Draft

Advisory Board on Radiation and Worker Health

National Institute for Occupational Safety and Health 

SC&A’s Evaluation of ORAUT-OTIB-0049, Revision 02, 

“Estimating Doses for Plutonium Strongly Retained

in the Lung” 

Contract No. 75D30119C04183

Document No. SCA-TR-2021-PR049, Revision 0

Prepared by

Joyce Lipsztein, PhD, CHP

Bob Barton, CHP

Rose Gogliotti, MS

Ron Buchanan, PhD, CHP

SC&A, Inc.

2200 Wilson Blvd., Suite 300

Arlington, VA 22201-3324

October 7, 2021

DISCLAIMER

This is a working document provided by the Centers for Disease Control and Prevention (CDC) 

technical support contractor, SC&A for use in discussions with the National Institute for 

Occupational Safety and Health (NIOSH) and the Advisory Board on Radiation and Worker 

Health (ABRWH), including its Working Groups or Subcommittees. Documents produced by 

SC&A, such as memorandum, white paper, draft or working documents are not final NIOSH or 

ABRWH products or positions, unless specifically marked as such. This document prepared by 

SC&A represents its preliminary evaluation on technical issues.

NOTICE: This document has been reviewed to identify and redact any information that is 

protected by the Privacy Act 5 U.S.C. § 552a and had been cleared for distribution. 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 2 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

SC&A, Inc. technical support for the Advisory Board on Radiation and Worker Health’s review of 

NIOSH dose reconstruction program 

Document title SC&A’s Evaluation of ORAUT-OTIB-0049, Revision 02, “Estimating 

Doses for Plutonium Strongly Retained in the Lung” 

Document number SCA-TR-2021-PR049

Revision number 0 (Draft)

Supersedes NA

Effective date October 7, 2021

Task manager Kathy Behling [signature on file]

Project manager Bob Barton, CHP [signature on file]

Document reviewer(s) Kathy Behling [signature on file] 

Record of revisions

Revision number Effective date Description of revision

0 (Draft) 10/7/2021 Initial issue
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 3 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Table of Contents

List of Tables................................................................................................................... 4

List of Figures.................................................................................................................. 4

Abbreviations and Acronyms........................................................................................... 5

1 Introduction and Background.................................................................................... 7

2 Overview of ORAUT-OTIB-0049, Revision 02.......................................................... 8

3 SC&A’s Evaluation of ORAUT-OTIB-0049, Revision 02 ........................................ 11

3.1 Evaluation of biokinetic model used in ORAUT-OTIB-0049............................. 11

3.2 Evaluation of attachment A, “Determination of solubility parameters for Super S 

model”.............................................................................................................. 12

3.3 Evaluation of the long-term absorption parameter........................................... 13

3.4 Evaluation of the short-term absorption parameters ........................................ 14

3.5 Binding of plutonium in the respiratory tract..................................................... 15

3.6 Systemic distribution, retention, and excretion of plutonium ............................ 15

4 Application of OTIB-0049 and IDOT_SS to Dose Reconstructions......................... 17

4.1 Overview of IDOT_SS tool and user guide ...................................................... 17

4.2 Comparison of doses derived using IDOT_SS for OTIB-0049, revision 02, with 

doses using previous OTIB-0049 guidance ..................................................... 18

4.3 Comparison of absorption parameters between OTIB-0049, revision 02, and 

ICRP Publication 141....................................................................................... 30

5 Summary of SC&A’s Evaluation of OTIB-0049, Revision 02 .................................. 36

6 References ............................................................................................................. 38
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 4 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

List of Tables

Table 1. Case A chronic Pu-239 IDOT_SS and Revision 01 (2010) derived doses and 

dose ratios..................................................................................................................... 23

Table 2. Case A acute Pu-239 IDOT_SS and Revision 01 (2010) derived doses and 

dose ratios..................................................................................................................... 25

Table 3. Case B chronic Pu-239 IDOT_SS and Revision 01 (2010) derived doses and 

dose ratios..................................................................................................................... 27

Table 4. Case B chronic Am-241 IDOT_SS and Revision 01 (2010) derived doses and 

dose ratios..................................................................................................................... 28

Table 5. Comparison of ORAUT-0049, revision 02, and ICRP Publication 141 

absorption parameters .................................................................................................. 30

Table 6. Comparison of organ-specific committed doses for the HAN-1 case .............. 31

List of Figures

Figure 1.Comparisons of acute Pu-239 intake of 1,000 dpm for the Revision 01 (2010) 

and revision 02 methods ............................................................................................... 20

Figure 2. Comparisons of the chronic Pu-239 intake of 100 dpm/d for 5 years for the 

Revision 01 (2010) and revision 02 methods ................................................................ 21

Figure 3. Case A ratio of IDOT_SS to Revision 01 (2010) derived total type SS Pu-239 

chronic doses ................................................................................................................ 24

Figure 4. Case A ratio of IDOT_SS to Revision 01 (2010) derived total type SS Pu-239 

acute doses................................................................................................................... 26

Figure 5. Case B ratio of IDOT_SS to Revision 01 (2010) derived total type SS chronic 

Pu-239 doses ................................................................................................................ 28

Figure 6. Case B ratio of IDOT_SS to Revision 01 (2020) derived total chronic type 

Am-241 doses ............................................................................................................... 29

Figure 7. Comparison of bioassay projections for the HAN-1 case using absorption 

parameters derived in OTIB-0049 and ICRP 141.......................................................... 33

Figure 8. Comparison of bioassay projections for the HAN-1 case using absorption 

parameters derived in OTIB-0049 and ICRP 141 (y-axis truncated at 0.006 Bq/d)....... 34

Figure 9. Comparison of bioassay projections for the HAN-1 case using absorption 

parameters derived in OTIB-0049 and ICRP 141 (y-axis in logarithmic form)............... 35
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 5 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Abbreviations and Acronyms

ABRWH Advisory Board on Radiation and Worker Health 

AF absorbed fraction 

AI alveolar-interstitial

ALV alveolar

Am americium

BB bronchial (region) 

BBBAS tissue in the bronchial region through which basal cells are distributed

Bq/d becquerel per day 

d-1 per day 

DOE U.S. Department of Energy 

dpm disintegrations per minute 

dpm/d disintegrations per minute per day 

DR dose reconstruction 

ET extrathoracic

ET1 anterior nasal passage

ET2 posterior nasal passage

f1 GI tract fraction

fA absorption from the alimentary tract

fb bound fraction 

Fr fraction of inhaled material absorbed by blood relatively rapidly

GI gastrointestinal

Gy gray 

HRTM human respiratory tract model

ICRP International Commission on Radiological Protection

IDOT_SS Internal Dose Tool, Super S 

IMBA Integrated Modules for Bioassay Analysis

INT interstitial

LLI lower large intestine

LN(ET) lymph nodes associated with the extrathoracic region

LN(TH) lymph nodes associated with the thoracic region

Mayak Mayak Production Association
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 6 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

NIOSH National Institute for Occupational Safety and Health

OIR Occupational Intakes of Radionuclides

ORAUT Oak Ridge Associated Universities Team

OTIB ORAUT technical information bulletin

Pu plutonium

RBM red bone marrow 

RFP Rocky Flats Plant

SEE specific effective energy

Sb bound dissolution rate 

Sr rate at which the material is absorbed 

Ss slow absorption rate 

SS Super S 

TBBAS tissue in the thoracic region through which basal cells are distributed 

TBSEC tissue in the thoracic region

ULI upper large intestine

USTUR United States Transuranium and Uranium Registries
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 7 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution.

