Radiation Risk Assessment Research Articles

Assessment of radiation risk from waste generated from mining and remediation process of granite ore

Assessment of radiation risk from waste generated from mining and remediation process of granite ore

Assessment of Radiation Risk from Background Radiation Exposures in Selected Hospitals within Makurdi Metropolis, North-Central, Nigeria

In this study, a radiation alert meter was used to measure background ionizing radiation levels in four hospitals in Makurdi Metropolis, Benue State, North Central, Nigeria. This aimed to determine the radiological health implications of the measured background ionizing radiation study area's populace. The background ionizing radiation exposure rate (indoor and outdoor) measured ranged from 0.0014 to 0.0019 mRhr-1 with average value 0.0017 mRhr-1, 0.0015 to 0.0024 mRhr-1 with average value 0.0019 mRhr-1, 0.0013 to 0.0025 mRhr-1 with average value 0.0018 mRhr-1 and 0.0012 to 0.0024 mRhr-1 with average value 0.0018 mRhr-1 for the selected hospitals A, B, C and D, respectively. The study showed that the mean equivalent dose rate levels are within the international commission on radiological protection's standard permissible limits. The mean annual effective dose equivalent (indoor and outdoor) for all the selected hospitals is within the recommended permissible limits of 1.00 mSvy-1 for the general public. In the selected hospitals A, B, C, and D, the estimated Dorgan values for the lungs, ovaries, bone marrow, testes, kidney, liver, and whole-body due to radiation exposure and inhalation are below tolerable international limits of 1.0 mSv yearly. Hence the selected hospitals are radiologically safe.

Mapping of ambient gamma radiation levels and risk assessment in some parts of Eastern Deccan Plateau, India

ABSTRACT Natural background gamma radiation levels in the indoors and outdoors of certain northern districts of Telangana State, situated on Deccan plateau, were measured with scintillation detector-based survey metre. It was observed that the absorbed gamma dose rates in the indoor and outdoor of the study area were found to vary from 106 nGyh−1 to 322 nGyh−1 with an average of 192 ± 48 nGyh−1, and 102 nGyh−1 to 331 nGyh−1 with an average of 172 ± 50 nGyh−1, respectively. Spatial distribution maps and isodose contours are created using inverse distance weighted technique. The histogram and quantile graphs of the indoor and outdoor natural background gamma radiation levels were observed to follow the structure of symmetrical distribution. The average ratio of indoor to outdoor gamma radiation levels was found to be 1.10. The influence of building materials on the natural background gamma radiation levels was discussed. The annual effective dose was found to vary from 0.20 to 1.89 mSv. The excess life cancer risk was also calculated.

Real-time Radiation Monitoring and Assessment of Radiation Risk on Public around BSMMU Hospital Campus, Dhaka, Bangladesh

Objective: Ionizing radiation is extensively used in the hospital for diagnosis and treatment procedures to patients and its usage increasing day by day with the socio-economic development of the country. The aim of the study is to monitor the real-time radiation around the Bangabandhu Sheikh Mujib Medical University (BSMMU) hospital campus and estimation of the radiation risk on public.
 Method: The real-time radiation monitoring around the BSMMU hospital campus was performed using digital portable radiation monitoring device (DPRMD). The DPRMD meets all European CE standards and the American “FCC 15 standard”. The DPRMD was placed at 1 meter above the ground on tripod and data taking time for each monitoring point (MP) was 1 hour. Each MP was identified using Garmin eTrex GPS device. 32 MPs were selected for taking the real-time radiation dose rates around the BSMMU hospital campus from August-September 2019.
 Results: The real-time radiation dose rates around the BSMMU hospital campus were ranged from 0.020-2.45 µSv/hr with an average of 0.211 ± 0.094 µSv/hr. The annual effective dose on public were ranged from 0.222 ± 0.052 mSv to 1.247 ± 0.071 mSv with an average of 0.368 ± 0.097 mSv. The excess life-time cancer risk (ELCR) on public was estimated based on the annual effective dose that ranged from 0.881×10-3 to 5.12×10-3 with an average value of 1.488×10-3 around the BSMMU hospital campus, which means that in every thousand people, one person is at the risk of developing cancer caused by the scattered radiation exposure from the hospital.
 Conclusion: Real-time radiation monitoring makes possible to ensure the protection the radiation worker and the public from unnecessary radiation hazard. The study also provides the instantaneous information of inappropriate operation of radiation generating equipments and improper handling of radioactive substances in the hospital.

