Man-made Sources Of Radiation Research Articles

Exposure to radiation and its health effects on the cardiovascular system

Worldwide, people are being exposed to natural and man-made sources of radiation. Epidemiological studies have shown an increased risk of vascular diseases in populations that have been exposed to ionizing radiation. Vascular endothelium is implicated as one of the targets for radiation leading to the development of cardiovascular diseases. However, the molecular mechanisms behind the development of radiation-induced cardiovascular disease in acute or chronic exposed people are not fully elucidated. The hypothesis that chronic low dose rate ionizing radiation accelerates the onset of senescence of primary human umbilical vein endothelial cells has been tested . Therefore, the study aimed to find out the relationship between radiation, heart disease, the devices used for diagnosis, and their relationship to increasing the risk of diseases from various aspects.

Mutational effects of chronic gamma radiation throughout the life cycle of Arabidopsis thaliana: Insight into radiosensitivity in the reproductive stage

Organisms living on Earth have always been exposed to natural sources of ionizing radiation, but following recent nuclear disasters, these background levels have often increased regionally due to the addition of man-made sources of radiation. To assess the mutational effects of ubiquitously present radiation on plants, we performed a whole-genome resequencing analysis of mutations induced by chronic irradiation throughout the life cycle of Arabidopsis thaliana grown under controlled conditions. We obtained resequencing data from 36 second generation post-mutagenesis (M2) progeny derived from 12 first generation (M1) lines grown under gamma-irradiation conditions, ranging from 0.0 to 2.0 Gray per day (Gy/day), to identify de novo mutations, including single base substitutions (SBSs) and small insertions/deletions (INDELs). The relationship between de novo mutation frequency and radiation dose rate from 0.0 to 2.0 Gy/day was assessed by statistical modeling. The increase in de novo mutations in response to irradiation dose fit the negative binomial model, which accounted for the high variability of mutation frequency observed. Among the different types of mutations, SBSs were more prevalent than INDELs, and deletions were more frequent than insertions. Furthermore, we observed that the mutational effects of chronic radiation were greater during the reproductive stage. These results will provide valuable insights into practical strategies for analyzing mutational effects in wild plants growing in environments with various mutagens.

Evaluation of radiation doses delivered to patients during conventional pelvis radiographic imaging in selected Nigerian hospitals

Diagnostic X-ray procedures remain the largest contributor to the population dose from man-made radiation sources; therefore, there is need for evaluation of the health risks connected with the use of ionizing radiation in X-ray examinations. The aim of this study is to investigate radiation dose in pelvis imaging procedures in some diagnostic centers in Southern part of Nigeria. Entrance Surface Air Kerma (ESAK) was calculated using exposure parameters obtained during examinations. A total of 160 adult patients undergoing pelvis AP radiography in nine (9) hospitals having ten X-ray centers were considered in the study. The mean ESAK calculated ranged from 1.08 to 16.16 mGy for pelvis AP and ranged from 1.15 to 10.06 mGy for pelvis LAT. Wide variations were found in the dose values obtained from various X-ray units even within the same center. The doses estimated in this study were found to be lower, when compared with the NRPB-HPA 2010 review for UK.

HEALTH STATUS OF CHILD POPULATION LIVING IN THE VICINITY OF THE FAR-EASTERN CENTER FOR RADIOACTIVE WASTE MANAGEMENT (FEC DALRAO)

Introduction. The subject of the study was the health of the child population of Dunai village located in the vicinity of radiation hazardous facilities - the Far-Eastern Center for Radioactive waste management (FEC DalRAO) and Shipyard-30 . Мaterial and Methods. The material of the study was age indices of the morbidity, disability, and mortality rate of children of Dunai village over the period between 2009 and 2013. The study uses indices averaged over a five-year period and the dynamics of their changes. results. The birth rate of the healthy child amounted of 54.6% versus 72.0% in the control group. In the morbidity structure, the rate of congenital malformations was higher 68.0 ± 0.4 and 42.8 ± 5.9 per 1000. Child disability was higher and accounted for 15.3 ± 3.3 per 1000 versus 10.4 ± 0.4 per 1000 in the control group. The child mortality rate was higher than in the comparison group and accounted for 1.8 per 1000 and 0.75 per 1000 respectively. Public doses induced by manmade radiation sources were lower than those established for the population in the Russian standards, however, the increased level of natural radioactivity was induced by radon, which generates in a dose of 3.23 mSv/y. conclusion. To protect the child population there are advised additional measures such as an organization of the permanently operating system of recreational and rehabilitation activities in respect to children.

