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Uranium Biokinetics Calculator Vers. B - HELP

(last updated 15 Nov 2022)

Contents:

Introduction
Calculator Panel · Control Panel · Output Chart · Result Details
Intake Parameters · Exposure Parameters
Model Description · Bibliography

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).
This version of the calculator incorporates an expansion to the ICRP model for the modeling of the excretion by hair, as proposed in [Li 2009]. This expansion is only valid for ingestion by adults.

(For the standard version of the calculator, go to Uranium Biokinetics Calculator).

For a given intake, the calculator determines the residual uranium retention in lung, kidney, and other selectable organs, and the uranium excretion in urine, faeces, and hair.
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:

No consideration of pre-existing uranium loads in the compartments - at start time all compartments are empty.

No consideration of radioactive decay (not of interest for the long half-lives of the natural uranium isotopes)

No consideration of any decay products, neither initially present, nor ingrowing

No dose calculations - this calculator only determines the biokinetic behaviour of the uranium intake in the human body. For dose calculations, see Uranium Radiation Individual Dose 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.
> See also: Study assesses uncertainty of ICRP dose factors for ingestion and inhalation of radionuclides

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 µg/(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 µg/g nephrotoxicity standard, a red square appears. The colour changes to dark red, if the value exceeds the current 3 µg/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, Urine, and Hair 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

once: single (acute) intake at time = 0
per day / per year: chronic intake at constant rate
per liter water (used for ingestion)
per kg food (used for ingestion)
per m³ air (used for inhalation)

Intake Duration (used for intake rates other than once)

Enter value and select appropriate unit (days / years), or select continuous exposure

Exposure Parameters

CAUTION: "Ingestion" and "adult" must be checked for the hair model to work properly!

Intake Route

Select one.

Type

Inhalation

Lung clearance type: Type F / M / S / other
Absorption parameters:
f_r: Fraction for rapid dissolution
s_r: Rapid dissolution rate [per day]
s_s: Slow dissolution rate [per day]

The default values for f_r, s_r, and s_s show up automatically upon selection of Type F, M, or S.
If type "other" is selected, individual values can be entered for f_r, s_r, and s_s.
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

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

Compound Absorption parameters Reference

f_r s_r [d^-1] s_s [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 CAUTION: "Ingestion" must be checked for the hair model to work properly!
Injection (directly into blood)

Summary of absorption parameter values for uranium oxides
Compound	Absorption parameters	Reference
f_r	s_r [d^-1]	s_s [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

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 µg 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 µg 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

Public (ICRP 71): 3 months, 1 year, 5 years, 10 years, 15 years, adult
CAUTION: "adult" must be checked for the hair model to work properly!
Worker (ICRP 68): adult worker

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 [µm] (used for inhalation)

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

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.
For the hair model, f₁ = 0.006 is used.

Fractional Absorption in the Gastrointestinal Tract

f₁

Public [ICRP 1995b] Worker
[ICRP 1994b]

3 mo 1 y - 15 y adult

Inhalation Type F 0.04 0.02

Type M

Type S 0.02 0.002

Ingestion most tetravalent compounds, e.g. UO₂, U₃O₈, UF₄ 0.04 0.02 0.006 0.002

all other compounds 0.02

Fractional Absorption in the Gastrointestinal Tract
	f₁
Public [ICRP 1995b]	Worker [ICRP 1994b]
3 mo	1 y - 15 y	adult
Inhalation	Type F	0.04	0.02
Type M
Type S	0.02	0.002
Ingestion	most tetravalent compounds, e.g. UO₂, U₃O₈, UF₄	0.04	0.02	0.006	0.002
all other compounds	0.02

Fractional Absorption in the Gastrointestinal Tract

f₁

WHO best judgment values
[WHO 2001]

Inhalation DU Default 0.02

Ingestion DU Default 0.002

Body weight [kg]

Fractional Absorption in the Gastrointestinal Tract
	f₁
	WHO best judgment values [WHO 2001]
Inhalation	DU Default	0.02
Ingestion	DU Default	0.002

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)

Hair growth rate [g per day]

Hair growth rate in grams per day (24h)

Model Description

ICRP 66 Respiratory Tract Model

(after [Bailey 2001])

ICRP 69 Systemic Model for Uranium

(after [Bailey 2001])

ICRP Gastro-Intestinal Tract Model

(after [Bailey 2001])

Hair model

This version of the calculator incorporates an expansion to the ICRP model for the modeling of the excretion by hair, as proposed in [Li 2009].
The model is based on uranium contents in urine and hair reported for Finnish populations consuming drinking water containing elevated concentrations of uranium. The model is applicable for chronic exposure and acute exposure events.
The model includes a new compartment for hair with transfers received from Plasma and ST₁, several changes to transfer rates between existing compartments, and a change to GI absorption f₁.

CAUTION: "Ingestion" and "adult" must be checked in the Exposure Parameters table for the hair model to work properly!

Compartment Names

Region Name ICRP Name Comment

Respiratory Tract Model

Extrathoracic

Extrathoracic Airways et1-sur ET₁ Anterior Nose

et2-sur ET₂ Posterior Nasal Passages, Larynx, Pharynx, Mouth

et2-seq ET_seq Extrathoracic Airways - Sequestration Comptmt.

ln-et LN_ET Lymphatics and Lymph Nodes, extra thoracic

Excretion excreta Environment Extrathoracic Excreta
Thoracic

Alveolar interstitial ai_1 AI₁

ai_2 AI₂

ai_3 AI₃

Bronchiolar (bb) bbe-gel bb_f, bb₁ Bronchioles - Fast Clearance

bbe-sol bb_s, bb₂ Bronchioles - Slow Clearance
bbe-seq bb_seq Bronchioles - Sequestration Comptmt.

Bronchial (BB) bbi-gel BB_f, BB₁ Bronchi - Fast clearance

bbi-sol BB_s, BB₂ Bronchi - Slow Clearance

bbi-seq BB_seq Bronchi - Sequestration Comptmt.

Lymph Nodes ln-th LN_TH 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

hair Hair

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.

Compartment Names
Region	Name	ICRP Name	Comment
Respiratory Tract Model
Extrathoracic
Extrathoracic Airways	`et1-sur`	ET₁	Anterior Nose
`et2-sur`	ET₂	Posterior Nasal Passages, Larynx, Pharynx, Mouth
`et2-seq`	ET_seq	Extrathoracic Airways - Sequestration Comptmt.
`ln-et`	LN_ET	Lymphatics and Lymph Nodes, extra thoracic
Excretion	`excreta`	Environment	Extrathoracic Excreta
Thoracic
Alveolar interstitial	`ai_1`	AI₁
`ai_2`	AI₂
`ai_3`	AI₃
Bronchiolar (bb)	`bbe-gel`	bb_f, bb₁	Bronchioles - Fast Clearance
`bbe-sol`	bb_s, bb₂	Bronchioles - Slow Clearance
`bbe-seq`	bb_seq	Bronchioles - Sequestration Comptmt.
Bronchial (BB)	`bbi-gel`	BB_f, BB₁	Bronchi - Fast clearance
`bbi-sol`	BB_s, BB₂	Bronchi - Slow Clearance
`bbi-seq`	BB_seq	Bronchi - Sequestration Comptmt.
Lymph Nodes	`ln-th`	LN_TH	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
`hair`		Hair
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

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

[Li 2009] Li W B, Karpas Z, Salonen L, et al.: A compartmental model of uranium in human hair for protracted ingestion of natural uranium in drinking water, in: Health Physics, Vol. 96, No. 6 (June), p. 636-645, 2009

[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.