Lessons from Chernobyl and prognosis for Fukushima: radiological consequences

The following are considered: results of large-scale radiation epidemiological studies of the health effects of the Chernobyl accident, radiation risks for emergency workers and the affected population; and verification of ICRP risk models taking into account data on the Chernobyl accident and preliminary prognostic estimates of potential radiological consequences of the Fukushima disaster.     

Psychological and perceived health effects of the Chernobyl disaster: a 20-year review

The mental health impact of Chernobyl is regarded by many experts as the largest public health problem unleashed by the accident to date. This paper reviews findings reported during the 20-y period after the accident regarding stress-related symptoms, effects on the developing brain, and cognitive and psychological impairments among highly exposed cleanup workers. With respect to stress-related symptoms, the rates of depressive, anxiety (especially post-traumatic stress symptoms), and medically unexplained physical symptoms are two to four times higher in Chernobyl-exposed populations compared to controls, although rates of diagnosable psychiatric disorders do not appear to be elevated. The symptom elevations were found as late as 11 y after the accident. Severity of symptomatology is significantly related to risk perceptions and being diagnosed with a Chernobyl-related health problem. In general, the morbidity patterns are consistent with the psychological impairments documented after other toxic events, such as the atomic bombings of Hiroshima and Nagasaki, the Three Mile Island accident, and Bhopal. With respect to the developing brain of exposed children who were in utero or very young when the accident occurred, the World Health Organization as well as American and Israeli researchers have found no significant associations of radiation exposure with cognitive impairments. Cognitive impairments in highly exposed cleanup workers have been reported by Ukrainian researchers, but these findings have not been independently confirmed. A seminal study found a significant excess death rate from suicide in cleanup workers, suggesting a sizable emotional toll. Given the magnitude and persistence of the adverse mental health effects on the general population, long-term educational and psychosocial interventions should be initiated that target primary care physicians, local researchers, and high risk populations, including participants in ongoing cohort studies.     

Health effects in a casual sample of immigrants to Israel from areas contaminated by the Chernobyl explosion.

We analyzed questionnaire and physician examination data for 1560 new immigrants from the former USSR divided into three groups by potential exposure to Chernobyl radiation. Two groups were chosen according to soil contamination by cesium-137 at former residences, as confirmed by our findings in a 137Cs body burden study. The third group consisted of "liquidators," persons who worked at the Chernobyl site after the disaster. Liquidators had greater self-reported incidences of symptoms commonly accepted as acute effects of radiation exposure, increases in prevalence of hypertension, and more health complaints. Excesses of bronchial asthma and health complaints were reported in children from the more exposed communities. Asthma prevalence in children potentially exposed in utero appears to be increased eightfold. Older adults from more exposed areas had more hypertension as assessed by history and measurements. These findings suggest the possible association of radiation exposure with several nonmalignant effects.     

Study protocol for the fukushima health management survey

Background: The accidents that occurred at the Fukushima Daiichi Nuclear Power Plant after the Great East Japan Earthquake on 11 March 2011 have resulted in long-term, ongoing anxiety among the residents of Fukushima, Japan. Soon after the disaster, Fukushima Prefecture launched the Fukushima Health Management Survey to investigate long-term low-dose radiation exposure caused by the accident. Fukushima Medical University took the lead in planning and implementing this survey. The primary purposes of this survey are to monitor the long-term health of residents, promote their future well-being, and confirm whether long-term low-dose radiation exposure has health effects. This report describes the rationale and implementation of the Fukushima Health Management Survey.Methods: This cohort study enrolled all people living in Fukushima Prefecture after the earthquake and comprises a basic survey and 4 detailed surveys. The basic survey is to estimate levels of external radiation exposure among all 2.05 million residents. It should be noted that internal radiation levels were estimated by Fukushima Prefecture using whole-body counters. The detailed surveys comprise a thyroid ultrasound examination for all Fukushima children aged 18 years or younger, a comprehensive health check for all residents from the evacuation zones, an assessment of mental health and lifestyles of all residents from the evacuation zones, and recording of all pregnancies and births among all women in the prefecture who were pregnant on 11 March. All data have been entered into a database and will be used to support the residents and analyze the health effects of radiation.Conclusions: The low response rate (<30%) to the basic survey complicates the estimation of health effects. There have been no cases of malignancy to date among 38 114 children who received thyroid ultrasound examinations. The importance of mental health care was revealed by the mental health and lifestyle survey and the pregnancy and birth survey. This long-term large-scale epidemiologic study is expected to provide valuable data in the investigation of the health effects of low-dose radiation and disaster-related stress.     

