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Abstract not provided.

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Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
Colorado State University and Australian Nuclear Science and Technology Organisation
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the 2015 RGC HPS Spring Technical Meeting held March 22-23, 2015 in Santa Fe, NM.
Country of Publication:
United States

Citation Formats

Kaspar, Matthew, Mat Johansen, and Alex Brandl. PU-239 ORGAN SPECIFIC DOSIMETRIC MODEL APPLIED TO NON-HUMAN BIOTA.. United States: N. p., 2015. Web.
Kaspar, Matthew, Mat Johansen, & Alex Brandl. PU-239 ORGAN SPECIFIC DOSIMETRIC MODEL APPLIED TO NON-HUMAN BIOTA.. United States.
Kaspar, Matthew, Mat Johansen, and Alex Brandl. 2015. "PU-239 ORGAN SPECIFIC DOSIMETRIC MODEL APPLIED TO NON-HUMAN BIOTA.". United States. doi:.
author = {Kaspar, Matthew and Mat Johansen and Alex Brandl},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2015,
month = 3

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  • In many cases, contaminants, such as radionuclides, can show highly localized spatial distributions in natural systems. Therefore, a key question for environmental assessment and monitoring becomes, how can these localized distributions of contaminants in the environment lead to organism exposure, and ultimately, the potential for effects to receptor biota? To address this question, an important first step is to conduct field surveys at sites of interest to map out the spatial distribution and extent of contaminants in areas that are being occupied and utilized by resident receptor biota. Work can then be conducted to establish predictive relationships between contaminant concentrationsmore » in biota tissues and those in environmental media with which biota interact, to gain an understanding of how representative ambient contaminant concentrations are of biota exposure. The objectives of this study were: - To conduct a field survey in a wetland ecosystem to characterize the spatial distribution of carbon- 14 ({sup 14}C), a radionuclide with dynamics in natural systems that can be described using a specific activity model; and - To determine whether {sup 14}C concentrations in environmental media reflect those measured in tissues of resident flora and fauna. A detailed field campaign was carried out in summer 2001 to characterize the spatial distribution and areal coverage of {sup 14}C in Duke Swamp, a wetland ecosystem on Atomic Energy of Canada Limited (AECL)'s Chalk River Laboratories (CRL) site that receives {sup 14}C through releases from an up-gradient Waste Management Area (WMA), primarily through groundwater influx. Sampling of surface vegetation (dominantly comprised of Sphagnum moss) was conducted at a total of 69 locations, with complementary sampling of air, soil, fungi, aerial insects, ground-dwelling insects, amphibians, small mammals and snakes being carried out at a subset of five locations with varying {sup 14}C concentrations. Concentrations of {sup 14}C in resident Duke Swamp biota were compared to levels measured in environmental media (including moss, soil and air) to determine whether concentrations in such media reflect animal exposure, for application in routine environmental monitoring programs on the CRL site. In general, for most types of receptor animals, {sup 14}C specific activities were found to be similar to or less than those measured in air, soil and surface vegetation at all locations sampled, suggesting that in most cases, estimates of {sup 14}C levels in animals could either be realistically or conservatively predicted based on the values measured in environmental media. In the case of fungi, receptor-to-media {sup 14}C specific activity ratios fell between 0.04 and 0.23 relative to air, between 0.03 and 0.70 relative to soil, and between 0.078 and 0.31 relative to moss. Small mammal specific activities also generally fell well below those that would be predicted based on specific activities measured in environmental media, with ratios ranging from 0.11 to 0.36 relative to air, from 0.17 to 0.85 relative to soil and from 0.21 to 0.58 relative to moss. Similar ratios were also established for snakes; however, a notable exception occurred for amphibians, a type of animal that tends to spend relatively more time in aquatic environments than the other species tested. In the case of Duke Swamp amphibians, animal-to-air {sup 14}C specific activity ratios ranged from 0.40 to 2.3, animal-to-soil ratios ranged from 0.81 to 3.4 and animal-to-moss ratios ranged from 1.5 to 2.4. These higher {sup 14}C levels in amphibians relative to the environmental media may be due to increased {sup 14}C exposure of aquatic or amphibious animals that occupy systems receiving inputs via groundwater. In such systems, {sup 14}C is incorporated in aquatic plants and animals, and later transferred to higher predatory species, such as amphibians, that consume them. Therefore, with the exception of amphibians and other aquatic receptor species, it is reasonable to estimate concentrations of {sup 14}C in receptor biota in wetland environments like Duke Swamp at CRL, based on measurements of {sup 14}C in environmental media, including air, soil and surface vegetation. In the case of Duke Swamp amphibians, environmental media concentrations could still be roughly predicted if they are multiplied by a 4-fold correction factor. In addition, our study findings also confirm that in cases where elevated {sup 14}C levels are highly localized, elevated exposures to resident biota are also highly localized. Such information is critical to the development of cost-effective environmental monitoring programs that are protective of nonhuman biota, while reducing the need to capture and euthanize animals during routine monitoring.« less
  • A quantitative kinetic clearance model for inhaled radioactive aerosols is discussed. Clearance of particles is competitive and assumed to be nonlinear. Mathematical models for calculating radiation doses to various respiratory tract tissues will be developed. The proposed model is expected to simplify calculating respiratory tract doses from bioassay data. (CBS)
  • The new respiratory tract model is based on the premise that the large differences in radiation sensitivity of respiratory tract tissues, and the wide range of doses they receive, argue for calculating specific tissue doses rather than average lung doses for radiation protection purposes. The new model is more complex than the current lung model because it describes deposition of inhaled radioactive material in the clearance from several tissues and regions of the respiratory tract and is applicable to the worldwide population of both workers and the public. 2 refs., 2 figs.
  • A task group has revised the dosimetric model of the respiratory tract used to calculate annual limits on intake of radionuclides. The revised model can be used to project respiratory tract doses for workers and members of the public from airborne radionuclides and to assess past exposures. Doses calculated for specific extrathoracic and thoracic tissues can be adjusted to account for differences in radiosensitivity and summed to yield two values of dose for the respiratory tract that are applicable to the ICRP tissue weighted dosimetry system.
  • Although the dosimetric model of the respiratory tract used in ICRP Publication 30 had not been shown to be seriously deficient for the purpose of calculating Annual Limits on Intake (ALIs) for workers, the availability of new information led the ICRP in 1984 to create a special Task Group to review the dosimetric model of the respiratory tract and, if justified, propose revisions or a new model. The Task Group directed its efforts toward improving the model used in Publication 30 rather than developing a completely new model. The objective was a model that would facilitate calculation of biologically meaningfulmore » doses; be consistent with morphological, physiological, and radiobiological characteristics of the respiratory tract; incorporate current knowledge; meet all radiation protection needs; be user friendly by not being unnecessarily sophisticated; be adaptable to development of computer software for calculation of relevant radiation doses from knowledge of a few readily measured exposure parameters; be equally useful for assessment purposes as for calculating ALIs; be applicable to all members of the world population; and consider the influence of smoking, air pollutants, and diseases of the inhalation, deposition, and clearance of radioactive particles from the respiratory tract. The model provides for calculation of a committed dose equivalent for each region, adjusted for the relative cancer sensitivity of that region, and for the summing of these to yield a committed dose equivalent for the entire respiratory tract. 3 figs.« less