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Amrenova A, Ainsbury E, Baudin C, Giussani A, Lochard J, Rühm W, Scholz-Kreisel P, Trott K, Vaillant L, Wakeford R, Zölzer F, Laurier D. Consideration of hereditary effects in the radiological protection system: evolution and current status. Int J Radiat Biol 2024:1-13. [PMID: 38190433 DOI: 10.1080/09553002.2023.2295289] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 11/21/2023] [Indexed: 01/10/2024]
Abstract
PURPOSE The purpose of this paper is to provide an overview of the methodology used to estimate radiation genetic risks and quantify the risk of hereditary effects as outlined in the ICRP Publication 103. It aims to highlight the historical background and development of the doubling dose method for estimating radiation-related genetic risks and its continued use in radiological protection frameworks. RESULTS This article emphasizes the complexity associated with quantifying the risk of hereditary effects caused by radiation exposure and highlights the need for further clarification and explanation of the calculation method. As scientific knowledge in radiation sciences and human genetics continues to advance in relation to a number of factors including stability of disease frequency, selection pressures, and epigenetic changes, the characterization and quantification of genetic effects still remains a major issue for the radiological protection system of the International Commission on Radiological Protection. CONCLUSION Further research and advancements in this field are crucial for enhancing our understanding and addressing the complexities involved in assessing and managing the risks associated with hereditary effects of radiation.
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Affiliation(s)
- A Amrenova
- Institute for Radiological Protection and Nuclear Safety, Fontenay-aux-Roses, France
| | | | - C Baudin
- Institute for Radiological Protection and Nuclear Safety, Fontenay-aux-Roses, France
| | - A Giussani
- BfS - Federal Office for Radiation Protection, Oberschleißheim, Germany
| | - J Lochard
- Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
| | - W Rühm
- BfS - Federal Office for Radiation Protection, Oberschleißheim, Germany
| | - P Scholz-Kreisel
- BfS - Federal Office for Radiation Protection, Oberschleißheim, Germany
| | - K Trott
- Deptartment Radiation Oncology, Technical University München, Fontenay-aux-Roses, France
| | | | - R Wakeford
- Centre for Occupational and Environmental Health, The University of Manchester, Manchester, UK
| | - F Zölzer
- Department of Health and Social Sciences, University of South Bohemia in České Budějovice, České Budějovice, Czech Republic
| | - D Laurier
- Institute for Radiological Protection and Nuclear Safety, Fontenay-aux-Roses, France
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Calabrese EJ, Selby PB. Background radiation and cancer risks: A major intellectual confrontation within the domain of radiation genetics with multiple converging biological disciplines. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2023; 20:621-632. [PMID: 37642576 DOI: 10.1080/15459624.2023.2252032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
This paper assesses the judgments of leading radiation geneticists and cancer risk assessment scientists from the mid-1950s to mid-1970s that background radiation has a significant effect on human genetic disease and cancer incidence. This assumption was adopted by the National Academy of Sciences (NAS) Biological Effects of Atomic Radiation (BEAR) I Genetics Panel for genetic diseases and subsequently applied to cancer risk assessment by other leading individuals/advisory groups (e.g., International Commission on Radiation Protection-ICRP). These recommendations assumed that a sizeable proportion of human mutations originated from background radiation due to cumulative exposure over prolonged reproductive periods and the linear nature of the dose-response. This paper shows that the assumption that background radiation is a significant cause of spontaneous mutation, genetic diseases, and cancer incidence is not supported by experimental and epidemiological findings, and discredits erroneous risk assessments that improperly influenced the recommendations of national and international advisory committees, risk assessment policies, and beliefs worldwide.