Current status and epidemiological research needs for achieving a better understanding of the consequences of the Chernobyl accident

Twenty years after the Chernobyl accident, there is no clearly demonstrated increase in the incidence of cancers in the most affected populations that can be attributed to radiation from the accident, except for the dramatic increase in thyroid cancer incidence among those exposed in childhood and adolescence. Increases in the incidence of cancers and other diseases have been reported in Belarus, the Russian Federation, and Ukraine, but much of the increase appears to be due to other factors, including improvements in diagnosis, reporting, and registration. Recent findings indicate a possible doubling of leukemia risk among Chernobyl liquidators and a small increase in the incidence of premenopausal breast cancer in the very most contaminated districts. Increased risks of cardiovascular diseases and cataracts have also been reported. These findings, however, need confirmation in well-designed analytical epidemiological studies with careful individual dose reconstruction. The absence of demonstrated increases in cancer risk--apart from thyroid cancer--is not the proof that no increase has in fact occurred. Based on the experience of atomic bomb survivors, and assuming that there is a linear, no-threshold dose-response relationship between exposure to ionizing radiation and the development of cancer in humans, a small increase in the relative risk of cancer is expected, even at the low to moderate doses received. Given the large number of individuals exposed, the absolute number of cancer cases caused could be substantial, particularly in the future. It is therefore essential to continue to use population registries to monitor trends in disease morbidity and mortality in the most contaminated areas, as well as among liquidators, in order to assess the public health impact of the accident. Studies of selected populations and diseases are also essential in order to study the real effect of the accident and compare it to predictions. Careful studies may in particular provide important information on the effect of exposure rate and exposure type in the low to medium dose range and on factors that may modify radiation effects. As such, they may have important consequences for the radiation protection of patients and of the general population in case of further nuclear emergencies.     

Health risks associated with environmental radiation exposures

Much is known about health effects associated with exposure to ionising radiation. Numerous epidemiologic studies of populations exposed to radiation under a variety of circumstances have been conducted. These studies have clearly shown that radiation exposure can result in an increased risk of many types of cancer, and the findings are supported by a substantial body of literature from experimental studies. Despite the fact that radiation exposures from environmental sources comprise a relatively minor component of total population exposure, this type of exposure is often the most feared by the public. An accident like Chernobyl or a natural disaster like that at Fukushima provides a unique opportunity to learn more about the health risks from environmental radiation exposures. However, establishing the infrastructure and expertise required to design and conduct all aspects of a complex field study presents formidable challenges. This paper summarises the principal findings from the main studies of environmental radiation exposure that have been successfully undertaken. Although such studies are often exceedingly difficult to conduct, and may be limited by an ecologic design, they can be informative in assessing risk. Any new environmental study that is initiated should focus on special circumstances; additional ecological studies are not recommended.     

Radiation occupational health interventions offered to radiation workers in response to the complex catastrophic disaster at the Fukushima Daiichi Nuclear Power Plant

The Fukushima Daiichi Nuclear Power Plant (NPP) 1 was severely damaged from the chain reaction of the Great East Japan Earthquake and Tsunami on 11 March 2011, and the consequent meltdown and hydrogen gas explosions. This resulted in the worst nuclear accident since the Chernobyl accident of 1986. Just as in the case of Chernobyl, emergency workers were recruited to conduct a wide range of tasks, including disaster response, rescuing activities, NPP containment, and radiation decontamination. This paper describes the types and efficacy of the various occupational health interventions introduced to the Fukushima NPP radiation workers. Such interventions were implemented in order to prevent unnecessary radiation overexposure and associated adverse health effects and work injuries. Less than 1% of all emergency workers were exposed to external radiation of >100 mSv, and to date no deaths or health adversities from radiation have been reported for those workers. Several occupational health interventions were conducted, including setting of new regulatory exposure limits, improving workers'' radiation dosimetry, administration of stable iodine, running an occupational health tracking system, and improving occupational medicine and preventative care. Those interventions were not only vital for preventing unnecessary radiation, but also for managing other general health issues such as mental health, heat illness and infectious diseases. Long-term administration of the aforementioned occupational health interventions is essential to ensure the ongoing support and care for these workers, who were put under one of the most severe occupational health risk conditions ever encountered.     

