1
|
Little MP, Bazyka D, de Gonzalez AB, Brenner AV, Chumak VV, Cullings HM, Daniels RD, French B, Grant E, Hamada N, Hauptmann M, Kendall GM, Laurier D, Lee C, Lee WJ, Linet MS, Mabuchi K, Morton LM, Muirhead CR, Preston DL, Rajaraman P, Richardson DB, Sakata R, Samet JM, Simon SL, Sugiyama H, Wakeford R, Zablotska LB. A Historical Survey of Key Epidemiological Studies of Ionizing Radiation Exposure. Radiat Res 2024; 202:432-487. [PMID: 39021204 PMCID: PMC11316622 DOI: 10.1667/rade-24-00021.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 04/23/2024] [Indexed: 07/20/2024]
Abstract
In this article we review the history of key epidemiological studies of populations exposed to ionizing radiation. We highlight historical and recent findings regarding radiation-associated risks for incidence and mortality of cancer and non-cancer outcomes with emphasis on study design and methods of exposure assessment and dose estimation along with brief consideration of sources of bias for a few of the more important studies. We examine the findings from the epidemiological studies of the Japanese atomic bomb survivors, persons exposed to radiation for diagnostic or therapeutic purposes, those exposed to environmental sources including Chornobyl and other reactor accidents, and occupationally exposed cohorts. We also summarize results of pooled studies. These summaries are necessarily brief, but we provide references to more detailed information. We discuss possible future directions of study, to include assessment of susceptible populations, and possible new populations, data sources, study designs and methods of analysis.
Collapse
Affiliation(s)
- Mark P. Little
- Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892-9778, USA
- Faculty of Health and Life Sciences, Oxford Brookes University, Headington Campus, Oxford, OX3 0BP, UK
| | - Dimitry Bazyka
- National Research Center for Radiation Medicine, Hematology and Oncology, 53 Melnikov Street, Kyiv 04050, Ukraine
| | | | - Alina V. Brenner
- Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan
| | - Vadim V. Chumak
- National Research Center for Radiation Medicine, Hematology and Oncology, 53 Melnikov Street, Kyiv 04050, Ukraine
| | - Harry M. Cullings
- Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan
| | - Robert D. Daniels
- National Institute for Occupational Safety and Health, Cincinnati, OH, USA
| | - Benjamin French
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Eric Grant
- Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan
| | - Nobuyuki Hamada
- Biology and Environmental Chemistry Division, Sustainable System Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan
| | - Michael Hauptmann
- Institute of Biostatistics and Registry Research, Brandenburg Medical School Theodor Fontane, 16816 Neuruppin, Germany
| | - Gerald M. Kendall
- Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Richard Doll Building, Old Road Campus, Headington, Oxford, OX3 7LF, UK
| | - Dominique Laurier
- Institute for Radiological Protection and Nuclear Safety, Fontenay aux Roses France
| | - Choonsik Lee
- Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892-9778, USA
| | - Won Jin Lee
- Department of Preventive Medicine, Korea University College of Medicine, Seoul, South Korea
| | - Martha S. Linet
- Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892-9778, USA
| | - Kiyohiko Mabuchi
- Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892-9778, USA
| | - Lindsay M. Morton
- Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892-9778, USA
| | | | | | - Preetha Rajaraman
- Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan
| | - David B. Richardson
- Environmental and Occupational Health, 653 East Peltason, University California, Irvine, Irvine, CA 92697-3957 USA
| | - Ritsu Sakata
- Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan
| | - Jonathan M. Samet
- Department of Epidemiology, Colorado School of Public Health, Aurora, Colorado, USA
| | - Steven L. Simon
- Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892-9778, USA
| | - Hiromi Sugiyama
- Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan
| | - Richard Wakeford
- Centre for Occupational and Environmental Health, The University of Manchester, Ellen Wilkinson Building, Oxford Road, Manchester, M13 9PL, UK
| | - Lydia B. Zablotska
- Department of Epidemiology and Biostatistics, School of Medicine, University of California, San Francisco, 550 16 Street, 2 floor, San Francisco, CA 94143, USA
| |
Collapse
|
2
|
Hamada N. Noncancer Effects of Ionizing Radiation Exposure on the Eye, the Circulatory System and beyond: Developments made since the 2011 ICRP Statement on Tissue Reactions. Radiat Res 2023; 200:188-216. [PMID: 37410098 DOI: 10.1667/rade-23-00030.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 06/13/2023] [Indexed: 07/07/2023]
Abstract
For radiation protection purposes, noncancer effects with a threshold-type dose-response relationship have been classified as tissue reactions (formerly called nonstochastic or deterministic effects), and equivalent dose limits aim to prevent occurrence of such tissue reactions. Accumulating evidence demonstrates increased risks for several late occurring noncancer effects at doses and dose rates much lower than previously considered. In 2011, the International Commission on Radiological Protection (ICRP) issued a statement on tissue reactions to recommend a threshold of 0.5 Gy to the lens of the eye for cataracts and to the heart and brain for diseases of the circulatory system (DCS), independent of dose rate. Literature published thereafter continues to provide updated knowledge. Increased risks for cataracts below 0.5 Gy have been reported in several cohorts (e.g., including in those receiving protracted or chronic exposures). A dose threshold for cataracts is less evident with longer follow-up, with limited evidence available for risk of cataract removal surgery. There is emerging evidence for risk of normal-tension glaucoma and diabetic retinopathy, but the long-held tenet that the lens represents among the most radiosensitive tissues in the eye and in the body seems to remain unchanged. For DCS, increased risks have been reported in various cohorts, but the existence or otherwise of a dose threshold is unclear. The level of risk is less uncertain at lower dose and lower dose rate, with the possibility that risk per unit dose is greater at lower doses and dose rates. Target organs and tissues for DCS are also unknown, but may include heart, large blood vessels and kidneys. Identification of potential factors (e.g., sex, age, lifestyle factors, coexposures, comorbidities, genetics and epigenetics) that may modify radiation risk of cataracts and DCS would be important. Other noncancer effects on the radar include neurological effects (e.g., Parkinson's disease, Alzheimer's disease and dementia) of which elevated risk has increasingly been reported. These late occurring noncancer effects tend to deviate from the definition of tissue reactions, necessitating more scientific developments to reconsider the radiation effect classification system and risk management. This paper gives an overview of historical developments made in ICRP prior to the 2011 statement and an update on relevant developments made since the 2011 ICRP statement.