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Affiliation(s)
- Edward J Calabrese
- Department of Environmental Health Sciences, Morrill I, N344, University of Massachusetts, Amherst, MA, USA
| | - Paul B Selby
- Retired from Oak Ridge National Laboratory, Oak Ridge, TN, USA
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Nikjoo H, Hoffmann G, Baverstock K. In Memoriam - Krishnaswami Sankaranarayanan (1933-2022). Mutat Res 2022; 825:111789. [PMID: 35763981 DOI: 10.1016/j.mrfmmm.2022.111789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 06/16/2022] [Indexed: 06/15/2023]
Affiliation(s)
- Hooshang Nikjoo
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford OX1 3PT, UK.
| | - George Hoffmann
- Department of Biology, College of the Holy Cross, Worcester, MA 01610, USA
| | - Keith Baverstock
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio Campus, Kuopio, Finland
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Ling Y, Wang G, Chen T, Fei X, Hu S, Shan Q, Hei D, Feng H, Jia W. Irradiation-catalysed degradation of methyl orange using BaF 2-TiO 2 nanocomposite catalysts prepared by a sol-gel method. ROYAL SOCIETY OPEN SCIENCE 2019; 6:191156. [PMID: 31824723 PMCID: PMC6837232 DOI: 10.1098/rsos.191156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 09/02/2019] [Indexed: 05/07/2023]
Abstract
BaF2-TiO2 nanocomposite material (hereinafter called the composite) was prepared by a sol-gel method. The composite surface area, morphology and structure were characterized by Brunauer-Emmett-Teller method, X-ray diffraction analysis and a scanning electron microscopy. The results showed that BaF2 and TiO2 form a PN-like structure on the surface of the composite. Composites were used to catalyse the degradation of methyl orange by irradiation with ultraviolet light, γ-rays and an electron beam (EB). It was demonstrated that the composite is found to be more efficient than the prepared TiO2 and commercial P25 in the degradation of methyl orange under γ-irradiation. Increasing the composite catalyst concentration within a certain range can effectively improve the decolorization rate of the methyl orange solution. However, when the composite material is used to catalyse the degradation of organic matter in the presence of ultraviolet light or 10 MeV EB irradiation, the catalytic effect is poor or substantially ineffective. In addition, a hybrid mechanism is proposed; BaF2 absorbs γ-rays to generate radioluminescence and further excites TiO2 to generate photo-charges. Due to the heterojunction effect, the resulting photo-charge will produce more active particles. This seems to be a possible mechanism to explain γ-irradiation's catalytic behaviour.
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Affiliation(s)
- Yongsheng Ling
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 211106 Nanjing, People's Republic of China
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, 215021 Suzhou, People's Republic of China
| | - Guang Wang
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 211106 Nanjing, People's Republic of China
| | - Ting Chen
- School of Environment Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, People's Republic of China
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, People's Republic of China
| | - Xionghui Fei
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 211106 Nanjing, People's Republic of China
| | - Song Hu
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 211106 Nanjing, People's Republic of China
| | - Qing Shan
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 211106 Nanjing, People's Republic of China
| | - Daqian Hei
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 211106 Nanjing, People's Republic of China
| | - Huajun Feng
- School of Environment Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, People's Republic of China
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, People's Republic of China
| | - Wenbao Jia
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, 211106 Nanjing, People's Republic of China
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, 215021 Suzhou, People's Republic of China
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Hoffmann GR. Twenty Years of Reflections in Mutation Research. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2019; 780:106-120. [PMID: 31395355 DOI: 10.1016/j.mrrev.2019.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/25/2019] [Indexed: 11/18/2022]
Abstract
Reflections is a component of Mutation Research Reviews devoted to historical and philosophical themes pertaining to the subject of mutation. Reflections was initiated in 1999 and has included a broad array of topics centered on mutation research, but overlapping other scientific fields and touching upon history, sociology, politics, philosophy and ethics. This commentary offers an editor's reflections on the 44 papers in the Reflections series, including the people who contributed to the series and the topics that they discussed.
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Affiliation(s)
- George R Hoffmann
- Department of Biology, College of the Holy Cross, One College Street, Worcester, MA 01610, USA.