1 Introduction and Background

On February 18, 2021, the Advisory Board on Radiation and Worker Health tasked SC&A with 

a technical review of ORAUT-OTIB-0049, revision 02, “Estimating Doses for Plutonium 

Strongly Retained in the Lung,” issued September 1, 2020 (NIOSH, 2020; “OTIB-0049”). This 

revision was issued to update the guidance for reconstructing intakes and doses from type Super 

S (SS) plutonium. The model couples the International Commission on Radiological Protection

(ICRP) Publication 130 (ICRP, 2015) human respiratory tract model (HRTM) with the ICRP 

Publication 67 (ICRP, 1993) systemic model and Publication 30 (ICRP, 1979) gastrointestinal

(GI) tract model. OTIB-0049, revision 02, constitutes a complete rewrite of the guidance 

document.

This report presents SC&A’s evaluation of the technical approach, methods used, and 

documentation in OTIB-0049, revision 02. SC&A notes that updated dose evaluation guidance 

has been issued by the ICRP and the appropriate mechanisms can be automated into the dose 

reconstructor’s existing tools, which would ensure consistency with current guidance and 

methodologies (ICRP, 2019).
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 8 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution.

2 Overview of ORAUT-OTIB-0049, Revision 02

The following is a brief outline of OTIB-0049:

• Purpose – Specifies a biokinetic model that merges guidance from ICRP Publication 130 

with Publications 67 and 30 to evaluate the deposition, retention, and removal of inhaled 

very insoluble (type SS) plutonium particulates from the respiratory tract.

• Background:

– Historical studies have shown that, in some instances, the rate of removal of 

plutonium from the lung was slower than predicted by type S. This phenomenon is 

known as type SS. 

– Prior versions of OTIB-0049 adjusted type S doses to account for type SS by 

increasing organ dose through the use of dose adjustment factors, which are 

summarized in table 4-8 of revision 01 PC-2 (NIOSH, 2010). In some cases, this 

approach uses an adjustment factor of 4, which the National Institute for 

Occupational Safety and Health (NIOSH) considered to be bounding.

– The current revision does not use adjustment factors and instead uses guidance from 

ICRP Publication 130 to develop new parameters to model type SS intakes and dose 

directly.

• Technical Basis – Section 4.0, pages 6–8, of OTIB-0049 provides the scientific basis for 

developing a new approach for assessing doses from type SS plutonium intakes.

– Biokinetic model (section 4.1):

o Discusses that the revised HRTM in ICRP Publication 130, “Occupational Intakes 

of Radionuclides: Part 1” (ICRP, 2015), is specifically designed to model 

biokinetics of type SS materials in the respiratory tract. By coupling

Publication 130 with Publication 67, “Age-Dependent Doses to Members of the 

Public from Intake of Radionuclides: Part 2 Ingestion Dose Coefficients” (ICRP,

1993), and Publication 30, “Limits for Intakes of Radionuclides by Workers”

(ICRP, 1979), a fully specified biokinetic model for type SS plutonium can be 

created.

o NIOSH’s “hybrid” model introduced modified dissolution parameters that lower 

predicted urinary excretion per unit intake to better match observed excretion in 

workers with type SS plutonium intakes, as follows:

 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 as slower rate (Ss) = 1×10-6
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 9 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

– Dosimetric model (section 4.2): 

o The ICRP system uses specific effective energy (SEE) to convert decays in a 

source region to dose in a target region. SEEs exist as source and target pairs, and 

their calculations include conversion factors, energy, yield, and the radiation 

weighting factor of the emitted radiation. The calculation also included an 

absorbed fraction (AF) and the mass of the target tissue.

o While it is not explicitly stated in ICRP Publication 130, NIOSH believes “it is 

clear that the ALV and INT compartments are also just two mathematical 

clearance rates from the same physical source region” (NIOSH, 2020, pp. 7–8). A 

single alveolar-interstitial (AI) source region will be assigned for decays in the 

alveolar (ALV) and interstitial (INT) compartments.

o ICRP Publication 130 combines regions BB1 and BB2 into a single bronchial

(BB) region. The weighting factors are used to produce a single BB AF that 

NIOSH will apply to the type SS model.

o ICRP Publication 130 removes the thoracic lymph nodes (LN(TH)) from the lung 

dose weighting factors. NIOSH indicates that, “Because ICRP has not yet 

published all parts of its new system, the system cannot yet be used in its entirety

. . . . Therefore, the original Publication 66 tissue weighting for calculating ‘lung’ 

dose will continue to be used” (NIOSH, 2020, p. 8). 

• Attachment A discusses the development and verification of solubility parameters for 

assessing type SS plutonium. Attachment A provides information on the derivation of the 

following parameters: 

– Isotopic ratio – Section A.1 discusses the development of isotopic ratios for

plutonium (Pu)-241 to americium (Am)-241 activity for assessing lung counting data 

and Pu-239 to Am-241 activity for assessing urine data.

– Data – Section A.2 discusses NIOSH’s assumptions regarding lung count data and 

urine data used to derive the isotopic ratios. 

– Long-term absorption parameter – Section A.3 presents the approach used to derive 

the slow absorption rate (Ss) of 1×10-6 using Am-241 lung count data. 

– Short-term absorption parameters – Section A.4 discusses the deviation of short-term 

absorption parameters Fr and Sr using the same lung count data and the derived slow 

absorption rate. 

– Verification of type SS model parameters – Section A.5 describes NIOSH’s 

verification process using the new type SS parameters and the HAN-1 case. 

– Note on chelation therapy – Section A.8 discusses that chelation therapy was 

performed on the HAN-1 case, but it was determined to be ineffective. However, 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 10 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

since chelation therapy was administered, early urine samples were eliminated from 

the modeling process.

• IDOT_SS (Internal Dose Tool, Super S) – NIOSH has also developed a tool, IDOT_SS, 

to implement the assessment of type SS plutonium. The IDOT_SS tool provides dose 

reconstructors with a consistent method of determining dose from inhalation of type SS 

plutonium using the methods outlined in OTIB-0049. 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 11 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

3 SC&A’s Evaluation of ORAUT-OTIB-0049, Revision 02 

The following sections summarize SC&A’s evaluation of the technical approach, methods used, 

and documentation in OTIB-0049. In addition, SC&A preliminarily reviewed the IDOT_SS tool 

to ensure that the tool is consistently and correctly implemented using guidance in OTIB-0049. 

3.1 Evaluation of biokinetic model used in ORAUT-OTIB-0049

Section 2.0 of ORAUT-OTIB-0049, revision 02 (NIOSH, 2020, p. 5), states the following: 

The purpose of this document is to specify a biokinetic model that is used to 

evaluate the deposition, retention, and removal of inhaled very insoluble (type SS) 

plutonium particulates from the respiratory tract. This model merges the latest 

International Commission on Radiological Protection (ICRP) Publication 130 

human respiratory tract model (HRTM) with the current Publication 67 plutonium 

systemic model and Publication 30 gastrointestinal (GI) tract model.

NIOSH further states in section 3.0: 

The Publication 130 lung model is intended to be coupled to new biokinetic 

models that have not yet been published. [NIOSH, 2020, p. 6]

3.1.1 SC&A’s comments on the biokinetic models

Reference biokinetic models were used here (i.e., by the ICRP Task Group) for analysis of the 

data. The ICRP published a new lung model as part of Publication 130 (ICRP, 2015) that 

represents a modification to the Publication 66 model (ICRP, 1994). The pertinent modification 

in the context of OTIB-0049 is that it slows down the mechanical clearance rate to a level that 

absorption parameters can be developed to account for highly insoluble plutonium (i.e., type SS 

material). In 2019, ICRP Publication 141 “Occupational Intakes of Radionuclides: Part 4” was 

issued, which provided new biokinetic models for actinides, including americium and plutonium. 

