Although some adverse effects on neurocognitive function have been reported in children and adolescents irradiated prenatally during the atomic bombings and the Chernobyl nuclear accident, little information is available for effects on the elderly. Here we evaluate the effects of prenatal exposure to atomic bomb radiation on subjective neurocognitive function in aged survivors. To evaluate neurocognitive impairment, we mailed the Neurocognitive Questionnaire (NCQ), a self-administered scale, to prenatally exposed survivors, including clinic visitors and non-visitors at the time of the 2011 and 2013 Adult Health Study (AHS) examinations. We received replies from 444 individuals (mean age, 66.9 ± 0.6 years). After adjusting for sex, city, and educational background, we found no significant effects of radiation, clinic visit, or interaction between radiation and clinic visit on the scores of the 4 NCQ factors of metacognition, emotional regulation, motivation/organization, and processing speed. Even in analyses considering gestational age at the time of the bombings, none of the 4 NCQ factor scores was related to maternal uterine dose. There remains the limitation that this study consisted of healthy survivors, but we found no significant radiation effect on late-life cognition in people prenatally exposed to atomic bomb radiation.

In 1945, atomic bombs were dropped on Hiroshima and Nagasaki. Approximately 70 000 Koreans are estimated to have been exposed to radiation from atomic bombs at that time. After Korea\'s Liberation Day, approximately 23 000 of these people returned to Korea. To investigate the long-term health and hereditary effects of atomic bomb exposure on the offspring, cohort studies have been conducted on atomic bomb survivors in Japan. This study is an ongoing cohort study to determine the health status of Korean atomic bomb survivors and investigate whether any health effects were inherited by their offspring. Atomic bomb survivors are defined by the Special Act On the Support for Korean Atomic Bomb Victims, and their offspring are identified by participating atomic bomb survivors. As of 2024, we plan to recruit 1500 atomic bomb survivors and their offspring, including 200 trios with more than 300 people. Questionnaires regarding socio-demographic factors, health behaviors, past medical history, laboratory tests, and pedigree information comprise the data collected to minimize survival bias. For the 200 trios, whole-genome analysis is planned to identify de novo mutations in atomic bomb survivors and to compare the prevalence of de novo mutations with trios in the general population. Active follow-up based on telephone surveys and passive follow-up with linkage to the Korean Red Cross, National Health Insurance Service, death registry, and Korea Central Cancer Registry data are ongoing. By combining pedigree information with the findings of trio-based whole-genome analysis, the results will elucidate the hereditary health effects of atomic bomb exposure.

Kazakhstan is known as a country with a complex radioecological situation resulting from different sources such as a natural radiation background, extensive activities of the industrial system of the former Soviet Union and a well-known testing of nuclear power weapons occurred in the Semipalatinsk Test Site (STS) area. The present study focuses on the assessment of the background of dicentric chromosomes in Kazakhstan\'s population, which is the starting point in the dose assessment of irradiated people, since the baseline level of spontaneous dicentrics can vary significantly in different populations. In this context, aiming to determine the background frequency of chromosome aberrations in the population of Kazakhstan, considering the heterogeneity of natural radiation background levels of its large territory, a selection of 40 control subjects living in four cities of North, South, West and East Kazakhstan was performed. The cytogenetic study on the selected groups showed fairly low background frequency values of chromosome aberrations (0.84 ± 0.83 per 1000 cells), comparable with other data in the literature on general populations, reporting background frequency values between 0.54 and 2.99 per 1000 cells. The obtained results should be taken into account when constructing the dose-effect calibration curve used in cytogenetic biodosimetry, as a \"zero\" dose point, which will reduce the uncertainty in quantifying the individual absorbed dose in emergency radiological situations.