Collapse
Affiliation(s)
- Nobuyuki Hamada
- Biology and Environmental Chemistry Division, Sustainable System Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), Chiba, Japan
| |
Collapse
|
3
|
Rajaraman P, Doody MM, Yu CL, Preston DL, Miller JS, Sigurdson AJ, Freedman DM, Alexander BH, Little MP, Miller DL, Linet MS. Cancer Risks in U.S. Radiologic Technologists Working With Fluoroscopically Guided Interventional Procedures, 1994-2008. AJR Am J Roentgenol 2016; 206:1101-8; quiz 1109. [PMID: 26998721 PMCID: PMC10986158 DOI: 10.2214/ajr.15.15265] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
OBJECTIVE The purpose of this study was to examine risks of cancer incidence and mortality among U.S. radiation technologists performing or assisting with fluoroscopically guided interventional procedures. SUBJECTS AND METHODS A nationwide prospective cohort of 90,957 radiologic technologists, who responded to a 1994-1998 survey that collected information on whether they had ever worked with fluoroscopically guided interventional procedures, was followed through completion of a subsequent cohort survey during 2003-2005 (for cancer incidence) or December 31, 2008 (for cancer mortality). Sex-adjusted hazard ratios (HRs) and 95% CIs were calculated by use of Cox proportional hazards models for incidence and mortality from all cancers other than nonmelanoma skin cancer and for specific cancer outcomes in participants who reported ever performing fluoroscopically guided interventional procedures compared with technologists who never performed these procedures. RESULTS The analysis showed an approximately twofold increased risk of brain cancer mortality (HR, 2.55; 95% CI, 1.48-4.40) and modest elevations in incidence of melanoma (HR, 1.30; 95% CI, 1.05-1.61) and in breast cancer incidence (HR, 1.16; 95% CI, 1.02-1.32) but not mortality (HR, 1.07; 95% CI, 0.69-1.66) among technologists who performed fluoroscopically guided interventional procedures compared with those who never performed these procedures. Although there was a small suggestive increase in incidence of all cancers combined, excluding nonmelanoma skin cancers (HR, 1.08; 95% CI, 1.00-1.17), mortality from all cancers combined, excluding nonmelanoma skin cancers, was not elevated (HR, 1.00; 95% CI, 0.88-1.14). We similarly observed no elevated risk of cancers of the thyroid, skin other than melanoma, prostate, lung, or colon and rectum or of leukemia that was not chronic lymphocytic leukemia among workers who performed fluoroscopically guided interventional procedures. CONCLUSION We observed elevated risks of brain cancer, breast cancer, and melanoma among technologists who performed fluoroscopically guided interventional procedures. Although exposure to low-dose radiation is one possible explanation for these increased risks, these results may also be due to chance or unmeasured confounding by nonradiation risk factors. Our results must be confirmed in other studies, preferably with individual radiation dose data.
Collapse
Affiliation(s)
- Preetha Rajaraman
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Rockville, MD 20892-9778, MD, USA
- Center for Global Health, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Rockville, MD 20892-9778, MD, USA
| | - Michele M. Doody
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Rockville, MD 20892-9778, MD, USA
| | - Chu Ling Yu
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Rockville, MD 20892-9778, MD, USA
| | | | | | - Alice J. Sigurdson
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Rockville, MD 20892-9778, MD, USA
| | - D. Michal Freedman
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Rockville, MD 20892-9778, MD, USA
| | - Bruce H. Alexander
- Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, MN, USA
| | - Mark P. Little
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Rockville, MD 20892-9778, MD, USA
| | - Donald L. Miller
- Office of In Vitro Diagnostics and Radiological Health, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, USA
| | - Martha S. Linet
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Rockville, MD 20892-9778, MD, USA
| |
Collapse
|
4
|
Rühm W, Azizova TV, Bouffler SD, Little MP, Shore RE, Walsh L, Woloschak GE. Dose-rate effects in radiation biology and radiation protection. Ann ICRP 2016; 45:262-279. [PMID: 26960819 DOI: 10.1177/0146645316629336] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Quantification of biological effects (cancer, other diseases, and cell damage) associated with exposure to ionising radiation has been a major issue for the International Commission on Radiological Protection (ICRP) since its foundation in 1928. While there is a wealth of information on the effects on human health for whole-body doses above approximately 100 mGy, the effects associated with doses below 100 mGy are still being investigated and debated intensively. The current radiological protection approach, proposed by ICRP for workers and the public, is largely based on risks obtained from high-dose and high-dose-rate studies, such as the Japanese Life Span Study on atomic bomb survivors. The risk coefficients obtained from these studies can be reduced by the dose and dose-rate effectiveness factor (DDREF) to account for the assumed lower effectiveness of low-dose and low-dose-rate exposures. The 2007 ICRP Recommendations continue to propose a value of 2 for DDREF, while other international organisations suggest either application of different values or abandonment of the factor. This paper summarises the current status of discussions, and highlights issues that are relevant to reassessing the magnitude and application of DDREF.