Lifetime Risk of Radiation Induced Severe Hereditary Stochastic (SHS) Effects in Medical Radiation Personnel

Background: Hereditary risk assessments in medical radiation workers must be accentuated as a precaution against genetic diseases. Ionizing radiations can induce hereditary or genetic radiation effects. Aim: To evaluate the lifetime risk of severe hereditary stochastic (SHS) effects in INMOL’s medical radiation personnel. Methods: The determination of the ‘whole-body’ effective doses was performed by ‘dose assessment algorithm’. We adopted the procedure described by ICRP for the assessment of lifetime severe hereditary annual risks by using ‘nominal probability coefficient’. Results: The AAEDs were between 1.41-1.79 mSv (in NM), 1.07-1.43 mSv (in RT) and 1.21-1.70 mSv (in RD) during 2014-2018. A declining trend is observed in AAED values in five consecutive years, due to improvements in radiation protection and safety measures. The risks of severe hereditary effects were also decreased from 2014-2018. The SHS risk was decreased from 5.012×10-4 to 3.948 ×10-4 in NM, 4.004×10-4 to 2.996×10-4 in RT and 4.76×10-4 to 3.388×10-4 in DR department. Conclusion: This study is emphasizing towards evaluating risks of hereditary effects from chronic exposure of radiations in occupational workers to avoid further late genetic complications. Such quantitative indicators would be useful in comparing other lifetime death risks from other harmful substances. Keywords: Hereditary Stochastic Effects; Annual Average Effective Doses; Nominal Probability Coefficient; Medical Radiation; Occupational Radiation Risk Assessments

Assessment of Radiation Risk on Healthcare Workers and Public in & around Two Largest Hospital Campuses of Bangladesh

Ionizing radiation gives tremendous benefit to mankind in the hospital through diagnosis and treatment to patients but unnecessary radiation may cause harm to healthcare workers & the public. The purpose of the study is to continuous radiation monitoring in & around the three largest radiological facilities of Bangladesh such as Atomic Energy Centre Dhaka (AECD), Dhaka Medical College Hospital (DMCH) & Bangabandhu Sheikh Mujib Medical University (BSMMU) campuses, and estimation of radiation risk on healthcare workers & public health. Continuous radiation monitoring was performed in & around the AECD, DMCH, BSMMU campuses from August-October 2020 using the Chemiluminescent Dosimeters. The yearly effective doses to healthcare workers and the public due to radiation released from the facilities were ranged from 0.606 ± 0.031 mSv to 0.801 ± 0.0.042 mSv with a mean of 0.707 ± 0.053 mSv. The excess lifetime cancer risk (ELCR) on healthcare workers & public health were evaluated based on the yearly effective dose and ranged from 2.486 Χ 10-3 to 3.287 Χ 10-3 with a mean of 2.900 Χ 10-3. The average yearly effective dose and ELCR on healthcare workers & public health were lower than those of the worldwide permissible values. Continuous radiation monitoring in & around the largest radiological facilities is required for detection of the radiation generating equipment’s malfunctions and improper handling of the radioactive materials. The study would help for minimization of radiation risk on healthcare workers & the public and this keeps the hospital’s environment free from radiation hazard.

Emergency Front-of-Neck Airway Rescue Via the Cricothyroid Membrane: A High-Resolution Computed Tomography Study of Airway Anatomy in Adults.