К разработке новых редакций норм радиационной безопасности и основных санитарных правил обеспечения радиационной безопасности

The objective of this work is to enhance national Radiation safety standards (NRB) and Basic Health Rules for Radiation Safety (OSPORB). 
 This article discusses proposals how to amend new versions of the fundamental regulatory documents – national NRB and OSPORB as regards the interpretation of the term “limit of the annual effective dose of manmade individual exposure” and the health physics limiting the content of artificial radionuclides in solid materials for their unrestricted use. 
 In current Radiation Safety Standards, NRB-99/2009 (paragraph 3.1.5.), in contrast to the Federal Law of 09.01.1996 No 3-FZ “On the Public Radiation Protection” and provisions of draft International Basic Safety Standards, annual effective dose means gross effective dose of external and internal exposure, received for the calendar year. The article describes the situation where the doses of a conditional worker do not exceed the dose limits in a single calendar year, i.e. < 50 mSv, however, for any arbitrarily taken time interval equal to one year, the annual dose limit of 50 mSv is repeatedly exceeded. Therefore, the following amendment is proposed to be made in new version of the NRB: “Annual effective dose means the sum of the effective external dose received for any arbitrarily taken time interval equal to one year and the ambient effective internal dose due to the intake of radionuclides in the body over the same period”.
 In current Basic Health Rules for Radiation Safety, OSPORB 99/2010, Annex 3 “The Specific Activities of Artificial Radionuclides, at which Unrestricted Use of Materials is Permitted” does not include the uranium isotopes 234U, 235U and 238U; this contradicts paragraph 5.2.10 of OSPORB-99/2010, according to which these isotopes should be attributed to manmade radiation sources. 
 The article justifies the expediency of establishing the upper value of the specific activity of 1 Bq/g for the main uranium radionuclides in solid materials in case of their unlimited use. 
 The supplement of Appendix 3 is proposed to the new version of the OSPORB with uranium isotopes 234U, 235U, 238U, setting the standard for their specific activity of 1 Bq/g in solid materials for unlimited use.

Радиационная обстановка на хвостохранилище Степногорского горно-химического комбината и прилегающих территориях. Сообщение I

Purpose: Assessment of the radiation situation at the tailing dump of the Stepnogorsk Mining-Chemical Combine (SMCC) and the settlements around.
 Material and methods: The tailing dumps of the SMCC and the settlements near located of Aksu, Kvartsytka and Zavodskaya were objects of the radioecological research. Field expedition studies were performed during the summer period and consisted in carrying out a detailed gamma survey of the territory of the investigated objects and settlements, sampling of surface waters, vegetation, surface and layered soil samples. In settlements, along with sampling and studying the gamma background, the equivalent equilibrium volume activity of radon daughters in residential and industrial premises was determined. To determine the concentrations of the studied radionuclides a background was selected, within which the levels of their global deposition were studied. To calculate the individual effective radiation dose of the population the National Radiation Protection Board methodology was used as the basis.
 Results: In the northern part of the tailing dump of the SMCC in the adjoining territory, a radioactive contamination site was found where the specific activity values for 226Ra, 232Th and 210Pb reach values of 1500–2000 Bq/kg. On the territory of the Aksu settlement, 5 local areas with the area from 25 to 1000 m2 were found, with the intensity of ambient dose equivalent of gamma radiation from 0.39 to 0.86 µSv/h. In the Zavodskaya village, two areas with increased levels of gamma radiation intensity were identified. 
 Conclusion: The obtained results of field work and laboratory analytical studies testify to the negative impact of the tailing dump of the SMCC on the environment of adjacent territories, expressed in contamination of soil, water and vegetation with radionuclides. The nature of the abnormal areas on the territory of the settlements of Aksu and Zavodskaya excludes their origin from the tailing dump of the SMCC. The appearance of these areas of contamination may be due to the use of materials of the 3rd class in sanitary and hygienic standards for improvement and road construction. The probable annual effective dose for the population living in the radioactive local areas of the Aksu ~6.5 mSv/year, at the normal rate of 1 mSv/year from man-made radiation sources.

