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Uranium Biokinetics Calculator - HELP

(last updated 5 Feb 2016)

Contents:


Introduction

This calculator performs calculations of the biokinetic behaviour of uranium intakes by inhalation, ingestion or injection (the latter being useful to assess the impact of embedded uranium shrapnel). It applies the full biokinetic model for uranium in the human body, as developed by the International Commission on Radiological Protection (ICRP).

(For another version of the calculator enlarged by compartment for hair, go to Uranium Biokinetics Calculator Vers. B).

For a given intake, the calculator determines the residual uranium retention in lung, kidney, and other selectable organs, and the uranium excretion in urine and faeces.
To facilitate comparison to existing standards, also the Specific Intake per day and kg body weight, and the uranium concentration in the kidney are shown.

The calculator also allows for the reverse operation, that is the determination of a prior intake, based on a given uranium concentration in urine, for example.

Intakes can be single (acute) intakes, chronic intakes at a constant rate over a limited period of time, or unlimited chronic intakes at a constant rate. The absorption parameters for the uranium compound of interest can be selected at the user's discretion, or ICRP's default parameters can be used.

See special instructions for offline use of this calculator.

The core of the calculator is based on portions of the ACTLITE code by K. F. Eckerman (1999). Other than formally solving the differential equations describing the biokinetic model, this software simply simulates the transport in the model in discrete time steps. While this method by definition introduces certain errors, it has been proven in [Leggett 1993] that these are negligible.

The model execution times are depending on the selected time range, and on the browser and computer used (a factor of 10 has been observed between various browser models on the same machine!). The internal time step width can be increased to decrease computing times at the expense of accuracy.
A new model run is only initiated, if the user changes a parameter that requires so. Otherwise, the new result is presented immediately.

Limitations of the calculator:

(These limitations are not inherent to the model, but they were chosen for simplification purposes.)

The parameters used for the calculation can be set in the Parameter tables. Most of these parameters show reasonable initial values which can be modified as needed.

It is the user's responsibility to enter a consistent set of parameters. The calculator does not check for inconsistencies, such as a mix of worker and public parameters, and the like. The user thus has the opportunity to verify the impact of a change in a single parameter, for example.

  Cautionary Notice:

The user should be aware that several of the parameters used in the biokinetic model are subject to variations and uncertainties, while the calculator produces only one result, without indicating these elements of uncertainty.

 


Calculator Panel

Enter a value into any one of the yellow-marked Calculator Panel fields, select the parameters and click the "Calculate" button to determine the corresponding values in the other Calculator Panel fields accordingly.

Note: Reverse operation (i.e. entry into field other than Intake) is only possible for fields that show non-zero values in forward mode (i.e. when entry made into Intake field).

These results are valid for the End Time given in the Control Panel and for the parameter settings chosen in the Parameter tables. Results for intermediate time steps can be viewed in the Result Details window.

The Specific Intake field shows the intake in micrograms per day and kg body weight (only for intake rates other than once). A red square appears, if the value exceeds WHO's current 0.6 g/(d·kg) standard.

The Kidney Concentration field shows the uranium concentration in the kidney in micrograms U per gram of kidney. If it exceeds the proposed 0.3 g/g nephrotoxicity standard, a red square appears. The colour changes to dark red, if the value exceeds the current 3 g/g standard.

Note: the value shown here is the kidney concentration at the End Time. Higher values may have occured earlier. For the maximum kidney concentration observed over the whole time period, see the Result Details window.

The Extra Region(s) pick list allows to select one or more source regions for an extra user-defined calculator field. To select more than one region, hold the CTRL-key while clicking the selections. If more than one option is selected, the retention from all selected source regions is summed up. Selection of a name shown in uppercase letters selects all associated source regions (the selection result can be verified in the Result Details window).
For the mapping of the compartments to the source regions, see the Result Details window (with Show Compartments enabled). See also table of compartment names below.

The primary units for the Faeces and Urine Excretion compartments are activity per day and cumulative activity. The other units are calculated using the conversion factors supplied in the parameter tables.

Any changes of a unit selection immediately update the values shown on the panel accordingly, as well as those shown in the Result Details window and the chart.

 


Control Panel

End Time [days / years] (affects numeric and chart output)
Time since intake (for single intake), or time since start of intake (for chronic intakes), for which the calculation results are to be shown in the Calculator Panel. The value is also used as end time for the numeric output in the Result Details window and the graphs in the chart.
Enter value and select appropriate unit days / years.
If the value entered is higher than allowable for the age range chosen, the calculator automatically switches to the next age range(s) and continues the computations with their parameters. This switching can lead to discontinuities in the output data, however.