Emergency front-of-neck airway rescue is recommended in a can't intubate, can't oxygenate clinical scenario. Cannula cricothyroidotomy has been reported as having a high failure rate. Our primary aim was to estimate the angle of the trachea in relation to the horizontal axis in a simulated emergency front-of-neck airway rescue position. Our secondary aims were to estimate the optimal cannula angle of approach and evaluate the anatomical relationship of the cricothyroid membrane (CTM) to adjacent structures. We also assessed whether the CTM lies above or below the neck midpoint, a point equidistant from the suprasternal notch (SSN), and the chin surface landmarks. All measurements were compared between the male and female subjects. Subjects having elective computed tomography of their thorax were consented to have extension of the computed tomography to include their neck. A preliminary radiation dose and risk assessment deemed the additional radiation to be of very low risk (level IIa). Subjects were positioned supinely on the computed tomography table. Standard neck extension was achieved by placing a pillow under the scapulae and a rolled towel under the neck to simulate emergency front-of-neck airway rescue positioning. Fifty-two subjects were included in this study: 31 men and 21 women. The mean angle of the trachea in relation to the horizontal axis was 25.5° (95% confidence interval [CI], 21.8-29.1) in men and 14.0° (95% CI, 11.5-16.5) in women. The mean minimum angles required for hypothetical cannula cricothyroidotomy for men and women were 55.2° (95% CI, 51.8-58.7) and 50.5° (95% CI, 45.4-55.6), respectively. The CTM was located lower in the neck in men compared to women. The CTM was located below the neck midpoint in 30 of 30 (100%) male subjects and 11 of 20 (55%) female subjects (P < .001). The trachea angulates posteriorly in a simulated emergency front-of-neck airway rescue position in supine subjects and to a greater degree in men compared to women (P < .001). The minimum angle required for hypothetical cannula cricothyroidotomy was >45° in the majority (75%) of subjects studied. A steeper cannula angle of approach may be more reliable and warrants further clinical study. If airway anatomy is indistinct and performing a vertical scalpel cricothyroidotomy, consideration should be given to performing this incision lower in the neck in men compared to women.

ЭМБРИОТОКСИЧЕСКИЕ И ТЕРАТОГЕННЫЕ ЭФФЕКТЫ γ-ИЗЛУЧЕНИЯ У РЫБ ДАНИО (DANIO RERIO)

The review considers investigations presenting experimental data on the embryotoxic and teratogenic effects of exposure to ionizing radiation in zebrafish (Danio rerio) which is a convenient model for experimental embryology and radiation biology. The molecular mechanisms involved in response to the ionizing radiation influence as well as determining the embryonic death level, development disorders of embryos are examined. The data on acute and chronic effects of ionizing radiation on embryos of various stages of development with wide range of dose rates are presented. It was shown that the influence of γ-radiation on the death and development of zebrafish embryos is nonmonotonic and depends both on the irradiation conditions and on the stage of embryogenesis. The results of such studies are extremely important for understanding the mechanisms of radiation-induced biological effects formation in the embryogenesis of vertebrates, including humans, as well as for developing methods and approaches to assessing radiation risk for a developing organism.

Radiation Risk Assessment on Public in Motijheel Thana, Dhaka, Bangladesh

Objective: The pollution free environment is required for healthy life. The real-time radiation monitoring is very important for radiation hazard detection in the environment. The excess life-time cancer risk (ELCR) on public is to assess based on the real-time radiation monitoring data in the area. Methods: The real-time radiation monitoring was performed using portable digital radiation monitoring device. This real-time digital portable radiation monitoring device meets all European CE standards as well as the American “FCC 15 standard”. The real-time digital portable radiation monitoring device was placed at 1 meter above the ground on tripod and data collection time for each monitoring point (MP) was 1 hour. 27 MPs were chosen for collection of real-time radiation data at various outdoor environment in Motijheel Thana, Dhaka from May-August 2018.Results: The real-time radiation dose rates at Motijheel Thana due to natural radionuclides were ranged from 0.095 ± 0.041 µSv.h-1 to 0.185 ± 0.042 µSv.h-1 with an average of 0.147 ± 0.047 µSv.h-1. The annual effective dose to public from outdoor environmental radiation at Motijheel Thana were found to be 0.166 ± 0.066 mSv to 0.324 ± 0.061 mSv with an average of 0.257 ± 0.039 mSv. Excess Life-time Cancer Risk (ELCR) on public are also estimated based on annual effective dose that is ranged from 0.662 ×10-3 to 1.289 ×10-3 with an average value of 1.025 ×10-3, which is higher than world average value of 0.29×10-3. Conclusion: This type of study is required for detection of the radiation hazard arising from the natu-ral as well as man-made sources and also for generation of the baseline database. From this study, it is observed that there is no pose any radiation hazard in the study area due to man-made sources.

