skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Estimation of radionuclide ingestion: Lessons from dose reconstruction for fallout from the Nevada Test Site

Abstract

The United States conducted atmospheric testing of nuclear devices at the Nevada Test Site from 1951 through 1963. In 1979 the U.S. Department of Energy established the Off-Site Radiation Exposure Review Project to compile a data base related to health effects from nuclear testing and to reconstruct doses to public residing off of the Nevada Test Site. This project is the most comprehensive dose reconstruction project to date, and, since similar assessments are currently underway at several other locations within and outside the U.S., lessons from ORERP can be valuable. A major component of dose reconstruction is estimation of dose from radionuclide ingestion. The PATHWAY food-chain model was developed to estimate the amount of radionuclides ingested. For agricultural components of the human diet, PATHWAY predicts radionuclide concentrations and quantities ingested. To improve accuracy and model credibility, four components of model analysis were conducted: estimation of uncertainty in model predictions, estimation of sensitivity of model predictions to input parameters, and testing of model predictions against independent data (validation), and comparing predictions from PATHWAY with those from other models. These results identified strengths and weaknesses in the model and aided in establishing the confidence associated with model prediction, which is a criticalmore » component risk assessment and dose reconstruction. For fallout from the Nevada Test Site, by far, the largest internal doses were received by the thyroid. However, the predicted number of fatal cancers from ingestion dose was generally much smaller than the number predicted from external dose. The number of fatal cancers predicted from ingestion dose was also orders of magnitude below the normal projected cancer rate. Several lessons were learned during the study that are relevant to other dose reconstruction efforts.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
145484
Report Number(s):
LA-UR-94-2972; UCRL-JC-125177; CONF-9409198-1
ON: DE94018309; TRN: 94:018876
DOE Contract Number:
W-7405-ENG-36; W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: NATO scientific committee on problems of the environment (SCOPE) meeting on radiation from nuclear test explosion, Barnaul (Russian Federation), 5-10 Sep 1994; Other Information: PBD: [1994]
Country of Publication:
United States
Language:
English
Subject:
56 BIOLOGY AND MEDICINE, APPLIED STUDIES; NEVADA TEST SITE; DOSE RATES; FALLOUT; FOOD CHAINS; FUNCTIONAL MODELS; RADIATION DOSES; INGESTION; ENVIRONMENTAL EXPOSURE PATHWAY; RISK ASSESSMENT; PUBLIC HEALTH