Log. Timescale (affects numeric and chart output)
If selected, a logarithmic time scale with start time = 1 day is used for the numeric output in the Result Details window and for the chart. Otherwise, a linear time scale with increments of at least one day is used.
A logarithmic time scale is highly recommended for End Times greater than 50 days (otherwise any peaks occuring on day 1 would be leveled out).
Note: the internal time steps used to evaluate the biokinetic model (and thus the execution time of the modeling calculation) are independent from those used for display purposes.

Speed Factor
Factor, by which the computing speed is increased (and the internal time step width for the model computations is increased), compared to the original ACTLITE code.
This parameter was introduced to enable the user to select an optimum balance of computing speed and accuracy required. Value must be 1, or higher. A value of 10 still produces reasonable results.

 


Output Chart

The result is shown here in graphical form. The End Time for the graph may be higher than selected in the Control Panel. The corresponding numerical data can be found below in the Result Details Window.

If Log. Vertical Scale is checked, the graphic data is shown with a logarithmic vertical scale, covering a range as entered in the Decades field. Otherwise, a linear vertical scale is used. The settings can be changed at any time and the new chart is produced immediately.

 


Result Details window

In this text output area, major input data is repeated and the output data is presented in tabular form. The contents of the field can be highlighted and copied for further use. The settings can be changed at any time and the new output is produced immediately.
Show: Compartments
Show also compartment, transfer, and source region definitions, and initial deposition
See also table of compartment names below.
Note: In case the computations involve more than one age range, only the transfer data for the first age range is shown.

Show: Intermediate Results
Show also numerical data for intermediate time steps (as used to produce the chart). Otherwise show the result for the End Time only (as used in the Calculator Panel)

Show: Fractions of Intake (affects numeric and chart output)
If checked, the numeric output is given as fraction of the intake (for single intake), or fraction of daily intake (for chronic intake), otherwise the units selected in the Calculator Panel are used.

 


Intake Parameters

Specific Activity [Bq/g]
Specific activity of the uranium taken in, in Becquerels per gram
Select from the default values, or enter individual value.
Note: this value is only used for conversion between mass and activity units; the calculator does not consider decay.

Intake Rate
select appropriate rate

Intake Duration (used for intake rates other than once)
Enter value and select appropriate unit (days / years), or select continuous exposure

 


Exposure Parameters

Intake Route
Select one.

Type
Inhalation

Lung clearance type: Type F / M / S / other
Absorption parameters:
fr: Fraction for rapid dissolution
sr: Rapid dissolution rate [per day]
ss: Slow dissolution rate [per day]

The default values for fr, sr, and ss show up automatically upon selection of Type F, M, or S.
If type "other" is selected, individual values can be entered for fr, sr, and ss.
Note: in case of type "other", a value for f1 must also be entered manually.

Classification of uranium compounds for worker inhalation
Type[ICRP 1994b][Ansoborlo 2002]
F (fast)Most hexavalent compounds,
eg. UF6, UO2F2 and UO2(NO3)2
UO4
M (moderate)Less soluble compounds,
eg. UO3, UF4, UCl4 and most other hexavalent compounds
Ammonium diuranate (ADU),
UF4, UO3,
mixed oxide from SILVA process
S (slow)Highly insoluble compounds,
eg. UO2 and U3O8
U3O8, UO2

Summary of absorption parameter values for uranium oxides
CompoundAbsorption parametersReference
frsr [d-1]ss [d-1]
UO4 0.87 0.93 0.024 [Ansoborlo 2002]
UO3 0.75 14 0.02 [Bailey 1998]
UO3 0.92 1.4 0.0036 [Hodgson 2000]
UO3 0.71 0.28 0.0011 [Ansoborlo 2002]
U3O8 0.044 0.49 0.00035 [Hodgson 2000]
U3O8 0.046 2.3 0.0012 [Ansoborlo 2002]
U3O8 0.03 2.1 0.00038 [Ansoborlo 2002]
UO2 - non-ceramic 0.011 0.95 0.00061 [Hodgson 2000]
UO2 - ceramic 0.008 1.3 0.00026 [Hodgson 2000]
UO2 0.03 1.3 0.0015 [Ansoborlo 2002]
UO2 0.01 nd(1) 0.00049 [Ansoborlo 2002]
UO2 0.01 nd(1) 0.00058 [Ansoborlo 2002]
WHO best judgment values for DU
DU Default 0.2 1 0.001[WHO 2001]
ICRP Defaults
Type F 1 100 -[ICRP 1994b]
Type M 0.1 100 0.005
Type S 0.001 100 0.0001
(1) nd: not determined
Source after: [Bailey 2001] Table A5