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Sankaranarayanan K, Nikjoo H. Genome-based, mechanism-driven computational modeling of risks of ionizing radiation: The next frontier in genetic risk estimation? MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 764:1-15. [PMID: 26041262 DOI: 10.1016/j.mrrev.2014.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/18/2014] [Indexed: 10/24/2022]
Abstract
Research activity in the field of estimation of genetic risks of ionizing radiation to human populations started in the late 1940s and now appears to be passing through a plateau phase. This paper provides a background to the concepts, findings and methods of risk estimation that guided the field through the period of its growth to the beginning of the 21st century. It draws attention to several key facts: (a) thus far, genetic risk estimates have been made indirectly using mutation data collected in mouse radiation studies; (b) important uncertainties and unsolved problems remain, one notable example being that we still do not know the sensitivity of human female germ cells to radiation-induced mutations; and (c) the concept that dominated the field thus far, namely, that radiation exposures to germ cells can result in single gene diseases in the descendants of those exposed has been replaced by the concept that radiation exposure can cause DNA deletions, often involving more than one gene. Genetic risk estimation now encompasses work devoted to studies on DNA deletions induced in human germ cells, their expected frequencies, and phenotypes and associated clinical consequences in the progeny. We argue that the time is ripe to embark on a human genome-based, mechanism-driven, computational modeling of genetic risks of ionizing radiation, and we present a provisional framework for catalyzing research in the field in the 21st century.
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Affiliation(s)
- K Sankaranarayanan
- Radiation Biophysics Group, Department of Oncology-Pathology, Karolinska Institutet, Box 260, P9-02, Stockholm SE 17176, Sweden
| | - H Nikjoo
- Radiation Biophysics Group, Department of Oncology-Pathology, Karolinska Institutet, Box 260, P9-02, Stockholm SE 17176, Sweden.
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Calabrese EJ. How the US National Academy of Sciences misled the world community on cancer risk assessment: new findings challenge historical foundations of the linear dose response. Arch Toxicol 2013; 87:2063-81. [PMID: 23912675 DOI: 10.1007/s00204-013-1105-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 07/11/2013] [Indexed: 12/17/2022]
Abstract
This paper extends several recent publications indicating that Hermann J. Muller: (1) Made deceptive statements during his Noble Prize Lecture on December 12, 1946, that were intended to promote the acceptance of the linear dose-response model for risk assessment for ionizing radiation and (2) that such actions of Muller were masked by a series of decisions by Muller's long-time colleague and esteemed radiation geneticist Curt Stern, affecting key publications in the mutation literature. Such actions further enhanced acceptance of the linearity dose-response model while preventing Muller's deceptions from being discovered. This paper provides documentation that Muller reinforced such practices within the scientific literature in the early 1950s, by supporting scientifically questionable actions of Stern. Detailed documentation is provided that demonstrates how these actions affected national and international risk assessment policy for ionizing radiation and chemical carcinogens via the recommendations of the National Academy of Sciences Biological Effects of Atomic Radiation committee in 1956, to adopt the linear dose-response model.
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Affiliation(s)
- Edward J Calabrese
- Department of Public Health, Environmental Health Sciences, University of Massachusetts, Morrill I, N344, Amherst, MA, 01003, USA,
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Origin of the linearity no threshold (LNT) dose-response concept. Arch Toxicol 2013; 87:1621-33. [PMID: 23887208 DOI: 10.1007/s00204-013-1104-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 07/11/2013] [Indexed: 12/16/2022]
Abstract
This paper identifies the origin of the linearity at low-dose concept [i.e., linear no threshold (LNT)] for ionizing radiation-induced mutation. After the discovery of X-ray-induced mutations, Olson and Lewis (Nature 121(3052):673-674, 1928) proposed that cosmic/terrestrial radiation-induced mutations provide the principal mechanism for the induction of heritable traits, providing the driving force for evolution. For this concept to be general, a LNT dose relationship was assumed, with genetic damage proportional to the energy absorbed. Subsequent studies suggested a linear dose response for ionizing radiation-induced mutations (Hanson and Heys in Am Nat 63(686):201-213, 1929; Oliver in Science 71:44-46, 1930), supporting the evolutionary hypothesis. Based on an evaluation of spontaneous and ionizing radiation-induced mutation with Drosophila, Muller argued that background radiation had a negligible impact on spontaneous mutation, discrediting the ionizing radiation-based evolutionary hypothesis. Nonetheless, an expanded set of mutation dose-response observations provided a basis for collaboration between theoretical physicists (Max Delbruck and Gunter Zimmer) and the radiation geneticist Nicolai Timoféeff-Ressovsky. They developed interrelated physical science-based genetics perspectives including a biophysical model of the gene, a radiation-induced gene mutation target theory and the single-hit hypothesis of radiation-induced mutation, which, when integrated, provided the theoretical mechanism and mathematical basis for the LNT model. The LNT concept became accepted by radiation geneticists and recommended by national/international advisory committees for risk assessment of ionizing radiation-induced mutational damage/cancer from the mid-1950s to the present. The LNT concept was later generalized to chemical carcinogen risk assessment and used by public health and regulatory agencies worldwide.
