scholarly journals Epidemiological Studies of Low-Dose Ionizing Radiation and Cancer: Rationale and Framework for the Monograph and Overview of Eligible Studies

2020 ◽  
Vol 2020 (56) ◽  
pp. 97-113 ◽  
Author(s):  
Amy Berrington de Gonzalez ◽  
Robert D Daniels ◽  
Elisabeth Cardis ◽  
Harry M Cullings ◽  
Ethel Gilbert ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Dose Response ◽  
Low Dose ◽  
Biological Effects ◽  
Epidemiological Studies ◽  
Solid Cancer ◽  
Systematic Bias ◽  
Cancer Risks ◽  
Low Dose Radiation ◽  
Dose Uncertainty

Abstract Whether low-dose ionizing radiation can cause cancer is a critical and long-debated question in radiation protection. Since the Biological Effects of Ionizing Radiation report by the National Academies in 2006, new publications from large, well-powered epidemiological studies of low doses have reported positive dose-response relationships. It has been suggested, however, that biases could explain these findings. We conducted a systematic review of epidemiological studies with mean doses less than 100 mGy published 2006–2017. We required individualized doses and dose-response estimates with confidence intervals. We identified 26 eligible studies (eight environmental, four medical, and 14 occupational), including 91 000 solid cancers and 13 000 leukemias. Mean doses ranged from 0.1 to 82 mGy. The excess relative risk at 100 mGy was positive for 16 of 22 solid cancer studies and 17 of 20 leukemia studies. The aim of this monograph was to systematically review the potential biases in these studies (including dose uncertainty, confounding, and outcome misclassification) and to assess whether the subset of minimally biased studies provides evidence for cancer risks from low-dose radiation. Here, we describe the framework for the systematic bias review and provide an overview of the eligible studies.

scholarly journals Epidemiological Studies of Low-Dose Ionizing Radiation and Cancer: Summary Bias Assessment and Meta-Analysis

2020 ◽  
Vol 2020 (56) ◽  
pp. 188-200 ◽  
Author(s):  
Michael Hauptmann ◽  
Robert D Daniels ◽  
Elisabeth Cardis ◽  
Harry M Cullings ◽  
Gerald Kendall ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Low Dose ◽  
Biological Effects ◽  
Meta Analysis ◽  
Epidemiological Studies ◽  
Positive Bias ◽  
Cancer Risks ◽  
Risk Estimates ◽  
Unit Dose ◽  
The Impact

Abstract Background Ionizing radiation is an established carcinogen, but risks from low-dose exposures are controversial. Since the Biological Effects of Ionizing Radiation VII review of the epidemiological data in 2006, many subsequent publications have reported excess cancer risks from low-dose exposures. Our aim was to systematically review these studies to assess the magnitude of the risk and whether the positive findings could be explained by biases. Methods Eligible studies had mean cumulative doses of less than 100 mGy, individualized dose estimates, risk estimates, and confidence intervals (CI) for the dose-response and were published in 2006–2017. We summarized the evidence for bias (dose error, confounding, outcome ascertainment) and its likely direction for each study. We tested whether the median excess relative risk (ERR) per unit dose equals zero and assessed the impact of excluding positive studies with potential bias away from the null. We performed a meta-analysis to quantify the ERR and assess consistency across studies for all solid cancers and leukemia. Results Of the 26 eligible studies, 8 concerned environmental, 4 medical, and 14 occupational exposure. For solid cancers, 16 of 22 studies reported positive ERRs per unit dose, and we rejected the hypothesis that the median ERR equals zero (P = .03). After exclusion of 4 positive studies with potential positive bias, 12 of 18 studies reported positive ERRs per unit dose (P  = .12). For leukemia, 17 of 20 studies were positive, and we rejected the hypothesis that the median ERR per unit dose equals zero (P  = .001), also after exclusion of 5 positive studies with potential positive bias (P  = .02). For adulthood exposure, the meta-ERR at 100 mGy was 0.029 (95% CI = 0.011 to 0.047) for solid cancers and 0.16 (95% CI = 0.07 to 0.25) for leukemia. For childhood exposure, the meta-ERR at 100 mGy for leukemia was 2.84 (95% CI = 0.37 to 5.32); there were only two eligible studies of all solid cancers. Conclusions Our systematic assessments in this monograph showed that these new epidemiological studies are characterized by several limitations, but only a few positive studies were potentially biased away from the null. After exclusion of these studies, the majority of studies still reported positive risk estimates. We therefore conclude that these new epidemiological studies directly support excess cancer risks from low-dose ionizing radiation. Furthermore, the magnitude of the cancer risks from these low-dose radiation exposures was statistically compatible with the radiation dose-related cancer risks of the atomic bomb survivors.