切尔诺贝利和福岛核事故的今昔对比及引发世人的深思

目的 重点介绍历史上发生的多起核事故中最为严重的1986年切尔诺贝利核事故和2011年福岛核事故。方法 回顾性分析了切尔诺贝利和福岛两次特大七级核事故的发生及抢险、核事故的剂量及对健康的影响。结果 切尔诺贝利核事故与福岛核事故的发生时间先后相距25年。就近期辐射损伤而言,福岛核事故可能仅次于切尔诺贝利核事故对人员的危害。从远期效应测评,切尔诺贝利核事故对抢险人员、附近居民、受放射性污染的不同年龄段人员带来的健康危害的现状也可能是福岛人明天的预警。结论 切尔诺贝利和福岛这两次特大七级核事故对当地居民健康及核工业发展等带来的负面影响是惨痛的,只有尽可能遏制核事故的发生,才能确保核安、辐安、民众心安。     

The Chernobyl experience in the area of retrospective dosimetry

The Chernobyl accident, which occurred on 26 April 1986 at a nuclear power plant located less than 150 km north of Kiev, was the largest nuclear accident to date. The unprecedented scale of the accident was determined not only by the amount of released activity, but also by the number of workers and of the general public involved, and therefore exposed to increased doses of ionising radiation. Due to the unexpected and large scale of the accident, dosimetry techniques and practices were far from the optimum; personal dosimetry of cleanup workers (liquidators) was not complete, and there were no direct measurements of the exposures of members of the public. As a result, an acute need for retrospective dose assessment was dictated by radiation protection and research considerations. In response, substantial efforts have been made to reconstruct doses for the main exposed cohorts, using a broad variety of newly developed methods: analytical, biological and physical (electron paramagnetic resonance spectroscopy of teeth, thermoluminescence of quartz) and modelling. This paper reviews the extensive experience gained by the National Research Center for Radiation Medicine, Academy of Medical Sciences, Ukraine in the field of retrospective dosimetry of large cohorts of exposed population and professionals. These dose reconstruction projects were implemented, in particular, in the framework of epidemiological studies, designed to follow-up the medical consequences of the Chernobyl accident and study health effects of ionizing radiation, particularly Ukrainian-American studies of cataracts and leukaemia among liquidators.     

Chernobyl Disaster Sequelae in Recent Immigrants to the United States from the former Soviet Union (FSU)

Long-term mental health sequelae of the 1986 Chernobyl disaster have been documented for exposed populations who remained in the former Soviet Union (FSU) (Havenaar et al., 1997), and in a cohort migrated to Israel (Cwikel et al., 1997). This paper reports on Chernobyl disaster sequelae in émigrés (n = 321) to the United States. Demographic characteristics, migration factors, and self-reported physical health were considered. Both geographical proximity to the 1986 disaster, and perception of radiation risk stood as long-term indicators of current psychological distress. Proximity was related to poor self-perceived physical health, as well as current symptoms of depression (p<.05), anxiety (p<.01), and Chernobyl-related trauma distress (p<.001) on standardized measures. Environmental contamination as a reason for migration was also associated with greater mental health symptomatology.     

Gesundheit nach Fukushima

This short paper reflects on the current situation after the Fukushima nuclear accident and the potential health consequences of the disaster. We discuss perspectives related to radiation protection activities as well as to epidemiologic monitoring and research in the affected regions in order to assess long-term effects of the accident.     

Health after Fukushima. A current perspective

This short paper reflects on the current situation after the Fukushima nuclear accident and the potential health consequences of the disaster. We discuss perspectives related to radiation protection activities as well as to epidemiologic monitoring and research in the affected regions in order to assess long-term effects of the accident.     

