Chernobyl, 10 years after: health consequences

A review of species differences in the control of, and response to, chemical-induced thyroid hormone perturbations leading to thyroid cancer

This review summarises the current state of knowledge regarding the physiology and control of production of thyroid hormones, the effects of chemicals in perturbing their synthesis and release that result in thyroid cancer. It does not consider the potential neurodevelopmental consequences of low thyroid hormones. There are a number of known molecular initiating events (MIEs) that affect thyroid hormone synthesis in mammals and many chemicals are able to activate multiple MIEs simultaneously. AOP analysis of chemical-induced thyroid cancer in rodents has defined the key events that predispose to the development of rodent cancer and many of these will operate in humans under appropriate conditions, if they were exposed to high enough concentrations of the affecting chemicals. There are conditions however that, at the very least, would indicate significant quantitative differences in the sensitivity of humans to these effects, with rodents being considerably more sensitive to thyroid effects by virtue of differences in the biology, transport and control of thyroid hormones in these species as opposed to humans where turnover is appreciably lower and where serum transport of T4/T3 is different to that operating in rodents. There is heated debate around claimed qualitative differences between the rodent and human thyroid physiology, and significant reservations, both scientific and regulatory, still exist in terms of the potential neurodevelopmental consequences of low thyroid hormone levels at critical windows of time. In contrast, the situation for the chemical induction of thyroid cancer, through effects on thyroid hormone production and release, is less ambiguous with both theoretical, and actual data, showing clear dose-related thresholds for the key events predisposing to chemically induced thyroid cancer in rodents. In addition, qualitative differences in transport, and quantitative differences in half life, catabolism and turnover of thyroid hormones, exist that would not operate under normal situations in humans.

Nationwide Increase in Complex Congenital Heart Diseases After the Fukushima Nuclear Accident

Background After the Chernobyl nuclear accident in 1986, an increase in the incidence of congenital heart disease ( CHD s) in the neighboring countries was reported. In 2011, Japan experienced the Great East Japan Earthquake and the nuclear accidents at Fukushima. However, a nationwide study of their effects has not been conducted yet. Methods and Results We used data covering the period between 2007 and 2014 from the annual surveys conducted by the Japanese Association for Thoracic Surgery, which included almost all of the operations pertaining to 46 types of CHD s in Japan. CHD s were divided into 2 groups based on complexity, the time of occurrence during heart development, and age at operation. We estimated the change in the number of the operations per 100 000 live births between pre- and postdisaster using a negative binomial generalized linear mixed model. Overall, a significant 14.2% (95% CI, 9.3-19.4) increase in the number of operations for complex CHD s in neonates and infants per 100 000 live births was found, whereas those performed for patients of 1 to 17 years old showed no significant change during the study period. Conclusions The number of operations for complex CHD s in neonates and infants in Japan significantly increased after the massive disaster, and its level was maintained thereafter. The number of operations for complex CHD was not equal but closely correlated to the live birth prevalence of complex CHD s. Therefore, some meaningful increase in the live birth prevalence can be assumed; however, the precise cause of the increase is unknown.

Exploring the Link between Radiation Exposure and Multifocal Basal Cell Carcinomas in a Former Chernobyl Clean-up Worker by Combining Different Molecular Biological Techniques

Thirty years after the Chernobyl nuclear power plant accident we report on a patient who was a clean-up worker, who subsequently developed multiple cutaneous basal cell carcinomas (BCCs). We used several methods to assess the biological long-term effects related to low-dose external and internal radiation exposure. Specifically, because BCC risk may be increased with ionizing radiation exposure, we endeavored to determine whether the multifocal BCCs were related to the patient's past clean-up work. We assessed cytogenetic changes using peripheral blood, and internal incorporation was measured with a whole-body counter. Gene expression alterations were determined and array-based comparative genomic hybridization was performed for copy number aberration analysis of available BCC samples. In 1,053 metaphase cells, the dicentric yield of 0.005 dicentrics, with acentrics/cell, was significantly increased compared to the established calibration curve (P < 0.001). A 2.5-fold increase in total translocations was observed compared to the expected translocation rate. No internal contamination was detected with the whole-body counter. At the RNA level, two of seven genes (HNRNPA1, AGAP4/6/8) indicated internal plutonium exposure associated with the lowest dose category found in Mayak workers (>0-0.055 Gy). Relevant DNA copy number changes were only detected within the most aggressive BCC focus. Our results suggest that the examined worker had low and more recent radiation exposure with presumably internalized radionuclides that were below the detection level of a whole-body counter. The multifocal BCC could not be related to past occupational radiation exposure. The findings from our study suggest that integrating different methodologies potentially provides an improved overall assessment of individual health risks associated with or excluding occupational radiation exposure.