Observation 1: ICRP has published updated biokinetic models appropriate for type SS 

plutonium 

SC&A suggests that (1) ICRP Publication 141 (ICRP, 2019) should be used to determine the 

Pu-239 dioxide absorption parameters and (2) absorption parameters from the alimentary tract

should be used for all type SS plutonium exposure estimates. Further, NIOSH should consider 

use of the dosimetric guidance for dose per activity content in the lungs and models for daily 

excretion in urine and feces.

Specifically, SC&A suggests that: 

1. ICRP Publication 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 Publication 141 value for Sr of 0.4 d-1, the rate at which the material is

absorbed, should be used.
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 12 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

3. The dosimetric data from ICRP Publication 141 should be used to determine the 

parameters for the inhalation of Pu-239 dioxide for all type SS plutonium. The dosimetric 

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. 

As specified in Section 3.0 of OTIB-0049 (NIOSH, 2020, p. 5), 

a handful of accidental intakes of plutonium oxides at the DOE Rocky Flats Plant 

(RFP) (Mann and Kirchner 1967), Hanford Site (Carbaugh, Bihl, and Sula 1991; 

Carbaugh and LaBone 2003; Bihl et al. 1988), Los Alamos National Laboratory 

. . ., and Savannah River Site (Carbaugh and LaBone 2003) have exhibited longterm retention of plutonium in the lung exceeding that predicted by the standard 

type S model. Recent autopsies on workers exposed to plutonium at the Mayak 

Production Association (Mayak) in Russia revealed a similar effect.

ICRP Publication 141 (2019), using similar literature, provided absorption parameters for very 

insoluble Pu-239 oxides: Fr = 0.004, Ss = 1×10-5 per day (d-1), Sr = 0.4d-1, and FA = 2×10-6

(ICRP, 2019, p. 337).

3.1.2 SC&A’s comments on data in the technical basis section for biokinetic models 

The technical basis for the biokinetic model is discussed in section 4.1 of OTIB-0049, 

revision 02 (NIOSH, 2020, pp. 6–7). This section lists NIOSH’s dissolution parameters for its 

hybrid model and identifies the fraction of inhaled material absorbed by blood relatively rapidly 

(Fr) as 0.001209. 

Observation 2: Section 4.1 of ORAUT-OTIB-0049, revision 02, lists an incorrect Fr value

The Fr value calculated by NIOSH, listed in attachment A of OTIB-0049, revision 02, and used 

in the IDOT_SS tool, is 0.001029. Section 4.1 of OTIB-0049 erroneously identifies the Fr value 

as 0.001209. 

3.2 Evaluation of attachment A, “Determination of solubility parameters for 

Super S model” 

The first two sentences in attachment A of OTIB-0049 (NIOSH, 2020, p. 13) state: 

While ICRP has published a new lung model, it has not published solubility 

parameters for plutonium. Therefore, solubility parameters are evaluated here for 

use with the type SS model.

3.2.1 SC&A’s comments on stated purpose of attachment A

As identified in observation 1, ICRP issued new biokinetic models in Publication 141, 

“Occupational Intakes of Radionuclides: Part 4,” in 2019. Publication 141 provides data 

concerning plutonium radioisotopes and presents information on chemical forms encountered in 

the workplace, data on inhalation, ingestion, and systemic biokinetics (including a review and 

discussion of the parameter values of the reference biokinetic models). 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 13 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution.

ICRP Publication 141 has suggested specific default absorption parameters values for Pu-239

dioxide, Fr = 0.004, Ss = 1 x 10-5

d-1, Sr = 0.4 d-1, and a default absorption parameter from the 

alimentary tract, FA = 2×10-6.

SC&A suggests that the Pu-239 dioxide absorption parameters and the absorption parameters 

from the alimentary tract specified in ICRP Publication 141 should be used for all other “Super 

S” plutonium dioxides, as implied in observation 1.

3.3 Evaluation of the long-term absorption parameter

In OTIB-0049, attachment A, pages 13–14, NIOSH states the following:

The original version of this TIB evaluated selected cases from RFP and Hanford 

that exhibited type SS behavior. A combination of one RFP case (RFP 872) and 

one Hanford case (HAN-1) resulted in worst-case correction factors at various 

times after an intake. However, in developing parameters for an actual model, it is 

not possible to use two different cases as one. . . .

The solubility parameters considered are Fr, Sr, and Ss. The parameter Fr

represents the fraction of the inhaled material that is absorbed by the blood 

relatively rapidly. Sr represents that rate at which the material is absorbed. The 

remaining fraction of the material (1 − Fr) is absorbed as a slower rate represented 

by Ss. . . .

In order to determine the appropriate solubility parameters, intakes were 

calculated a number of times from either lung or urine data. All the intake 

calculations discussed were performed using a least squares fit of the applicable 

data.

The slow absorption rate parameter was calculated using the data on Am-241 retention in the 

lung. The default type S value from ICRP Publication 66 was reduced by a factor of 10, and the 

Am-241 intake calculated. The results for several iterations of reducing the value by factors of 10 

at each interaction showed that, once reduced below 1×10-6, there was essentially no difference 

in the results. Thus, OTIB-0049 (NIOSH, 2020) assigned the value of Ss = 10-6 d-1 as the slow

dissolution rate.

3.3.1 SC&A’s comments on long-term absorption parameters

According to ICRP Publication 141, the most informative case study is the 35-year followup of a 

group of workers who inhaled plutonium dioxide in the 1965 Rocky Flat Plant Fire, described in 

revision 01 PC-2 of OTIB-0049 (NIOSH, 2010) and Mann and Kirchner (1967). Gregoratto et al. 

(2010) analyzed nine cases based on lung measurements obtained from NIOSH (2007) on behalf 

of ICRP. Six RFP workers were exposed to plutonium from a fire in October 1965. Gregoratto 

et al. (2010) analyzed the lung and urine data for the six workers; the median values were 

Fr = 0.005 and Ss = 4×10-6 d-1, as specified in ICRP Publication 141 (ICRP, 2019, p. 295).

In addition, ICRP analyzed the United States Transuranium and Uranium Registries (USTUR)

autopsy and bioassay data of two workers involved in the 1965 RFP fire with the two highest 

exposures (Avtandilashvili et al., 2012, 2013). For both cases, around 1 percent was absorbed 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 14 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

relatively rapidly, with half-times of around 8 hours (Sr = 1 d-1) and 16 hours (Sr = 2 d-1). The 

estimated value of Ss in both cases is 5×10-6 d-1 (ICRP, 2019, p. 295). ICRP explains that the 

factors giving credence to this value of the slow dissolution rate are (1) it is a human study, (2) it 

contains detailed measurements, (3) it analyzes both bioassay and autopsy data, and (4) the long 

duration (many years between exposure and autopsy). However, the measurements are on two 

subjects who received unusually high exposures (3 gray (Gy) to AI region by 18 years post 

intake, and 3 Gy to AI region by 43 years post intake). One subject also had previous exposure to 

coal mine dust and was a smoker. The values of Ss for the human studies range from 4×10-6 to 

4.5×10-5, with a geometric mean of 9×10-6 d-1. 

