MJP Risk Assessment Inc.

Denver, CO, United States

MJP Risk Assessment Inc.

Denver, CO, United States
Time filter
Source Type

Beck H.L.,New York | Till J.E.,Risk Assessment Corporation | Grogan H.A.,Cascade Scientific Inc. | Aanenson J.W.,Freeman Inc. | And 3 more authors.
Radiation Research | Year: 2017

Both red bone marrow and male breast doses with associated uncertainty have been reconstructed for a 1,982-person subset of a cohort of 114, 270 military personnel (referred to as "atomic veterans") who participated in U.S. atmospheric nuclear weapons testing from 1945 to 1962. The methods used to calculate these doses and corresponding uncertainty have been reported in detail by Till et al. in an earlier publication. In this current article we report the final results of those calculations. These doses are being used in a case-cohort design epidemiological investigation of leukemia and male breast cancer. This cohort of atomic veterans is one component in a broader-scope study of approximately one million U.S. persons designed to investigate risk from chronic low-dose radiation exposure. Doses to the atomic veterans in this sub-cohort were relatively low, with approximately two-thirds receiving red bone marrow doses <5 mGy and only four individuals receiving a red bone marrow dose >50 mGy. The average red bone marrow dose for members of the sub-cohort was 5.9 mGy. Doses to male breast were approximately 20% higher than red bone marrow doses. The uncertainty in the estimated doses was relatively low, considering relevant personnel dosimetry was available for only about 25% of the subjects, and most of the doses were reconstructed from film badges worn by co-workers or from the individual's military record and military unit activities. The average coefficient of variation for the individual dose estimates was approximately 0.5, comparable to the uncertainty in doses estimated for the Japanese A-bomb survivors. Although the reconstructed red bone marrow doses were about 36% lower on average than the conservative doses previously estimated by the military for compensation, the overall correlation was quite good, suggesting that the estimates of doses from external exposure by the military for all ∼115,000 cohort members could be adjusted appropriately and used in further epidemiological analyses. © 2017 by Radiation Research Society.

Skryabin A.M.,The Republican Research Center for Radiation Medicine and Human Ecology | Drozdovitch V.,U.S. National Cancer Institute | Belsky Y.,The Republican Research Center for Radiation Medicine and Human Ecology | Leshcheva S.V.,The Republican Research Center for Radiation Medicine and Human Ecology | And 4 more authors.
Radiation Protection Dosimetry | Year: 2010

This paper aims to determine the thyroid volumes in children and teenagers living in Gomel and Mogilev Oblasts, which are the areas of Belarus that were most affected by the Chernobyl accident. Results of thyroid volume measurements performed in 1991-1996 by the Sasakawa Memorial Health Foundation were used to evaluate the variation by age of the thyroid volumes for girls and boys aged from 5 to 16 y. Thyroid volumes for age groups without measurements were also estimated. For a given age and gender, the differences between children from Gomel and Mogilev Oblasts do not exceed 12 %, which is relatively small when the variability of individual values is considered. For children of a given age, the individual values show a variability characterised by geometric standard deviation (GSD) of 1.25-1.4. Values of thyroid mass that were derived from the measured thyroid volumes are being used within the framework of the on-going Belarusian-American cohort study of thyroid cancer and other thyroid diseases after the Chernobyl accident to estimate with more accuracy the thyroid doses that were received by the cohort members. Published by Oxford University Press 2010.

Drozdovitch V.,U.S. National Cancer Institute | Khrutchinsky A.,Institute for Nuclear Problems | Kukhta T.,National Academy of Sciences of Belarus | Luckyanov N.,U.S. National Cancer Institute | And 5 more authors.
Journal of Environmental Radioactivity | Year: 2013

Results of all available meteorological and radiation measurements that were performed in Belarus during the first three months after the Chernobyl accident were collected from various sources and incorporated into a single database. Meteorological information such as precipitation, wind speed and direction, and temperature in localities were obtained from meteorological station facilities. Radiation measurements include gamma-exposure rate in air, daily fallout, concentration of different radionuclides in soil, grass, cow's milk and water as well as total beta-activity in cow's milk. Considerable efforts were made to evaluate the reliability of the measurements that were collected. The electronic database can be searched according to type of measurement, date, and location. The main purpose of the database is to provide reliable data that can be used in the reconstruction of thyroid doses resulting from the Chernobyl accident. © 2012.

