Elevated childhood cancer incidence proximate to U.S. nuclear power plants

Health Effects of Occupational and Environmental Exposures to Nuclear Power Plants: A Meta-Analysis and Meta-Regression

PURPOSE OF REVIEW

Numerous epidemiological studies have shown increased health risks among workers and residents living near nuclear power plants exposed to radiation levels meeting regulatory dose limits. This study aimed to evaluate the association between radiation exposure and disease risks among these populations exposed to radiation levels meeting the current regulatory dose limits.

RECENT FINDINGS

We searched four databases (Cochrane Library, PubMed, ScienceDirect, and Web of Science) for studies published before August 2023, screened eligible studies (inclusion and exclusion criteria based on population, exposure, comparator, and outcome framework), and collected data on exposure indicators and disease risks. We applied random-effects models of meta-analysis to estimate the pooled effects and meta-regression to assess the dose-response relationship (radiation dose rate for workers and distance for residents). We identified 47 studies, 13 with worker and 34 with resident samples, covering 175 nuclear power plants from 17 countries, encompassing samples of 480,623 workers and 7,530,886 residents. Workers had a significantly lower risk for all-cancer and a significantly higher risk for mesothelioma. Residents had significantly higher risks for all-cancer, thyroid cancer, and leukemia. Notably, children under 5 years old showed the highest risk for all-cancer. Our meta-regression showed a significantly positive dose-response relationship between cumulative dose of radiation exposure and risk for circulatory disease among workers. Our findings demonstrated higher risks for mesothelioma for workers and all-cancer, thyroid cancer, and leukemia for residents exposed to low-dose radiation from nuclear power plants. Some included studies did not adjust for cancer risk confounders, which could overestimate the association between radiation exposure and cancer risk and increase the risk of bias.

Low dose or low dose rate ionizing radiation-induced health effect in the human

The extensive literature review on human epidemiological studies suggests that low dose ionizing radiation (LDIR) (≤100 mSv) or low dose rate ionizing radiation (LDRIR) (<6mSv/H) exposure could induce either negative or positive health effects. These changes may depend on genetic background, age (prenatal day for embryo), sex, nature of radiation exposure, i.e., acute or chronic irradiation, radiation sources (such as atomic bomb attack, fallout from nuclear weapon test, nuclear power plant accidents, ⁶⁰Co-contaminated building, space radiation, high background radiation, medical examinations or procedures) and radionuclide components and human epidemiological experimental designs. Epidemiological and clinical studies show that LDIR or LDRIR exposure may induce cancer, congenital abnormalities, cardiovascular and cerebrovascular diseases, cognitive and other neuropsychiatric disorders, cataracts and other eye and somatic pathology (endocrine, bronchopulmonary, digestive, etc). LDIR or LDRIR exposure may also reduce mutation and cancer mortality rates. So far, the mechanisms of LDIR- or LDRIR -induced health effect are poorly understood. Further extensive studies are still needed to clarify under what circumstances, LDIR or LDRIR exposure may induce positive or negative effects, which may facilitate development of new therapeutic approaches to prevent or treat the radiation-induced human diseases or enhance radiation-induced positive health effect.

Comparative analyses of studies of childhood leukemia and magnetic fields, radon and gamma radiation

In this paper we compare the findings of epidemiologic studies of childhood leukemia that examined at least two of ELF magnetic fields and/or distance to power lines, and exposure to radon and gamma radiation or distance to nuclear plants. Many of the methodologic aspects are common to studies of non-ionising (i.e. ELF-MF) and ionising radiation. A systematic search and review of studies with more than one exposure under study identified 33 key and 35 supplementary papers from ten countries that have been included in this review. Examining studies that have looked at several radiation exposures, and comparing similarities and differences for the different types of radiation, through the use of directed acyclic graphs, we evaluate to what extent bias, confounding and other methodological issues might be operating in these studies. We found some indication of bias, although results are not clear cut. There is little evidence that confounding has had a substantial influence on results. Influence of the residential mobility on the study conduct and interpretation is complex and can manifest as a selection bias, confounding, increased measurement error or could also be a potential risk factor. Other factors associated with distance to power lines and to nuclear power plants should be investigated. A more complete and consistent reporting of results in the future studies will allow for a more informative comparison across studies and integration of results.