ICRP Publication 141 (2019) derived specific absorption parameter values from a study by 

Carbaugh and La Bone (2003). This study provided the data for the “HAN-1” case, which 

NIOSH used to develop the solubility parameters for type SS plutonium. According to 

ICRP Publication 141, information on the early rapid absorption phase was difficult to analyze 

because of the possible enhancement of urine excretion due to the administration of diethylene 

triamine pentaacetic acid. ICRP’s estimated value of the slow dissolution rate was of the order of 

Ss = 10-5 d-1 (p. 297) for the Hanford case study (HAN-1), while NIOSH derived Ss = 1×10-6 d-1. 

ICRP also analyzed autopsy data from 20 former Mayak workers considered to be exposed to 

plutonium oxide alone (Puncher et al., 2017). ICRP estimated a value of Ss = 4.5×10-5 d-1, (ICRP, 

2019, p. 296). According to ICRP Publication 141 (2019), factors giving credence to these data

include (1) it is a human study, (2) it contains a large number of subjects, and (3) the evaluation 

covers a sufficiently long duration. However, the exposures are less well characterized than in 

the other studies considered, and there is very limited bioassay information. 

Based on these studies and some limited animal studies, ICRP derived a specific default slow 

dissolution rate of Ss = 1×10-5 d-1 (ICRP, 2019, p. 305). SC&A considers the ICRP default Ss

value to be an appropriate long-term absorption rate. 

3.4 Evaluation of the short-term absorption parameters 

To assess the rapid dissolution rate (Sr), OTIB-0049 assumed a constant value for the slow 

dissolution rate of Ss = 1×10-6 d-1 and then used the HAN-1 lung counting data for americium

while varying the short-term absorption parameters. NIOSH concluded that varying the fraction 

of rapidly dissolved material (Fr) and Sr had little effect on the calculated intake. Urine data were

then applied, even though the individual was chelated. Varying the Fr value had a large effect on 

the calculated intake, while the Sr showed a smaller effect. NIOSH ultimately assigned the rapid

absorption parameters for the type SS model as Fr = 0.001029 and Sr = 100.1. 

3.4.1 SC&A’s comments on short-term absorption parameters

ICRP Publication 141 (2019) assigned the value of 0.4 d-1 for the rapid dissolution rate (Sr) based 

on animal and human studies but did not consider it appropriate to use urine excretion rates from 

chelated individuals, citing and showing the importance of early excretion rates and its 

dependence on Sr. 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 15 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

As identified in observation 1, new biokinetic models have been published in ICRP 

Publication 141. SC&A suggests that NIOSH consider using the ICRP Publication 141 value of 

0.4 d-1 for its rapid dissolution rate (Sr).

3.5 Binding of plutonium in the respiratory tract

ICRP Publication 141 gave consideration to a long-term “bound” state of plutonium. 

Specifically, it states:

For some elements, a significant fraction of the dissolved material is absorbed

slowly. In some cases, this can be represented by formation of particulate material

(which is subject to clearance by particle transport). In others, some dissolved 

material appears to be attached to lung structural components, and removed only 

by absorption to blood. To represent the latter type of time-dependent uptake, it is 

assumed that a fraction, fb, of the dissolved material is retained in the ‘bound’ 

state, from which it goes into blood at a rate sb. Evidence for retention in the 

bound state, rather than by transformation into particulate material, may be in one 

or more forms, such as systemic uptake rather than faecal clearance of the

retained material; slower clearance than for insoluble particles deposited in the

same region of the respiratory tract; or autoradiography showing diffuse rather 

than focal retention of activity. [ICRP, 2019, p. 15] 

As binding occurs after dissolution of the inhaled material, it is assumed to be independent of the 

initial chemical form. After reviewing human and animal data, ICRP assigned the value of 

0.2 percent for the bound fraction (fb) to be applied to the whole respiratory tract, except for the 

ET1 region, for all plutonium compounds, and a bound dissolution rate (Sb) equal to zero. 

Observation 3: NIOSH failed to consider long-term binding of plutonium

There is no reference to long-term binding of plutonium in OTIB-0049. 

3.6 Systemic distribution, retention, and excretion of plutonium

The plutonium model of ICRP Publication 67 (1993) was updated and is described in detail in 

ICRP Publication 141 (2019). Publication 141 summarizes the main differences from the 

previous model, which include: 

• deposition fractions to bone and liver 

• circulation in blood and turnover to tissues and clearance from blood to urine 

• rapid, intermediate, and slow phases of removal from liver 

• circulation deposits in trabecular and cortical bone and removal and change with time in 

urinary clearance of circulating plutonium 

• transfer of plutonium from blood to kidneys and urinary bladder
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 16 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution.

Observation 4: Rev. 02, has not used ICRP 141 updates to the ICRP 67 systemic model

OTIB-0049, revision 02 (NIOSH, 2020), uses the ICRP Publication 67 (“ICRP 67”) systemic 

model instead of the updated model described in ICRP Publication 141 (“ICRP 141”). Excretion 

rates using the two models should be compared.

As identified in observation 1, new biokinetic models have been published in ICRP 

Publication 141 (2019). SC&A suggest that the dosimetric data for the inhalation of Pu-239

dioxide should be used for all type SS plutonium as given in ICRP Publication 141, as well as 

the dose per activity content in the lungs and in daily excretion of urine and feces.

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), as described in ICRP Publication 134 (ICRP, 2016), 

Publication 137 (ICRP, 2017), and Publication 141 (ICRP, 2019), should be used to calculate 

dose per intake coefficients, dose per content functions, and reference bioassay functions for 

Pu-239 dioxides (type SS plutonium). Data for intake by inhalation, ingestion, and for direct 

uptake to the blood are provided. The electronic annex covers a range of physicochemical forms 

of aerosols with median sizes ranging from an activity median thermodynamic diameter of 

0.001 micrometer to an activity median aerodynamic diameter of 20 micrometers. The dataset 

was calculated for the reference worker. 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 17 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

4 Application of OTIB-0049 and IDOT_SS to Dose Reconstructions

SC&A notes that OTIB-0049 lacks guidance on how to apply type SS plutonium and makes no 

mention of the tool developed for its implementation. SC&A only became aware of the 

IDOT_SS tool when they inquired if NIOSH had created a tool to support OTIB-0049. 

The following sections present SC&A’s review of the basic functionality of the tool as well as 

some scoping calculations to better understand the practical implications the new methodology 

has for dose reconstructions (DRs). Section 4.1 provides a basic description of the tool. 

Section 4.2 compares the use of absorption parameters derived in attachment A of OTIB-0049, 

revision 02, with the absorption parameters in ICRP Publication 141 (2019). This comparison 

includes scoping calculations using typical claimant bioassay data to understand the practical 

difference between the newer method for assessing plutonium strongly retained in the lung 

(OTIB-0049, revision 02, with the IDOT_SS tool) and the older method (OTIB-0049, 

revision 01 PC-2, with the Integrated Modules for Bioassay Analysis (IMBA) program). To 

illustrate this comparison, SC&A used the bioassay data for the HAN-1 case discussed in 

attachment A of OTIB-0049, revision 02, and provided by NIOSH in the example input file, 

“Example_Lung.IDOT.” 

Observation 6: OTIB-0049 lacks information about its application to dose reconstruction

SC&A found limited guidance for dose reconstructors on how to apply the guidance in 

OTIB-0049 to a DR. Clear, unambiguous guidance is necessary to ensure cases are processed 

consistently. OTIB-0049 should specify that the IDOT_SS tool has been developed for the 

implementation of its guidance. 

