SC&A’s Evaluation of 

ORAUT-OTIB-0049, 

Revision 02, “Estimating 

Doses for Plutonium 

Strongly Retained in the 

Lung”

Rose Gogliotti, MS

Advisory Board on Radiation and Worker 

Heath, Subcommittee for Procedure Reviews

November 3, 2021
Timeline

◆ Revision 01 PC-2 issued November 29, 2010

◆ Revision 02 issued September 1, 2020

– Total rewrite

◆ Board tasked SC&A with review of revision 02 on 

February 18, 2021

– SC&A issued review October 7, 2021

2
Purpose of OTIB-0049

◆ Specifies a biokinetic model to evaluate the 

deposition, retention, and removal of inhaled very 

insoluble (type super S or type SS) plutonium 

particulates from the respiratory tract

3
What is type Super S plutonium?

◆ Historical studies have shown that, in some 

instances, the rate of removal of plutonium from 

the lung was slower than predicted by type S

– Organ doses over time were underpredicted by type S

◆ Phenomenon known as type Super S (SS) 

4
NIOSH’s new approach

◆ Combines guidance from ICRP 130, ICRP 67, 

and ICRP 30 

◆ “hybrid” model introduces modified dissolution 

parameters that lower predicted urinary excretion 

– fraction of inhaled material absorbed by blood relatively 

rapidly (Fr) = 0.001029

– rate at which material is absorbed (Sr) = 100.1

– remaining fraction of material (1 − Fr) absorbed at 

slower rate (Ss) = 1×10-6

5
Observation 1

ICRP has published 

updated biokinetic 

models appropriate 

for type SS 

plutonium 

SC&A suggests: 

1. ICRP 141 should be used to determine 

the Pu-239 dioxide absorption 

parameters, and the absorption 

parameters from the alimentary tract 

should be used for all other type SS 

plutonium dioxides. 

2. The ICRP 141 Sr value of 0.4 d-1, the rate 

at which the material is absorbed, should 

be used.

3. The dosimetric data from ICRP 141 

should be used to determine the 

parameters for the inhalation of 

Pu-239 dioxide for all type SS plutonium. 

These data should also be used to 

determine the parameters for the dose 

per activity content in the lungs and in 

daily excretion of urine and feces.

6
Comparison of parameters

7

Parameter description ORAUT-0049

rev. 02 value

ICRP 141 

value

Fraction of rapidly dissolved material (Fr

) 0.001029 0.004

Rapid dissolution rate (Sr

) 100.1 0.4

Slow dissolution rate (Ss) 1x10-6 1x10-5

Fraction of dissolved material retained in 

a bound state (Fb)

Not evaluated 

(default value in 

IDOT_SS is 0)

0.002

Bound dissolution rate (Sb)

Not evaluated 

(default value in 

IDOT_SS is 0)

0

GI tract fraction (f1) or fraction to the 

alimentary tract (fA) 1x10-5 2x10-6
Observation 2

Section 4.1 of 

OTIB-0049, rev. 02, 

lists an incorrect Fr

value

◆ The Fr value calculated by 

NIOSH, listed in attachment A 

of OTIB-0049, rev. 02, and 

used in the IDOT_SS tool, is 

0.001029. Section 4.1 of 

OTIB-0049 erroneously 

identifies the Fr values of 

0.001209. 

8
Observation 3

NIOSH failed to 

consider long-term 

binding of 

plutonium

◆ There is no reference to longterm binding of plutonium in 

OTIB-0049.

◆ ICRP 141 identifies in some 

instances that some dissolved 

material appears to be 

attached to lung structural 

components and is removed 

only by absorption to blood.

◆ ICRP assigned the value of 

0.2% for the bound fraction (fb) 

to the whole respiratory tract, 

(except for the ET1 region).

9
Observation 4

Revision 02 has 

not used ICRP 141 

updates to the 

ICRP 67 systemic 

model

◆ ICRP Publication 141 updates 

the plutonium model of ICRP 

Publication 67.

◆ OTIB-0049, revision 02, uses 

the ICRP Publication 67 

systemic model instead of the 

updated model.

◆ Excretion rates using the two 

models should be compared.

10
Observation 5

NIOSH should 

consider using the 

OIR Data Viewer 

software

◆ SC&A suggests that the 

Occupational Intakes of 

Radionuclides (OIR) Data 

Viewer software (the electronic 

annex to the OIR series), 

ICRP 134, ICRP 137, and 

ICRP 141 should be used to 

calculate dose per intake 

coefficients, dose per content 

functions, and reference 

bioassay functions for Pu-239 

dioxides (type SS plutonium).