A Short Latency between Radiation Exposure from Nuclear Plants and Cancer in Young Children

Previous reports document a short latency of cancer onset in young children exposed to low doses of radioactivity. The standard mortality ratio (SMR) for cancer in children dying before age ten rose in the period 6–10 years after the Three Mile Island and Chernobyl accidents in populations most exposed to fallout. SMRs near most nuclear power plants were elevated 6–10 years after startup, particularly for leukemia. Cancer incidence in children under age ten living near New York and New Jersey nuclear plants increased 4–5 years after increases in average strontium-90 in baby teeth, and declined 4–5 years after Sr-90 averages dropped. The assumption that Sr-90 and childhood cancer are correlated is best supported for a supralinear dose-response, meaning the greatest per-dose risks are at the lowest doses. Findings document that the very young are especially susceptible to adverse effects of radiation exposure, even at relatively low doses.

Reach: An Unprecedented European Initiative for Regulating Industrial Chemicals

In February 2001, the European Commission (EC) released a White Paper, REACH 2001, detailing unique and unprecedented legislative proposals for the regulation of industrial chemicals, based on the Precautionary Principle. The object of these proposals was to reverse the escalating incidence of avoidable cancers, a wide range of other industrial diseases, and environmental contamination. However, REACH was aggressively opposed by the European and U.S. chemical industries, and even more so by the U.S. administration. The EC responded by making major concessions in its October 2003 REACH-based legislative proposals. This report critically analyzes REACH, and its 2003 revised proposals, and recommends that REACH be strengthened, not weakened. Furthermore, the report urges that regulatory policies of the United States and other industrialized nations be drastically reformed to comply with those of REACH.

Central nervous system (CNS) cancer in children and young people in the European Union and its involvements with socio-economic and environmental factors

Malignant central nervous system (CNS) tumors are the leading cause of death by cancer in children and the second commonest pediatric cancer type. Despite several decades of epidemiologic research, the etiology of childhood CNS tumors is still largely unknown. A few genetic syndromes and therapeutic ionizing radiation are thought to account for 5-10% of childhood cancer, but the etiology of other cases remains unknown. Nongenetic causes, like environmental agents, are thought to explain them. However, as very few epidemiologic studies have been conducted, it is not surprising that nongenetic risk factors have not been detected. The biggest difference between cancers for which there are good etiologic clues and those for which there are none could be the number of relevant studies. This study, which covers the 1980-2011 period, identified links between CNS cancer evolution and the socio-economic and environmental indicators in the same space and time limits in the European Union.

Effects of chronic low level radiation in the population residing in the high level natural radiation area in Kerala, India: employing heritable DNA mutation studies

To study the effect of chronic low level radiation, 4040 meiosis were screened at eight microsatellite and five minisatellite (2485 and 1555 meiosis respectively) marker loci in people residing in high and normal level natural radiation areas of Kerala. Variants in the repeat length of allele were considered as mutants. Mutation rates (expressed as the number of mutations observed in the total number of meiosis) were 6.4×10(-3) (16/2485) and 2.6×10(-3) (4/1555) at microsatellite and minisatellite respectively. The germline microsatellite mutation frequency of father was 1.78 times higher at 7.52×10(-3) (8/1064) compared to 4.22×10(-3) (6/1421) of mother (P=0.292, Fisher's Exact two-sided test). The paternal and maternal mutation rates at minisatellite loci were more or less similar at 2.78×10(-3) (2/719) and 2.39×10(-3) (2/836), respectively (P=1.0, Fisher's Exact two-sided test). Higher but statistically non-significant microsatellite mutation frequency was observed in HLNRA compared to NLNRA (7.25×10(-3) vs 3.64×10(-3); P=0.547). The apparent increase in the mutation rate of microsatellite loci with the increase in radiation dose was also not statistically significant. All the four minisatellite mutation observed were from HLNRA (1198 meiosis) and no mutation was observed among 357 meiosis screened from NLNRA families. All the markers used in the present study were in the non-coding region and hence mutations in these regions may not cause adverse health effects, but the study is important in understanding the effect of chronic low level radiation.