Ingestion
Injection (directly into blood)
The Injection case can be used to assess the impacts of embedded uranium shrapnel. According to [Hooper 1999], uranium concentrations in urine of 4.47 and 6.40 g per g creatinine were observed with 1991 Gulf War veterans with embedded DU shrapnel in 1993/1994 and in 1995, respectively. [Leggett 2003] found that the ICRP Biokinetic Model can reasonably be applied also in the case of embedded DU shrapnel. Assuming equilibrium between DU uptake from the shrapnel to blood and DU excretion in urine, and assuming further an excretion rate of 2 g creatinine per day, a DU uptake into blood of approx. 10 g per day can be determined. This value can be entered as a continuous intake rate by injection per day.

all other compounds / most tetravalent compounds, e.g. UO2, U3O8, UF4
select accordingly

Age at Intake
Select appropriate category and/or age.
The age shown is the nominal age for each range. Computations start from this nominal age. The nominal age for adults is taken as 20 years. If the End Time selected in the Control Panel is higher than allowable for the age range chosen, the calculator automatically switches to the next age range(s) and continues the computations with their parameters.

Dependent Values
These values are initialized according to the selections made in the left part of this parameter table, but they can be overwritten as needed.
Overwriting a value applies to the current age range only. Different values can be entered for other age ranges, without the prior entered values being lost. This allows the application of user-defined parameters even for cases where the computation runs through more than one age range. Caution: any change of Intake Route or Absorption Parameters resets the default values.

AMAD [m] (used for inhalation)
Activity median aerodynamic diameter (AMAD) of particles inhaled
[ICRP 1994a] assumes by default for occupational exposure that the AMAD is 5 m, and for environmental exposure of members of the public that the AMAD is 1 m.

Breathing rate [m3/h] at [h per year / % of time] (used for inhalation with intake rate "per m3 air")
Breathing (ventilation) rate in cubic meters per hour and applicable occupancy in hours per year or percent of total time.
The default values for the breathing rate are chosen from [EPA 1997]

Water consumption rate [ltr per day] (used for ingestion with intake rate "per liter water")
The default values are taken from [EPA 1997]

Food consumption rate [kg per day] (used for ingestion with intake rate "per kg food")
The default values are taken from [EPA 1997] for grains

GI absorption f1
Fractional Absorption in the Gastrointestinal Tract
The f1 value is the fraction of an element passing through the GI tract directly absorbed to body fluids.
The ICRP default values show up automatically in this field upon selection of material type and age. If, however, lung clearance type "other" is selected, a value for f1 must be entered manually, since no default exists in this case.

Fractional Absorption in the Gastrointestinal Tract
f1
Public [ICRP 1995b]Worker
[ICRP 1994b]
3 mo1 y - 15 yadult
InhalationType F0.040.02
Type M
Type S0.020.002
Ingestionmost tetravalent compounds, e.g. UO2, U3O8, UF40.040.020.002
all other compounds0.02

Fractional Absorption in the Gastrointestinal Tract
f1
WHO best judgment values
[WHO 2001]
InhalationDU Default0.02
IngestionDU Default0.002

Body weight [kg]
Total body mass in kilograms

Kidney Mass [g]
Kidney mass in grams

Urine volume [ltr per day]
Urine volume in liters per day (24h)

Creatinine excretion in urine [g creatinine per day ]
Creatinine excretion with urine in grams per day (24h)

Faeces mass [g per day]
Faeces mass in grams per day (24h)

 

Model Description

ICRP 66 Respiratory Tract Model

ICRP 66 Respiratory Tract Model
(after [Bailey 2001])

 

ICRP 69 Systemic Model for Uranium

ICRP 69 Systemic Model for Uranium
(after [Bailey 2001])

 

ICRP Gastro-Intestinal Tract Model

ICRP GI Tract Model
(after [Bailey 2001])

 