11
Comparison of methods

Revision 01

◆ Did not actually model 

type SS

◆ Applied CF to modeled 

type S to account for 

Super S

◆ Intakes from urinary 

excretion modeled using 

factor of 4 approach 

implemented through 

OTIB-0049 Tool

Revision 02

◆ New model for type SS

◆ No adjustment factors

◆ Uses ICRP guidance and 

historical intakes to 

develop new dose and 

intake parameters

◆ Minimal guidance on 

application to a DR case

12
Observation 6

OTIB-0049 lacks 

information about 

its application to 

dose 

reconstruction

◆ SC&A found limited guidance 

instructing dose reconstuctors 

how to apply the guidance to a 

DR. 

◆ Unambiguous guidance is 

necessary to ensure cases are 

processed consistently.

◆ OTIB-0049 should specify that 

a tool has been developed for 

the implementation of 

guidance.

13
IDOT user interface

◆ Internal Dosimetry Tool

◆ Replaces old IMBA and 

OTIB-0049 tool

◆ Similar to IMBA interface

– Main

– Bio

– Annual Dose

– Committed Dose

14
IDOT documentation

◆ Additional documentation

– User Guide

– DCAS-RPT-007

– IDOT Bioassay and Dose Benchmark

◆ SC&A confirmed tool is functioning 

◆ SC&A did not review supporting files in detail or perform 

independent benchmarking/validation calculations

15
Comparison of doses (rem) from 5-year 

100dpm/d chronic intake of Pu-239

16
Analysis of two cases using typical 

DR data

◆ Case A: short exposure period and long latent period

◆ Case B: long exposure period and short latent period

◆ Derived IDOT_SS intakes and organ doses using typical 

DR bioassay data

◆ Derived IMBA intakes and used revision 01 PC-2 of 

OTIB-0049 (2010; “Revision 01 (2010)”) to derive organ 

doses using the same typical DR bioassay data

◆ Compared the organ doses derived by the two methods

17
Analysis of Case A bioassay data –

chronic Pu-239

18

Testes

Ovaries

Liver

Bone surfaceUterusSkin

RBM

Stomach

LLI

LN(TH)

Lung

AI

BB

ET1

TBBAS-BBBAS

ET2

LN(ET)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Dose ratio (IDOT_SS/Rev 01)

Organ
Analysis of Case A bioassay data –

acute Pu-239

19

Skin

Testes

Ovaries

Liver

Bone surfaceUterus

RBM

Stomach

LLI

LN(TH)

Lung

AI

ET1

BB

TBBAS-BBBAS

ET2

LN(ET)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Dose ratio (IDOT_SS/Rev 01)

Organ
Analysis of Case B bioassay data –

chronic Pu-239

20

Liver

Testes

Ovaries

Bone surface

Thyroid

Skin

RBM

Kidney

Lung

BB

AI

LN(TH)

ET1

LLI

TBBAS-BBBAS

ET2

LN(ET)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Dose ratio (IDOT_SS/Rev 01)

Organ
Analysis of Case B bioassay data –

chronic Am-24

21

Liver

Brain

Skin

Gall bladder

Thyroid

Muscle

Pancreas

Adrenals

Breast

RBM

Heart wall

Stomach

Bone surface

Small intestine

Testes

Ovaries

Kidney

LN(TH)

AI

Lung

LLI

LN(ET)

TBBAS-BBBAS

ET2

ET1

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

Dose ratio (IDOT_SS/Rev 01)

Organ
Results of analysis of two cases

◆ Doses to the thoracic and extrathoracic regions 

can be greater using the IDOT_SS method 

compared to using the Revision 01 (2010) 

method 

◆ Doses to the systemic organs are generally less 

using the IDOT_SS method compared to using 

the Revision 01 (2010) method

22
Observation 7

A program 

evaluation report 

may be required

◆ NIOSH should specify if the dose 

results using the methods in 

revision 02 have been compared to 

the doses derived using the former 

methods for assessing intakes of 

type SS plutonium. 

◆ It is important to establish if there are 

situations where the doses derived 

using revision 02 are greater than 

those derived using the previous 

OTIB-0049 methods, which may 

necessitate a PER.

◆ Preliminary analysis indicates organs 

in the thoracic and extrathoracic 

regions may receive higher doses 

using revision 02 in some instances.

23
Finding 1

IDOT_SS does not 

provide annual 

doses for the 

urinary bladder

◆ SC&A found that, while 

IDOT_SS would calculate a 

total committed dose to the 

urinary bladder, the results 

returned for the annual doses 

to the urinary bladder were 

“N/A.”

24
Comparison of bioassay projections 

for the HAN-1 case

25

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1976 1979 1982 1984 1987 1990

Pu Excretion Rate (Bq/d)

Year

Real Data Calculated OTIB-0049 Calculated ICRP141
Observation 8

ICRP 

Publication 141 

parameters appear 

to be more 

claimant favorable

◆ Analysis of the HAN-1 case 

indicates that use of the 

ICRP 141-derived absorption 

parameters results in higher 

doses to all evaluated organs 

when compared to the 

OTIB-0049-derived absorption 

parameters. 

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Questions?

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