DNA damage, repair monitoring and epigenetic DNA methylation changes in seedlings of Chernobyl soybeans

This pilot study was carried out to assess the effect of radio-contaminated Chernobyl environment on plant genome integrity 27 years after the accident. For this purpose, nuclei were isolated from root tips of the soybean seedlings harvested from plants grown in the Chernobyl area for seven generations. Neutral, neutral-alkaline, and methylation-sensitive comet assays were performed to evaluate the induction and repair of primary DNA damage and the epigenetic contribution to stress adaptation mechanisms. An increased level of single and double strand breaks in the radio-contaminated Chernobyl seedlings at the stage of primary root development was detected in comparison to the controls. However, the kinetics of the recovery of DNA breaks of radio-contaminated Chernobyl samples revealed that lesions were efficiently repaired at the stage of cotyledon. Methylation-sensitive comet assay revealed comparable levels in the CCGG methylation pattern between control and radio-contaminated samples with a slight increase of approximately 10% in the latter ones. The obtained preliminary data allow us to speculate about the onset of mechanisms providing an adaptation potential to the accumulated internal irradiation after the Chernobyl accident. Despite the limitations of this study, we showed that comet assay is a sensitive and flexible technique which can be efficiently used for genotoxic screening of plant specimens in natural and human-made radio-contaminated areas, as well as for safety monitoring of agricultural products.

Follow-up studies on genome damage in children after Chernobyl nuclear power plant accident

As children are more susceptible to ionizing radiation than adults, each nuclear accident demands special attention and care of this vulnerable population. The Chernobyl nuclear disaster occurred in a region populated with a large number of children, but despite all efforts and expertise of nuclear specialists, it was not possible to avoid casualties. As vast regions of Ukraine, Belarus and Russia were exposed to doses of ionizing radiation, which are known to be related with different diseases, shortly after the accident medical surveillance was launched, which also included analysis of genome damage. Child population affected by internal and external radiation consisted of subjects exposed prenatally, postnatally (both evacuated and non-evacuated), born by irradiated fathers who worked as liquidators, and parents exposed environmentally. In all groups of children during the last 30 years who were exposed to doses which were significantly higher than that recommended for general population of 1 mSv per year, increased genome damage was detected. Increased genome damage includes statistically higher frequency of dicentric and ring chromosomes, chromated and chromosome breaks, acentric fragments, translocations, and micronuclei. The presence of rogue cells confirmed internal contamination. Genome instability and radiosensitivity in children was detected both in evacuated and continuously exposed children. Today the population exposed to ionizing radiation in 1986 is in reproductive period of life and follow-up of this population and their offspring is of great importance. This review aims to give insight in results of studies, which reported genome damage in children in journals without language restrictions.

Iodine intake as a risk factor for thyroid cancer: a comprehensive review of animal and human studies

Thyroid cancer (TC) is the most common endocrine malignancy and in most countries, incidence rates are increasing. Although differences in population iodine intake are a determinant of benign thyroid disorders, the role of iodine intake in TC remains uncertain. We review the evidence linking iodine intake and TC from animal studies, ecological studies of iodine intake and differentiated and undifferentiated TC, iodine intake and mortality from TC and occult TC at autopsy, as well as the case–control and cohort studies of TC and intake of seafood and milk products. We perform a new meta-analysis of pooled measures of effect from case–control studies of total iodine intake and TC. Finally, we examine the post-Chernobyl studies linking iodine status and risk of TC after radiation exposure. The available evidence suggests iodine deficiency is a risk factor for TC, particularly for follicular TC and possibly, for anaplastic TC. This conclusion is based on: a) consistent data showing an increase in TC (mainly follicular) in iodine deficient animals; b) a plausible mechanism (chronic TSH stimulation induced by iodine deficiency); c) consistent data from before and after studies of iodine prophylaxis showing a decrease in follicular TC and anaplastic TC; d) the indirect association between changes in iodine intake and TC mortality in the decade from 2000 to 2010; e) the autopsy studies of occult TC showing higher microcarcinoma rates with lower iodine intakes; and f) the case control studies suggesting lower risk of TC with higher total iodine intakes.

Risk and safety concerns in anesthesiology practice: The present perspective

Newer developments and advancements in anesthesiology, surgical, and medical fields have widened the functional scope of anesthesiologist thus increasing his professional responsibilities and obligations. While at workplace, anesthesiologist is exposed to a wide array of potential hazards that can be detrimental to his overall health. Numerous risks and safety concerns have been mentioned in the literature, but the magnitude of challenges in anesthesiology practice are far greater than those cited and anticipated. Many times these challenging situations are unavoidable and the attending anesthesiologist has to deal with them on an individual basis. These hazards not only affect the general health but can be extremely threatening in various other ways that can increase the potential risks of morbidity and mortality. This article is an attempt to bring a general awareness among anesthesia fraternity about the various health hazards associated with anesthesia practice. Also, a genuine attempt has been made to enumerate the various preventive methods and precautions that should be adopted to make practice of anesthesiology safe and smooth.

The epidemic of thyroid cancer in the United States: the role of endocrinologists and ultrasounds

BACKGROUND

The incidence of thyroid cancer has increased at an alarming rate in both men and women in the United States. The etiology of this epidemic is unclear. We tested the hypothesis that a significant component of this epidemic is due to increased detection of occult disease. We examined whether the density of endocrinologists and general surgeons as well as employment of cervical ultrasonography were factors associated with this epidemic.

METHODS

Thyroid cancer incidence rates by states were obtained from the United States Cancer Statistics 1999-2009 reported by the National Program of Cancer Registries. The densities of endocrinologists and general surgeons and the employment of cervical ultrasonography were calculated on a statewide basis and correlated with the incidence of thyroid cancer.