Chumak V.,National Research Center for Radiation Medicine | Drozdovitch V.,U.S. National Cancer Institute | Kryuchkov V.,Burnasyan Federal Medical Biophysical Center | Bakhanova E.,National Research Center for Radiation Medicine | And 10 more authors.
Health Physics | Year: 2015

This paper describes dose reconstruction for a joint Ukrainian-American case-control study of leukemia that was conducted in a cohort of 110,645 male Ukrainian cleanup workers of the Chornobyl (Chernobyl) accident who were exposed to various radiation doses over the 1986-1990 time period. Individual bone-marrow doses due to external irradiation along with respective uncertainty distributions were calculated for 1,000 study subjects using the RADRUE method, which employed personal cleanup history data collected in the course of an interview with the subject himself if he was alive or with two proxies if he was deceased. The central estimates of the bone-marrow dose distributions range from 3.7 × 10-5 to 3,260 mGy, with an arithmetic mean of 92 mGy. The uncertainties in the individual stochastic dose estimates can be approximated by lognormal distributions; the average geometric standard deviation is 2.0. © 2015 Lippincott Williams & Wilkins.

Likhtarov I.,Ukrainian Radiation Protection Institute | Kovgan L.,Ukrainian Radiation Protection Institute | Masiuk S.,Ukrainian Radiation Protection Institute | Chepurny M.,Ukrainian Radiation Protection Institute | And 9 more authors.
Health Physics | Year: 2013

For the purpose of improving retrospective internal thyroid dose estimations for children and adolescents following the Chernobyl accident, age- and gender-dependent thyroid masses have been estimated for the children of Kiev and Zhytomyr oblasts, which are two of the most contaminated regions of Northern Ukraine. For children ages 6-16 y, the thyroid masses were based on the measurements by ultrasound of the thyroid volumes of about 60,000 children performed by the Sasakawa Memorial Health Foundation in the 1990s. For children aged 0 to 36 mo, because thyroid mass values for Ukrainian children were not found in the literature, autopsies were performed for the specific purpose of this paper. Thyroid mass values for children aged 3-5 and 17-18 y were either interpolated or extrapolated from the measured data sets. The results for children aged 6-16 y indicate that the thyroid masses of rural children are, on average, slightly higher (by about 8%) than the thyroid masses of urban children. The geometric means of the thyroid masses were estimated as 5.2 g, 9.0 g, and 15.8 g for boys and 5.2 g, 9.4 g, and 16.0 g for girls aged 5, 10, and 15 y, respectively. Those values are greater than the reference values that ICRP recommends for iodine-sufficient populations, thus reflecting the fact that the northern part of Ukraine is iodine-deficient. Copyright © 2012 Health Physics Society.

Likhtarov I.,Ukrainian Academy of Sciences | Kovgan L.,Ukrainian Academy of Sciences | Masiuk S.,Ukrainian Academy of Sciences | Talerko M.,Ukrainian Academy of Sciences | And 7 more authors.
Health Physics | Year: 2014

