It has been considered difficult to detect the biological effects of low-dose radiation exposure below approximately 100 mSv in humans. Serum proteomic analysis and oxidative modification profiling were conducted with blood samples collected from residents of a newly discovered high-level natural background radiation area (annual effective dose approximately 50 mSv y^-1) and normal-level area (1.22 mSv y^-1) in Mamuju, Indonesia, where many people have been living for generations. Dose-dependent oxidative modifications in amino acid sequences of human serum albumin, especially the 162^nd and 356^th tyrosine residues and 111^th and 470^th methionine residues, were found. None of these findings have been reported in humans exposed to chronic low-dose radiation. It can be used as a biomarker not only for the assessment of the presence or absence of radiation exposure but also for dose prediction in living organisms for chronic radiation. These results suggest that traces of radiation exposure are recorded in serum albumin and that there is a possibility of a new methodology that can evaluate biological responses below 100 mSv.

Ten years have elapsed since the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, and the relative contribution of natural radiation is increasing in Fukushima Prefecture due to the reduced dose of artificial radiation. In order to accurately determine the effective dose of exposure to artificial radiation, it is necessary to evaluate the effective dose of natural as well as artificial components. In this study, we measured the gamma-ray pulse-height distribution over the accessible area of Namie Town, Fukushima Prefecture, and evaluated the annual effective dose of external exposure by distinguishing between natural and artificial radionuclides. The estimated median (range) of absorbed dose rates in air from artificial radionuclides as of 1 April 2020, is 133 (67–511) nGy h⁻¹ in the evacuation order cancellation zone, and 1306 (892–2081) nGy h⁻¹ in the difficult-to-return zone. The median annual effective doses of external exposures from natural and artificial radionuclides were found to be 0.19 and 0.40 mSv in the evacuation order cancellation zone, and 0.25 and 3.9 mSv in the difficult-to-return zone. The latest annual effective dose of external exposure discriminated into natural and artificial radionuclides is expected to be utilized for radiation risk communication.

The details of the dose-dependent response of serum proteins exposed to ionizing radiation, especially the oxidative modification response in amino acid sequences of albumin, the most abundant protein, are unknown. Thus, a proteomic analysis of the serum components from mice exposed to total body X-irradiation (TBI) ranging from 0.5 Gy to 3.0 Gy was conducted using LC-MS/MS. The analysis of oxidative modification sequences of albumin (mOMSA) in TBI mouse serum revealed significant moderate or strong correlations between the X-irradiation exposure dose and modification of 11 mOMSAs (especially the 97th, 267th and 499th lysine residues, 159th methionine residue and 287th tyrosine residues). In the case of X-irradiation of serum alone, significant correlations were also found in the 14 mOMSAs. In addition, a dose-dependent variation in six proteins (Angiotensinogen, Odorant-binding protein 1a, Serine protease inhibitor A3K, Serum paraoxonase/arylesterase 1, Prothrombin and Epidermal growth factor receptor) was detected in the serum of mice exposed to TBI. These findings suggest the possibility that the protein variation and serum albumin oxidative modification responses found in exposed individuals are important indicators for considering the effects of radiation on living organisms, along with DNA damage, and suggests their possible application as biomarkers of radiation dose estimation.

The recently discovered high-level natural background radiation area (HBRA) of Mamuju in Indonesia provides a unique opportunity to study the biological effects of chronic low-dose radiation exposure on a human population. The mean total effective dose in the HBRA was approximately 69.6 mSv y⁻¹ (range: 47.1 to 115.2 mSv y⁻¹), based on a re-evaluation of the individual radiation exposure dose; therefore, proteomic analyses of serum components and oxidative modification profiling of residents living in the HBRA were reconducted using liquid chromatography-tandem mass spectrometry. The analysis of the oxidative modification sequences of human serum albumin revealed significant moderate correlations between the radiation dose and the modification of 12 sequences, especially the 111th methionine, 162nd tyrosine, 356th tyrosine, and 470th methionine residues. In addition, a dose-dependent variation in 15 proteins of the serum components was detected in the serum of residents exposed to chronic low-dose radiation. These findings suggest that the alterations in the expression of specific proteins and the oxidative modification responses of serum albumin found in exposed humans may be important indicators for considering the effects of chronic low-dose radiation exposure on living organisms, implying their potential utility as biomarkers of radiation dose estimation.

Objective: The spread of COVID-19 has made it difficult to provide training in medical treatment in a radiation disaster. In this study, we will examine the effects and challenges of using a hybrid approach that combines online and face-to-face components. Methods: A total of 5 face-to face and 25 online medical staff participated in the training program. This program was conducted by using multiple cameras for live coverage, while protective clothing and decontamination kits had been sent in advance to the participants so that they could experience face-to-face and online learning at the same time. Results: Participants reported a high level of satisfaction and achievement with the style of delivery. They also experienced problems such as fatigue due to long hours, and dissatisfaction with the debriefing. Conclusions: In designing new online training, it is necessary to consider the quantity and content of the program, and to take participant fatigue into consideration.

Free radicals, including reactive oxygen species resulting from oxidative stress, are one of the major causes of biological disorders and are known to be closely related to the onset of lifestyle-related diseases such as aging, atherosclerosis, and diabetes, and their complications. Hydroxyl radicals, the most reactive and cytotoxic of reactive oxygen species, are selectively reduced by hydrogen. We have developed a method to produce more stable hydrogen water by dispersing hydrogen in water using ultra-fine bubbles (UFBs) with a bubble diameter of less than 1 μm. The present study reported on the functional characteristics of antioxidant long-life UFB hydrogen water. UFB hydrogen water with excellent storage stability is expected to have a variety of potential medical applications, including radiation damage reduction.