Collapse
Affiliation(s)
- W Rühm
- a Helmholtz Centre Munich, German Research Centre for Environmental Health, Department for Radiation Sciences, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - T V Azizova
- b Southern Urals Biophysics Institute, Russian Federation
| | - S D Bouffler
- c Centre for Radiation, Chemical and Environmental Hazards, Public Health England, UK
| | - M P Little
- d Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, USA
| | - R E Shore
- e New York University School of Medicine, USA
| | - L Walsh
- f Federal Office for Radiation Protection, Germany
| | - G E Woloschak
- g Department of Radiation Oncology, Northwestern University, Feinberg School of Medicine, USA
| |
Collapse
|
5
|
Barrett HH, Myers KJ, Hoeschen C, Kupinski MA, Little MP. Task-based measures of image quality and their relation to radiation dose and patient risk. Phys Med Biol 2015; 60:R1-75. [PMID: 25564960 PMCID: PMC4318357 DOI: 10.1088/0031-9155/60/2/r1] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The theory of task-based assessment of image quality is reviewed in the context of imaging with ionizing radiation, and objective figures of merit (FOMs) for image quality are summarized. The variation of the FOMs with the task, the observer and especially with the mean number of photons recorded in the image is discussed. Then various standard methods for specifying radiation dose are reviewed and related to the mean number of photons in the image and hence to image quality. Current knowledge of the relation between local radiation dose and the risk of various adverse effects is summarized, and some graphical depictions of the tradeoffs between image quality and risk are introduced. Then various dose-reduction strategies are discussed in terms of their effect on task-based measures of image quality.
Collapse
Affiliation(s)
- Harrison H. Barrett
- College of Optical Sciences, University of Arizona, Tucson, AZ
- Center for Gamma-Ray Imaging, Department of Medical Imaging, University of Arizona, Tucson, AZ
| | - Kyle J. Myers
- Division of Imaging and Applied Mathematics, Office of Scientific and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD
| | - Christoph Hoeschen
- Department of Electrical Engineering and Information Technology, Otto-von-Guericke University, Magdeburg, Germany
- Research unit Medical Radiation Physics and Diagnostics, Helmholtz Zentrum München, Oberschleissheim, Germany
| | - Matthew A. Kupinski
- College of Optical Sciences, University of Arizona, Tucson, AZ
- Center for Gamma-Ray Imaging, Department of Medical Imaging, University of Arizona, Tucson, AZ
| | - Mark P. Little
- Division of Cancer Epidemiology and Genetics, Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD
| |
Collapse
|
6
|
Little MP, Kukush AG, Masiuk SV, Shklyar S, Carroll RJ, Lubin JH, Kwon D, Brenner AV, Tronko MD, Mabuchi K, Bogdanova TI, Hatch M, Zablotska LB, Tereshchenko VP, Ostroumova E, Bouville AC, Drozdovitch V, Chepurny MI, Kovgan LN, Simon SL, Shpak VM, Likhtarev IA. Impact of uncertainties in exposure assessment on estimates of thyroid cancer risk among Ukrainian children and adolescents exposed from the Chernobyl accident. PLoS One 2014; 9:e85723. [PMID: 24489667 PMCID: PMC3906013 DOI: 10.1371/journal.pone.0085723] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 12/01/2013] [Indexed: 11/17/2022] Open
Abstract
The 1986 accident at the Chernobyl nuclear power plant remains the most serious nuclear accident in history, and excess thyroid cancers, particularly among those exposed to releases of iodine-131 remain the best-documented sequelae. Failure to take dose-measurement error into account can lead to bias in assessments of dose-response slope. Although risks in the Ukrainian-US thyroid screening study have been previously evaluated, errors in dose assessments have not been addressed hitherto. Dose-response patterns were examined in a thyroid screening prevalence cohort of 13,127 persons aged <18 at the time of the accident who were resident in the most radioactively contaminated regions of Ukraine. We extended earlier analyses in this cohort by adjusting for dose error in the recently developed TD-10 dosimetry. Three methods of statistical correction, via two types of regression calibration, and Monte Carlo maximum-likelihood, were applied to the doses that can be derived from the ratio of thyroid activity to thyroid mass. The two components that make up this ratio have different types of error, Berkson error for thyroid mass and classical error for thyroid activity. The first regression-calibration method yielded estimates of excess odds ratio of 5.78 Gy−1 (95% CI 1.92, 27.04), about 7% higher than estimates unadjusted for dose error. The second regression-calibration method gave an excess odds ratio of 4.78 Gy−1 (95% CI 1.64, 19.69), about 11% lower than unadjusted analysis. The Monte Carlo maximum-likelihood method produced an excess odds ratio of 4.93 Gy−1 (95% CI 1.67, 19.90), about 8% lower than unadjusted analysis. There are borderline-significant (p = 0.101–0.112) indications of downward curvature in the dose response, allowing for which nearly doubled the low-dose linear coefficient. In conclusion, dose-error adjustment has comparatively modest effects on regression parameters, a consequence of the relatively small errors, of a mixture of Berkson and classical form, associated with thyroid dose assessment.