Radiation Risk Assessment on Public in Motijheel Thana, Dhaka, Bangladesh

Objective: The pollution free environment is required for healthy life. The real-time radiation monitoring is very important for radiation hazard detection in the environment. The excess life-time cancer risk (ELCR) on public is to assess based on the real-time radiation monitoring data in the area. Methods: The real-time radiation monitoring was performed using portable digital radiation monitoring device. This real-time digital portable radiation monitoring device meets all European CE standards as well as the American “FCC 15 standard”. The real-time digital portable radiation monitoring device was placed at 1 meter above the ground on tripod and data collection time for each monitoring point (MP) was 1 hour. 27 MPs were chosen for collection of real-time radiation data at various outdoor environment in Motijheel Thana, Dhaka from May-August 2018.Results: The real-time radiation dose rates at Motijheel Thana due to natural radionuclides were ranged from 0.095 ± 0.041 µSv.h-1 to 0.185 ± 0.042 µSv.h-1 with an average of 0.147 ± 0.047 µSv.h-1. The annual effective dose to public from outdoor environmental radiation at Motijheel Thana were found to be 0.166 ± 0.066 mSv to 0.324 ± 0.061 mSv with an average of 0.257 ± 0.039 mSv. Excess Life-time Cancer Risk (ELCR) on public are also estimated based on annual effective dose that is ranged from 0.662 ×10-3 to 1.289 ×10-3 with an average value of 1.025 ×10-3, which is higher than world average value of 0.29×10-3. Conclusion: This type of study is required for detection of the radiation hazard arising from the natu-ral as well as man-made sources and also for generation of the baseline database. From this study, it is observed that there is no pose any radiation hazard in the study area due to man-made sources.

Evolution of ICRP Models for Taking into Account the Irregularity of Irradiation over Time When Assessing Radiation Risk

Evolution of ICRP Models for Taking into Account the Irregularity of Irradiation over Time When Assessing Radiation Risk

Dose-effect relationships of 12C6+ ions-induced dicentric plus ring chromosomes, micronucleus and nucleoplasmic bridges in human lymphocytes in vitro

Purpose The objective of this research was to explore the dose-effect relationships of dicentric plus ring (dic + r), micronucleus (MN) and nucleoplasmic bridges (NPB) induced by carbon ions in human lymphocytes. Materials and methods Venous blood samples were collected from three healthy donors. 12C6+ ions beam was used to irradiate the blood samples at the energy of 330 MeV and linear energy transfer (LET) of 50 keV/μm with a dose rate of 1 Gy/min in the spread-out Bragg peak. The irradiated doses were 0 (sham irradiation), 1, 2, 3, 4, 5 and 6 Gy. Dic + r chromosomes aberrations were scored in metaphases. The cytokinesis-block micronucleus cytome (CBMN) was conducted to analyze MN and NPB. The maximum low-dose relative biological effectiveness (RBEM) values of the induction of dic + r, MN and NPB in human lymphocytes for 12C6+ ions irradiation was calculated relative to 60Co γ-rays. Results The frequencies of dic + r, MN and NPB showed significantly increases in a dose-depended manner after exposure to 12C6+ ions. The distributions of dic + r and MN exhibited overdispersion, while the distribution of NPB agreed with Poisson distribution at all doses. Linear-quadratic equations were established based on the frequencies of dic + r and MN. The dose-response curves of NPB frequencies followed a linear model. The derived RBEM values for dic + r, MN and NPB in human lymphocytes irradiated with 12C6+ ions were 8.07 ± 2.73, 2.69 ± 0.20 and 4.00 ± 2.69 in comparison with 60Co γ-rays. Conclusion The dose-response curves of carbon ions-induced dic + r, MN and NPB were constructed. These results could be helpful to improve radiation risk assessment and dose estimation after exposed to carbon ions irradiation.