Results of the 66-th Session of the United Nations Scientific Committee on the Effects of the Atomic Radiation (UNSCEAR) (Vienna, 10–14 June, 2019)

2019 ◽  
Vol 64 (5) ◽  
pp. 81-88
Author(s):  
В. Уйба ◽  
V. Uyba ◽  
А. Аклеев ◽  
A. Akleev ◽  
Т. Азизова ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Radiation Exposure ◽  
Nuclear Power ◽  
Occupational Exposures ◽  
Epidemiological Studies ◽  
Future Research ◽  
Second Primary ◽  
Cancer Risks ◽  
Low Dose Radiation ◽  
Effects Of Radiation

The current paper is devoted to the outcomes of the 66-th UNSCEAR Session which took place in Vienna during 10–14 June 2018. Within the framework of the meetings of the Working Group and subgroups the documents on the following projects were discussed: R.733. Evaluation of selected health effects and inference of risk due to radiation exposure. R.734. Evaluation of medical exposures to ionizing radiation. R.735. Evaluation of occupational exposures to ionizing radiation. R.736. Lung cancer from exposure to radon. R.737. Biological mechanisms relevant for the inference of cancer risks from low-dose radiation. R.738. Levels and effects of radiation exposure due to the accident at the Fukushima Daiichi nuclear power station: implications of information published since the 2013 UNSCEAR report. R.739. Second primary cancer after radiotherapy. R.740. Epidemiological studies of radiation and cancer. The Committee also discussed: the future research program; report to the UN General Assembly; implementation of a strategy plan to improve collection, analysis and dissemination of data on radiation exposure; public outreach activity including the strategy for the period 2020–2024.

scholarly journals Changing Attitude Toward Radiation Carcinogenesis and Prospects for Novel Low-Dose Radiation Treatments

2016 ◽  
Vol 15 (6) ◽  
pp. 732-736 ◽  
Author(s):  
Yehoshua Socol ◽  
James S. Welsh
Keyword(s):  
Ionizing Radiation ◽  
Low Dose ◽  
Epidemiological Studies ◽  
International Commission ◽  
Radiation Hazard ◽  
Radiological Protection ◽  
Low Doses ◽  
Low Dose Radiation ◽  
Radiation Treatments ◽  
Dose Radiation

All procedures involving ionizing radiation, whether diagnostic or therapeutic, are subject to strict regulation, and public concerns have been raised about even the low levels of radiation exposures involved in diagnostic imaging. During the last 2 decades, there are signs of more balanced attitude to ionizing radiation hazards, as opposed to the historical “radiophobia.” The linear no-threshold hypothesis, based on the assumption that every radiation dose increment constitutes increased cancer risk for humans, is increasingly debated. In particular, the recent memorandum of the International Commission on Radiological Protection admits that the linear no-threshold hypothesis predictions at low doses (that International Commission on Radiological Protection itself has used and continues to use) are “speculative, unproven, undetectable, and ‘phantom’.” Moreover, numerous experimental, ecological, and epidemiological studies suggest that low doses of ionizing radiation may actually be beneficial to human health. Although these advances in scientific understanding have not yet yielded significant changes in radiation regulation and policy, we are hopeful such changes may happen in the relatively near future. This article reviews the present status of the low-dose radiation hazard debate and outlines potential opportunities in the field of low-dose radiation therapy.

scholarly journals Outcome Assessment in Epidemiological Studies of Low-Dose Radiation Exposure and Cancer Risks: Sources, Level of Ascertainment, and Misclassification

2020 ◽  
Vol 2020 (56) ◽  
pp. 154-175 ◽  
Author(s):  
Martha S Linet ◽  
Mary K Schubauer-Berigan ◽  
Amy Berrington de González
Keyword(s):  
Outcome Assessment ◽  
Low Dose ◽  
International Classification Of Diseases ◽  
Epidemiological Studies ◽  
Cancer Risks ◽  
Low Dose Radiation ◽  
Loss To Follow Up ◽  
Classification Of Diseases

