Minimum latency effects for cancer associated with exposures to radiation or other carcinogens.

Background: In estimating radiation-associated cancer risks a fixed period for the minimum latency is often assumed. Two empirical latency functions have been used to model latency, continuously increasing from 0. A stochastic biologically-based approach yields a still more plausible way of describing latency and can be directly estimated from clinical data.

Frequentist model averaging for analysis of dose-response in epidemiologic studies with complex exposure uncertainty.

In epidemiologic studies, association estimates of an exposure with disease outcomes are often biased when the uncertainties of exposure are ignored. Consequently, corresponding confidence intervals (CIs) will not have correct coverage. This issue is particularly problematic when exposures must be reconstructed from physical measurements, for example, for environmental or occupational radiation doses that were received by a study population for which radiation doses cannot be measured directly.

Concepts of association between cancer and ionising radiation: accounting for specific biological mechanisms.

The probability that an observed cancer was caused by radiation exposure is usually estimated using cancer rates and risk models from radioepidemiological cohorts and is called assigned share (AS). This definition implicitly assumes that an ongoing carcinogenic process is unaffected by the studied radiation exposure. However, there is strong evidence that radiation can also accelerate an existing clonal development towards cancer.

Modelling air pollution around nuclear power plants: validation of dispersion models using tracer data.

The Šoštanj exercise of the Modelling and Data for Radiological Impact Assessments I Urban Environments Working Group took advantage of a set of measurement data from a 1991 tracer experiment to test atmospheric dispersion models for emissions from point sources over complex terrain. The data set included emissions of SOfrom the stacks of the Šoštanj Thermal Power Plant in Slovenia, measurements of the SOat a number of locations in the surrounding area up to 7 km from the plant, and meteorological data from several monitoring stations, all as measured half-hour average values. Two sets of meteorological conditions were modelled: (a) a simple situation with a strong wind blowing from a point source directly towards a monitoring station; and (b) a complex situation involving a temperature inversion and convective mixing.

Assessment of doses in contaminated urban areas: modelling exercise based on Fukushima data.

State-of-the-art dose assessment models were applied to estimate doses to the population in urban areas contaminated by the Fukushima Daiichi Nuclear Power Plant accident. Assessment results were compared among five models, and comparisons of model predictions with actual measurements were also made. Assessments were performed using both probabilistic and deterministic approaches.

Modelling the atmospheric dispersion of radiotracers in small-scale, controlled detonations: validation of dispersion models using field test data.

A series of modelling exercises, based on field tests conducted in the Czech Republic, were carried out by the 'Urban' Working Groups as part of the International Atomic Energy Agency's Environmental Modelling for Radiation Safety II, Modelling and Data for Radiological Impact Assessment (MODARIA) I and MODARIA II international data compilation and model validation programmes. In the first two of these programmes, data from a series of field tests involving dispersion of a radiotracer,Tc, from small-scale, controlled detonations were used in a comparison of model predictions with field measurements of deposition. In the third programme, data from a similar field test, involving dispersion ofLa instead ofTc, were used.

Urban working groups in the IAEA's model testing programmes: overview from the MODARIA I and MODARIA II programmes.

The IAEA's model testing programmes have included a series of Working Groups concerned with modelling radioactive contamination in urban environments. These have included the Urban Working Group of Validation of Environmental Model Predictions (1988-1994), the Urban Remediation Working Group of Environmental Modelling for Radiation Safety (EMRAS) (2003-2007), the Urban Areas Working Group of EMRAS II (2009-2011), the Urban Environments Working Group of (Modelling and Data for Radiological Impact Assessments) MODARIA I (2013-2015), and most recently, the Urban Exposures Working Group of MODARIA II (2016-2019). The overarching objective of these Working Groups has been to test and improve the capabilities of computer models used to assess radioactive contamination in urban environments, including dispersion and deposition processes, short-term and long-term redistribution of contaminants following deposition events, and the effectiveness of various countermeasures and other protective actions, including remedial actions, in reducing contamination levels, human exposures, and doses to humans.

Parameter Values for Estimation of Internal Doses from Ingestion of Radioactive Fallout from Nuclear Detonations.