Collaborative efforts are needed among the scientific community to advance the adverse outcome pathway concept in areas of radiation risk assessment

Disease prevention and prediction have led to the generation of phenotypically based methods for deriving the limits of safety across toxicological disciplines. In the ionizing radiation field, human data has formed the basis of the linear-no-threshold (LNT) model for risk estimates. However, uncertainties around its accuracy at low doses and low dose-rates have led to passionate debates on its effectiveness to derive radiation risk estimates under these conditions. Concerns arise from the linear extrapolation of data from high doses to low doses, below 0.1 Gy where there is considerable variability in the scientific literature. Efforts to address these controversies have led to a mountain of mechanistic data to improve the understanding of molecular and cellular effects related to phenotypic changes. These data provide fragments of information that have yet to be combined and used effectively to improve modeling, reduce uncertainties, and update radiation protection approaches. This paper suggests a better consolidation of mechanistic research may serve to guide priority research and facilitate translation to risk assessment. An effective approach that may be implemented is the organization of data using the adverse outcome pathway (AOP) framework, a programme that has been launched by the Organization for Economic Cooperation and Development in the chemical toxicology field. The AOP concept has proved beneficial to human health and ecological toxicological fields, demonstrating possibilities for better linkages of mechanistic data to phenotypic effects. A similar approach may be beneficial to the field of radiation research. However, for this to work effectively, collaborative efforts are needed among the scientific communities in the area of AOP development and documentation. Studies will need to be evaluated, re-organized and integrated into AOPs. Here, details of the AOP approach and areas it could support in the radiation field are discussed. In addition, challenges are highlighted and steps to integration are outlined. Organizing studies in this manner will facilitate a better understanding of our current knowledge in the radiation field and help identify areas where more focused work can be undertaken. This will, in turn, allow for improved linkage of mechanistic data to human relevance and better support radiation risk assessments.

Радиационный риск и вероятностный анализ безопасности третьего уровня объектов использования атомной энергии

The paper considers the current state in the field of level 3 probabilistic safety assessment (PSA Level 3) of nuclear facilities. The issues on rationing individual and social risks in various indus-tries and practice of legislative control in some countries are examined. Some attention is paid to the identification of acceptable risk level and features of radiation risk perception. The paper ad-dresses possibilities of use of PSA Level 3 methodology for radiation risk assessment. We pro-pose a practical approach to quantify specific features that may affect individual, collective and social radiation-associated cancer risks at the initial stage of severe radiation accidents at nuclear power plants. PSA Level 3 capacities are demonstrated on the example of individual and social radiation risks assessment at the initial stage of a severe accident at a model nuclear power plant. When performing numerical simulations of the consequences of the accident of such type with the program developed at the Nuclear Safety Institute of the Russian Academy of Sciences, the nuclide composition of the emission is similar to one of the emissions during the Fukushima accident, and the distribution of population density and weather conditions correspond to real values in Fukushima Prefecture. We evaluated the effectiveness of various options for protective countermeasures based on the results of risk assessments. We have shown that the PSA Level 3 methodology allows us to obtain information about the risks associated with accidents at nuclear facilities in the form of standard risk-informative safety management methods. This will strength-en scientific and technical support for the processes of interaction with experts, decision-makers, the media and the public in making a wide range of decisions in the event of a threat, occurrence and elimination of the consequences of an emergency with a radiation factor.