THE RELATIONSHIP BETWEEN GLOBAL ENVIRONMENTAL PROBLEMS, POPULATION HEALTH, AND DEVELOPMENT OF NUCLEAR POWER INDUSTRY

The article describes the relationship of global environmental problems and population health with development of nuclear power industry. Atomic energy industry does not consume oxygen and emit greenhouse gases. European countries with a highly developed atomic energy industry are recognized as ecologically clean regions of Europe. World nuclear industry reduces the worldwide coal combustion by 440 million tons. In Russia, the occupational diseases are not as frequently encountered in the cities with nuclear facilities as in Russia as a whole in spite of the fact that in these cities the surveys are conducted more often and cover a greater amount of people. The exposure due to exploitation of man-made radiation sources is 0.14 %, and from nuclear power plants - 0.01 % of the total radiation dose, which is 100 times lower than the norm - 1 mSv/year. The authors have studied the influence of nuclear power industry on human health and have proved that the fears associated with risks are exaggerated. The risk-based approach speaks volumes for the nuclear power industry's advantages and safety for population health. According to sociologists, the support for atomic energy industry is constantly growing.

Cavernous Hemangioma Based on Posterior Fossa Dura

Aim: According to the UNSCEAR 2008 report, physicians, technicians, nurses and others involved in the medical field with a total number of monitored staff exceeding 7.5 million workers constitute the largest single group of occupationally exposed to man-made sources of radiation. The objective of this work was to compare our tertiary care medical Centre occupational radiation dose levels to the ones published in the UNSCEAR 2008 report. Materials and Methods: Examination of the personal dosimetry records of the past five years from 2012 to 2016 is conducted and average radiation doses received by the staff are calculated including the total accumulated last 5 years doses. The radiation doses were measured using thermo luminescence dosimeters (TLD). The total number of monitored staff was 538 and 274 from our medical center and from the other centers that we cover respectively. Results: The levels of occupational exposures in our hospital and other medical institutions compares very well with the internationally and nationally reported results. The annual average for the five years period under examination in this work was 0.4, 0.8 and 0.5 mSv for the diagnostic radiology, nuclear medicine and radiation therapy groups respectively. Our minimal detection limit for personal dosimetry reporting is 0.1 mSv. Conclusions: The results of the measured annual doses were well below the ICRP recommended annual dose limit of 20 mSv. Our results compare very well with the UNSCEAR 2008 report. In general the application of ionizing radiation in Medicine is a safe practice for the occupationally exposed workers.

The Human Capital Cost of Radiation: Long-Run Evidence from Exposure Outside the Womb

This paper studies the long-term effect of radiation on cognitive skills. We use regional variation in nuclear fallout caused by the Chernobyl disaster in 1986, which led to a permanent increase in radiation levels in most of Europe. To identify a causal effect, we exploit the fact that the degree of soil contamination depended on rainfall within a critical ten-day window after the disaster. Based on unique geo-coded survey data from Germany, we show that people who lived in highly-contaminated areas in 1986 perform significantly worse in standardized cognitive tests 25 years later. This effect is driven by the older cohorts in our sample (born before 1976), whereas we find no effect for people who were first exposed during early childhood. These results are consistent with radiation accelerating cognitive decline during older ages. Moreover, they suggest that radiation has negative effects even when people are first exposed as adults, and point to significant external costs of man-made sources of radiation.

Strategies to Prevent the Emergence of Radiation-Induced Malignancies.