4.1 Overview of IDOT_SS tool and user guide

NIOSH provided SC&A with version 1.02, dated July 20, 2021, of the IDOT_SS tool. It is 

SC&A’s understanding that all DRs that assess type SS plutonium and/or americium will use this 

tool. NIOSH also provided SC&A with a user’s guide for the tool. The tool is a Microsoft Excel 

macro file with four primary pages: 

• Main: This tab allows the input of up to 10 intakes of a single americium or plutonium 

radionuclide. The solubility type defaults to type SS with the option to modify the 

solubility parameters. The page also allows users to select the activity and dose units used 

in calculations. The tab is comparable in functionality to the home/start page in the 

IMBA program. 

• BIO: This tab allows users to input bioassay data from urine, fecal, lung, and whole-body 

counts. A button allows users to calculate intakes from bioassay data. A second button 

allows users to calculate projected bioassay data from intakes. This tab has similar 

functionality to the “Bioassay Calculation” page in IMBA.

• Annual Dose: This tab allows users to input cancer information and exposure start date.

A single button allows users to calculate annual organ doses from the intake information

that is input or derived in previous tabs.
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 18 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

• Committed: A single button on the page allows users to calculate the committed dose to 

various organs and a committed effective dose.

For this review, SC&A did not review the calculations used in the tool or implementation of the 

tool through the user’s guide. The calculations in the tool are completed in a password-protected 

part of the tool, and SC&A does not currently have access to view how they are being 

implemented. The calculations supporting the tool are documented in DCAS-RPT-007 (NIOSH, 

2019). According to DCAS-RPT-007, additional benchmarking data are provided in a June 20, 

2019, “IDOT Bioassay and Dose Benchmark” file. Detailed review of these documents and the 

tool calculations are outside of the scope of this tasking and would require subsequent tasking by 

the Subcommittee for Procedure Reviews. 

4.2 Comparison of doses derived using IDOT_SS for OTIB-0049, revision 02, 

with doses using previous OTIB-0049 guidance

SC&A used the IDOT_SS tool to perform scoping calculations to better understand and 

characterize the effects on DR using the new methodology for assessing doses to plutonium 

strongly retained in the lung. The scoping calculations are intended to assist in this determination 

but are illustrative and do not encompass all of the many potential exposure assessment 

scenarios.

This section compares doses derived using the following new and previous versions of 

OTIB-0049 guidance: 

• OTIB-0049, revision 02 (NIOSH, 2020), using IDOT_SS 

• OTIB-0049, revision 01 PC-2 (NIOSH, 2010); as the guidance in this 2010 page-change 

revision is essentially unchanged from revision 01 (NIOSH, 2007), this report will 

hereafter use “Revision 01 (2010)” as shorthand to indicate the relevant previous 

guidance 

To assess the impacts of the revision to OTIB-0049, SC&A first modeled equal intakes of 

type SS with the new and previous revision methodology for two scenarios: 

1. an acute Pu-239 intake of 1,000 disintegrations per minute (dpm) 

2. a chronic Pu-239 intake of 100 disintegrations per minute per day (dpm/d) for 5 years 

Each scenario assumed that the intake was detected by urinalysis. A cancer was modeled from 

each of the organ groups in table 4-8 of revision 01 PC-2: lungs, extra-thoracic (ET), GI tract, 

and systemic organs. Two organs from the ET group, lymph nodes associated with the 

extrathoracic region (LN(ET)) and the posterior nasal passage (ET2), were selected because of 

the variation expected within the organ grouping. SC&A modeled the organ dose up to 50 years 

post exposure and compared the results of the two models. The results of this assessment are 

shown in figures 1 and 2. As expected, these figures clearly show that the calculation of equal 

intakes of type SS Pu-239 using the OTIB-0049 Revision 01 (2010) and revision 02 approaches 

can lead to vastly different organ doses. In these examples, the Revision 01 (2010) method 

resulted in the calculation of a larger dose that the newer method except for LN(ET). 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 19 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Additionally, SC&A modeled intakes and corresponding doses using bioassay results from two 

typical cases. These calculations and the quantitative results are presented and discussed in 

sections 4.2.1–4.2.3. 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 20 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the Privacy Act 5 U.S.C. § 552a and has been cleared for 

distribution. 

Figure 1.Comparisons of acute Pu-239 intake of 1,000 dpm for the Revision 01 (2010) and revision 02 methods 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 21 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the Privacy Act 5 U.S.C. § 552a and has been cleared for 

distribution. 

Figure 2. Comparisons of the chronic Pu-239 intake of 100 dpm/d for 5 years for the Revision 01 (2010) and revision 02 methods
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 22 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

4.2.1 Purpose of scoping calculations

As part of its review of the IDOT_SS tool, SC&A performed scoping calculations designed to 

evaluate the following:

• Compare IDOT_SS organ doses to the previous method, Revision 01 (2010) (which used

IMBA and revision 01 PC-2 of OTIB-0049), when typical claimant data are used. In this 

context, the term “organ” refers to either an organ or tissue, whichever is appropriate.

• Determine the ratio of derived doses for the thoracic, extrathoracic, GI tract, and systemic 

organs using IDOT_SS compared to using Revision 01 (2010). 

• OTIB-0049, revision 02, indicates a slower removal rate for Pu-239 and Am-241 

solubility type SS compared to Revision 01 (2010). Therefore, SC&A performed 

analyses to determine if the derived doses using IDOT_SS compared to using the 

previous guidance are generally: 

– greater for organs in the thoracic and extrathoracic regions because of longer 

retention times

– less for systemic organs because of slower release from the thoracic and extrathoracic 

regions 

• Determine if there are DR situations where the organ doses, especially to the thoracic and 

extrathoracic regions, could be greater when using IDOT_SS compared to using 

Revision 01 (2010). If so, a program evaluation report would be necessary to rework 

previous DR cases involving type SS solubility. 

4.2.2 Analysis results for two evaluated cases

SC&A used typical DR data to analysis two cases, designated A and B,1 in the evaluation of 

IDOT_SS. Case A represents a typical case with a relatively short exposure period (several 

years) but a long latent period. Case B represents a typical case with a relatively long exposure 

period compared to the latent period. SC&A performed the following analyses:

1 “A” and “B” are arbitrary labels SC&A assigned for purposes of this discussion to protect the confidentiality of 

the data.

• The bioassay data from each of the cases were used in IDOT_SS to derive projected 

Pu-239, or Am-241, chronic and acute intakes. IDOT_SS was then used to derive the 

annual type SS doses and the total dose up until the selected date of cancer diagnosis for 

each organ of interest. 

• The bioassay data from each of the cases were used in IMBA to derive projected Pu-239, 

or Am-241, chronic and acute intakes for type S solubility. Revision 01 PC-2 of OTIB0049 was then used to adjust the type S annual dose to type SS annual dose to each of the 

organs of interest (as recommended in table 4-8 and table D-1 of revision 01 PC-2 of 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 23 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

OTIB-0049) (NIOSH, 2010). The total dose up until the date of cancer diagnosis for each 

organ of interest was determined.

• The ratio of the resulting total dose derived using IDOT_SS compared to the total dose 

derived using the previous guidance was determined for each organ of interest up until 

the date of cancer diagnosis, and a summary plot was constructed. For plutonium, 17 total 

organs were analyzed in each case; these included the common cancer sites in the DR 

plus the organs with the highest committed dose. The organs with the highest committed 

dose included organs in the thoracic and extrathoracic regions. Only Case B was analyzed

for americium. Dose comparisons from Am-241 intakes were performed for 25 organs; 

these included the common cancer sites in the DR plus additional organs selected to 

include the thoracic and extrathoracic regions, which are important for type SS solubility 

analysis. 

The analyses for Cases A and B are presented in sections 4.2.2.1 and 4.2.2.2, respectively. 