Оценка радиационных рисков злокачественных новообразований среди населения регионов России, загрязнённых радионуклидами вследствие аварии на Чернобыльской АЭС

Some areas of the Russian Federation were contaminated with radionuclides released as a re-sult of the Chernobyl accident. The current paper clarifies some items of the previously published study based on NRER (National Radiation-Epidemiological Registry, the Registry) data. The pre-vious issue presented estimates of radiation risks of cancer incidence among the population of four the most contaminated regions of the Russian Federation: Bryansk, Kaluga, Oryol and Tula oblasts. Risks of thyroid cancer are estimated with account of screening effect. The cohort con-sisted of more than 327 thousand people resided in the contaminated areas. The average dose to the thyroid of children and adolescents was 0.174 Gy, the average dose to the thyroid of adults was 0.035 Gy. Thyroid cancer was diagnosed in 1549 members of the cohort during the follow-up period from 1991 over 2019, among them 423 cases were children and adolescents at the accident and 1126 cases were adults. Significant increase in thyroid cancer incidence was ob-served in adults exposed internally through the intake of iodine-131 at a young age. The statisti-cally significant radiation risk of thyroid cancer persists over 30 years after exposure. The risk de-creases with increasing the attained age. In people exposed to radiation before the age of 1 year and reaching the age of 20 years, the coefficient of excess relative risk of thyroid cancer (ERR/Gy) was 4.61. Radiation associated thyroid cancer is attributed to 20.6% of the cohort mem-bers exposed internally through the intake of radioiodine isotopes in their childhood and adoles-cence, and thyroid cancer from intake of radioiodine is attributed to 58% of cases exposed to ra-diation under 4 years of age. Marked screening effect (ES) was found during the disease diag-nosing, screening coefficient was 5.6 for children and 2.1 for adults. There were not attributed to radiation statistically significant risks of solid cancers, including radiation induced breast cancer in females, in the cohort of people resided in the areas contaminated with radionuclides. Radia-tion risk of leukemia was also not identified, although the average value of excess relative risk in men exceeded zero. Further observations of the cohort of persons resided in areas contaminated with radionuclides will increase the statistical power of radiation-epidemiological studies and clarify the assessment of radiation risks of human for chronic exposure at low doses.

Методика оценки радиационных рисков медицинского облучения на примере многократного прохождения компьютерной томографии

Currently the application of diagnostic imaging procedures is extended. After the COVID-19 out-break the number of radiological examinations have increased significantly. The number of re-peated radiological examinations increased as well. Although the risk of cancer from single radi-ological scanning is small, risk from multiple imaging has not been estimated yet. The develop-ment of methodology for assessment of cancer risks from multiple radiological examinations is needed. This paper presents the procedure for assessment of radiation risks from multiple radio-logical examinations of any type. The validity of the developed approach was tested on the ex-ample of assessment of lifetime attributable risk (LAR) of cancer incidence from multiple com-puted tomography (CT) examinations, the results are discussed in the paper. The authors devel-oped the method for estimating radiation detriment from multiple radiological CT scans for re-maining life years. The method is based on equivalent radiation doses to organs and tissues of a patient’s body. Tables of LARs values per dose unit for males and females within the age range 0-95 years and a step of 5 years were designed. The tables were computed for the following cancer sites: bladder, breast, colon, bone marrow, liver, lungs, esophagus, ovary, stomach, thy-roid and other solid. The authors estimated cancer risks for a female, she was exposed to radia-tion from CT scanning. The female’s risks assessed with the developed methodology were com-pared with radiation risks estimated with mathematical model ICRP (Publication 103). The com-parison showed that the difference between risks estimated with the developed method and the risks estimated with the ICRP model did not exceed 12%. In models sex and age were account-ed, medical and demographic data applicable to the Russian population were taken into account as well.