In collaboration with the Ukrainian Research Center for Radiation Medicine, the U.S. National Cancer Institute initiated a cohort study of children and adolescents exposed to Chornobyl fallout in Ukraine to better understand the long-term health effects of exposure to radioactive iodines. All 13,204 cohort members were subjected to at least one direct thyroid measurement between 30 April and 30 June 1986 and resided at the time of the accident in the northern parts of Kyiv, Zhytomyr, or Chernihiv Oblasts, which were the most contaminated territories of Ukraine as a result of radioactive fallout from the Chornobyl accident. Thyroid doses for the cohort members, which had been estimated following the first round of interviews, were re-evaluated following the second round of interviews. The revised thyroid doses range from 0.35 mGy to 42 Gy, with 95% of the doses between 1 mGy and 4.2 Gy, an arithmetic mean of 0.65 Gy, and a geometric mean of 0.19 Gy. These means are 70% of the previous estimates, mainly because of the use of countryspecific thyroid masses. Many of the individual thyroid dose estimates show substantial differences because of the use of an improved questionnaire for the second round of interviews. Limitations of the current set of thyroid dose estimates are discussed. For the epidemiologic study, the most notable improvement is a revised assessment of the uncertainties, as shared and unshared uncertainties in the parameter values were considered in the calculation of the 1,000 stochastic estimates of thyroid dose for each cohort member. This procedure makes it possible to perform a more realistic risk analysis. Copyright © 2014 Health Physics Society.

Drozdovitch V.,U.S. National Cancer Institute | Minenko V.,Institute for Nuclear Problems | Khrouch V.,Burnasyan Federal Medical Biophysical Center | Leshcheva S.,Republican Research Center for Radiation Medicine and Human Ecology | And 10 more authors.
Radiation Research | Year: 2013

The U.S. National Cancer Institute, in collaboration with the Belarusian Ministry of Health, is conducting a study of thyroid cancer and other thyroid diseases in a cohort of about 12,000 persons who were exposed to fallout from the Chernobyl accident in April 1986. The study subjects were 18 years old or younger at the time of exposure and resided in Belarus in the most contaminated areas of the Gomel and Mogilev Oblasts, as well as in the city of Minsk. All cohort members had at least one direct thyroid measurement made in April-June 1986. Individual data on residential history, consumption of milk, milk products and leafy vegetables as well as administration of stable iodine were collected for all cohort members by means of personal interviews conducted between 1996 and 2007. Based on the estimated 131I activities in the thyroids, which were derived from the direct thyroid measurements, and on the responses to the questionnaires, individual thyroid doses from intakes of 131I were reconstructed for all cohort members. In addition, radiation doses to the thyroid were estimated for the following minor exposure pathways: (a) intake of short-lived 132I, 133I and 132Te by inhalation and ingestion; (b) external irradiation from radionuclides deposited on the ground; and (c) ingestion intake of 134Cs and 137Cs. Intake of 131I was the major pathway for thyroid exposure; its mean contribution to the thyroid dose was 92%. The thyroid doses from 131I intakes varied from 0.5 mGy to almost 33 Gy; the mean was estimated to be 0.58 Gy, while the median was 0.23 Gy. The reconstructed doses are being used to evaluate the risk of thyroid cancer and other thyroid diseases in the cohort. © 2013 by Radiation Research Society. All rights of reproduction in any form reserved.

Drozdovitch V.,U.S. National Cancer Institute | Minenko V.,Institute for Nuclear Problems | Golovanov I.,Burnasyan Federal Medical Biophysical Center | Khrutchinsky A.,Institute for Nuclear Problems | And 8 more authors.
Radiation Research | Year: 2015

Deterministic thyroid radiation doses due to iodine-131 (131I) intake were reconstructed in a previous article for 11,732 participants of the Belarusian-American cohort study of thyroid cancer and other thyroid diseases in individuals exposed during childhood or adolescence to fallout from the Chernobyl accident. The current article describes an assessment of uncertainties in reconstructed thyroid doses that accounts for the shared and unshared errors. Using a Monte Carlo simulation procedure, 1,000 sets of cohort thyroid doses due to 131I intake were calculated. The arithmetic mean of the stochastic thyroid doses for the entire cohort was 0.68 Gy. For two-thirds of the cohort the arithmetic mean of individual stochastic thyroid doses was less than 0.5 Gy. The geometric standard deviation of stochastic doses varied among cohort members from 1.33 to 5.12 with an arithmetic mean of 1.76 and a geometric mean of 1.73. The uncertainties in thyroid dose were driven by the unshared errors associated with the estimates of values of thyroid mass and of the 131I activity in the thyroid of the subject; the contribution of shared errors to the overall uncertainty was small. These multiple sets of cohort thyroid doses will be used to evaluate the radiation risks of thyroid cancer and noncancer thyroid diseases, taking into account the structure of the errors in the dose estimates. © 2015 by Radiation Research Society.