4.2.2.1 Case A

Exposure: Pu-239 at a U.S. Department of Energy (DOE) site. Relatively short exposure period 

(several years).

Diagnosis: Relatively long latent period.

Bioassays: Urinalysis for Pu-239. Assumed continuous monitoring during employment that

indicated both potential chronic and acute exposures.

IDOT_SS projected intakes: 8,100 dpm/d chronic Pu-239 and 6.78E6 dpm acute Pu-239. 

Annual and total Pu-239 type SS chronic and acute doses up until the date of cancer diagnosis 

for 17 organs of interest were derived.

IMBA projected intakes: 1,772 dpm/d chronic Pu-239 S and 1.49E6 dpm acute Pu-239 type S. 

Type S annual doses were derived in IMBA and adjusted to type SS annual doses as 

recommended in table 4-8 and table D-1 of revision 01 PC-2 of OTIB-0049. Annual and total 

Pu-239 type SS chronic and acute doses up until the date of cancer diagnosis for 17 organs of 

interest were derived.

Table 1 lists the derived doses and the ratios of IDOT_SS-derived total chronic type SS Pu-239 

doses compared to the total chronic type SS doses derived using Revision 01 (2010). 

Table 1. Case A chronic Pu-239 IDOT_SS and Revision 01 (2010) derived doses and dose 

ratios 

Organ IDOT_SS dose

(rem)

Revision 01 (2010)

dose (rem)

Dose ratio 

(IDOT_SS/ 

Revision 01 (2010)) 

Testes 1.52E+00 1.20E+01 0.13

Ovaries 1.49E+00 1.18E+01 0.13

Liver 2.39E+01 1.89E+02 0.13
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 24 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Organ IDOT_SS dose

(rem)

Revision 01 (2010)

dose (rem)

Dose ratio 

(IDOT_SS/ 

Revision 01 (2010)) 

Bone surface 1.14E+02 8.97E+02 0.13

Uterus 1.92E-01 1.51E+00 0.13

Skin 1.93E-01 1.52E+00 0.13

RBM 5.58E+00 4.29E+01 0.13

Stomach 2.12E-01 1.61E+00 0.13

LLI 5.64E-01 1.82E+00 0.31

LN(TH) 8.89E+04 2.10E+05 0.42

Lung 1.59E+03 2.92E+03 0.55

AI 3.83E+03 6.46E+03 0.59

BB 5.78E+02 9.47E+02 0.61

ET1 1.03E+01 1.46E+01 0.70

TBBAS or BBBAS 1.63E+02 2.01E+02 0.81

ET2 2.33E+03 7.17E+02 3.24

LN(ET) 9.89E+03 1.35E+03 7.35

Figure 3 shows a summary plot of the ratio of IDOT_SS-derived total chronic type SS Pu-239 

doses compared to the total chronic type SS doses derived using the Revision 01 (2010) method. 

Figure 3. Case A ratio of IDOT_SS to Revision 01 (2010) derived total type SS Pu-239 chronic 

doses
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 25 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Table 2 lists the derived doses and the ratio comparing IDOT_SS-derived total acute type SS 

Pu-239 doses with the total acute type SS doses derived using the Revision 01 (2010) method. 

Table 2. Case A acute Pu-239 IDOT_SS and Revision 01 (2010) derived doses and dose ratios

Organ IDOT_SS dose

(rem)

Revision 01 (2010)

dose (rem)

Dose ratio (IDOT_SS/

Revision 01 (2010)) 

Skin 2.04E-01 1.67E+00 0.12

Testes 1.65E+00 1.32E+01 0.12

Ovaries 1.62E+00 1.30E+01 0.12

Liver 2.60E+01 2.08E+02 0.13

Bone surface 1.24E+02 9.88E+02 0.13

Uterus 2.08E-01 1.66E+00 0.13

RBM 6.08E+00 4.76E+01 0.13

Stomach 2.29E-01 1.76E+00 0.13

LLI 6.18E-01 2.00E+00 0.31

LN(TH) 9.58E+04 2.16E+05 0.44

Lung 1.74E+03 2.77E+03 0.63

AI 4.19E+03 6.46E+03 0.65

ET1 1.13E+01 1.62E+01 0.70

BB 6.35E+02 7.33E+02 0.87

TBBAS or BBBAS 1.79E+02 1.60E+02 1.12

ET2 2.56E+03 7.95E+02 3.22

LN(ET) 1.08E+04 1.49E+03 7.24

Figure 4 shows a summary plot of the ratio of IDOT_SS-derived total acute type SS Pu-239 

doses compared to the total acute type SS doses derived using the Revision 01 (2010) method. 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 26 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Figure 4. Case A ratio of IDOT_SS to Revision 01 (2010) derived total type SS Pu-239 acute 

doses

4.2.2.2 Case B

Exposure: Pu-239 and Am-241 at a DOE site, relatively long exposure period. 

Diagnosis: Relatively short latent period.

Bioassays: Urinalysis for Pu-239 and chest counts for Am-241. Assumed continuous monitoring 

during employment that indicated only chronic exposure for both Pu-239 and Am-241. 

IDOT_SS projected intakes: 117 dpm/d chronic Pu-239 and 0.644 dpm/d chronic Am-241. 

Annual and total chronic doses up until date of cancer diagnosis for Pu-239 type SS for 17 

organs of interest and Am-241 for 25 organs of interest were derived. 

IMBA projected intakes: 12.78 dpm/d chronic Pu-239 S and 0.0690 dpm/d chronic Am-241. 

Type S annual Pu-239 and Am-241 doses were derived in IMBA and adjusted to type SS annual 

doses as recommended in table 4-8 and table D-1 of revision 01 PC-2 of OTIB-0049. Organs of 

highest dose were all systemic for Am-241 intakes and did not require type SS adjustment 

factors. Therefore, additional organs were analyzed to include the thoracic and extrathoracic 

regions that would require type SS dose adjustments, for a total of 25 organs. Annual and total 

chronic doses up until the date of cancer diagnosis for Pu-239 type SS and Am-241 were derived 

for the organs of interest.

Table 3 lists the derived doses and the ratios of IDOT_SS-derived total chronic type SS Pu-239 

doses compared to the total chronic type SS doses derived using the Revision 01 (2010) method. 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 27 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Table 3. Case B chronic Pu-239 IDOT_SS and Revision 01 (2010) derived doses and dose 

ratios

Organ IDOT_SS dose Revision 01 (2010) dose Dose ratio (IDOT_SS/

Revision 01 (2010)) 

Liver 4.88E-01 1.10E+00 0.44

Testes 2.98E-02 6.72E-02 0.44

Ovaries 2.93E-02 6.60E-02 0.44

Bone surface 2.27E+00 5.08E+00 0.45

Thyroid 3.65E-03 8.07E-03 0.45

Skin 3.79E-03 8.33E-03 0.45

RBM 1.64E-01 3.60E-01 0.46

Kidney 1.61E-02 3.39E-02 0.48

Lung 5.61E+01 7.03E+01 0.80

BB 4.55E+01 4.77E+01 0.95

AI 1.12E+02 1.13E+02 0.99

LN(TH) 4.85E+02 3.59E+02 1.35

ET1 9.68E-01 6.36E-01 1.52

LLI 3.85E-02 2.48E-02 1.55

TBBAS or BBBAS 1.52E+01 8.30E+00 1.83

ET2 2.17E+02 3.35E+01 6.48

LN(ET) 1.72E+02 2.17E+01 7.91

Figure 5 shows a summary plot of the ratio of IDOT_SS-derived total chronic type SS doses 

compared to the total chronic type SS Pu-239 doses derived using the Revision 01 (2010) 

method. 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 28 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Figure 5. Case B ratio of IDOT_SS to Revision 01 (2010) derived total type SS chronic Pu-239 

doses

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

Table 4 lists the derived doses and the ratios of IDOT_SS-derived total chronic Am-241 doses 

compared to the total chronic doses derived using the Revision 01 (2010) method. 