Collapse
Affiliation(s)
- Mark P Little
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America
| | - Alexander G Kukush
- Ukrainian Radiation Protection Institute, Kyiv, Ukraine ; Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
| | | | - Sergiy Shklyar
- Ukrainian Radiation Protection Institute, Kyiv, Ukraine ; Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
| | - Raymond J Carroll
- Department of Statistics, Blocker Building, Texas A&M University, College Station, Texas, United States of America
| | - Jay H Lubin
- Biostatistics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America
| | - Deukwoo Kwon
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America ; Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida, United States of America
| | - Alina V Brenner
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America
| | - Mykola D Tronko
- State Institution "Institute of Endocrinology and Metabolism of Academy of Medical Sciences of Ukraine", Kyiv, Ukraine
| | - Kiyohiko Mabuchi
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America
| | - Tetiana I Bogdanova
- State Institution "Institute of Endocrinology and Metabolism of Academy of Medical Sciences of Ukraine", Kyiv, Ukraine
| | - Maureen Hatch
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America
| | - Lydia B Zablotska
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, United States of America
| | - Valeriy P Tereshchenko
- State Institution "Institute of Endocrinology and Metabolism of Academy of Medical Sciences of Ukraine", Kyiv, Ukraine
| | - Evgenia Ostroumova
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America
| | - André C Bouville
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America
| | - Vladimir Drozdovitch
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America
| | | | - Lina N Kovgan
- Ukrainian Radiation Protection Institute, Kyiv, Ukraine
| | - Steven L Simon
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, United States of America
| | - Victor M Shpak
- State Institution "Institute of Endocrinology and Metabolism of Academy of Medical Sciences of Ukraine", Kyiv, Ukraine
| | | |
Collapse
|
7
|
Little MP. Do non-targeted effects increase or decrease low dose risk in relation to the linear-non-threshold (LNT) model? Mutat Res 2010; 687:17-27. [PMID: 20105434 PMCID: PMC3076714 DOI: 10.1016/j.mrfmmm.2010.01.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
In this paper we review the evidence for departure from linearity for malignant and non-malignant disease and in the light of this assess likely mechanisms, and in particular the potential role for non-targeted effects. Excess cancer risks observed in the Japanese atomic bomb survivors and in many medically and occupationally exposed groups exposed at low or moderate doses are generally statistically compatible. For most cancer sites the dose-response in these groups is compatible with linearity over the range observed. The available data on biological mechanisms do not provide general support for the idea of a low dose threshold or hormesis. This large body of evidence does not suggest, indeed is not statistically compatible with, any very large threshold in dose for cancer, or with possible hormetic effects, and there is little evidence of the sorts of non-linearity in response implied by non-DNA-targeted effects. There are also excess risks of various types of non-malignant disease in the Japanese atomic bomb survivors and in other groups. In particular, elevated risks of cardiovascular disease, respiratory disease and digestive disease are observed in the A-bomb data. In contrast with cancer, there is much less consistency in the patterns of risk between the various exposed groups; for example, radiation-associated respiratory and digestive diseases have not been seen in these other (non-A-bomb) groups. Cardiovascular risks have been seen in many exposed populations, particularly in medically exposed groups, but in contrast with cancer there is much less consistency in risk between studies: risks per unit dose in epidemiological studies vary over at least two orders of magnitude, possibly a result of confounding and effect modification by well known (but unobserved) risk factors. In the absence of a convincing mechanistic explanation of epidemiological evidence that is, at present, less than persuasive, a cause-and-effect interpretation of the reported statistical associations for cardiovascular disease is unreliable but cannot be excluded. Inflammatory processes are the most likely mechanism by which radiation could modify the atherosclerotic disease process. If there is to be modification by low doses of ionizing radiation of cardiovascular disease through this mechanism, a role for non-DNA-targeted effects cannot be excluded.
Collapse
Affiliation(s)
- M P Little
- Department of Epidemiology and Biostatistics, Imperial College School of Public Health, Faculty of Medicine, St Mary's Campus, Norfolk Place, London W2 1PG, UK.
| |
Collapse
|
8
|
Little MP. Cancer and non-cancer effects in Japanese atomic bomb survivors. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2009; 29:A43-A59. [PMID: 19454804 DOI: 10.1088/0952-4746/29/2a/s04] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The survivors of the atomic bombings in Hiroshima and Nagasaki are a general population of all ages and sexes and, because of the wide and well characterised range of doses received, have been used by many scientific committees (International Commission on Radiological Protection (ICRP), United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), Biological Effects of Ionizing Radiations (BEIR)) as the basis of population cancer risk estimates following radiation exposure. Leukaemia was the first cancer to be associated with atomic bomb radiation exposure, with preliminary indications of an excess among the survivors within the first five years after the bombings. An excess of solid cancers became apparent approximately ten years after radiation exposure. With increasing follow-up, excess risks of most cancer types have been observed, the major exceptions being chronic lymphocytic leukaemia, and pancreatic, prostate and uterine cancer. For most solid cancer sites a linear dose response is observed, although in the latest follow-up of the mortality data there is evidence (p = 0.10) for an upward curvature in the dose response for all solid cancers. The only cancer sites which exhibit (upward) curvature in the dose response are leukaemia, and non-melanoma skin and bone cancer. For leukaemia the dose response is very markedly upward curving, indeed largely describable as a pure quadratic dose response, particularly in the low dose (0-2 Sv) range. Even 55 years after the bombings over 40% of the Life Span Study cohort remain alive, so continued follow-up of this group is vital for completing our understanding of long-term radiation effects in people. In general, the relative risks per unit dose among the Japanese atomic bomb survivors are greater than those among comparable subsets in studies of medically exposed individuals. Cell sterilisation largely accounts for the discrepancy in relative risks between these two populations, although other factors may contribute, such as the generally higher underlying cancer risks in the medical series than in the Japanese atomic bomb survivors. Risks among occupationally exposed groups such as nuclear workforces and underground miners are generally consistent with those observed in the Japanese atomic bomb survivors. In general, consistent patterns of variation of risk with age at exposure are also seen in all studies-risks for all cancer types diminish with increasing age at exposure. There are also excess risks of various types of non-malignant disease in the Japanese atomic bomb survivors, in particular cardiovascular, respiratory and digestive diseases. Indeed, risks are elevated to much the same degree for a number of non-malignant disease endpoints, suggestive of bias. However, in contrast with the cancer data, there is much less consistency in the pattern of risk between the atomic bomb survivors and other exposed groups; for example, radiation-associated respiratory and digestive diseases have not been seen in these other groups. Although cardiovascular risks have been seen elsewhere, particularly in medically exposed groups, in contrast with the cancer data there is much less consistency in risk between studies: risks per unit dose in epidemiological studies vary over at least two orders of magnitude, possibly as a result of confounding factors. In the absence of a convincing mechanistic explanation of epidemiological evidence, at present a cause-and-effect interpretation of the reported statistical associations for cardiovascular disease is unreliable but cannot be excluded. Further epidemiological and biological evidence will allow a firmer conclusion to be drawn.