RESULTS

Age-standardized incidence rates of thyroid cancer have increased in every state in the United States. Significant regional variations were noted, with the highest incidence rates in the northeast and the lowest in the south. The incidence rates were significantly correlated with the density of endocrinologists (r = 0.58, p<0.0001 for males; r = 0.44, p = 0.0031 for females) and the employment of cervical ultrasonography (r = 0.40, p = 0.0091 for males; r = 0.36, p = 0.0197 for females). Both the density of endocrinologists and general surgeons and employment of cervical ultrasonography could explain 57% of the variability in state-level incidence for males and 49% for females.

CONCLUSIONS

These data offer evidence to suggest that the epidemic of thyroid cancer is due to increased detection of a reservoir of previously occult disease. The increased detection of thyroid cancer results in therapeutic interventions including surgery and radioactive thyroid treatment that may be of limited benefit.

Exposure to radionuclides in smoke from vegetation fires

Naturally occurring radionuclides of uranium, thorium, radium, lead and polonium were determined in bushes and trees and in the smoke from summer forest fires. Activity concentrations of radionuclides in smoke particles were much enriched when compared to original vegetation. Polonium-210 ((210)Po) in smoke was measured in concentrations much higher than all other radionuclides, reaching 7,255 ± 285 Bq kg(-1), mostly associated with the smaller size smoke particles (<1.0 μm). Depending on smoke particle concentration, (210)Po in surface air near forest fires displayed volume concentrations up to 70 m Bq m(-3), while in smoke-free air (210)Po concentration was about 30 μ Bq m(-3). The estimated absorbed radiation dose to an adult member of the public or a firefighter exposed for 24h to inhalation of smoke near forest fires could exceed 5 μSv per day, i.e, more than 2000 times above the radiation dose from background radioactivity in surface air, and also higher than the radiation dose from (210)Po inhalation in a chronic cigarette smoker. It is concluded that prolonged exposure to smoke allows for enhanced inhalation of radionuclides associated with smoke particles. Due to high radiotoxicity of alpha emitting radionuclides, and in particular of (210)Po, the protection of respiratory tract of fire fighters is strongly recommended.

Gender difference in the health risk perception of radiation from Fukushima in Japan: the role of hegemonic masculinity

This paper presents the preliminary findings of gender difference in the perception of radiation risk in the aftermath of the Fukushima nuclear disaster in Japan. In-depth interviews were conducted with the residents of Fukushima and other parts of Japan in November 2011 and July 2012. Compared to mothers, fathers in general expressed less concern for radiation. Fathers prioritized their responsibilities as the breadwinner for their families and saw radiation risk as a threat to economic stability and masculine identity. As a result, mothers' health concerns were dismissed, and they were prevented from taking preventive actions. The social norms in the dominant institutions such as corporations and the government influenced men's perception of radiation risk. The findings illustrate the importance of sociocultural context in which meanings of health risk are constructed.

Emotional consequences of nuclear power plant disasters

The emotional consequences of nuclear power plant disasters include depression, anxiety, post-traumatic stress disorder, and medically unexplained somatic symptoms. These effects are often long term and associated with fears about developing cancer. Research on disasters involving radiation, particularly evidence from Chernobyl, indicates that mothers of young children and cleanup workers are the highest risk groups. The emotional consequences occur independently of the actual exposure received. In contrast, studies of children raised in the shadows of the Three Mile Island (TMI) and Chernobyl accidents suggest that although their self-rated health is less satisfactory than that of their peers, their emotional, academic, and psychosocial development is comparable. The importance of the psychological impact is underscored by its chronicity and by several studies showing that poor mental health is associated with physical health conditions, early mortality, disability, and overuse of medical services. Given the established increase in mental health problems following TMI and Chernobyl, it is likely that the same pattern will occur in residents and evacuees affected by the Fukushima meltdowns. Preliminary data from Fukushima indeed suggest that workers and mothers of young children are at risk of depression, anxiety, psychosomatic, and post-traumatic symptoms both as a direct result of their fears about radiation exposure and an indirect result of societal stigma. Thus, it is important that non-mental health providers learn to recognize and manage psychological symptoms and that medical programs be designed to reduce stigma and alleviate psychological suffering by integrating psychiatric and medical treatment within the walls of their clinics.Introduction of Emotional Consequences of Nuclear Power Plant Disasters (Video 2:15, http://links.lww.com/HP/A34).

Radioactivity from Fukushima nuclear accident detected in Lisbon, Portugal

The radioactivity released from the Fukushima Dai-ichi nuclear accident was transported around the globe by atmospheric processes. Several artificial radionuclides were detected and measured in aerosols and atmospheric surface depositions in the Lisbon area during late March and early April 2011. The highest concentrations measured in aerosols were those of particulate (131)I, 1.39 ± 0.08 mBq m(-3). Cesium-134, (137)Cs and (132)Te were also determined but at lower concentrations. The total atmospheric depositions on the ground were higher on the first week of April with values for (131)I, (134)Cs, and (137)Cs of 0.92 ± 0.11, 0.59 ± 0.06, and 0.62 ± 0.12 Bq m(-2), respectively. The four artificial radionuclides measurable, (131)I, (132)Te (134)Cs, and (137)Cs, caused little radiation exposure to the members of the public, that was five orders of magnitude lower than the ionizing radiation effective dose limits for members of the public for one year (1 mSv y(-1)).