Citation Formats

Breshears, D.D., Whicker, F.W., Kirchner, T.B., and Anspaugh, L.R.. Estimation of radionuclide ingestion: Lessons from dose reconstruction for fallout from the Nevada Test Site. United States: N. p., 1994. Web.
Breshears, D.D., Whicker, F.W., Kirchner, T.B., & Anspaugh, L.R.. Estimation of radionuclide ingestion: Lessons from dose reconstruction for fallout from the Nevada Test Site. United States.
Breshears, D.D., Whicker, F.W., Kirchner, T.B., and Anspaugh, L.R.. Thu . "Estimation of radionuclide ingestion: Lessons from dose reconstruction for fallout from the Nevada Test Site". United States. doi:. https://www.osti.gov/servlets/purl/145484.
@article{osti_145484,
title = {Estimation of radionuclide ingestion: Lessons from dose reconstruction for fallout from the Nevada Test Site},
author = {Breshears, D.D. and Whicker, F.W. and Kirchner, T.B. and Anspaugh, L.R.},
abstractNote = {The United States conducted atmospheric testing of nuclear devices at the Nevada Test Site from 1951 through 1963. In 1979 the U.S. Department of Energy established the Off-Site Radiation Exposure Review Project to compile a data base related to health effects from nuclear testing and to reconstruct doses to public residing off of the Nevada Test Site. This project is the most comprehensive dose reconstruction project to date, and, since similar assessments are currently underway at several other locations within and outside the U.S., lessons from ORERP can be valuable. A major component of dose reconstruction is estimation of dose from radionuclide ingestion. The PATHWAY food-chain model was developed to estimate the amount of radionuclides ingested. For agricultural components of the human diet, PATHWAY predicts radionuclide concentrations and quantities ingested. To improve accuracy and model credibility, four components of model analysis were conducted: estimation of uncertainty in model predictions, estimation of sensitivity of model predictions to input parameters, and testing of model predictions against independent data (validation), and comparing predictions from PATHWAY with those from other models. These results identified strengths and weaknesses in the model and aided in establishing the confidence associated with model prediction, which is a critical component risk assessment and dose reconstruction. For fallout from the Nevada Test Site, by far, the largest internal doses were received by the thyroid. However, the predicted number of fatal cancers from ingestion dose was generally much smaller than the number predicted from external dose. The number of fatal cancers predicted from ingestion dose was also orders of magnitude below the normal projected cancer rate. Several lessons were learned during the study that are relevant to other dose reconstruction efforts.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 1994},
month = {Thu Sep 01 00:00:00 EDT 1994}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • This paper provides a brief overview of the methodology developed to estimate the transport of radionuclides through agricultural ecosystems to persons of various ages, lifestyles, and geographic locations. The methodology, embodied in the computer code PATHWAY, was used to convert estimates of fallout deposition to time-dependent concentrations of radionuclides in food products, total intakes by people, and organ-specific doses from 21 radionuclides in fallout from 86 nuclear test events. A summary of model prediction uncertainties, an assessment of predictive accuracy, and a discussion of the relative importance of different exposure pathways is also provided. 14 refs.
  • The U.S. Department of Energy initiated the Radiation Exposure Review Project to provide a critical reexamination of radiation doses to people resulting from testing nuclear devices at the Nevada Test Site. One part of this effort focused on the dose resulting from the ingestion of contaminated food. The PATHWAY radionuclide transport model was developed to provide estimates of food concentrations for 20 radionuclides for each of 86 test events and 15 agricultural scenarios. These results were then used as input to the Human Ingestion model to provide dose estimates for individuals and populations in 9 western states. The model consideredmore » the life-style and age of the people, and accounted for the transport of milk between locations. Estimates of uncertainty were provided for all doses using Monte Carlo simulation techniques. Propagation of uncertainty between the PATHWAY model and the Human Ingestion model required the development of special strategies to ensure that the inherent correlations between concentrations of the radionuclides in foods were handled properly. In addition, the size of the input data base (60 megabytes), the number of cases to consider (over 30,000), and the number of Monte Carlo simulations (over 6 million) required the development of efficient and reliable methods of data access and storage while running simulations concurrently on up to 14 UNIX workstations. The problems encountered in this effort are likely to be typical of any dose reconstruction involving geographically heterogeneous environmental conditions. This paper documents the methods used to disaggregate the system to achieve computation efficiency, the methods used to propagate uncertainty through the model system, and the techniques used to manage data in a distributed computing environment. The radionuclide and age specific dose factors used in the analysis are also provided.« less
  • This paper summarizes individual and collective dose estimates for the internal organs of hypothetical yet representative residents of selected communities that received measurable fallout from nuclear detonations at the Nevada Test Site. The doses, which resulted from ingestion of local and regional food products contaminated with over 20 radionuclides, were estimated with use of the PATHWAY food-chain-transport model to provide estimates of central tendency and uncertainty. The thyroid gland received much higher doses than other internal organs and tissues. In a avery few cases, infants might have received thyroid doses in excess of 1 Gy, depending on location, diet, andmore » timing of fallout. {sup 131}I was the primary thyroid dose contributor, and fresh milk was the main exposure pathway. With the exception of the thyroid, organ doses from the ingestion pathway were much smaller (<3%) than those from external gamma exposure to deposited fallout. Doses to residents living closest to the Nevada Test Site were contributed mainly by a few fallout events; doses to more distantly located people were generally smaller, but a greater number of events provided measurable contributions. The effectiveness of different fallout events in producing internal organ doses through ingestion varied dramatically with seasonal timing of the test, with maximum dose per unit fallout occurring for early summer depositions when milk cows were on pasture and fresh, local vegetables were used. Within specific communities, internal doses differed by age, sex, and lifestyle. Collective internal dose estimates for specific geographic areas are provided.« less
  • In 1987 the US Department of Energy funded a formal, extensive monitoring program for the flora and fauna on the Nevada Test Site. The goal was to understand and record changes with time In the distribution and abundance of the plants and animals. The need to detect changes, rather than do a one-time characterization, required careful selection of parameters and the use of permanent plots to distinguish spatial from temporal variability. Repeated measurements of the same plots revealed errors and imprecision which required changes in training and data collection techniques. Interpretation of trends after several years suggested it will bemore » important to monitor not only changes, but causes of change, such as soil moisture and herbivory. Finally, the requirement for records to be available over long periods of time poses problems of archiving and publication. This report consists of viewgraphs presenting the findings of the study.« less
  • Results from a long-term (9 year) field study of the distribution of radionuclides around an underground nuclear explosion cavity at the Nevada Test Site are reviewed. The goals of this Radionuclide Migration project are to examine the rates of migration underground in various media and to determine the potential for movement, both on and off the Nevada Test Site, of radioactivity from such explosions, with particular interest in possible contamination of water supplies. Initial studies were undertaken near the site of the low-yield test Cambric, which was detonated 73 m beneath the water table in tuffaceous alluvium. Solid samples weremore » obtained from just below ground surface to 50 m below the detonation point, and water was sampled from five different regions in the vicinity of the explosion. Ten years after the test, most of the radioactivity was found to be retained in the fused debris in the cavity region and no activity above background was found 50 m below. Only tritium and {sup 90}Sr were presented in water in the cavity at levels greater than recommended concentration guides for water in uncontrolled areas. A satellite well is being used to remove water 91 m from the detonation point. During seven years (7 x 10{sup 6} m{sup 3}) of pumping, tritium, {sup 85}Kr, {sup 36}Cl, and {sup 129}I have been detected in the water. Approximately 40% of the total tritium from the cavity region has been removed by pumping at the satellite well, and the maximum in the tritium concentration is clearly defined. Use of sensitive analytical techniques has permitted measurement of the very low concentrations of {sup 36}Cl and {sup 129}I present in the water. The {sup 36}Cl peak precedes the tritiated water, possibly as a result of anion exclusion. Additional analyses are in progress to better define the shape of the {sup 129}I concentration curve.« less