严重核事故应急救援人员的心理危机干预

切尔诺贝利核事故和福岛核事故表明严重核事故对参与应急救援的人员会产生巨大的心理效应,他们会与事故受害者一样产生一系列的精神心理问题。本文通过分析切尔诺贝利核事故和福岛核事故后应急救援人员产生的精神心理健康问题,借鉴重大自然灾害、疫情等救援人员心理危机干预的方法,结合核事故应急救援人员面临的特殊情况,提出核事故应急救援人员的心理危机干预方法。这套方法包括事故前应急救援人员的心理健康评估与培训、事故中应急救援人员的心理救助、自我调试和心理危机干预以及事故后的长期心理援助。通过有效的心理危机干预,降低核事故对应急救援人员的心理影响。     

Assessment of the Risk of Medium-Term Internal Contamination in Minamisoma City,Fukushima, Japan,after the Fukushima Dai-ichi Nuclear Accident

Background: The Fukushima Dai-ichi nuclear disaster, the first level-7 major nuclear disaster since Chernobyl, raised concerns about the future health consequences of exposure to and intake of radionuclides. Factors determining the risk and level of internal radiation contamination after a nuclear accident, which are a key to understanding and improving current nuclear disaster management, are not well studied.Objective: We investigated both the prevalence and level of internal contamination in residents of Minamisoma, and identified factors determining the risk and levels of contamination.Methods: We implemented a program assessing internal radiation contamination using a whole body counter (WBC) measurement and a questionnaire survey in Minamisoma, between October 2011 and March 2012.Results: Approximately 20% of the city’s population (8,829 individuals) participated in the WBC measurement for internal contamination, of which 94% responded to the questionnaire. The proportion of participants with detectable internal contamination was 40% in adults and 9% in children. The level of internal contamination ranged from 2.3 to 196.5 Bq/kg (median, 11.3 Bq/kg). Tobit regression analysis identified two main risk factors: more time spent outdoors, and intake of potentially contaminated foods and water.Conclusions: Our findings suggest that, with sensible and reasonable precautions, people may be able to live continuously in radiation-affected areas with limited contamination risk. To enable this, nuclear disaster response should strictly enforce food and water controls and disseminate evidence-based and up-to-date information about avoidable contamination risks.Citation: Sugimoto A, Gilmour S, Tsubokura M, Nomura S, Kami M, Oikawa T, Kanazawa Y, Shibuya K. 2014. Assessment of the risk of medium-term internal contamination in Minamisoma City, Fukushima, Japan, after the Fukushima Dai-ichi Nuclear accident. Environ Health Perspect 122:587–593; http://dx.doi.org/10.1289/ehp.1306848     

Somatic health effects of Chernobyl: 30 years on

2016 marked the 30th anniversary of the Chernobyl Nuclear Power Plant accident. We and others wrote reviews for the 25th anniversary. Since then, additional papers have appeared and it seems timely to highlight lessons learned. To present, not a systematic review, but a commentary drawing attention to notable findings. We include not only recent reports and updates on previous results, but key findings from prior Chernobyl studies. The dose-dependent increase in Papillary Thyroid Cancer (PTC) following childhood I-131 exposure in Ukraine and Belarus has now been shown to persist for decades. Studies of post-Chernobyl PTCs have produced novel information on chromosomal rearrangements and gene fusions, critical to understanding molecular mechanisms. Studies of clean-up workers/liquidators suggest dose-related increases of thyroid cancer and hematological malignancies in adults. They also report increases in cardiovascular and cerebrovascular disease. If confirmed, these would have significant public health and radiation protection implications. The lens opacities following low to moderate doses found earlier are also a concern, particularly among interventional radiologists who may receive substantial lens doses. Finally, there is some, inconsistent, evidence for genetic effects among offspring of exposed persons. Further efforts, including improved dosimetry, collection of information on other risk factors, and continued follow-up/monitoring of established cohorts, could contribute importantly to further understand effects of low doses and dose-rates of radiation, particularly in young people, and ensure that appropriate public health and radiation protection systems are in place. This will require multinational collaborations and long-term funding.     

Status of the vestibular analyzer and psychophysiologic parameters in miners and crew members cleaning up the consequences of the Chernobyl nuclear plant accident]

Status of the vestibular analyzer and psychophysiologic parameters were studied in 20 miners with the long length of service and in 16 liquidators of Chernobyl atomic power station accident consequences. Liquidators showed the reliably increased latent periods of P1, N1 and P2 spikes of vestibular evoked potentials, considerably increased latent time of the complicated oculomotor reaction and lowered rate of information processing. Exposure to increased radiation dose during the work at Chernobyl atomic power station was a main factor to influence on the functional status of vestibular analyzer.     