Environmental contaminants and children's health: Cause for concern, time for action

The present paper provides an outline of the developmental and behavioural characteristics that make children, especially the fetus and young child, more vulnerable to contaminants than adults. The major categories of contaminants are briefly described. The evidence for their possible effects on neurobehavioural development; immune, endocrine and respiratory systems; childhood cancer based on research studies with animals; children exposed to catastrophic 'accidents' involving overdose exposures; and pregnant women and children from communities with high 'background' levels of contamination who participated in studies is reviewed. While the data are worrisome, especially for children living in northern and certain urban communities, much remains to be learned about possible subtle effects and the potential for long term effects of the current background contamination experienced by the majority of Canadian children before its significance to their health can be fully evaluated. The present regulatory processes, which are based on risk assessment, are so cumbersome and costly that the great majority of chemicals in use have not been fully evaluated, and the ingenuity of new chemical production continually exceeds the capacity to test the new chemicals. Moreover, despite past insistence on scientific proof of adverse effects and safety, unanticipated effects have occurred that will threaten the sustainability of human life unless more effective control measures are taken to limit the release of toxic substances and persistent chemicals into the environment. Therefore, the shortcomings of risk assessment are discussed, and the precautionary principle, which is used in some countries and is proposed for use internationally as an alternative measure that may offer improved control for the future, is outlined. Finally, opportunities for physician action are suggested.

Endocrine effects of Fukushima: Radiation-induced endocrinopathy

The unfortunate accidents of Chernobyl and Fukushima have led to an enormous amount of radioactive material being released into the atmosphere. Radiation exposure to the human body may be as a result of accidents, such as those in Chernobyl and Fukushima, or due to occupational hazards, such as in the employees of nuclear plants, or due to therapeutic or diagnostic procedures. These different sources of radiations may affect the human body as a whole or may cause localized damage to a certain area of the body, depending upon the extent and dosage of the irradiation. More or less every organ is affected by radiation exposure. Some require a higher dose to be affected while others may be affected at a lower dose. All the endocrine glands are susceptible to damage by radiation exposure; however, pituitary, thyroid and gonads are most likely to be affected. In addition to the endocrine effects, the rates of birth defects and carcinomas may also be increased in the population exposed to excessive radiation.

Emergency preparedness for higher risk populations: psychosocial considerations

This paper was meant to be on 'vulnerable populations', as some population sub-groups do require special care, special planning and special integration of needs. However, the issue should be reframed in terms of groups at higher risks. The text explains how (1) there are contextual vulnerabilities, in (a) higher susceptibility, i.e. higher exposure to risk, (b) higher sensitivity, i.e. higher damage or higher brittleness, and (c) weaknesses and gaps in the emergency system; (2) that these higher susceptibility, sensitivity and system weaknesses involve important psychosocial considerations, which may stem from socio-demographic status or ripple effects in the community; and finally, (3) that addressing those 'soft spots' using the phrase 'vulnerable populations' can be misleading and disserving because it disempowers, stigmatises and deters one from a more thorough analysis.

Determinants of participation in a longitudinal two-stage study of the health consequences of the Chornobyl nuclear power plant accident

Background

The determinants of participation in long-term follow-up studies of disasters have rarely been delineated. Even less is known from studies of events that occurred in eastern Europe. We examined the factors associated with participation in a longitudinal two-stage study conducted in Kyiv following the 1986 Chornobyl nuclear power plant accident.

Methods

Six hundred child-mother dyads (300 evacuees and 300 classmate controls) were initially assessed in 1997 when the children were 11 years old, and followed up in 2005–6 when they were 19 years old. A population control group (304 mothers and 327 children) was added in 2005–6. Each assessment point involved home interviews with the children and mothers (stage 1), followed by medical examinations of the children at a clinic (stage 2). Background characteristics, health status, and Chornobyl risk perceptions were examined.

Results

The participation rates in the follow-up home interviews were 87.8% for the children (88.6% for evacuees; 87.0% for classmates) and 83.7% for their mothers (86.4% for evacuees and 81.0% for classmates). Children's and mothers' participation was predicted by one another's study participation and attendance at the medical examination at time 1. Mother's participation was also predicted by initial concerns about her child's health, greater psychological distress, and Chornobyl risk perceptions. In 1997, 91.2% of the children had a medical examination (91.7% of evacuees and 90.7% of classmates); in 2005–6, 85.2% were examined (83.0% of evacuees, 87.7% of classmates, 85.0% of population controls). At both times, poor health perceptions were associated with receiving a medical examination. In 2005–6, clinic attendance was also associated with the young adults' risk perceptions, depression or generalized anxiety disorder, lower standard of living, and female gender.

Conclusion

Despite our low attrition rates, we identified several determinants of selective participation consistent with previous research. Although evacuee status was not associated with participation, Chornobyl risk perceptions were strong predictors of mothers' follow-up participation and attendance at the medical examinations. Understanding selective participation offers valuable insight for future longitudinal disaster studies that integrate psychiatric and medical epidemiologic research.