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Mulvihill JJ. Preconception exposure to mutagens: medical and other exposures to radiation and chemicals. J Community Genet 2012; 3:205-11. [PMID: 22752838 PMCID: PMC3419286 DOI: 10.1007/s12687-012-0104-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 06/01/2012] [Indexed: 12/14/2022] Open
Abstract
Contrary to intuition, no environmental exposure has been proved to cause human germ line mutations that manifest as heritable disease in the offspring, not among the children born to survivors of the American atomic bombs in Japan nor in survivors of cancer in childhood, adolescence, or young adulthood who receive intensive chemotherapy, radiotherapy, or both. Even the smallest of recent case series had sufficient statistical power to exclude, with the usual assumptions, an increase as small as 20 % over baseline rates. One positive epidemiologic study of a localized epidemic of Down syndrome in Hungary found an association with periconceptual exposure to a pesticide used in fish farming, trichlorfon. Current population and occupational guidelines to protect against genetic effects of ionizing radiation should continue, with the understanding they are based on extrapolations from mouse experiments and mostly on males. Presently, pre-conceptual counseling for possible germ cell mutation due to the environment can be very reassuring, at least based on, in a sense, the worst-case exposures of cancer survivors. Prudence demands further study. Future work will address the issue with total genomic sequencing and epigenomic analysis.
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Affiliation(s)
- John J Mulvihill
- Department of Pediatrics, College of Medicine, University of Oklahoma, 1200 N Children's Avenue, Oklahoma City, OK, 73104, USA,
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10
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Dallas LJ, Keith-Roach M, Lyons BP, Jha AN. Assessing the Impact of Ionizing Radiation on Aquatic Invertebrates: A Critical Review. Radiat Res 2012; 177:693-716. [DOI: 10.1667/rr2687.1] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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11
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Baverstock K, Karotki AV. Towards a unifying theory of late stochastic effects of ionizing radiation. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2011; 718:1-9. [DOI: 10.1016/j.mrgentox.2010.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 09/29/2010] [Accepted: 10/03/2010] [Indexed: 12/31/2022]
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12
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Wassom JS, Malling HV, Sankaranarayanan K, Lu PY. Reflections on the origins and evolution of genetic toxicology and the Environmental Mutagen Society. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2010; 51:746-760. [PMID: 20839221 DOI: 10.1002/em.20589] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
This article traces the development of the field of mutagenesis and its metamorphosis into the research area we now call genetic toxicology. In 1969, this transitional event led to the founding of the Environmental Mutagen Society (EMS). The charter of this new Society was to "encourage interest in and study of mutagens in the human environment, particularly as these may be of concern to public health." As the mutagenesis field unfolded and expanded, new wording appeared to better describe this evolving area of research. The term "genetic toxicology" was coined and became an important subspecialty of the broad area of toxicology. Genetic toxicology is now set for a thorough reappraisal of its methods, goals, and priorities to meet the challenges of the 21st Century. To better understand these challenges, we have revisited the primary goal that the EMS founders had in mind for the Society's main mission and objective, namely, the quantitative assessment of genetic (hereditary) risks to human populations exposed to environmental agents. We also have reflected upon some of the seminal events over the last 40 years that have influenced the advancement of the genetic toxicology discipline and the extent to which the Society's major goal and allied objectives have been achieved. Additionally, we have provided suggestions on how EMS can further advance the science of genetic toxicology in the postgenome era. Any oversight or failure to make proper acknowledgment of individuals, events, or the citation of relevant references in this article is unintentional.