Abstract Background Outcome assessment problems and errors that could lead to biased risk estimates in low-dose radiation epidemiological studies of cancer risks have not been systematically evaluated. Methods Incidence or mortality risks for all cancers or all solid cancers combined and for leukemia were examined in 26 studies published in 2006–2017 involving low-dose (mean dose ≤100 mGy) radiation from environmental, medical, or occupational sources. We evaluated the impact of loss to follow-up, under- or overascertainment, outcome misclassification, and changing classifications occurring similarly or differentially across radiation dose levels. Results Loss to follow-up was not reported in 62% of studies, but when reported it was generally small. Only one study critically evaluated the completeness of the sources of vital status. Underascertainment of cancers (“false negatives”) was a potential shortcoming for cohorts that could not be linked with high-quality population-based registries, particularly during early years of exposure in five studies, in two lacking complete residential history, and in one with substantial emigration. False positives may have occurred as a result of cancer ascertainment from self- or next-of-kin report in three studies or from enhanced medical surveillance of exposed patients that could lead to detection bias (eg, reporting precancer lesions as physician-diagnosed cancer) in one study. Most pediatric but few adult leukemia studies used expert hematopathology review or current classifications. Only a few studies recoded solid cancers to the latest International Classification of Diseases or International Classification of Diseases for Oncology codes. These outcome assessment shortcomings were generally nondifferential in relation to radiation exposure level except possibly in four studies. Conclusion The majority of studies lacked information to enable comprehensive evaluation of all major sources of outcome assessment errors, although reported data suggested that the outcome assessment limitations generally had little effect on risk or biased estimates towards the null except possibly in four studies.

Biological effects of low level exposures to ionizing radiation: Theory and practice

2010 ◽  
Vol 29 (4) ◽  
pp. 275-281 ◽  
Author(s):  
Shu-Zheng Liu
Keyword(s):  
Ionizing Radiation ◽  
Low Dose ◽  
Biological Effects ◽  
Combined Treatment ◽  
Experimental Studies ◽  
Theory And Practice ◽  
Tumor Control ◽  
Low Dose Radiation ◽  
Radiation Theory ◽  
Dose Radiation

This paper briefly reviewed recent reports on the epidemiological and experimental data on low dose radiation effects that support the concept of radiation hormesis. These reports point to the possibility of existence of a threshold dose in cancer induction by ionizing radiation and in some cases the occurrence of hormetic effects with stimulation of host defense mechanisms. The possibility of the use of low dose radiation in cancer treatment to improve the outcome of conventional radiotherapy was raised by citing previous reports on experimental studies, which showed increased efficacy in tumor control with significant reduction of total dose of radiation when low dose radiation was used in the combined treatment protocol.

scholarly journals A systematic review on the effect of low-dose radiation on hearing

2021 ◽  
Author(s):  
Srikanth Nayak ◽  
Arivudai Nambi ◽  
Sathish Kumar ◽  
P Hariprakash ◽  
Pradeep Yuvaraj ◽  
...  
Keyword(s):  
Systematic Review ◽  
Ionizing Radiation ◽  
Radiation Exposure ◽  
Low Dose ◽  
Behavioral Symptoms ◽  
National Council ◽  
Low Dose Radiation ◽  
Cochlear Function ◽  
High Frequencies ◽  
Dose Radiation

AbstractNumerous studies have documented the adverse effects of high-dose radiation on hearing in patients. On the other hand, radiographers are exposed to a low dose of ionizing radiation, and the effect of a low dose of radiation on hearing is quite abstruse. Therefore, the present systematic review aimed to elucidate the effect of low-dose ionizing radiation on hearing. Two authors independently carried out a comprehensive data search in three electronic databases, including PUBMED/MEDLINE, CINAHL, and SCOPUS. Eligible articles were independently assessed for quality by two authors. Cochrane Risk of Bias tool was used assess quality of the included studies. Two articles met the low-dose radiation exposure criteria given by Atomic Energy Regulatory Board (AERB) and National Council on Radiation Protection (NCRP) guidelines. Both studies observed the behavioral symptoms, pure-tone hearing sensitivity at the standard, extended high frequencies, and the middle ear functioning in low-dose radiation-exposed individuals and compared with age and gender-matched controls. One study assessed the cochlear function using transient-evoked otoacoustic emissions (TEOAE). Both studies reported that behavioral symptoms of auditory dysfunction and hearing thresholds at extended high frequencies were higher in radiation-exposed individuals than in the controls. The current systematic review concludes that the low-dose ionizing radiation may affect the hearing adversely. Nevertheless, further studies with robust research design are required to explicate the cause and effect relationship between the occupational low-dose ionizing radiation exposure and hearing.

scholarly journals Effects of exposure to low-dose ionizing radiation on changing platelets: a prospective cohort study