The Chornobyl accident and cognitive functioning: a follow-up study of infant evacuees at age 19 years

BACKGROUND

The cognitive and academic outcomes of infants exposed to radiation after the meltdown at Chornobyl have been intensely debated. Western-based investigations indicate that no adverse effects occurred, but local studies reported increased cognitive impairments in exposed compared with non-exposed children. Our initial study found that at age 11 years, school grades and neuropsychological performance were similar in 300 children evacuated to Kiev as infants or in utero compared with 300 classmate controls, yet more evacuee mothers believed that their children had memory problems. This study re-examined the children's performance and academic achievement at age 19 years.

METHOD

In 2005-2006, we conducted an 8-year follow-up of the evacuees (n=265) and classmate controls (n=261) assessed in Kiev in 1997. Outcomes included university attendance, tests of intelligence, attention, and memory, and subjective appraisals of memory problems. Scores were standardized using a local population-based control group (n=327). Analyses were stratified by parental education.

RESULTS

Evacuees and classmates performed similarly and in the normal range on all tests, and no differential temporal changes were found. The results were comparable for the in utero subsample. The rates of university attendance and self-reported memory problems were also similar. Nevertheless, the evacuee mothers were almost three times as likely to report that their children had memory problems compared with controls.

CONCLUSIONS

Chornobyl did not influence the cognitive functioning of exposed infants although more evacuee mothers still believed that their offspring had memory problems. These lingering worries reflect a wider picture of persistent health concerns as a consequence of the accident.

Post-disaster physical symptoms of firefighters and police officers: role of types of exposure and post-traumatic stress symptoms

OBJECTIVES

To examine the relationships between exposure to the air disaster in Amsterdam and multiple physical symptoms among firefighters and police officers, and to explore the role of post-traumatic stress symptoms (PTSS) herein.

DESIGN

Historic cohort study.

METHODS

On average 8.5 years post-disaster, exposed professional firefighters (N=334) and police officers (N=834) and their nonexposed colleagues (N=194 and N=634, respectively) completed questionnaires on disaster exposure and current symptoms. Logistic regression with adjustment for background characteristics was used to compare exposed and nonexposed workers. PTSS were added to these models, as was the interaction between exposure and PTSS, to explore potential mediating and modifying effects, respectively.

RESULTS

Exposed workers reported multiple physical symptoms significantly more often. Multiple physical symptoms seemed to have particularly affected the exposed firefighters who rescued people, and the exposed police officers who supported injured victims and workers, who were involved in the identification of or search for victims and human remains, who witnessed the immediate disaster scene or had a close one affected by the disaster. These exposure effects were essentially independent of PTSS, and no significant interactions between exposure and PTSS were found.

CONCLUSIONS

In conclusion, the excess in post-disaster multiple physical symptoms in exposed workers could not be attributed to PTSS.

Psychosocial responses to environmental incidents: a review and a proposed typology

OBJECTIVE

The objective of this review was to propose a typology for understanding the diversity of psychosocial reactions to environmental incidents.

METHODOLOGY

The first section provides an introduction and background to the topic; we then attempt to provide a typology of psychosocial responses to environmental incidents.

RESULTS

Response to an environmental incident can be usefully considered in terms of the exposure, the response of the individual, the action of professionals, the response of the community, and the influence of the society in which the incident occurs. We reviewed each of these factors.

CONCLUSIONS

By examining incidents in an ordered framework, we suggest that a more comprehensive understanding is possible. We also suggest some basic ways in which the psychosocial management of such difficult and diverse incidents could be improved.

Epidemiological study air disaster in Amsterdam (ESADA): study design

Background

In 1992, a cargo aircraft crashed into apartment buildings in Amsterdam, killing 43 victims and destroying 266 apartments. In the aftermath there were speculations about the cause of the crash, potential exposures to hazardous materials due to the disaster and the health consequences. Starting in 2000, the Epidemiological Study Air Disaster in Amsterdam (ESADA) aimed to assess the long-term health effects of occupational exposure to this disaster on professional assistance workers.

Methods/Design

Epidemiological study among all the exposed professional fire-fighters and police officers who performed disaster-related task(s), and hangar workers who sorted the wreckage of the aircraft, as well as reference groups of their non-exposed colleagues who did not perform any disaster-related tasks. The study took place, on average, 8.5 years after the disaster. Questionnaires were used to assess details on occupational exposure to the disaster. Health measures comprised laboratory assessments in urine, blood and saliva, as well as self-reported current health measures, including health-related quality of life, and various physical and psychological symptoms.

Discussion

In this paper we describe and discuss the design of the ESADA. The ESADA will provide additional scientific knowledge on the long-term health effects of technological disasters on professional workers.