Cancer risk in adult residents near nuclear power plants in Korea - a cohort study of 1992-2010

This study evaluated cancer risk for adult residents near Nuclear Power Plants (NPPs) in Korea through a valid prospective cohort study during 1992-2010. The study cohort was composed of 11,367 adults living within a five km radius from the NPPs for the exposed and 24,809 adults for the non-exposed or reference cohort set at two different levels of proximity; 5-30 km radius and more than 30 km radius away from NPPs. In 303,542.5 person-years of follow-up, a total of 2,298 cancer cases of all sites, or 1,377 radio-inducible cancers diagnosed during 1992-2008 were ascertained. Multiple adjusted hazard ratios and 95% confidence intervals were estimated using multivariate Cox proportional hazard model. There were no epidemiological evidence for increased risk of cancer due to radiation from NPPs. Radiological study results or surveillance data of radiation doses around NPPs could be well documented for risk estimation of radio-inducible cancers, instead of epidemiological study results of the long-time required. Continuous surveillance of quantitative measures of dose levels around NPPs and radiation exposures to the residents is warranted.

Prenatal, early life, and childhood exposure to genotoxicants in the living environment

Health disorders and diseases related to environmental exposure in children such as cancer and immunologic disturbances (asthma, allergies) are on the rise. However, complex transplacental and prepubertal genotoxicology is given very limited consideration, even though intrauterine development and early childhood may be critical for elucidating the cancer aetiology. The foetus is transplacentally exposed to contaminants in food and environment such as various chemicals, drugs, radiochemically contaminated water and air. Target organs of xenobiotic action may differ between the mother and the foetus due to specific stage of developmental physiology and enzyme distribution. This in turn may lead to different levels of clastogenic and aneugenic metabolites of the same xenobiotic in the mother and the foetus. Adult's protective behaviour is not sufficient to isolate children from radioisotopes, pesticides, toxic metals and metalloids, environmental tobacco smoke, endocrine disrupting chemicals, and various food contaminants, which are just a part of the stressors present in a polluted environment. In order to improve legislation related to foetus and child exposure to genotoxic and possibly carcinogenic agents, oncologists, paediatricians, environmental health specialists, and genotoxicologists should work together much more closely to make a more effective use of accumulated scientific data, with the final aim to lower cancer incidence and mortality.

Childhood cancer incidence in proximity to nuclear power plants in Illinois

The objective of this study was to examine childhood cancer incidence in proximity to nuclear power plants in Illinois. Cancer cases diagnosed among Illinois children 0 to 14 years old from 1986 through 2005 were included in the study. Standardized incidence ratio (SIR) was calculated for the geographic zones defined by the proximity to nuclear power plants. The results show that children living within 10 miles of any nuclear power plant did not have significant increase in incidence for leukemia (period 1986-1995: SIR = 0.85 [95% confidence interval, CI: 0.54-1.26]; period 1996-2005: 1.23 [0.91-1.64]), lymphomas [period 1986-1995: 1.38 [0.77-2.27]; period 1996-2005: 0.77 [0.37-1.42]), or other cancer sites. Neither did the children living 10 to 20 miles or 20 to 30 miles from any nuclear power plants. This study did not find any significant childhood cancer excess among children living near nuclear plants and did not observe any dose-response patterns.