Chernobyl vis-à-vis the nuclear future: an international perspective

The paper aims to provide an international perspective on the consequences of the Chernobyl accident vis-à-vis the future development of the use of nuclear energy for peaceful purposes. It describes the major international initiatives that were undertaken over the years in order to quantify the consequences of the Chernobyl accident, and also analyzes the impact of the accident on the development of nuclear energy taking account of the perception of its consequences. The paper revisits the historical saga flowing since the fateful explosion at the Chernobyl Nuclear Power Plant in the Ukraine 20 y ago. It looks at some of the misunderstandings about the consequences of the accident and explores the worldwide nuclear stagnation that followed Chernobyl, surveying the negative public reaction and also the possibilities of a nuclear revival. It finally searches for a way forward, concluding that an effective international nuclear safety regime is urgently needed with the purpose of preventing catastrophes like Chernobyl from occurring and also that the Chernobyl consequences need to be readdressed properly. The paper concludes with an appeal to the radiation protection community to resolve once and for all the difficult issues of attributing health effects to low-level radiation exposure.     

Consequences of the nuclear power plant accident at Chernobyl

The Chernobyl Nuclear Power Plant accident, in the Ukrainian Soviet Socialist Republic (SSR), on April 26, 1986, was the first major nuclear power plant accident that resulted in a large-scale fire and subsequent explosions, immediate and delayed deaths of plant operators and emergency service workers, and the radioactive contamination of a significant land area. The release of radioactive material, over a 10-day period, resulted in millions of Soviets, and other Europeans, being exposed to measurable levels of radioactive fallout. Because of the effects of wind and rain, the radioactive nuclide fallout distribution patterns are not well defined, though they appear to be focused in three contiguous Soviet Republics: the Ukrainian SSR, the Byelorussian SSR, and the Russian Soviet Federated Socialist Republic. Further, because of the many radioactive nuclides (krypton, xenon, cesium, iodine, strontium, plutonium) released by the prolonged fires at Chernobyl, the long-term medical, psychological, social, and economic effects will require careful and prolonged study. Specifically, studies on the medical (leukemia, cancers, thyroid disease) and psychological (reactive depressions, post-traumatic stress disorders, family disorganization) consequences of continued low dose radiation exposure in the affected villages and towns need to be conducted so that a coherent, comprehensive, community-oriented plan may evolve that will not cause those already affected any additional harm and confusion.     

Radiation epidemiology: a perspective on Fukushima

For nearly 100 years, epidemiologic studies of human populations exposed to ionising radiation have provided quantitative information on health risks. High dose deterministic (tissue reaction) effects result when sufficient numbers of functioning cells are killed, such as in bone marrow depression that can lead to death. Lower dose stochastic effects are probabilistic in nature and include an increased risk of cancer later in life and heritable genetic defects, although genetic conditions in the children of irradiated parents have yet to be convincingly demonstrated. Radiation studies are of diverse populations and include not only the Japanese atomic bomb survivors, but also patients treated with radiation for malignant and non-malignant disease; patients exposed for diagnostic purposes; persons with intakes of radionuclides; workers occupationally exposed; and communities exposed to environmental and accidentally released sources of radiation. Much is known about radiation and its risks. The major unanswered question in radiation epidemiology, however, is not whether radiation causes cancer, but what the level of risk is following low dose (<100 mSv) or low dose rate exposures. Paracelsus is credited with first articulating that the 'poison is in the dose', which for radiation epidemiology translates as 'the lower the dose, the lower the risk' and, an important corollary, the lower the dose, the greater the difficulty in detecting any increase in the number of cancers possibly attributable to radiation. In contrast to the Chernobyl reactor accident, the Fukushima reactor accident has to date resulted in no deterministic effects and no worker deaths. Estimates to date of population doses suggest very low uptakes of radioactive iodine which was a major determinant of the epidemic of thyroid cancer following childhood exposures around Chernobyl. The estimates to date of population doses are also much lower (and the distribution much narrower) than the doses for which cancer excesses have been detected among atomic bomb survivors after 60 years of follow-up. Studies of populations exposed to low doses are also limited in their ability to account for important lifestyle factors, such as cigarette smoking and medical x-ray exposures, which could distort findings. Studies of the Fukushima population should be and are being considered for reassurance and health care reasons. Apart from as regards the extreme psychological stress caused by the horrific loss of life following the tsunami and the large-scale evacuation from homes and villages, such studies have limited to no chance of providing information on possible health risks following low dose exposures received gradually over time--the estimated doses (to date) are just too small.