Table 4. Case B chronic Am-241 IDOT_SS and Revision 01 (2010) derived doses and dose 

ratios

Organ IDOT_SS dose Revision 01 (2010) dose Dose ratio (IDOT_SS

/Revision 01 (2010)) 

Liver 3.80E-03 7.39E-02 0.051

Brain 3.22E-05 5.39E-04 0.060

Skin 3.29E-05 5.40E-04 0.061

Gall bladder 3.35E-05 5.42E-04 0.062

Thyroid 3.19E-05 5.05E-04 0.063

Muscle 3.53E-05 5.41E-04 0.065

Pancreas 3.56E-05 5.41E-04 0.066

Adrenals 3.70E-05 5.42E-04 0.068

Breast 3.72E-05 5.41E-04 0.069

RBM 1.81E-03 2.35E-02 0.077

Heart wall 4.34E-05 5.44E-04 0.080

Stomach 4.53E-05 5.46E-04 0.083

Bone surface 3.21E-02 3.48E-01 0.092

Small intestine 5.92E-05 5.53E-04 0.107

Testes 6.40E-04 4.87E-03 0.131
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 29 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Organ IDOT_SS dose Revision 01 (2010) dose Dose ratio (IDOT_SS

/Revision 01 (2010)) 

Ovaries 6.45E-04 4.79E-03 0.135

Kidney 3.12E-04 2.23E-03 0.140

LN(TH) 6.24E+00 4.23E+01 0.148

AI 1.44E+00 2.79E+00 0.517

Lung 7.36E-01 1.16E+00 0.634

LLI 5.05E-04 7.77E-04 0.650

LN(ET) 2.21E+00 8.35E-01 2.652

TBBAS or BBBAS 2.05E-01 5.93E-02 3.463

ET2 2.74E+00 5.16E-01 5.324

ET1 2.31E-01 3.73E-02 6.198

Figure 6 shows a summary plot of the ratio of IDOT_SS-derived total chronic Am-241 doses 

compared to the total chronic Am-241 doses derived using the Revision 01 (2010) method. 

Figure 6. Case B ratio of IDOT_SS to Revision 01 (2020) derived total chronic type Am-241 

doses

4.2.3 Summary conclusions from Case A and B analysis

SC&A’s analysis of Case A and Case B bioassay data using both IDOT_SS and Revision 01 

(2010) identified the following observation: 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 30 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

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 program 

evaluation report. 

SC&A’s analysis of two DR cases using typical bioassay data comparing the older and newer 

methods for assessing plutonium strongly retained in the lung found that organ doses in the 

thoracic and extrathoracic regions increased with the new method, while doses to other systemic 

organs decreased. Therefore, a program evaluation report would appear warranted for 

noncompensated cases with covered illnesses involving the thoracic and extrathoracic regions. 

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.” This occurs 

for all examples analyzed by SC&A. 

4.3 Comparison of absorption parameters between OTIB-0049, revision 02, and 

ICRP Publication 141

As noted in Sections 2 and 3, the main purpose of OTIB-0049 was to derive absorption 

parameters for use in assessing exposures to plutonium strongly retained in the lung (i.e., 

type SS). Absorption parameters designed to address exposures to plutonium exhibiting this 

behavior were also developed in ICRP Publication 141 (ICRP, 2019). Table 5 compares the two 

sets of absorption parameters.

Table 5. Comparison of ORAUT-0049, revision 02, and ICRP Publication 141 absorption

parameters

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) 1×10-6 1×10-5

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) 1×10-5 2×10-6 

SC&A entered the absorption parameters in table 5 into the IDOT_SS tool along with the 

exposure information (e.g., date and type of exposure, subsequent urinalysis measurements, etc.) 

for the HAN-1 case as provided by NIOSH in the calculation file. “Example_Lung.IDOT.” 

SC&A then ran the tool to compare the resulting doses as well as the general fit of the projected 

bioassay results to the actual observed bioassay results. SC&A found that, for the HAN-1 case, 

the total committed effective dose using the OTIB-0049 absorption parameters was 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 31 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

approximately 80 percent of the committed effective dose using the ICRP Publication 141 

parameters. Table 6 displays the ratio of the organ-specific committed effective doses 

(OTIB-0049, revision 02/ICRP 141) as a percentage of the ICRP Publication 141 dose estimate.

Percentages ranged from 20 percent to 87 percent. 

Observation 8: ICRP Publication 141 absorption parameters appear to be more claimant 

favorable

Analysis of the HAN-1 case indicates that use of the ICRP Publication 141-derived absorption 

parameters results in higher doses to all evaluated organs when compared to the OTIB-0049-

derived absorption parameters.

Table 6. Comparison of organ-specific committed doses for the HAN-1 case 

Organ OTIB-0049, rev. 02, 

committed dose (rem)

ICRP 141 committed 

dose (rem) Ratio OTIB-0049/ICRP 141

Adrenals 1.710E-02 7.524E-02 0.23

U. bladder 1.709E-02 7.523E-02 0.23

Brain 1.709E-02 7.523E-02 0.23

Breast 1.710E-02 7.524E-02 0.23

Gall bladder 1.709E-02 7.523E-02 0.23

Heart 1.712E-02 7.527E-02 0.23

Kidney 4.346E-02 2.173E-01 0.20

Liver 2.085E+00 9.550E+00 0.22

Muscle 1.711E-02 7.525E-02 0.23

Ovaries 1.295E-01 5.887E-01 0.22

Pancreas 1.709E-02 7.523E-02 0.23

Testes 1.320E-01 6.001E-01 0.22

Thyroid 1.709E-02 7.523E-02 0.23

RBM 4.939E-01 2.417E+00 0.20

Bone surface 9.842E+00 4.455E+01 0.22

Stomach 1.789E-02 7.627E-02 0.23

Small intestine 1.909E-02 7.781E-02 0.25

ULI 2.921E-02 9.084E-02 0.32

LLI 5.265E-02 1.210E-01 0.44

Skin 1.709E-02 7.523E-02 0.23

Spleen 1.710E-02 7.524E-02 0.23

Thymus 1.709E-02 7.524E-02 0.23

Uterus 1.709E-02 7.523E-02 0.23

ET1 1.006E+00 1.348E+00 0.75

ET2 2.289E+02 2.915E+02 0.79

LN(ET) 8.586E+02 1.012E+03 0.85

TBSEC 4.874E+00 6.409E+00 0.76

TBBAS 1.603E+01 2.057E+01 0.78
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 32 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Organ OTIB-0049, rev. 02, 

committed dose (rem)

ICRP 141 committed 

dose (rem) Ratio OTIB-0049/ICRP 141

BB 5.569E+01 7.050E+01 0.79

AI 3.470E+02 4.153E+02 0.84

LN(TH) 7.013E+03 8.088E+03 0.87

Lung 1.446E+02 1.743E+02 0.83

Colon 3.934E-02 1.039E-01 0.38

Esophagus 1.709E-02 7.524E-02 0.23

Figures 7–9 compare the projected bioassay values using the absorption parameters derived in 

OTIB-0049 versus those derived in ICRP Publication 141. As expected, the projected bioassay 

calculated using the derived absorption parameters in OTIB-0049 provides a better fit to the 

actual measured results. This was to be expected, because the absorption parameters were 

modeled based on the observed bioassay and thus would provide the best estimate of the actual 