Environmental factors and childhood acute leukemias and lymphomas

This review considers recent studies regarding the role of environmental factors in the etiology of childhood leukemia and lymphoma. Potential environmental risk factors identified for childhood leukemia include exposure to magnetic fields of more than 0.4 micro Tessla, exposure to pesticides, solvents, benzene and other hydrocarbons, maternal alcohol consumption (but only for certain genotypes), contaminated drinking water, infections, and high birth weight. The finding of space-time clustering and seasonal variation also supports a role for infections. There is little evidence linking childhood leukemia with lifetime exposure to ionizing radiation although fetal exposures to X-rays are associated with increased risk. Breast-feeding, consumption of fresh fruit and vegetables and having allergies all appear to be protective. Burkitt lymphoma (BL) is confined to areas of the world where malaria is endemic, with the additional involvement of the Epstein-Barr virus (EBV) as a co-factor. Environmental risk factors suggested for other types of non-Hodgkin lymphoma (NHL) include exposure to ionizing radiation (both lifetime and antenatal), pesticides, and, in utero exposure to cigarette smoke, benzene and nitrogen dioxide (via the mother). Hodgkin lymphoma (HL) is especially associated with higher levels of socioeconomic deprivation, but breast-feeding seems to confer lower risk. This is consistent with an infection or immune-response mediated etiology for HL.

Epidemiological studies of leukaemia in children and young adults around nuclear facilities: a critical review

The existence of an increased risk of childhood leukaemia near nuclear installations is a recurrent issue. A review of the related epidemiological literature is presented here. Results for 198 nuclear sites throughout 10 countries were included in the review. In addition to local studies, 25 multi-site studies have been published for eight countries. A large variability was noticed in the quality of the data as well as in the definition of the study population and in the methods of analysis. Many studies present important limits that make the results difficult to interpret. The review confirms that some clusters of childhood leukaemia cases exist locally. However, results based on multi-site studies around nuclear installations do not indicate an increased risk globally. Many studies were launched to investigate possible origins of the observed clusters around specific sites, but up to now, none of the proposed hypotheses have explained them.

Trends in childhood cancer incidence: review of environmental linkages

Cancer in children is rare and accounts for about 1% of all malignancies. In the developed world, however, it is the commonest cause of disease-related deaths in childhood, carrying with it a great economic and emotional cost. Cancers are assumed to be multivariate, multifactorial diseases that occur when a complex and prolonged process involving genetic and environmental factors interact in a multistage sequence. This article explores the available evidence for this process, primarily from the environmental linkages perspective but including some evidence of the genetic factors.

2004 update of dosimetry for the Utah Thyroid Cohort Study

In the 1980s, individual thyroid doses and uncertainties were estimated for members of a cohort of children identified in 1965 in Utah and Nevada who had potentially been exposed to fallout from the Nevada Test Site. That reconstruction represented the first comprehensive assessment of doses received by the cohort and was the first large effort to assess the uncertainty of dose on an individual person basis. The data on dose and thyroid disease prevalence during different periods were subsequently used in an analysis to determine risks of radiogenic thyroid disease. This cohort has received periodic medical follow-up to observe changes in disease frequency and to reassess the previously reported radiation-related risks, most recently after a Congressional mandate in 1998. In a recent effort to restore the databases and computer codes used to estimate doses in the 1980s, various deficiencies were found in the estimated doses due to improperly operating computer codes, corruption of secondary data files, and lack of quality control procedures. From 2001 through 2004, the dosimetry system was restored and corrected and all doses were recalculated. In addition, two parameter values were updated. While the mean of all doses has not changed significantly, many individual doses have changed by more than an order of magnitude.

An unexpected rise in strontium-90 in US deciduous teeth in the 1990s

For several decades, the United States has been without an ongoing program measuring levels of fission products in the body. Strontium-90 (Sr-90) concentrations in 2089 deciduous (baby) teeth, mostly from persons living near nuclear power reactors, reveal that average levels rose 48.5% for persons born in the late 1990s compared to those born in the late 1980s. This trend represents the first sustained increase since the early 1960s, before atmospheric weapons tests were banned. The trend was consistent for each of the five states for which at least 130 teeth are available. The highest averages were found in southeastern Pennsylvania, and the lowest in California (San Francisco and Sacramento), neither of which is near an operating nuclear reactor. In each state studied, the average Sr-90 concentration is highest in counties situated closest to nuclear reactors. It is likely that, 40 years after large-scale atmospheric atomic bomb tests ended, much of the current in-body radioactivity represents nuclear reactor emissions.