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Affiliation(s)
- John S Wassom
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
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Johnston J, Comello RJ, Vealé BL, Killion J. Radiation Exposure Dose Trends and Radiation Dose Reduction Strategies in Medical Imaging. J Med Imaging Radiat Sci 2010; 41:137-144. [DOI: 10.1016/j.jmir.2010.06.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 05/19/2010] [Accepted: 06/10/2010] [Indexed: 10/24/2022]
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Taylor M, Cieslak M, Rees GS, Oojageer A, Leith C, Bristow C, Tawn EJ, Winther JF, Boice JD. Comparison of germ line minisatellite mutation detection at the CEB1 locus by Southern blotting and PCR amplification. Mutagenesis 2010; 25:343-9. [PMID: 20228094 DOI: 10.1093/mutage/geq011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Identification of de novo minisatellite mutations in the offspring of parents exposed to mutagenic agents offers a potentially sensitive measure of germ line genetic events induced by ionizing radiation and genotoxic chemicals. Germ line minisatellite mutations (GMM) are usually detected by hybridizing Southern blots of unamplified size-fractionated genomic DNA with minisatellite probes. However, this consumes a relatively large amount of DNA, requires several steps and may lack sensitivity. We have developed a polymerase chain reaction (PCR)-based GMM assay, which we applied to the hypermutable minisatellite, CEB1. Here, we compare the sensitivity and specificity of this assay with the conventional Southern hybridization method using DNA from 10 spouse pairs, one parent of each pair being a survivor of cancer in childhood, and their 20 offspring. We report that both methods have similar specificity but that the PCR method uses 250 times less DNA, has fewer steps and is better at detecting GMM with single repeats provided that specific guidelines for allele sizing are followed. The PCR GMM method is easier to apply to families where the amount of offspring DNA sample is limited.
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Affiliation(s)
- Malcolm Taylor
- School of Cancer and Enabling Sciences, University of Manchester, St Mary's Hospital, Manchester, UK.
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Hall EJ. Is there a place for quantitative risk assessment? JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2009; 29:A171-84. [PMID: 19454800 PMCID: PMC3684965 DOI: 10.1088/0952-4746/29/2a/s12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The use of ionising radiations is so well established, especially in the practice of medicine, that it is impossible to imagine contemporary life without them. At the same time, ionising radiations are a known and proven human carcinogen. Exposure to radiation in some contexts elicits fear and alarm (nuclear power for example) while in other situations, until recently at least, it was accepted with alacrity (diagnostic x-rays for example). This non-uniform reaction to the potential hazards of radiation highlights the importance of quantitative risk estimates, which are necessary to help put things into perspective. Three areas will be discussed where quantitative risk estimates are needed and where uncertainties and limitations are a problem. First, the question of diagnostic x-rays. CT usage over the past quarter of a century has increased about 12 fold in the UK and more than 20 fold in the US. In both countries, more than 90% of the collective population dose from diagnostic x-rays comes from the few high dose procedures, such as interventional radiology, CT scans, lumbar spine x-rays and barium enemas. These all involve doses close to the lower limit at which there are credible epidemiological data for an excess cancer incidence. This is a critical question; what is the lowest dose at which there is good evidence of an elevated cancer incidence? Without low dose risk estimates the risk-benefit ratio of diagnostic procedures cannot be assessed. Second, the use of new techniques in radiation oncology. IMRT is widely used to obtain a more conformal dose distribution, particularly in children. It results in a larger total body dose, due to an increased number of monitor units and to the application of more radiation fields. The Linacs used today were not designed for IMRT and are based on leakage standards that were decided decades ago. It will be difficult and costly to reduce leakage from treatment machines, and a necessary first step is to refine the available radiation risks at the fractionated high doses characteristic of radiotherapy. The dose response for carcinogenesis is known for single doses up to about 2 Sv from the A-bomb data, but the shape at higher fractionated doses is uncertain. Third, the proliferation of proton facilities. The improved dose distribution made possible by charged particle beams has created great interest and led to the design and building of many expensive proton centres. However, due to technical problems, most facilities use passive scattering, rather than spot scanning, to spread the pencil beam to cover realistic target volumes. This process, together with the methods used of final collimation, results in substantial total body doses of neutrons. The relative biological effectiveness of these neutrons is not well known, and the risk estimates are therefore uncertain. Unless and until the risks are known with more certainty, it is difficult to know how much effort and cost should be directed towards reducing, or eliminating, the neutron doses. These three examples, where uncertainties in quantitative risk estimates result in important practical problems, will be discussed.
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Affiliation(s)
- Eric J Hall
- Columbia University Medical Center, New York, NY, USA
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