predict such results. This was due to the inadequacy of the mathematical model used for the prediction. Therefore, we have newly created a genetic effect prediction simulator “WAMSIM” based on the calculation principle of a mathematical model “WAM (Whack-A-Mole) model” that can show the variation of genetic effects in a dose rate-dependent manner. Since the WAM model includes the time component as a parameter, it is possible to estimate the fluctuation of the genetic effect even in experimental conditions in which the dose rate changes over time and/or in fractionated irradiation. In this report, we have actually used WAMSIM to predict the effects on the next generation in mice that have been continuously irradiated with low LET radiation for a long period of time or in mice that have received fractionated irradiation. As a result, we have obtained some important findings to keep in mind when conducting irradiation experiments.
The risk of leukemia related with radiation exposure was pointed out in a case report of a physician in 1911 and in subsequent reports. After that, many cohort studies among nuclear workers have been conducted in various countries on the leukemia risk at low dose and/or low dose rate radiation. However, these studies did not have consistent conclusions. INWORKS and UK NRRW cohort studies argued high risk with leukemia excluding chronic lymphocytic leukemia (CLL) mainly due to chronic myelogenous leukemia (CML), on the other hand, the 15-country study and J-EPISODE study did not show significant high risk of CML. There are some possibilities of this discrepancies and one of that may be based on lacking in statistical power because of that leukemia is a rare disease. Other possibilities of these discrepancies between these studies are based on the differences of dose rate, main component of cohorts, and statistical methods. In this paper, we summarize the subtypes of leukemia, baseline mortality by each study, and methods and results from the major radiation epidemiological studies.
After the accident at the Fukushima Daiichi Nuclear Power Station, artificial radionuclides such as radioactive cesium and iodine were released into the environment. It caused great anxiety not only in the vicinity of the Fukushima Daiichi Nuclear Power Station but also in other regions of Japan. Some members of the Japan Health Physics Society (JHPS) which is a leading academic society in Japan in the field of radiation protection volunteered to establish the website called “Question and Answer about radiation in Daily Life” just after the accident to reduce the anxiety of the residents about the health effects of radiation. After that, Committee of “Question and Answer about radiation in Daily Life” was established in August 2011 in JHPS, and this activity had been carried out under the responsibility of the society that answered with sincerity against questions from the public as specialists until February 2013. The number of questions on the website had gradually decreased as time passed; therefore, the Committee members decided to end these activities in February 2013. In this paper, following contents were shown; the activities of the Q&A website for about two years, the issues of the stance on our activities, the information related to the website activities and the analysis of Twitter data. Based on the experience and the knowledge obtained from these activities, the issues and experiences that can be utilized in the initial response to emergencies for radiation protection experts as well as other fields are presented.
Monthly samples of atmospheric dust and depositions were collected at monitoring stations in the area surrounding Higashidori Nuclear Power Station. 7Be, 210Pb, and gross α and β radioactivity were measured to understand the effect of the nuclear power station on the surrounding environment and the amounts of air radiation and radionuclides in this area. The seasonal variation patterns of the 7Be and 210Pb atmospheric concentrations were similar and both had two peaks. The coefficients of determination of gross α and β radioactivity and 210Pb atmospheric concentration were high, suggesting that the contribution of 222Rn radioactive decay products was large for both types of radioactivity. The coefficients of determination of the 7Be and 210Pb deposition fluxes were high, and the total deposition velocity of both 7Be and 210Pb showed a seasonal variation pattern that had major peaks in summer and winter. However, the coefficient of determination of the 7Be total deposition velocity and monthly precipitation was higher than that of the 210Pb total deposition velocity, which suggests that precipitation was a more important factor for the deposition flux of 7Be than for 210Pb.
A study on radiation health effects for residents around the Semipalatinsk Nuclear Test Site has been conducted by REA of Japan and NNC of the Republic of Kazakhstan. In this study, we established a new cohort. The present paper describes the method for individual dose estimation relevant to the consequences of nuclear tests for residents in 10 villages around the test site and presents part of the results. External doses were calculated based on air dose rates reported in the literature soon after the nuclear tests. Internal doses due to inhalation were estimated based on the air concentration of radionuclides calculated from the air dose rate. Internal doses due to ingestion were estimated based on the ground deposition of radionuclides calculated based on the air dose rate. The external dose was much higher than the internal dose. The total dose varied by village, with the highest dose observed in Chermushki followed by Dolon, Sarjal, Karaul, and Akubulak. These results are in reasonable agreement with doses reported by others so far.