Collapse
Affiliation(s)
- M P Little
- Department of Epidemiology and Public Health, Imperial College, London W2 1PG, UK.
| |
Collapse
|
9
|
Little MP, Wakeford R, Tawn EJ, Bouffler SD, Berrington de Gonzalez A. Risks associated with low doses and low dose rates of ionizing radiation: why linearity may be (almost) the best we can do. Radiology 2009; 251:6-12. [PMID: 19332841 DOI: 10.1148/radiol.2511081686] [Citation(s) in RCA: 240] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Mark P Little
- Department of Epidemiology and Public Health, Imperial College Faculty of Medicine, St Mary's Campus, Norfolk Place, London W2 1PG, England.
| | | | | | | | | |
Collapse
|
10
|
Smyth MD, Narayan P, Tubbs RS, Leonard JR, Park TS, Loukas M, Grabb PA. Cumulative diagnostic radiation exposure in children with ventriculoperitoneal shunts: a review. Childs Nerv Syst 2008; 24:493-7. [PMID: 18180935 DOI: 10.1007/s00381-007-0560-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Children may be more vulnerable to diagnostic radiation exposure because of the increased dose-volume ratio and the increased lifetime risk per unit dose of radiation from early exposure. Moreover, recent radiological literature suggests that exposure to ionizing radiation from imaging studies may play a role in the later development of malignancies. MATERIALS AND METHODS We review the literature and present two illustrative clinical examples of children (each child developed head and neck malignancies during their late teen years) with hydrocephalus requiring multiple cerebrospinal fluid (CSF) shunt revisions and diagnostic computerized tomography (CT) scans throughout their life. DISCUSSION The literature reviewed suggests that children are more prone to diagnostic radiation exposure. Although it is not possible to prove that the multiple diagnostic studies result in malignancies, our review of the literature and illustrative cases describing malignancy risk and radiation exposure should give clinicians pause when considering requesting multiple diagnostic CT studies in children during the evaluation of possible CSF shunt dysfunction. Alternative tests such as "shunt MRI" protocols should be considered for patients and used whenever possible to minimize exposure to ionizing radiation.
Collapse
Affiliation(s)
- Matthew D Smyth
- Pediatric Neurosurgery, St. Louis Children's Hospital, Washington University, St. Louis, MO, USA
| | | | | | | | | | | | | |
Collapse
|
11
|
Charles MW. Radon exposure of the skin: I. Biological effects. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2007; 27:231-52. [PMID: 17768326 DOI: 10.1088/0952-4746/27/3/r01] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Radon progeny can plate out on skin and give rise to exposure of the superficial epidermis from alpha emitters Po-218 (7.7 MeV, range approximately 66 microm) and Po-214 (6 MeV, range approximately 44 microm). Dose rates from beta/gamma emitters Pb-214 and Bi-214 are low and only predominate at depths in excess of the alpha range. This paper reviews the evidence for a causal link between exposure from radon and its progeny, and deterministic and stochastic biological effects in human skin. Radiation induced skin effects such as ulceration and dermal atrophy, which require irradiation of the dermis, are ruled out for alpha irradiation from radon progeny because the target cells are considerably deeper than the range of alpha particles. They have not been observed in man or animals. Effects such as erythema and acute epidermal necrosis have been observed in a few cases of very high dose alpha particle exposures in man and after acute high dose exposure in animals from low energy beta radiations with similar depth doses to radon progeny. The required skin surface absorbed doses are in excess of 100 Gy. Such effects would require extremely high levels of radon progeny. They would involve quite exceptional circumstances, way outside the normal range of radon exposures in man. There is no definitive identification of the target cells for skin cancer induction in animals or man. The stem cells in the basal layer which maintain the epidermis are the most plausible contenders for target cells. The majority of these cells are near the end of the range of radon progeny alpha particles, even on the thinnest body sites. The nominal depth of these cells, as recommended by the International Commission on Radiological Protection (ICRP), is 70 microm. There is evidence however that some irradiation of the hair follicles and/or the deeper dermis, as well as the inter-follicular epidermis, is also necessary for skin cancer induction. Alpha irradiation of rodent skin that is restricted to the epidermis does not produce skin cancer. Accelerator generated high energy helium and heavy ions can produce skin cancer in rodents at high doses, but only if they penetrate deep into the dermis. The risk figures for radiation induced skin cancer in man recommended by the ICRP in 1990 are based largely on x and beta irradiated cohorts, but few data exist below absorbed doses of about 1 Gy. The only plausible finding of alpha-radiation induced skin cancer in man is restricted to one study in Czech uranium miners. There is no evidence in other uranium miners and the Czech study has a number of shortcomings. This review concludes that the overall balance of evidence is against causality of radon progeny exposure and skin cancer induction. Of particular relevance is the finding in animal studies that radiation exposure of cells which are deeper than the inter-follicular epidermis is necessary to elicit skin cancer. In spite of this conclusion, a follow-on paper evaluates the attributable risk of radon to skin cancer in the UK on the basis that target cells for skin cancer induction are the cells in the basal layer of the inter-follicular epidermis-since this is the conservative assumption made by international bodies such as the International Commission on Radiological Protection (ICRP) for general radiological protection purposes.