Uncertainty and sensitivity analysis in assessment of the thyroid cancer risk related to Chernobyl fallout in Eastern France

The increase in the thyroid cancer incidence in France observed over the last 20 years has raised public concern about its association with the 1986 nuclear power plant accident at Chernobyl. At the request of French authorities, a first study sought to quantify the possible risk of thyroid cancer associated with the Chernobyl fallout in France. This study suffered from two limitations. The first involved the lack of knowledge of spontaneous thyroid cancer incidence rates (in the absence of exposure), which was especially necessary to take their trends into account for projections over time; the second was the failure to consider the uncertainties. The aim of this article is to enhance the initial thyroid cancer risk assessment for the period 1991-2007 in the area of France most exposed to the fallout (i.e., eastern France) and thereby mitigate these limitations. We consider the changes over time in the incidence of spontaneous thyroid cancer and conduct both uncertainty and sensitivity analyses. The number of spontaneous thyroid cancers was estimated from French cancer registries on the basis of two scenarios: one with a constant incidence, the other using the trend observed. Thyroid doses were estimated from all available data about contamination in France from Chernobyl fallout. Results from a 1995 pooled analysis published by Ron et al. were used to determine the dose-response relation. Depending on the scenario, the number of spontaneous thyroid cancer cases ranges from 894 (90% CI: 869-920) to 1,716 (90% CI: 1,691-1,741). The number of excess thyroid cancer cases predicted ranges from 5 (90% UI: 1-15) to 63 (90% UI: 12-180). All of the assumptions underlying the thyroid cancer risk assessment are discussed.

Projecting the time trend of thyroid cancers: its impact on assessment of radiation-induced cancer risks

The incidence of thyroid cancer, which may be induced by ionizing radiation, has been rising in most Western countries for more than 20 years. In France, public worry about this increase and its possible connection with the fallout from Chernobyl led the government to ask for an evaluation of the health impact of this accident and an assessment of the feasibility of an epidemiological study. These requests raise two methodological questions: Which risk model should be used to relate exposure to risk? What is known about the spontaneous incidence rate of thyroid cancers? This article analyzes the impact of the time trend in the spontaneous incidence of thyroid cancers over the past 20 years in France when evaluating the risk of radiation-induced cancer. Age-period-cohort models were used to model the trend of spontaneous incidence from 1978 through 1997 and then to apply two scenarios for projections up to 2007: one with a constant incidence, the other using the trend observed over the past 20 years. Then the risk was assessed for a hypothetical population of 30,000 children aged 0 to 15 y, exposed to a hypothetical 0.1 Gy thyroid dose. The analysis shows that consideration of the trend instead of a constant spontaneous incidence can yield substantial differences in the risk estimates for thyroid cancer.

Environment and health: vital intersection or contested territory?

The effects of environmental exposure, broadly defined as any exposure from outside the body, on human health are unquestionably the most important determinants of public health. While important genetic determinants of disease exert their effects irrespective of exposure from outside the body, these do not contribute as much to the overall public health burden of disease as factors such as tobacco smoke, poor quality water, inadequate or contaminated food, occupational exposures to dusts and chemicals, motor vehicle accidents, interpersonal violence, air pollution, and other factors external to the body. In many cases, genetic predisposition and environmental exposures combined cause disease in an individual, so it may be impossible to separate out individual biological contributions from various external factors. Nevertheless, it is widely understood that public health concerns populations and communities, and that environmental determinants of health have been paramount throughout human history.

The congenital anomalies registry in Belarus: a tool for assessing the public health impact of the Chernobyl accident

A national population-based malformation registry (BNR) has been in operation since 1979 in Belarus, one of the countries most heavily exposed to the contamination from the Chernobyl accident of 26 April 1986. We describe its methodology and its compliance with established criteria, evaluate the completeness of its reporting, and analyze the data collected in four administrative regions with contrasting contamination levels from 1983 through 1999. Nine easily diagnosed malformations have been monitored since 1983. Reporting completeness exceeds 85% for all periods and all regions. In all periods, the prevalence at birth of these malformations was lower in the most contaminated regions and showed a similar positive time trend in areas of low and high contamination. We conclude that the BNR is a reliable tool for studying the possible effects on congenital malformations caused by the Chernobyl accident. Although the trend we observed may be explained by better ascertainment and prenatal diagnosis, a real increase cannot be ruled out.

Thyroid cancers in France and the Chernobyl accident: risk assessment and recommendations for improving epidemiological knowledge

From 1975 to 1995, the incidence of thyroid cancer in the French population increased by a factor of 5.2 in men and 2.7 in women, thereby raising public concerns about its association with the nuclear accident at Chernobyl. A study performed at the request of French health authorities sought to quantify the potential risk of thyroid cancer associated with the Chernobyl fallout in France in order to determine if this risk could be observed through an epidemiological approach. The study focused on the most exposed population: those living in eastern France and younger than 15 y at the time of the Chernobyl nuclear power plant accident (26 April 1986). The number of spontaneous thyroid cancers in this population was predicted from French cancer registry data, and the thyroid doses were estimated from all available data about contamination in France. Associated risks were calculated with different risk models, all based on a linear no-threshold dose-effect relationship. Under this hypothesis, from 1.3 to 22 excess thyroid cancer cases were predicted for the 1991-2000 period, compared with the 212 spontaneous cases (0.5 to 10.5%) predicted, and from 11.2 to 55.2 excess cases were predicted for 1991-2015, compared with the 1,342 spontaneous cases (0.8 to 4.1%) predicted. These risk calculations indicate that the Chernobyl fallout cannot explain the entire increase in thyroid cancers in France, and that it is improbable that an epidemiological study could demonstrate such an excess. The surveillance of thyroid cancers in France should be enhanced.