2021 ◽  
Vol 26 (1) ◽  
Author(s):  
Ning Liu ◽  
Yang Peng ◽  
Xinguang Zhong ◽  
Zheng Ma ◽  
Suiping He ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Ionizing Radiation ◽  
Dose Response ◽  
Low Dose ◽  
Linear Trend ◽  
Hematological Parameters ◽  
Response Relationship ◽  
Dose Response Relationship ◽  
Spline Models ◽  
Cumulative Radiation Dose

Abstract Background Numerous studies have concentrated on high-dose radiation exposed accidentally or through therapy, and few involve low-dose occupational exposure, to investigate the correlation between low-dose ionizing radiation and changing hematological parameters among medical workers. Methods Using a prospective cohort study design, we collected health examination reports and personal dose monitoring data from medical workers and used Poisson regression and restricted cubic spline models to assess the correlation between changing hematological parameters and cumulative radiation dose and determine the dose-response relationship. Results We observed that changing platelet of 1265 medical workers followed up was statistically different among the cumulative dose groups (P = 0.010). Although the linear trend tested was not statistically significant (Ptrend = 0.258), the non-linear trend tested was statistically significant (Pnon-linear = 0.007). Overall, there was a correlation between changing platelets and cumulative radiation dose (a change of βa 0.008 × 109/L during biennially after adjusting for gender, age at baseline, service at baseline, occupation, medical level, and smoking habits; 95% confidence interval [CI] = 0.003,0.014 × 109/L). Moreover, we also found positive first and then negative dose-response relationships between cumulative radiation dose and changing platelets by restricted cubic spline models, while there were negative patterns of the baseline service not less than 10 years (− 0.015 × 109/L, 95% CI = − 0.024, − 0.007 × 109/L) and radiation nurses(− 0.033 × 109/L, 95% CI = − 0.049, − 0.016 × 109/L). Conclusion We concluded that although the exposure dose was below the limit, medical workers exposed to low-dose ionizing radiation for a short period of time might have increased first and then decreased platelets, and there was a dose-response relationship between the cumulative radiation dose and platelets changing.

Epidemiological studies of CT scans and cancer risk: the state of the science

2021 ◽  
Vol 94 (1126) ◽  
pp. 20210471 ◽  
Author(s):  
Amy Berrington de Gonzalez ◽  
Elisa Pasqual ◽  
Lene Veiga
Keyword(s):  
Brain Tumors ◽  
Effective Dose ◽  
Dose Response ◽  
Public Health Problem ◽  
Epidemiological Studies ◽  
Ct Scans ◽  
Medical Record Linkage ◽  
Cancer Risks ◽  
Organ Doses ◽  
Study Methodology

20 years ago, 3 manuscripts describing doses and potential cancer risks from CT scans in children raised awareness of a growing public health problem. We reviewed the epidemiological studies that were initiated in response to these concerns that assessed cancer risks from CT scans using medical record linkage. We evaluated the study methodology and findings and provide recommendations for optimal study design for new efforts. We identified 17 eligible studies; 13 with published risk estimates, and 4 in progress. There was wide variability in the study methodology, however, which made comparison of findings challenging. Key differences included whether the study focused on childhood or adulthood exposure, radiosensitive outcomes (e.g. leukemia, brain tumors) or all cancers, the exposure metrics (e.g. organ doses, effective dose or number of CTs) and control for biases (e.g. latency and exclusion periods and confounding by indication). We were able to compare results for the subset of studies that evaluated leukemia or brain tumors. There were eight studies of leukemia risk in relation to red bone marrow (RBM) dose, effective dose or number of CTs; seven reported a positive dose–response, which was statistically significant (p < 0.05) in four studies. Six of the seven studies of brain tumors also found a positive dose–response and in five, this was statistically significant. Mean RBM dose ranged from 6 to 12 mGy and mean brain dose from 18 to 43 mGy. In a meta-analysis of the studies of childhood exposure the summary ERR/100 mGy was 1.78 (95%CI: 0.01–3.53) for leukemia/myelodisplastic syndrome (n = 5 studies) and 0.80 (95%CI: 0.48–1.12) for brain tumors (n = 4 studies) (p-heterogeneity >0.4). Confounding by cancer pre-disposing conditions was unlikely in these five studies of leukemia. The summary risk estimate for brain tumors could be over estimated, however, due to reverse causation. In conclusion, there is growing evidence from epidemiological data that CT scans can cause cancer. The absolute risks to individual patients are, however, likely to be small. Ongoing large multicenter cohorts and future pooling efforts will provide more precise risk quantification.

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