This paper suggests values or probability distributions for a variety of parameters used in estimating internal doses from radioactive fallout due to ingestion of food. Parameters include those needed to assess the interception and initial retention of radionuclides by vegetation, translocation of deposited radionuclides to edible plant parts, root uptake by plants, transfer of radionuclides from vegetation into milk and meat, transfer of radionuclides into non-agricultural plants and wildlife, and transfer from food and drinking water to mother's milk (human breast milk). The paper includes discussions of the weathering half-life for contamination on plant surfaces, biological half-lives of organisms, food processing (culinary factors), and contamination of drinking water.

A Methodology for Calculation of Internal Dose Following Exposure to Radioactive Fallout from the Detonation of a Nuclear Fission Device.

The purpose of this paper is to provide a methodology for the calculation of internal doses of radiation following exposure to radioactive fallout from the detonation of a nuclear fission device. Reliance is on methodology previously published in the open literature or in reports not readily available, though some new analysis is also included. Herein, we present two methodologic variations: one simpler to implement, the other more difficult but more flexible.

A Methodology for Estimating External Doses to Individuals and Populations Exposed to Radioactive Fallout from Nuclear Detonations.

A methodology of assessment of the doses from external irradiation resulting from the ground deposition of radioactive debris (fallout) from a nuclear detonation is proposed in this paper. The input data used to apply this methodology for a particular location are the outdoor exposure rate at any time after deposition of fallout and the time-of-arrival of fallout, as indicated and discussed in a companion paper titled "A Method for Estimating the Deposition Density of Fallout on the Ground and on Vegetation from a Low-yield Low-altitude Nuclear Detonation." Example doses are estimated for several age categories and for all radiosensitive organs and tissues identified in the most recent ICRP publications.

A Method for Estimating the Deposition Density of Fallout on the Ground and on Vegetation from a Low-yield, Low-altitude Nuclear Detonation.

This paper describes a relatively simple model developed from observations of local fallout from US and USSR nuclear tests that allows reasonable estimates to be made of the deposition density (activity per unit area) on both the ground and on vegetation for each radionuclide of interest produced in a nuclear fission detonation as a function of location and time after the explosion. In addition to accounting for decay rate and in-growth of radionuclides, the model accounts for the fractionation (modification of the relative activity of various fission and activation products in fallout relative to that produced in the explosion) that results from differences in the condensation temperatures of the various fission and activation products produced in the explosion. The proposed methodology can be used to estimate the deposition density of all fallout radionuclides produced in a low yield, low altitude fission detonation that contribute significantly to dose.

Dose Estimation for Exposure to Radioactive Fallout from Nuclear Detonations.

In recent years, the prospects that a nuclear device might be detonated due to a regional or global political conflict, by violation of present nuclear weapons test ban agreements, or due to an act of terrorism, has increased. Thus, the need exists for a well conceptualized, well described, and internally consistent methodology for dose estimation that takes full advantage of the experience gained over the last 70 y in both measurement technology and dose assessment methodology. Here, the models, rationale, and data needed for a detailed state-of-the-art dose assessment for exposure to radioactive fallout from nuclear detonations discussed in five companion papers are summarized.

Fluoroscopy X-Ray Organ-Specific Dosimetry System (FLUXOR) for Estimation of Organ Doses and Their Uncertainties in the Canadian Fluoroscopy Cohort Study.

As part of ongoing efforts to assess lifespan disease mortality and incidence in 63,715 patients from the Canadian Fluoroscopy Cohort Study (CFCS) who were treated for tuberculosis between 1930 and 1969, we developed a new FLUoroscopy X-ray ORgan-specific dosimetry system (FLUXOR) to estimate radiation doses to various organs and tissues. Approximately 45% of patients received medical procedures accompanied by fluoroscopy, including artificial pneumothorax (air in pleural cavity to collapse of lungs), pneumoperitoneum (air in peritoneal cavity), aspiration of fluid from pleural cavity and gastrointestinal series. In addition, patients received chest radiographs for purposes of diagnosis and monitoring of disease status.

Estimation of Heights and Body Masses of Tuberculosis Patients in the Canadian Fluoroscopy Cohort Study for Use in Individual Dosimetry.

