Pathway: a dynamic food-chain model to predict radionuclide ingestion after fallout deposition

Journal Article · Mon Jun 01 04:00:00 EDT 1987 · Health Phys.; (United States)

DOI:https://doi.org/10.1097/00004032-198706000-00003· OSTI ID:6272858

Whicker, F W; Kirchner, T B

This manuscript describes the structure and basis for parameter values of a computerized food-chain transport model for radionuclides. The model, called PATHWAY, estimates the time-integrated ingestion intake by humans of 20 radionuclides after a single deposition from the atmosphere to the landscape. The model solves a set of linear, coupled differential equations to estimate the inventories and concentrations of radionuclides in soil, vegetation, animal tissues and animal products as a function of time following deposition. Dynamic processes in the model include foliar interception, weathering and absorption; plant growth, uptake, harvest and senescence; soil resuspension, percolation, leaching and tillage; radioactive decay; and livestock ingestion, absorption and excretion. Human dietary data are included to permit calculation of time-dependent radionuclide ingestion rates, which are then numerically integrated. The model considers seasonal changes in the biomass of vegetation and animal diets, as well as specific plowing and crop-harvest dates; thus the integrated radionuclide intakes by humans are dependent on the seasonal timing of deposition. The agricultural data base represents the arid and semi-arid regions of the western United States. The foliar deposition parameters apply to regional fallout out to a few hundred miles from nuclear detonations at the Nevada Test Site. With modification, the model could be applied to chronic or other acute releases, providing the ground deposition in Bq m-2 could be estimated. The output of PATHWAY (Bq ingested per Bq m-2 deposited) may be multiplied by the deposition and a dose conversion factor (Gy Bq-1) to yield an organ-specific dose estimate. The model may be run deterministically to yield single estimates or stochastically (''Monte-Carlo'' mode) to provide distributional output that reflects uncertainty in the output due to uncertainty in parameters.

• Research Organization: Colorado State Univ., Fort Collins
• OSTI ID: 6272858
• Journal Information: Health Phys.; (United States), Journal Name: Health Phys.; (United States) Vol. 6; ISSN HLTPA
• Country of Publication: United States
• Language: English

Related Subjects

560161* -- Radionuclide Effects
Kinetics
& Toxicology-- Man
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
COMPUTERIZED SIMULATION
CONTAMINATION
DIFFERENTIAL EQUATIONS
DOSE-RESPONSE RELATIONSHIPS
ENVIRONMENTAL TRANSPORT
EQUATIONS
FALLOUT
FOOD CHAINS
INGESTION
INTAKE
ISOTOPES
MASS TRANSFER
MATHEMATICAL MODELS
PLANTS
RADIOISOTOPES
RADIONUCLIDE KINETICS
SEASONAL VARIATIONS
SIMULATION
TIME DEPENDENCE
VARIATIONS