DEAR EDITOR, Radiations are categorized as ionizing radiation (viz., alpha particle, beta particles, neutrons, etc.,) and nonionizing radiation (viz., infrared, microwaves, radio waves, etc.,) based on their ability/inability to liberate electrons from atoms or molecules.[1,2] Humans are generally exposed to both natural and man-made sources of radiation during the course of their lives.[1,2] Although radiation has definitive applications in fields such as medicine, industry, and research, it remains a major cause of health concern if not properly used.[1,3] Multiple adverse consequences, such as acute events (such as skin burns and local radiation injuries); malignancy; congenital anomalies; and even death, have been reported in cases of exposure to radiations beyond the permissible limits.[1,2,3] Furthermore, subsequent to a nuclear accident, a remarkable rise in the incidence of psychological distress and psychiatric conditions (such as posttraumatic stress disorder, anxiety disorders, depression, and alcohol abuse) have been observed among the survivors.[4,5] However, attributes such as age at the time of exposure, type of radiation, radiation dose, exposure duration, and sensitivity of tissues/organs, eventually determine the extent of radiation-induced damage.[1,6,7] It has been observed that incidence of radiation-induced malignancy/complications is still on the rise in heterogeneous settings, because of the presentation of clinical symptoms after a long interval; poor awareness among general population about the sources or side effects of radiation; limited orientation of medical students about assessment of radiation exposure; the absence or poor quality of protective devices in industries; nonutilization of the protective equipments despite their availability; no uniformity in the preplacement examination or regular health check-up; lack of infrastructure to enable early diagnosis; and limited access to information about supportive care services.[1,3,5] To address the above-mentioned challenges and thus bring about a significant reduction in the incidence of radiation associated malignancy, there is a crucial need that policy makers should explore all possible sources of radiation exposure, and then develop interventions in coordination with different stakeholders.[1,5] These strategies include promoting thorough risk assessment among the exposed persons;[4] developing a model to establish a relationship between time since exposure/age at exposure to radiation-induced malignancy;[7] advocating implementation of appropriate preventive strategies in the industries;[3] sensitizing physicians, population, and health professionals about radiation-induced malignancies;[3] developing guidelines to ensure standardized case management based on the exposed dose of radiation and patient-related variables;[8] establishing a mechanism to ensure follow-up of at-risk populations to encourage early detection and prompt initiation of specific treatment;[4,8] building a strategic plan to enable preparedness, evacuation and relocation of people at times of any nuclear accident;[4,5] and fostering linkages with international organizations to strengthen the overall system.[1] In conclusion, both ionizing and nonionizing radiations have been attributed to the causation of multiple cancers. Thus, it is the responsibility of the policy makers and other stakeholders to work in collaboration to eventually reduce the contribution of radiation on the development of malignancies. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Current Evidence for Developmental, Structural, and Functional Brain Defects following Prenatal Radiation Exposure.

Ionizing radiation is omnipresent. We are continuously exposed to natural (e.g., radon and cosmic) and man-made radiation sources, including those from industry but especially from the medical sector. The increasing use of medical radiation modalities, in particular those employing low-dose radiation such as CT scans, raises concerns regarding the effects of cumulative exposure doses and the inappropriate utilization of these imaging techniques. One of the major goals in the radioprotection field is to better understand the potential health risk posed to the unborn child after radiation exposure to the pregnant mother, of which the first convincing evidence came from epidemiological studies on in utero exposed atomic bomb survivors. In the following years, animal models have proven to be an essential tool to further characterize brain developmental defects and consequent functional deficits. However, the identification of a possible dose threshold is far from complete and a sound link between early defects and persistent anomalies has not yet been established. This review provides an overview of the current knowledge on brain developmental and persistent defects resulting from in utero radiation exposure and addresses the many questions that still remain to be answered.

E-035 Cranial Radiation Exposure during Cerebral Angiography

IntroductionRadiation exposure to patients and personnel remains a major concern in the practice of interventional radiology. Medical personnel using radiation now account for more than half of all radiation workers...