This paper documents the estimation of mean heights and body masses, by age and sex, used in development of organ-specific dose conversion coefficients for external radiation for a historical cohort of about 64,000 patients from the Canadian Fluoroscopy Cohort Study. Patients were exposed to repeated fluoroscopy and chest radiography examinations in the course of treatment for tuberculosis in residential medical facilities throughout Canada between 1930 and 1969. Using Canadian national survey data and extensive literature review, mean heights and masses were obtained for the White population of Canada during the time period of interest, and the differences in mean body mass between tuberculosis patients and the general population were estimated.

ProZES: the methodology and software tool for assessment of assigned share of radiation in probability of cancer occurrence.

ProZES is a software tool for estimating the probability that a given cancer was caused by preceding exposure to ionising radiation. ProZES calculates this probability, the assigned share, for solid cancers and hematopoietic malignant diseases, in cases of exposures to low-LET radiation, and for lung cancer in cases of exposure to radon. User-specified inputs include birth year, sex, type of diagnosed cancer, age at diagnosis, radiation exposure history and characteristics, and smoking behaviour for lung cancer.

Organ Doses from Chest Radiographs in Tuberculosis Patients in Canada and Their Uncertainties in Periods from 1930 to 1969.

This paper describes a study to estimate absorbed doses to various organs from film-based chest radiographs and their uncertainties in the periods 1930 to 1948, 1949 to 1955, and 1956 to 1969. Estimated organ doses will be used in new analyses of risks of cancer and other diseases in tuberculosis patients in Canada who had chest fluoroscopic and radiographic examinations in those periods. In this paper, doses to lungs, female breast, active bone marrow, and heart from a single chest radiograph in adults and children of ages 1, 5, 10, and 15 y in the Canadian cohort and their uncertainties are estimated using (1) data on the tube voltage (kV), total filtration (mm Al), tube-current exposure-time product (mA s), and tube output (mR [mA s]) in each period; (2) assumptions about patient orientation, distance from the source to the skin of a patient, and film size; and (3) new calculations of sex- and age-specific organ dose conversion coefficients (organ doses per dose in air at skin entrance).

Methods to account for uncertainties in exposure assessment in studies of environmental exposures.

Background: Accurate exposure estimation in environmental epidemiological studies is crucial for health risk assessment. Failure to account for uncertainties in exposure estimation could lead to biased results in exposure-response analyses. Assessment of the effects of uncertainties in exposure estimation on risk estimates received a lot of attention in radiation epidemiology and in several studies of diet and air pollution.

NCRP Report 181, Evaluation of the Relative Effectiveness of Low-energy Photons and Electrons in Inducing Cancer in Humans: A Critique and Alternative Analysis.

A recent report from the National Council on Radiation Protection and Measurements presents an evaluation of the effectiveness of low-energy photons and electrons, relative to higher-energy photons, in inducing cancer in humans. The objective of that evaluation was to develop subjective probability distributions of an uncertain quantity, denoted by ρ, to represent ranges of credible values of the effectiveness of five groups of low-energy radiations (L): photons at about 1.5 keV; 15 to 30 keV photons; 40 to 60 keV photons; >60 to 150 keV photons; and electrons from beta decay of tritium (H).

Probability Distribution of Dose and Dose-Rate Effectiveness Factor for use in Estimating Risks of Solid Cancers From Exposure to Low-Let Radiation.

This paper presents an analysis to develop a subjective state-of-knowledge probability distribution of a dose and dose-rate effectiveness factor for use in estimating risks of solid cancers from exposure to low linear energy transfer radiation (photons or electrons) whenever linear dose responses from acute and chronic exposure are assumed. A dose and dose-rate effectiveness factor represents an assumption that the risk of a solid cancer per Gy at low acute doses or low dose rates of low linear energy transfer radiation, RL, differs from the risk per Gy at higher acute doses, RH; RL is estimated as RH divided by a dose and dose-rate effectiveness factor, where RH is estimated from analyses of dose responses in Japanese atomic-bomb survivors. A probability distribution to represent uncertainty in a dose and dose-rate effectiveness factor for solid cancers was developed from analyses of epidemiologic data on risks of incidence or mortality from all solid cancers as a group or all cancers excluding leukemias, including (1) analyses of possible nonlinearities in dose responses in atomic-bomb survivors, which give estimates of a low-dose effectiveness factor, and (2) comparisons of risks in radiation workers or members of the public from chronic exposure to low linear energy transfer radiation at low dose rates with risks in atomic-bomb survivors, which give estimates of a dose-rate effectiveness factor.