Perception of risk and subjective health among victims of the Chernobyl disaster

Several studies have demonstrated that the nuclear power plant accident at Chernobyl in 1986 had a strong impact on the subjective health of the inhabitants in the surrounding regions and that the majority of these health complaints appear to be stress-related. An epidemiological survey among the adult population of the Gomel region in Belarus near Chernobyl showed higher rates of self-reported health problems, psychological distress and medical service use in this region than in a comparable unexposed region. This paper presents an analysis of data on cognitive factors that were collected in this study. The findings support the hypothesis that cognitive variables such as risk perception and sense of control play an important role as mediating factors in the explanation of the observed health differences between the exposed and non-exposed regions. A tentative model is presented to further clarify the role of risk perception in the occurrence of non-specific health complaints after such ecological disasters.

Three somatic genetic biomarkers and covariates in radiation-exposed Russian cleanup workers of the chernobyl nuclear reactor 6-13 years after exposure

Three somatic mutation assays were evaluated in men exposed to low-dose, whole-body, ionizing radiation. Blood samples were obtained between 1992 and 1999 from 625 Russian Chernobyl cleanup workers and 182 Russian controls. The assays were chromosome translocations in lymphocytes detected by FISH, hypoxanthine phosphoribosyltransferase (HPRT) mutant frequency in lymphocytes by cloning, and flow cytometic assay for glycophorin A (GPA) variant frequency of both deletion (N/Ø) and recombination (N/N) events detected in erythrocytes. Over 30 exposure and lifestyle covariates were available from questionnaires. Among the covariates evaluated, some increased (e.g. age, smoking) and others decreased (e.g. date of sample) biomarker responses at a magnitude comparable to Chernobyl exposure. When adjusted for covariates, exposure at Chernobyl was a statistically significant factor for translocation frequency (increase of 30%, 95% CI of 10%-53%, P = 0.002) and HPRT mutant frequency (increase of 41%, 95% CI of 19%-66%, P < 0.001), but not for either GPA assay. The estimated average dose for the cleanup workers based on the average increase in translocations was 9.5 cGy. Translocation analysis is the preferred biomarker for low-dose radiation dosimetry given its sensitivity, relatively few covariates, and dose-response data. Based on this estimated dose, the risk of exposure-related cancer is expected to be low.

The long-term mental health effects of nuclear trauma in recent Russian immigrants in the United States

The long-term mental health sequelae (15 years) of the 1986 Chernobyl nuclear disaster in the former Soviet Union (FSU) were assessed in survivors migrated to the United States, as part of an ongoing study. Using a retrospective, cross-sectional design with standardized Russian mental health measures, a sample of 261 Russians residing in the New York tristate area were tested for multiple domains of mental health functioning. Multivariate analyses pointed to aspects of the accident and its negative repercussions as reliable predictors of current psychological distress. Russians who had lived closer to the disaster, and had greater exposure to it, currently experience higher levels of anxiety (p < .0004) and posttraumatic reactions (p < .03) than those who had lived at a further distance. These findings are consistent with reports of long-term sequelae in Chernobyl survivors migrated to Israel (Remennick, 2002), as well as those remaining in the FSU (Havenaar et al., 1997). Implications of long-term traumatic sequelae, especially in the complex perimigration context, are discussed.

Survival of children with thyroid cancer in Europe 1978--1989

Thyroid cancers are rare in childhood with between 0.4 and 1.5 cases per million, 2--3 times as frequent in girls as in boys. However, following the Chernobyl accident, a remarkable incidence increase was observed in children exposed to radioactive iodine fall-out. Survival after thyroid cancer in childhood is thus of interest. In the EUROCARE II study, excluding most of Eastern Europe, a total of 165 childhood thyroid cancers were reported during the period 1978--1989, of which 134 were aged 10--14 years. The childhood cancer registry in England and Wales contributed 39% of the cases, and another 24% came from the Nordic countries, the rest from other parts of west, south, east and central Europe. The 5-year survival was for both genders combined 97% (95% confidence interval (CI): 93--99), 98% (95% CI: 91--100) for boys and 97% (95% CI: 91--99) for girls, with no significant difference between the genders. Survival was high during the entire study period, and variations influenced by the small numbers. As for adults, long-term follow-up beyond 10--20 years is needed to clearly demonstrate excess mortality as a consequence of the cancer.

Iodine kinetics and effectiveness of stable iodine prophylaxis after intake of radioactive iodine: a review

Ingestion of potassium iodide (KI) offers effective protection against irradiation of the thyroid after accidental exposure to radioactive iodine. This prophylaxis aims at rapidly obtaining maximal thyroid protection without adverse effects. This article reviews studies on iodine kinetics in humans and on the efficacy of KI in protecting the thyroid. In adults with normal thyroid function, ingestion of 100 mg of iodide just before exposure to radioactive iodine blocks at least 95% of the thyroid dose. If exposure persists after iodide ingestion (100 mg), the percentage of averted dose may decrease significantly. Daily ingestion of a dose of 15 mg of KI would then maintain the thyroid blockade at a level above 90%. The efficacy of iodide and the occurrence of antithyroid effects also depend on external and individual factors such as dietary iodine intake, thyroid function, and age. The KI dosage regimen should be adjusted for age at exposure. For the fetus, the newborn, children, and adolescents, the risk of radiation-induced thyroid cancer in case of accidental exposure to radioactive iodine justifies KI prophylaxis, despite the risk of hypothyroidism, especially in newborns. For the elderly, the benefits of KI may be lower than the risk of iodine-induced hyperthyroidism.