Gamma dose rate due to natural and manmade radiation sources from a nuclear facility in Mexico

The environmental external gamma dose rate has been determined at the Mexican Nuclear Research Centre and surrounding communities, located in a forest area. Outdoor direct measurements of external gamma exposure and absorbed dose rates in air were performed using passive integrating thermoluminescent dosimeters. Radiological measurements were also carried out with a portable high pressure ionization chamber. The gamma dose rate was evaluated from data obtained along 10 years measurements. The activity concentrations of 40K, 226Ra, 232Th, 137Cs, and 235U in surface soil samples at sampling sites are also presented. The radionuclide activity concentrations were determined by low background gamma spectrometry with hyper-pure germanium detectors. A site specific lineal model to describe the relationship between the external gamma dose rate and the 226Ra concentration values in the soil is proposed.

Evaluation of image quality and patient dose in conventional radiography examinations in radiology centers in Sistan and Baluchestan, Iran and comparing with that of international guidelines levels

The major means of exposure to man-made sources of radiation is due to diagnostic examinations with X-ray. In the current research, for making practical the programs of reducing the patient's absorbed dose and increasing the quality of radiographic images in Sistan and Baluchestan hospitals, the patients surface dose and image quality were evaluated. In the first stage of experiment, the image quality and the cause of low quality of images was evaluated for a period of one month, and the patient dose for 10 adults in 7 projection were calculated in this study. Then the quality control tests were conducted to determine the equipment failures and provide appropriate corrective actions. Subsequently in the second stage of study, the image quality and patients dose were compared with the first stage of experimental data. The ESAK mean for all the centers, before and after implementing the quality control program was achieved as 0.48±0.30 and 0.37±0.20 for chest (anterior-posterior), 3.4±1.67 and 3.13±1.25 for lumbar spine (anteriorposterior), 8.81±7.72 and 7.56 ±5.99 for lumbar spine (lateral), 3.56±1.85 and 3.34±1.74 for the abdomen (anteriorposterior), 2.79±1.40 and 2.71 ±1.24 for pelvis (anterior-posterior), 2.27±1.43 and 2.1±1.25 for the skull (anteriorposterior) and 1.50±0.87 and 1.43±0.76 for the skull (lateral), respectively.(the data are based on mGy). The radiographic images quality was also increased between 0 to 10% after implementing quality control program. Results obtained show that a quality control program to reduce patient dose and increase radiographic image quality is necessary to ensure that all radiological examinations are performed under the terms of less received dose for the patients and the received images have good quality.

Evaluation of image quality and patient dose in conventional radiography examinations in radiology centers in Sistan and Baluchestan, Iran and comparing with that of international guidelines levels

The major means of exposure to man-made sources of radiation is due to diagnostic examinations with X-ray. In the current research, for making practical the programs of reducing the patient's absorbed dose and increasing the quality of radiographic images in Sistan and Baluchestan hospitals, the patients surface dose and image quality were evaluated. In the first stage of experiment, the image quality and the cause of low quality of images was evaluated for a period of one month, and the patient dose for 10 adults in 7 projection were calculated in this study. Then the quality control tests were conducted to determine the equipment failures and provide appropriate corrective actions. Subsequently in the second stage of study, the image quality and patients dose were compared with the first stage of experimental data. The ESAK mean for all the centers, before and after implementing the quality control program was achieved as 0.48±0.30 and 0.37±0.20 for chest (anterior-posterior), 3.4±1.67 and 3.13±1.25 for lumbar spine (anteriorposterior), 8.81±7.72 and 7.56 ±5.99 for lumbar spine (lateral), 3.56±1.85 and 3.34±1.74 for the abdomen (anteriorposterior), 2.79±1.40 and 2.71 ±1.24 for pelvis (anterior-posterior), 2.27±1.43 and 2.1±1.25 for the skull (anteriorposterior) and 1.50±0.87 and 1.43±0.76 for the skull (lateral), respectively.(the data are based on mGy). The radiographic images quality was also increased between 0 to 10% after implementing quality control program. Results obtained show that a quality control program to reduce patient dose and increase radiographic image quality is necessary to ensure that all radiological examinations are performed under the terms of less received dose for the patients and the received images have good quality.