Collapse
Affiliation(s)
- M W Charles
- School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| |
Collapse
|
12
|
Charles MW. Radon exposure of the skin: II. Estimation of the attributable risk for skin cancer incidence. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2007; 27:253-74. [PMID: 17768327 DOI: 10.1088/0952-4746/27/3/r02] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
A preceding companion paper has reviewed the various factors which form the chain of assumptions that are necessary to support a suggested link between radon exposure and skin cancer in man. Overall, the balance of evidence was considered to be against a causal link between radon exposure and skin cancer. One factor against causality is evidence, particularly from animal studies, that some exposure of the hair follicles and/or the deeper dermis, as well as the inter-follicular epidermis, is required-beyond the range of naturally occurring alpha particles. On this basis any skin cancer risk due to radon progeny would be due only to beta and gamma components of equivalent dose, which are 10-100 times less than the alpha equivalent dose to the basal layer. Notwithstanding this conclusion against causality, calculations have been carried out of attributable risk (ATR, the proportion of cases occurring in the total population which can be explained by radon exposure) on the conservative basis that the target cells are, as is often assumed, in the basal layer of the epidermis. An excess relative risk figure is used which is based on variance weighting of the data sources. This is 2.5 times lower than the value generally used. A latent period of 20 years and an RBE of 10 are considered more justifiable than the often used values of 10 years and 20 respectively. These assumptions lead to an ATR of approximately 0.7% (0.5-5%) at the nominal UK indoor radon level of 20 Bq m(-3). The range reflects uncertainties in plate-out. Previous higher estimates by various authors have made more pessimistic assumptions. There are some indications that radon progeny plate-out may be elevated out of doors, particularly due to rainfall. Although average UK outdoor radon levels ( approximately 4 Bq m(-3)) are much less than average indoor levels, and outdoor residence time is on average about 10%, this might have the effect of increasing the ATR several-fold. This needs considerable further study. Ecological epidemiology data for the South West of England provide no evidence for elevated skin cancer risks at radon levels <100 Bq m(-3). Case-control or cohort studies would be necessary to address the issue authoritatively.
Collapse
Affiliation(s)
- M W Charles
- School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| |
Collapse
|
13
|
Shimada Y, Nishimura M, Kakinuma S, Yamauchi K, Imaoka T, Amasaki Y, Shang Y, Kawaguchi I, Doi M. Combined Effect of Ionizing Radiation and Alkylating Agents on Cancer Induction. Genes Environ 2007. [DOI: 10.3123/jemsge.29.29] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|
14
|
Sasaki S, Fukuda N. Temporal variation of excess mortality rate from solid tumors in mice irradiated at various ages with gamma rays. JOURNAL OF RADIATION RESEARCH 2005; 46:1-19. [PMID: 15802854 DOI: 10.1269/jrr.46.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The influence of age at the time of irradiation on the lifetime risk for excess mortality from solid tumors, and on the temporal pattern of variation in the excess mortality rate, was analyzed using data obtained from a study of female B6C3F1 mice, which was conducted at the National Institute of Radiological Sciences, Chiba, Japan. Mice were irradiated with 1.9-Gy gamma rays at day 17 in intra-uterine age, or day 0, 7, 35, 105 or 365 in postnatal age. Control and irradiated mice were allowed to live out their entire life span under a specific pathogen-free condition. The primary cause of death for each mouse was determined by macroscopic and microscopic examination. The lifetime excess mortality from solid tumors was apparently higher in the mice irradiated during the neonatal to puberty period than in the mice irradiated during the intra-uterine or adult period. The median of time for manifestation of lifetime excess mortality since irradiation was shortest among mice exposed at 365 days of age and longest among mice exposed at 17 days of intra-uterine age. The excess mortality rate at any attained age was not independent of the age at irradiation. The excess mortality rate increased with increasing age, and the excess relative risk decreased with increasing age. The temporal variations of the excess mortality rate and background mortality rate were analyzed using the additive multi-stage model, which includes the assumptions that radiation-related carcinogenesis superimposes on background carcinogenesis, and that both radiation-related and background carcinogenesis involve multiple stages. The results of the analysis strongly suggested that the number of stages for manifestation of radiation-related carcinogenesis was less than that in background carcinogenesis for various types of solid tumors, and that the majority of stages were common in both radiation-related and background carcinogenesis. The additive multi-stage model well described the observed findings on the length of the latent period and temporal variations of the excess mortality rate and excess relative risk. It should be stressed that the magnitude of the lifetime risk was not only determined by a decrease in the number of hits for carcinogenesis but was also determined by another parameter which decides the initial value of excess mortality rate. Furthermore, we estimated the rate of decrease in the number of remaining hits for carcinogenesis, and it was found that the rate of decrease in the number of remaining hits was higher in several irradiated groups than that in the background carcinogenesis. However, radiation-induced genomic instability and/or delayed mutation may be of secondary importance when radiation was delivered promptly, because the present analysis revealed that the major action of radiation took place soon after irradiation, as one or more hits for transitions of stages for carcinogenesis.
Collapse
Affiliation(s)
- Shunsaku Sasaki
- National Institute of Radiological Sciences, Anagawa, Chiba, Japan.
| | | |
Collapse
|
15
|
Abstract
Ionizing radiation has been the subject of intense epidemiological investigation. Studies have demonstrated that exposure to moderate-to-high levels can cause most forms of cancer, leukaemia and cancers of the breast, lung and thyroid being particularly sensitive to induction by radiation, especially at young ages at exposure. Predominant among these studies is the Life Span Study of the cohort of survivors of the atomic bombings of Japan in 1945, but substantial evidence is derived from groups exposed for medical reasons, occupationally or environmentally. Notable among these other groups are underground hard rock miners who inhaled radioactive radon gas and its decay products, large numbers of patients irradiated therapeutically and workers who received high doses in the nuclear weapons programme of the former USSR. The degree of carcinogenic risk arising from low levels of exposure is more contentious, but the available evidence points to an increased risk that is approximately proportional to the dose received. Epidemiological investigations of nonionizing radiation have established ultraviolet radiation as a cause of skin cancer. However, the evidence for a carcinogenic effect of other forms of nonionizing radiation, such as those associated with mobile telephones or electricity transmission lines, is not convincing, although the possibility of a link between childhood leukaemia and extremely low-frequency electromagnetic fields cannot be dismissed entirely.