Health status and internal radiocontamination assessment in children exposed to the fallout of the Chernobyl accident

The Chernobyl fallout caused release of radioisotope contaminants in a very large area that includes Belarus, the Ukraine, and the Russian Federation. In this study, the authors monitored the health status and level of internal contamination in 422 children who resided in the aforementioned areas and who were < or = 10 y of age at the time of the accident. The children came to Italy for a 1-mo period between 1991 and 1992. During this time, the children underwent pediatric checkups and biochemical, immunological, and thyroid analyses. All children underwent whole-body counter measurements, and urine radiotoxicological analysis was performed for 224 of them. The 24 children evacuated from Pripiat, a village very close to the Chernobyl reactor site, were selected for cytogenetic analysis. All of these children continue to have a detectable internal contamination of caesium radioisotopes. This condition is likely the result of ground and foodstuff contamination in the various areas. The children did not evidence overt pathologies related to ionizing radiation. However, minor alterations in immunological and thyroid parameters were observed in the group of the evacuated children. Traditional cytogenetic dosimetry was not possible, but the occurrence of acentric fragments was observed-indicating a persistent effect of continuous exposure to low doses of radiation.

Total gene deletions and mutant frequency of the HPRT gene as indicators of radiation exposure in Chernobyl liquidators

This study was conducted to determine the utility of deletion spectrum and mutant frequency (MF) of the hypoxanthine phosphoribosyl transferase gene (HPRT) as indicators of radiation exposure in Russian Liquidators who served in 1986 or 1987 in the clean up effort following the nuclear power plant accident at Chernobyl. HPRT MF was determined using the cloning assay for 117 Russian Controls and 122 Liquidators whose blood samples were obtained between 1991 and 1998. Only subjects from whom mutants were obtained for deletion analysis are included. Multiplex PCR analysis was performed on cell extracts of 1080 thioguanine resistant clones from Controls and 944 clones from Liquidators. Although the deletion spectra of Liquidators and Controls were similar overall, the Liquidator deletion spectrum was heterogeneous over time. Most notable, the proportion of total gene deletions was higher in 1991-1992 Liquidators than in Russian Controls (chi 2 = 10.5, p = 0.001) and in 1993-1994 Liquidators (chi 2 = 8.3, p = 0.004), and was marginally elevated relative to 1995-1996 Liquidators (chi 2 = 3.3, p = 0.07). This type of mutations has been highly associated with radiation exposure. Total gene deletions were not increased after 1992. Band shift mutations were also increased in the 1991-1992 Liquidators but were associated with increased MF of both Liquidators and Controls (p = 0.009), not with increased MF in 1991-1992 Liquidators (p = 0.7), and hence are not believed to be associated with radiation exposure. Regression analysis demonstrated that relative to Russian Controls HPRT MF was elevated in Liquidators overall when adjusted for age and smoking status (37%, p = 0.0001), and also was elevated in Liquidators sampled in 1991-1992 (72%, p = 0.0076), 1993-1994 (22%, p = 0.037), and 1995-1996 (62%, p = 0.0001). In summary, HPRT MF was found to be the more sensitive and persistent indicator of radiation exposure, but the specificity of total gene deletions led to detection of probable heterogeneity of radiation exposure within the exposed population.

Teratogen update: radiation and Chernobyl

The 1986 nuclear reactor accident at Chernobyl caused nonuniform radiocontamination of air and land, primarily within regions of the former Soviet Union and Western Europe. Major exposure groups included the reactor workers, villagers evacuated from within 30 km of the accident, the "liquidators" who decontaminated the evacuation zone afterward, those in radiocontaminated villages not evacuated, and "others" not in the latter categories. The possibility of being exposed to radiation caused considerable anxiety, especially among pregnant women. Were teratogenic levels of radiation (> or = 0.1 Gy) exposure attained? To date there is no consistent proof that this level of radiation exposure was received. Nevertheless, thousands of induced abortions were performed. Radioiodine (I-131) caused thyroid cancer in young children in portions of Belarus, the Ukraine, and Russia. It is not known but very possible that I-131 fetal thyroid exposure contributed to this observation. The relationship between mental retardation and radiation exposure has not been confirmed. Leukemia and other cancers, while predicted for the liquidators (mainly males), has not been found in the other exposure groups at this time. Investigations of aborted fetuses and newborns in Belarus showed an increase in the frequency of both congenital and fetal abnormalities in high and low Cs-137 contaminated regions. This study is unreliable due to detection and selection biases. Accident and environmental factors unrelated to radiation doses may have contributed to these observations. Occasional positive teratogenic studies in less contaminated regions of Western Europe are suspect because of the low radiation doses received. There is no substantive proof regarding radiation-induced teratogenic effects from the Chernobyl accident.