Luminescence dosimetry in a contaminated settlement of the Techa River valley, Southern Urals, Russia

Abstract Optically stimulated luminescence (OSL) dosimetry is applied to quartz extracted from bricks from a mill in a contaminated village (Muslyumovo) of the Techa River valley, Southern Urals, Russia, for the purpose of dose reconstruction. Previous works [ Goksu et al., 2002 . First international intercomparison of luminescence techniques using samples from the Techa river valley. Health Phys. 82, 94–101] have shown that the expected dose due to man-made sources of radiation in the bricks is in the same range as the background dose due to natural sources of radiation, therefore a precise estimate of the cumulative and background dose is of utmost importance. Cumulative doses could be assessed with OSL with a precision of around 4% and lie between 450 and 600 mGy. The background dose was carefully determined by a combination of laboratory measurements, in-situ gamma spectrometry and Monte Carlo modelling. The results show that the gamma-dose rate of the soil was overestimated and the fractional brick gamma-dose rate underestimated in previous studies, but that the overall gamma-dose rate was nearly correct, due to mutual compensation. The obtained anthropogenic doses in brick measured with OSL lie between 200 and 300 mGy, show variability between adjacent bricks within error limits for one spot but a significant difference for two samples is observed for another spot. A distinct dependency of measured dose upon sample height is observed, which is an indication of a source distribution, which extends over a large area and up to a certain depth into the soil and in which higher contaminated areas are located at a greater distance to the mill than lower contaminated areas. A measured dose–depth profile is compared with previously published Monte Carlo calculations to verify the source energy.

TH-B-213A-01: Risks From Occupational Radiation Exposures

Radiologists and radiologic technicians were among the earliest occupational groups to be exposed to ionizing radiation, and still constitute one of the largest groups of workers exposed to man-made sources of radiation whilst at work. Studies of human populations exposed to acute, high doses of ionizing radiation have proved valuable in assessing the link between radiation and cancer and have been used to derive quantitative estimates of risk. However, the applicability of these estimates to the assessment of risks following fractionated or low level exposures remains uncertain. A number of epidemiologic studies have been conducted therefore to assess the potential risks from medical occupational exposure directly, including studies of radiologists in the UK, US and China and a cohort of radiologic technicians radiographers in the U.S. This lecture will provide an overview of these epidemiological studies and their findings, as well as a description of a new study of physicians that perform fluoroscopically guided procedures that we are currently running at the National Cancer Institute. The use of cancer risk projection models that we have developed to estimate potential lifetime cancer risk following specified exposure histories will also be described with examples. Learning Objectives: 1. Understand the strengths and limitations of the epidemiologic studies of medical radiation workers 2. Understand the strengths and limitations of risk projection models to estimate lifetime cancer risks from occupational radiation exposures

Personal dose monitoring in hospitals: global assessment, critical applications and future needs

It is known that medical applications using ionising radiation are wide spread and still increasing. Physicians, technicians, nurses and others constitute the largest group of workers occupationally exposed to man-made sources of radiation. Many hospital workers are consequently subjected to routine monitoring of professional radiation exposures. in the university hospital, UZ Brussel, 600 out of 4000 staff members are daily monitored for external radiation exposures. The most obvious applications of ionising radiation are diagnostic radiology, diagnostic or therapeutic use of radionuclides in nuclear medicine and external radiation therapy or brachytherapy in radiotherapy departments. Other important applications also include various procedures in interventional radiology (IR), in vitro biomedical research and radiopharmaceutical production around cyclotrons. Besides the fact that many of the staff members, involved in these applications, are not measurably exposed, detailed studies were carried out at workplaces where routine dose monitoring encounters difficulties and for some applications where relatively high occupational exposures can be found. most of the studies are concentrated around nuclear medicine applications and IR. They contain assessments of both effective dose and doses at different parts of the body. The results contribute to better characterisation of the different workplaces in a way that critical applications can be identified. Moreover, conclusions point out future needs for practical routine dose monitoring and optimisation of radiation protection.