Compartment Names
RegionNameICRP NameComment
Respiratory Tract Model
Extrathoracic
Extrathoracic Airways et1-sur ET1 Anterior Nose
et2-sur ET2 Posterior Nasal Passages, Larynx, Pharynx, Mouth
et2-seq ETseq Extrathoracic Airways - Sequestration Comptmt.
ln-et LNET Lymphatics and Lymph Nodes, extra thoracic
Excretion excreta Environment Extrathoracic Excreta
Thoracic
Alveolar interstitial ai_1AI1 
ai_2AI2 
ai_3AI3 
Bronchiolar (bb) bbe-gel bbf, bb1 Bronchioles - Fast Clearance
bbe-sol bbs, bb2 Bronchioles - Slow Clearance
bbe-seq bbseq Bronchioles - Sequestration Comptmt.
Bronchial (BB) bbi-gel BBf, BB1 Bronchi - Fast clearance
bbi-sol BBs, BB2 Bronchi - Slow Clearance
bbi-seq BBseq Bronchi - Sequestration Comptmt.
Lymph Nodes ln-th LNTH Lymphatics and Lymph Nodes, thoracic
Systemic Model
Blood blood Plasma Blood (Plasma)
blood_1 RBC Blood (red blood corpuscules)
Skeleton c_bone-s   Cortical Bone Surface
c_bone-v   Cortical Bone Volume, non-exchangeable
c_bone-v_e   Cortical Bone Volume, exchangeable
t_bone-s   Trabecular Bone Surface
t_bone-v   Trabecular Bone Volume, non-exchangeable
t_bone-v_e   Trabecular Bone Volume, exchangeable
Kidneys kidneys_1   Kidneys (urinary path)
kidneys_2   Kidneys (other kidney tissue)
Liver liver_1   Liver 1
liver_2   Liver 2
Other Soft Tissues other_0 ST0 Other Soft Tissues (rapid turnover)
other_1 ST1 Other Soft Tissues (intermediate turnover)
other_2 ST2 Other Soft Tissues (slow turnover)
Urinary Bladder ub_cont   Urinary Bladder Contents
Excretion urine   Urine
Gastro-Intestinal Tract Model
GI Tract st_cont ST Stomach Contents
si_cont SI Small Intestine Contents
uli_cont ULI Upper Large Intestine Contents
lli_cont LLI Lower Large Intestine Contents
Excretion feces   Faeces

Compartments ai_4, ai_5, ai_6 and those with suffix "_t" are used for internal computing purposes only.


Bibliography

[Ansoborlo 2002] Ansoborlo E, Chazel V, Hengé-Napoli M H, Pihet P, Rannou A, Bailey M R, Stradling N: Determination of the physical and chemical properties, biokinetics, and dose coeficients of uranium compounds handled during nuclear fuel fabrication in France, in: Health Physics Vol. 82, No. 3, p. 279-289, 2002

[Bailey 1998] Bailey M R, Guilmette R A, Jarvis N S, Roy M: Practical application of the new ICRP human respiratory tract model, in: Radiation Protection Dosimetry Vol. 79, p. 17-22, 1998

[Bailey 2001] Bailey M R, Phipps A W: The health hazards of depleted uranium munitions, ANNEXE A - Current ICRP models used to assess intakes of uranium, The Royal Society, London (UK), 2001

[Eckerman 1999] Eckerman K F, Kerr G D: Y-12 Uranium Exposure Study, Report No. ORNL/TM-1999/114, Oak Ridge National Lab., TN (US), Aug. 5, 1999, 92 p.

[EPA 1997] Exposure Factors Handbook, U.S. Environmental Protection Agency, August 1997

[Hodgson 2000] Hodgson A, Moody J C, Stradling G N, Bailey M R, Birchall A: Application of the ICRP human respiratory tract model to uranium compounds produced during the manufacture of nuclear fuel. National Radiological Protection Board, NRPB-M1156: Chilton, Oxon, 2000

[Hooper 1999] Hooper F J, Squibb K S, Siegel E L, et al.: Elevated urine uranium excretion by soldiers with retained uranium shrapnel, in: Health Physics Vol. 77, No. 5 (Nov.), p. 512-519, 1999

[ICRP 1975] Report of the Task Group on Reference Man. International Commission on Radiological Protection (ICRP). ICRP Publication 23. Pergamon Press, Oxford, England, 1975

[ICRP 1994a] Human Respiratory Tract Model for Radiological Protection. ICRP Publication 66. Annals of the ICRP Vol. 24 No. 1-3. Elsevier Science Ltd: Oxford, 1994

[ICRP 1994b] Dose coefficients for intakes of radionuclides by workers. ICRP Publication 68. Annals of the ICRP Vol. 24 No. 4. Elsevier Science Ltd: Oxford, 1994

[ICRP 1995b] Age-dependent doses to members of the public from intake of radionuclides: Part 4 Inhalation dose coefficients. ICRP Publication 71. Annals of the ICRP Vol. 25 No. 3-4. Elsevier Science Ltd: Oxford, 1995

[Leggett 1993] Leggett R W, Eckerman K F, Williams L R: An Elementary Method for Implementing Complex Biokinetic Models, in: Health Physics Vol. 64, No. 3, p.260-278, 1993

[Leggett 2003] Leggett R W, Pellmar, T C: The biokinetics of uranium migrating from embedded DU fragments, in: Journal of Environmental Radioactivity, Vol. 64, p. 205-225, 2003

[WHO 2001] Depleted uranium - Sources, Exposure and Health Effects, WHO/SDE/PHE/01.1, Department of Protection of the Human Environment, World Health Organization, Geneva, April 2001, 209 p.

See also:

 

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