An Investigation of Natural Background Radiation and Health Risk Assessment in Kohgiluyeh and Boyer-Ahmad Province, Iran

Background: The natural radiation, which comes from the environment, is one of the most important cancer risk sources. Objectives: This study aimed to measure the natural background radiations (BRs) and estimate the annual effective dose (AED), as well as the health risks in Kohgiluyeh and Boyer-Ahmad Province, Iran. Methods: background radiations for both indoors and outdoors were measured using a Geiger-Muller detector (X5C plus) in eight cities. Five points were chosen in each city for the BR measurements, and in each point, five stations were randomly selected and measured. Results: The average outdoor and indoor dose rates were obtained 136.9 ± 12.5 and 149.3 ± 19.8 nSv.h-1, respectively. The mean AEDs for adults, children, and infants were 0.17, 0.19, and 0.22 mSv.y-1 resulting from the outdoor exposure, in that order, and these values for indoor irradiation were 0.73, 0.84, and 0.94 mSv.y-1. The percentage of excess lifetime cancer risks due to indoor exposure was 4.6% for whole populations and 3% for adults. The heritable effects risk for these groups were 0.17 and 0.073%, respectively. Conclusions: The findings of the present study indicated that the average value of BR dose rates was higher than the global value. The reason can be due to the high exposure levels of hot springs, igneous rock, and high altitudes in Kohgiluyeh and Boyer-Ahmad Province.

Translational approaches for radiation risk assessment

This special issue of the International Journal of Radiation Biology entitled Translational Approaches for Radiation Risk Assessment was inspired by two special technical sessions arranged by the D...

Assessment of Lifetime Attributable Risk for Public Health Sustainability from the Fukushima Accident

The study aimed at reassessing the radiological risk from exposure to ionizing radiation from Fukushima Daiichi nuclear power plant accident. The estimated risks from the study were compared with World Health Organization (WHO) risk assessment estimates for validity and verification. A Radiation Risk Assessment Tool (RadRAT) was used to estimate Lifetime Attributable Risks (LAR) of cancer upon exposure. All solid cancers, leukemia, and thyroid cancer risks for ages of 1, 10, and 20 years (infants, children, and adults) in 100,000 persons at exposure were estimated. For solid cancers, LAR (10−2) was estimated in a range of 0.223∼0.668 and 0.345∼1.24 for males and females, respectively, whereas the LAR (10−2) for leukemia was estimated at 0.0155∼0.055 and 0.0118∼0.0375 for males and females, respectively. LAR (10−2) for thyroid cancer ranged from 0.0722∼0.545 and 0.0369∼0.265, respectively.

Projecting thyroid cancer risk to the general public from radiation exposure following hypothetical severe nuclear accidents in Canada

A robust emergency management framework can limit radiation exposures and effectively minimise the potentially devastating consequences of a nuclear emergency. We projected thyroid cancer risk resulting from two hypothetical severe nuclear accidents occurring at the Darlington nuclear power plant (NPP) located in Ontario, Canada. Single- and multi-unit accidents were considered. A dose assessment was previously performed using the MELCOR Accident Consequences Code System. The generic criteria used to select the appropriate protective actions are described in the Ontario Provincial Nuclear Emergency Response Plan (PNERP). We hypothesised protection actions only within the 10 kilometre (km) radius of the NPP given the time sensitivity of iodine thyroid blocking. The excess risk of developing thyroid cancer was projected using the US National Cancer Institute’s radiation risk assessment tool RadRAT. We projected zero dose, and subsequently zero risk of developing thyroid cancer for people living within 10 km of the NPP, due to effective implementation of selected protective actions. Based on centreline doses, at the 12 km radius, excess childhood thyroid cancer risks for a one-year-old female as the most critical receptor were projected to be approximately 600% and 130% compared to the baseline were projected for the single- and multi-unit scenarios, respectively. The risk of developing thyroid cancer was projected to be low for adults for both scenarios. The results of this modelling study provide insights into the effectiveness of protective actions in reducing radiation-related thyroid cancer risk when considering hypothetical severe nuclear accidents. Implementation of select protective actions protects the population living near the Darlington NPP. The projected increase of developing thyroid cancer for children living beyond 10 km could potentially be eliminated with additional mitigation measures specified in the PNERP.