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Recent analysis of all solid cancer incidence (1958-2009) in the Life Span Study (LSS) revealed evidence of upward curvature in the radiation dose response among males but not females. Upward curvature in sex-averaged excess relative risk (ERR) for all solid cancer mortality (1950-2003) was also observed in the 0-2 Gy dose range. As reasons for non-linearity in the LSS are not completely understood, we conducted dose-response analyses for all solid cancer mortality and incidence applying similar methods [1958-2009 follow-up, DS02R1 doses, including subjects not-in-city (NIC) at the time of the bombing] and statistical models. Incident cancers were ascertained from Hiroshima and Nagasaki cancer registries, while cause of death was ascertained from death certificates throughout Japan. The study included 105,444 LSS subjects who were alive and not known to have cancer before January 1, 1958 (80,205 with dose estimates and 25,239 NIC subjects). Between 1958 and 2009, there were 3.1 million person-years (PY) and 22,538 solid cancers for incidence analysis and 3.8 million PY and 15,419 solid cancer deaths for mortality analysis. We fitted sex-specific ERR models adjusted for smoking to both types of data. Over the entire range of doses, solid cancer mortality dose-response exhibited a borderline significant upward curvature among males (P = 0.062) and significant upward curvature among females (P = 0.010); for solid cancer incidence, as before, we found a significant upward curvature among males (P = 0.001) but not among females (P = 0.624). The sex difference in magnitude of dose-response curvature was statistically significant for cancer incidence (P = 0.017) but not for cancer mortality (P = 0.781). The results of analyses in the 0-2 Gy range and restricted lower dose ranges generally supported inferences made about the sex-specific dose-response shape over the entire range of doses for each outcome. Patterns of sex-specific curvature by calendar period (1958-1987 vs. 1988-2009) and age at exposure (0-19 vs. 20-83) varied between mortality and incidence data, particularly among females, although for each outcome there was an indication of curvature among 0-19-year-old male survivors in both calendar periods and among 0-19-year-old female survivors in the recent period. Collectively, our findings indicate that the upward curvature in all solid cancer dose response in the LSS is neither specific to males nor to incidence data; its evidence appears to depend on the composition of sites comprising all solid cancer group and age at exposure or time. Further follow up and site-specific analyses of cancer mortality and incidence will be important to confirm the emerging trend in dose-response curvature among young survivors and unveil the contributing factors and sites.

The Japanese Lifespan Study (LSS) of the A-Bomb survivors is the principal basis of the current legal radiological framework. Evidence provided for the first time here shows that internal exposure to radiologically significant quantities of Uranium-234 contained in sub-micron particle rainout from the un-fissioned weapon warhead, the Black Rain, is a missing exposure in the LSS analysis. It is argued that this is responsible for a background excess cancer risk in all the LSS dose groups. This, together with epidemiological evidence based on unexposed controls falsifies the LSS cancer vs. dose regression coefficients for internal exposure.

The Life Span Study (LSS) of Japanese atomic bomb survivors has served as the primary basis for estimates of radiation-related disease risks that inform radiation protection standards. The long-term follow-up of radiation-monitored nuclear workers provides estimates of radiation-cancer associations that complement findings from the LSS. Here, a comparison of radiation-cancer mortality risk estimates derived from the LSS and INWORKS, a large international nuclear worker study, is presented. Restrictions were made, so that the two study populations were similar with respect to ages and periods of exposure, leading to selection of 45,625 A-bomb survivors and 259,350 nuclear workers. For solid cancer, excess relative rates (ERR) per gray (Gy) were 0.28 (90% CI 0.18; 0.38) in the LSS, and 0.29 (90% CI 0.07; 0.53) in INWORKS. A joint analysis of the data allowed for a formal assessment of heterogeneity of the ERR per Gy across the two studies (P = 0.909), with minimal evidence of curvature or of a modifying effect of attained age, age at exposure, or sex in either study. There was evidence in both cohorts of modification of the excess absolute risk (EAR) of solid cancer by attained age, with a trend of increasing EAR per Gy with attained age. For leukemia, under a simple linear model, the ERR per Gy was 2.75 (90% CI 1.73; 4.21) in the LSS and 3.15 (90% CI 1.12; 5.72) in INWORKS, with evidence of curvature in the association across the range of dose observed in the LSS but not in INWORKS; the EAR per Gy was 3.54 (90% CI 2.30; 5.05) in the LSS and 2.03 (90% CI 0.36; 4.07) in INWORKS. These findings from different study populations may help understanding of radiation risks, with INWORKS contributing information derived from cohorts of workers with protracted low dose-rate exposures.

Several studies have been conducted on cerebrovascular disease mortality in Atomic bomb survivors. Previous studies have investigated the relationship between mortality and initial radiation dose after adjusting for the effects of sex and age at the time of the bombing (ATB), and detected a weak (but statistically significant) dose-response relationship was detected. The objective of the present study was to examine whether the sex- and age ATB-specific cerebrovascular disease mortality among Hiroshima atomic bomb survivors can be explained by the initial radiation dose. At Hiroshima University, a cohort study has been conducted with Hiroshima Atomic Bomb Survivors (ABS) since 1970. We selected 30,378 subjects from the ABS who were exposed at 3.5 km or less from the hypocenter and still alive on January 1, 1970. These subjects were followed up until December 31, 2010. The cohort data were stratified with respect to sex and age ATB into 10-year age groups. For each stratum, using Cox regression, we performed survival analyses of the risk of cerebrovascular mortality using the initial radiation dose and the exposure distance (the ground distance between the exposure location and the hypocenter) as explanatory variables. The results indicated that the risks to females exposed at 10 to 19 years old were highly dependent on the initial radiation dose (hazard ratio: 1.51, p < 0.001), while the risks to males were not. There might exist some radiation exposure effects limited to women who were in their teens at the time of exposure. However, the background mechanisms remain unclear, necessitating further study.

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