Radijaciono opterecenje pacijenata u konvencionalnoj dijagnostickoj radiologiji - analiza radioloske prakse u Srbiji

X-rays are by far most significant contributor to total population dose from man-made sources of radiation. Diagnostic reference levels provide frameworks to reduce variability. The aim of this study is to establish, for the first time, a baseline for national diagnostic reference levels in Serbia for the most common X-ray examination types. Dose estimates are based on measurements of kerma-area product and Entrance surface air kerma for at least ten patients for each examination type, in each of 16 randomly selected hospitals in Serbia. Mean, median and third quartile values of patient doses are reported. Results have shown wide variation of mean hospital doses. Entrance surface doses were compared with previously published diagnostic reference levels. Doses for all studied examination types except chest radiography were within European DRL. The reasons for dose variation are discussed. The findings emphasize the importance of regular patient dose measurement to ensure that patient doses are kept as low as reasonable achievable.

Occupational exposure, epidemiology and compensation

The data summarized in this section are taken mainly from the 2000 Report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and generally refer to occupational exposures assessed to have been experienced during the earlyand mid-1990s [1]. Occupational exposures in the United Kingdom from 1998 to 2003 have been reviewed recently by the Radiation Protection Division of the Health Protection Agency [2]. Soon after its discovery by Roentgen in 1895, ionizing radiation was exploited in medicine as a diagnostic and therapeutic tool, leading to the inadvertent exposure of medical staff. In the early years of the 20th century, exposures to medical personnel tended to be large, sometimes leading to deterministic effects such as epilation and skin burns. The first substantial epidemiological evidence for the carcinogenic effects of radiation was obtained from observations on radiologists. The use of radiation in medicine grew throughout the last century and currently includes a variety of diagnostic techniques (e.g. fluoroscopy and cardiac catheterization), dental radiography, radionuclides used for organ imaging in nuclear medicine, radiotherapy and other uses such as biomedical research. Initially, it was X-rays that were employed, but techniques became more sophisticated such that other radiations [e.g. densely ionizing alpha particles (He) and neutrons] were introduced. Medical workers now constitute the largest group occupationally exposed to man-made sources of radiation: throughout the world, 2.5 million medical workers are monitored for exposure to radiation (the majority of these being employed in the countries of the Organization for Economic Cooperation and Development), leading to an average annual collective effective dose of 1000 person.Sv. In contrast to the high-level exposures experienced by early medical workers, the reported annual occupational doses in excess of 15 mSv are now rare. The industrial use of radiation is multifarious and includes radiography, irradiation (e.g. the sterilization of medical products), luminizing, radionuclide production and distribution, well logging and accelerator operation. Some 0.75 million workers are monitored for exposure, leading to an average annual collective effective dose of 400 person.Sv. Although individual doses are generally small, a few workers (such as those involved in site radiography) receive annual doses in excess of 15 mSv, and occasionally serious over-exposures are reported. The luminizing of dials with radium-based paint in the first half of the last century led to accidental ingestion of the paint and, particularly in the United States, high intakes of radium. Occupational exposure also occurs in educational establishments ( 0.33 million monitored workers worldwide) and in veterinary medicine ( 50 000 radiation workers), leading to average annual collective effective doses of 30 person.Sv and 10 person.Sv, respectively. The discovery of neutron-induced nuclear fission in the 1930s led to the development of the nuclear weapons and power industries in the second half of the 20th century and consequent occupational exposure to natural and man-made sources of radiation. Workers in these industries are involved in mining and processing of uranium, nuclear fuel production, reactor operation, irradiated fuel reprocessing and product and waste management. Additional occupational exposures occur in research and development activities and in production and testing of nuclear weapons. The exposure of workers at the Mayak facility in the Southern Urals to external sources of gamma and neutron radiation and to alphaemitting plutonium before 1959 were very high, occasionally sufficiently so to produce deterministic effects. The total number of monitored workers in the commercial nuclear fuel cycle is 0.8 million and the average annual collective effective dose is 1500 person.Sv. Accurate figures for the defence industry are difficult to come by, but the annual collective effective dose worldwide is likely to be in the range of 100–300 person.Sv. By far, the largest source of occupational exposure is naturally occurring radiation. The excess risk of lung Correspondence to: Richard Wakeford, 6 Bourne Street, Wilmslow, Cheshire SK9 5HD, UK. Formerly: British Nuclear Fuels plc, 1100 Daresbury Park, Warrington WA4 4GQ, UK. e-mail: richard.wakeford@Gmail.com