Khrutchinsky A.,Institute for Nuclear Problems | Drozdovitch V.,U.S. National Cancer Institute | Kutsen S.,Institute for Nuclear Problems | Minenko V.,Belarusian Medical Academy of Post Graduate Education | And 4 more authors.
Applied Radiation and Isotopes | Year: 2012

This paper presents results of Monte Carlo modeling of the SRP-68-01 survey meter used to measure exposure rates near the thyroid glands of persons exposed to radioactivity following the Chernobyl accident. This device was not designed to measure radioactivity in humans. To estimate the uncertainty associated with the measurement results, a mathematical model of the SRP-68-01 survey meter was developed and verified. A Monte Carlo method of numerical simulation of radiation transport has been used to calculate the calibration factor for the device and evaluate its uncertainty. The SRP-68-01 survey meter scale coefficient, an important characteristic of the device, was also estimated in this study. The calibration factors of the survey meter were calculated for 131I, 132I, 133I, and 135I content in the thyroid gland for six age groups of population: newborns; children aged 1yr, 5yr, 10yr, 15yr; and adults. A realistic scenario of direct thyroid measurements with an "extended" neck was used to calculate the calibration factors for newborns and one-year-olds. Uncertainties in the device calibration factors due to variability of the device scale coefficient, variability in thyroid mass and statistical uncertainty of Monte Carlo method were evaluated. Relative uncertainties in the calibration factor estimates were found to be from 0.06 for children aged 1yr to 0.1 for 10-yr and 15-yr children. The positioning errors of the detector during measurements deviate mainly in one direction from the estimated calibration factors. Deviations of the device position from the proper geometry of measurements were found to lead to overestimation of the calibration factor by up to 24 percent for adults and up to 60 percent for 1-yr children. The results of this study improve the estimates of 131I thyroidal content and, consequently, thyroid dose estimates that are derived from direct thyroid measurements performed in Belarus shortly after the Chernobyl accident. © 2012.

Till J.E.,Risk Assessment Corporation | Aanenson J.W.,Freeman Inc. | Grogan H.A.,Cascade Scientific Inc. | Mohler H.J.,Bridger Scientific Inc. | Voilleque P.G.,MJP Risk Assessment Inc.
Radiation Research | Year: 2014

Methods were developed to calculate individual estimates of exposure and dose with associated uncertainties for a sub-cohort (1,857) of 115,329 military veterans who participated in at least one of seven series of atmospheric nuclear weapons tests or the TRINITY shot carried out by the United States. The tests were conducted at the Pacific Proving Grounds and the Nevada Test Site. Dose estimates to specific organs will be used in an epidemiological study to investigate leukemia and male breast cancer. Previous doses had been estimated for the purpose of compensation and were generally high-sided to favor the veteran's claim for compensation in accordance with public law. Recent efforts by the U.S. Department of Defense (DOD) to digitize the historical records supporting the veterans' compensation assessments make it possible to calculate doses and associated uncertainties. Our approach builds upon available film badge dosimetry and other measurement data recorded at the time of the tests and incorporates detailed scenarios of exposure for each veteran based on personal, unit, and other available historical records. Film badge results were available for approximately 25% of the individuals, and these results assisted greatly in reconstructing doses to unbadged persons and in developing distributions of dose among military units. This article presents the methodology developed to estimate doses for selected cancer cases and a 1% random sample of the total cohort of veterans under study. © 2014 by Radiation Research Society.

Loading MJP Risk Assessment Inc. collaborators
Loading MJP Risk Assessment Inc. collaborators