Collapse
|
16
|
Little MP. The bystander effect model of Brenner and Sachs fitted to lung cancer data in 11 cohorts of underground miners, and equivalence of fit of a linear relative risk model with adjustment for attained age and age at exposure. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2004; 24:243-255. [PMID: 15511016 DOI: 10.1088/0952-4746/24/3/003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Bystander effects following exposure to alpha-particles have been observed in many experimental systems, and imply that linearly extrapolating low dose risks from high dose data might materially underestimate risk. Brenner and Sachs (2002 Int. J. Radiat. Biol. 78 593-604; 2003 Health Phys. 85 103-8) have recently proposed a model of the bystander effect which they use to explain the inverse dose rate effect observed for lung cancer in underground miners exposed to radon daughters. In this paper we fit the model of the bystander effect proposed by Brenner and Sachs to 11 cohorts of underground miners, taking account of the covariance structure of the data and the period of latency between the development of the first pre-malignant cell and clinically overt cancer. We also fitted a simple linear relative risk model, with adjustment for age at exposure and attained age. The methods that we use for fitting both models are different from those used by Brenner and Sachs, in particular taking account of the covariance structure, which they did not, and omitting certain unjustifiable adjustments to the miner data. The fit of the original model of Brenner and Sachs (with 0 y period of latency) is generally poor, although it is much improved by assuming a 5 or 6 y period of latency from the first appearance of a pre-malignant cell to cancer. The fit of this latter model is equivalent to that of a linear relative risk model with adjustment for age at exposure and attained age. In particular, both models are capable of describing the observed inverse dose rate effect in this data set.
Collapse
Affiliation(s)
- M P Little
- Department of Epidemiology and Public Health, Imperial College Faculty of Medicine, St Mary's Campus, Norfolk Place, London W2 1PG, UK.
| |
Collapse
|
17
|
Abstract
This paper reviews current knowledge on the deterministic and stochastic risks (the latter including the risk of cancer and of hereditary disease) associated with exposure to ionizing radiation. Particular attention is paid to cancer risks following exposure to man-made low linear energy transfer radiation. Excess cancer risks have been observed in the Japanese atomic bomb survivors and in many medically and occupationally exposed groups. In general, the relative risks among Japanese survivors of atomic-bomb explosions are greater than those among comparable subsets in studies of medically exposed individuals. Cell sterilization largely accounts for the discrepancy in relative risks between these two populations, although other factors may contribute, such as the generally higher underlying cancer risks in the medical series than in the Japanese atomic bomb survivors. Risks among occupationally exposed groups such as nuclear workforces and underground miners are generally consistent with those observed in the Japanese atomic bomb survivors.
Collapse
Affiliation(s)
- M P Little
- Department of Epidemiology and Public Health, Imperial College Faculty of Medicine, St Mary's Campus, London, UK.
| |
Collapse
|
18
|
Hunter N, Charles MW. The impact of possible modifications to the DS86 dosimetry on neutron risk and relative biological effectiveness. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2002; 22:357-370. [PMID: 12546224 DOI: 10.1088/0952-4746/22/4/302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The current DS86 dosimetry system for the Japanese bomb survivors indicates that neutron doses were so low that they prevent the direct derivation of any useful estimates of neutron risk. However, the large body of thermal neutron activation measurements carried out over many years in Hiroshima and Nagasaki appear to indicate that current DS86 neutron doses may have been significantly underestimated in Hiroshima. An earlier companion paper has provided an update of neutron activation measurements. While a large body of data appears to support a significant increase, there is ongoing debate and review regarding its validity. However, as yet, there are no detailed, peer-reviewed, published refutations of the neutron activation data which appear to support an increase in neutron doses. In this paper, we consider the impact of possible future revisions in the DS86 dosimetry on radiation risk estimates. We consider the extreme range of possibilities from maintaining the existing DS86 values, to changes in neutron doses in accord with the majority of existing neutron activation data. We have used the latest cancer incidence data and cancer mortality data for the A-bomb survivors, and neutron doses have been modified using a neutron revision factor (NRF) in line with the latest thermal neutron activation measurements in Hiroshima. In contrast to previous analyses, a nonlinear relationship between log(NRF) and slant range has been used which better represents the data beyond slant ranges of approximately 1 km. The impact on the evaluation of neutron relative biological effectiveness (RBE) and gamma radiation risk estimates has been assessed. While DS86 neutron doses are too low to allow any useful direct evaluation of neutron risk or neutron RBE, it becomes possible to derive more meaningful values if neutron doses are increased in Hiroshima in line with the broad range of thermal neutron activation measurements. The uncertainties are smallest for the cancer incidence data. The best estimates of neutron RBE give upper 95% confidence limits of about 6 for all solid tumours for the incidence data and about 28 for the mortality data. The uncertainties in neutron RBE for leukaemia incidence are larger, and estimation at doses below about 0.1 Gy is not possible. There is no significant change in the excess relative risk for gamma radiation for all solid tumours taken together, compared with the current DS86 dosimetry. The results preclude neutron RBE values significantly greater than the current ICRP radiation weighting factors, which range between 5 and 20, depending on energy. Whether or not the Japanese bomb survivors can indeed form the basis for useful, directly determined neutron risks clearly depends on the veracity of existing neutron activation data. This is currently the subject of careful international scrutiny and the outcome is eagerly awaited.
Collapse
Affiliation(s)
- Nezahat Hunter
- National Radiological Protection Board, Chilton, Oxon OX11 0RQ, UK.
| | | |
Collapse
|
19
|
Hunter N, Charles MW. An update on the discrepancy between calculated and measured neutron-induced radioactivity levels in Hiroshima. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2002; 22:345-356. [PMID: 12546223 DOI: 10.1088/0952-4746/22/4/301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The thermal neutron activation measurements carried out over many years in Hiroshima and Nagasaki have been the subject of ongoing debate in recent years because they indicate that current DS86 neutron doses may have been significantly underestimated in Hiroshima. Long-lived neutron activation products, 60Co, 152Eu, 154Eu and 36Cl, which are still detectable today using modern analytical techniques, appear to indicate that DS86 calculated thermal neutron activation products decrease with distance more rapidly than the measured values. The latest thermal neutron activation measurements have been collated and a new relationship for the measured to calculated (M/C) ratio of induced activity has been derived as a function of slant range. This indicates a stronger dependence of M/C on slant range than previously derived by Straume et al (1992 Health Phys. 63 421-6) and emphasises even more the discrepancy between measured and calculated (DS86) neutron doses at distances beyond 1 km. While the main body of thermal neutron activation data appears to support a significant increase in the DS86 neutron dose component in Hiroshima, there are some thermal neutron activation measurements and some very recent fast neutron activation measurements which suggest that the discrepancy may not be so great. The extent of the required revision to the neutron component of the DS86 dosimetry remains the subject of ongoing new neutron activation measurements and re-analysis of existing published measurements. A companion paper considers the impact on radiation risk estimates of possible modifications to the DS86 dosimetry system on the basis of a broad range of interpretations of the neutron activation data.
Collapse
Affiliation(s)
- Nezahat Hunter
- National Radiological Protection Board, Chilton, Oxon OX11 0RQ, UK.
| | | |
Collapse
|
20
|
Miyazawa T, Sato H, Hatakeyama K, Kitagawa T, Kominami R. Allelic losses in mouse skin tumors induced by gamma-irradiation of p53 heterozygotes. Jpn J Cancer Res 2002; 93:994-9. [PMID: 12359052 PMCID: PMC5927138 DOI: 10.1111/j.1349-7006.2002.tb02475.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Skin tumors were induced by gamma-irradiation in F(1) mice between C3H/He or BALB/c and MSM carrying a p53-deficient allele. The incidence was 39.1% (34/87) in p53(KO/+) mice of the C3H/MSM genetic background and 14.3% (19/133) in those of the BALB/MSM background. Interestingly, most of the tumors (82%) lost the wild-type p53 allele and no skin tumor was found in p53(+ / +) F(1) mice. This suggests a requirement of p53 loss for the skin cancer development. Genome scan localized a chromosomal locus showing frequent allelic losses near D12Mit2, which may harbor a tumor suppressor gene. In addition, 23 loci distributed on 13 chromosomes exhibited allelic losses at frequencies of more than 20%. The genome-wide occurrence of allelic losses suggests that genomic instability of the skin tumors may be implicated in radiation-induced carcinogenesis. The present study is the first to report a mouse model system useful for the analysis of radiation induction of skin cancer in man.
Collapse
Affiliation(s)
- Tomonori Miyazawa
- Department of Gene Regulation, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | | | | | | | | |
Collapse
|
21
|
Little MP. Estimates of neutron relative biological effectiveness derived from the Japanese atomic bomb survivors. Int J Radiat Biol 1997; 72:715-26. [PMID: 9416794 DOI: 10.1080/095530097142870] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE To investigate neutron relative biological effectiveness. MATERIALS AND METHODS The latest Japanese atomic bomb survivor cancer incidence and mortality datasets with the current (DS86) dosimetry system are analysed using generalized relative risk models and generalized absolute risk models, both with and without recently indicated adjustments to the Hiroshima DS86 neutron dose estimates. RESULTS Without adjustments to the Hiroshima neutron doses, the best estimate of neutron relative biological effectiveness for all tumours in the incidence data is 63.3 (95% CI < 0-275.3) when a generalized relative risk model is used; when a generalized absolute risk model is used in the incidence data the best estimate is 53.5 (95% CI < 0-201.0); when a generalized relative risk model is used in the mortality data, the best estimate is 287.7 (95% CI 38.0- > 10[3]). When likely adjustments are made to the Hiroshima neutron doses the best estimate of neutron relative biological effectiveness in the incidence data using a generalized relative risk model is 15.1 (95% CI < 0-51.4); when a generalized absolute risk model is used in the incidence data the best estimate is 9.0 (95% CI < 0-32.9); when a generalized relative risk model is used in the mortality data the best estimate is 55.1 (95% CI 9.5-280.3). Although there are no significant differences between groupings of the solid tumour sites in their estimated neutron relative biological effectiveness, there are indications that the neutron relative biological effectiveness of solid tumours is lower than that of leukaemia, whether or not adjustments are made to the Hiroshima neutron dose estimates. Uncertainties in the likely adjustments to the DS86 Hiroshima neutron and gamma dose estimates as well as uncertainties in the modelling of excess risk in the two cities (Hiroshima and Nagasaki) imply that these findings should be treated with caution. CONCLUSIONS Likely adjustments to the Hiroshima neutron dose estimates imply a substantial increase in information on neutron relative biological effectiveness. Whether or not adjustments are made to the Hiroshima neutron doses, there are indications of inconsistency between the estimates of neutron relative biological effectiveness for solid tumours and leukaemia. Dosimetric and modelling uncertainties mean that these findings should be treated with caution.
Collapse
Affiliation(s)
- M P Little
- National Radiological Protection Board, Chilton, Didcot, Oxon, UK
| |
Collapse
|