HAN-1 excretion pattern but may be indicative of overfitting. However, it is worth noting that 

ICRP Publication 141 still provided a reasonably good fit to the observed HAN-1 bioassay data, 

thus reinforcing the supposition that the ICRP-derived parameters are appropriate for universal 

modeling of plutonium strongly retained in the lung. While the projected bioassay in the HAN-1 

case was more closely approximated using the OTIB-0049 derived absorption parameters, use of 

the ICRP recommended parameters still resulted in a reasonably good fit to the observed 

bioassay data in this case. Thus, SC&A maintains that the ICRP Publication 141 parameters are 

likely more appropriate for generic application in DR cases involving plutonium strongly 

retained in the lung. 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 33 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Figure 7. Comparison of bioassay projections for the HAN-1 case using absorption parameters 

derived in OTIB-0049 and ICRP 141
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 34 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Figure 8. Comparison of bioassay projections for the HAN-1 case using absorption parameters 

derived in OTIB-0049 and ICRP 141 (y-axis truncated at 0.006 Bq/d)

0.000

0.001

0.002

0.003

0.004

0.005

0.006

1976 1979 1982 1984 1987 1990

Pu Excretion Rate (Bq/d)

Year

Real Data Calculated OTIB-0049 Calculated ICRP141
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 35 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

Figure 9. Comparison of bioassay projections for the HAN-1 case using absorption parameters 

derived in OTIB-0049 and ICRP 141 (y-axis in logarithmic form)
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 36 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution.

5 Summary of SC&A’s Evaluation of OTIB-0049, Revision 02

SC&A evaluated OTIB-0049, revision 02, in view of current publications available. The 

following is a summary of SC&A’s finding and observations that indicate that further discussion 

or clarification is needed.

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.”

Observation 1: ICRP has published updated biokinetic models appropriate for type SS 

plutonium

SC&A suggests that (1) ICRP Publication 141 should be used to determine the Pu-239 dioxide 

absorption parameters and (2) absorption parameters from the alimentary tract should be used for 

all type SS plutonium exposure estimates. Further, NIOSH should consider use of the dosimetric 

guidance for dose per activity content in the lungs and models for daily excretion in urine and 

feces.

Specifically, SC&A suggests that: 

1. ICRP Publication 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 Publication 141 value for Sr of 0.4 d-1, the rate at which the material is 

absorbed, should be used.

3. The dosimetric data from ICRP Publication 141 should be used to determine the 

parameters for the inhalation of Pu-239 dioxide for all type SS plutonium. The dosimetric 

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.

Observation 2: Section 4.1 of ORAUT-OTIB-0049, revision 02, lists an incorrect Fr value

Section 4.1 of OTIB-0049, revision 0,2 cites an Fr value of 0.001209, rather than the NIOSHcalculated value of 0.001029.

Observation 3: NIOSH failed to consider long-term binding of plutonium

There is no reference to long-term binding of plutonium in OTIB-0049.

Observation 4: Rev. 02 has not used ICRP 141 updates to the ICRP 67 systemic model

The plutonium model of ICRP Publication 67 (ICRP, 1993) was updated and is described in 

detail in ICRP Publication 141 (ICRP, 2019). OTIB-0049, revision 02 (NIOSH, 2020), uses the 

ICRP Publication 67 systemic model instead of the updated model. Excretion rates using the two 

models should be compared.
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 37 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution.

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 Publication 134 (ICRP, 2016), Publication 137 (ICRP, 

2017), and Publication 141 (ICRP, 2019) should be used to calculate dose per intake coefficients, 

dose per content functions, and reference bioassay functions for Pu-239 dioxides (type SS 

plutonium).

Observation 6: OTIB-0049 lacks information about its application to dose reconstruction

SC&A found limited guidance for dose reconstructors on how to apply the guidance in 

OTIB-0049 to a DR. Clear, unambiguous guidance is necessary to ensure cases are processed 

consistently.

Observation 7: A program evaluation report may be required

NIOSH should specify if the dose results using the methods in revision 02 of OTIB-0049 have 

been compared to the doses derived using the former methods for assessing intakes of type SS 

plutonium. In particular, 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 program evaluation report.

Analysis of two DR cases that compared the older and newer methods for assessing plutonium 

strongly retained in the lung found that organ doses in the thoracic and extrathoracic regions 

increased with the new method, while doses to other systemic organs decreased. Therefore, a 

program evaluation report would appear warranted for noncompensated cases with covered 

illnesses involving the thoracic and extrathoracic regions.

Observation 8: ICRP Publication 141 absorption parameters appear to be more claimant 

favorable

Analysis of the HAN-1 case indicates that use of the ICRP Publication 141-derived absorption 

parameters results in higher doses to all evaluated organs when compared to the OTIB-0049-

derived absorption parameters.
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 38 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

6 References

Avtandilashvili, M., Brey, R., & James, A. C. (2012). Maximum likelihood analysis of bioassay 

data from long-term follow-up of two refractory PuO2 inhalation cases. Health Phys. 103(1), 70–

79. 

Avtandilashvili, M., Brey, R. R., & Birchall, A. (2013). Application of Bayesian inference to the 

bioassay data from long-term follow-up of two refractory PuO2 inhalation cases. Health Physics,

104(4), 394–404. 

Bihl, D. E., Lynch, T. P., Carbaugh, E. H., & Sula, M. J. (1988). Methods to improve routine 

bioassay monitoring for freshly separated, poorly transported plutonium (PNL-6695). Pacific 

Northwest Laboratory. https://www.osti.gov/servlets/purl/6800906

Carbaugh, E. H., Bihl, D. E., & Sula, M. J. (1991). Long-term follow-up of HAN-1, an acute 

plutonium oxide inhalation case. Radiation Protection Dosimetry, 38(1–3), 99–104. SRDB Ref. 

ID 18052 

Carbaugh, E. H., & La Bone, T. R. (2003). Two case studies of highly insoluble plutonium 

inhalation with implications for bioassay. Radiation Protection Dosimetry, 105(1–4), 133–138. 

SRDB Ref. ID 18053 

Gregoratto, D., Bailey, M. R., & Marsh, J. W. (2010). Modelling particle retention in the 

alveolar-interstitial region of the human lungs. J. Radiol. Prot., 30, 491–512. 

International Commission on Radiological Protection. (1979). Limits for intakes of radionuclides 

by workers (Publication 30, Part 1). Ann. ICRP, 2(3-4). 

International Commission for Radiological Protection. (1993). Age-dependent doses to members 

of the public from intake of radionuclides: Part 2 ingestion dose coefficients (Publication 67). 

Ann. ICRP, 23(3-4). 

International Commission on Radiological Protection. (1994). Human respiratory tract model for 

radiological protection (Publication 66). Ann. ICRP, 24(1-3). 

International Commission on Radiological Protection. (2006). Human alimentary tract model for 

radiological protection (Publication 100). Ann. ICRP, 36(1-2). 

International Commission on Radiological Protection. (2015). Occupational intakes of 

radionuclides: Part 1 (Publication 130). Ann. ICRP, 44(2). 

International Commission on Radiological Protection. (2016). Occupational intakes of 

radionuclides: Part 2 (Publication 134). Ann. ICRP 45(3/4).

International Commission on Radiological Protection. (2017). Occupational intakes of 

radionuclides: Part 3. ICRP Publication 137. Ann. ICRP 46(3/4). 
Effective date: 10/7/2021 Revision No. 0 (Draft) Document No.: SCA-TR-2021-PR049 Page 39 of 39

NOTICE: This document has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

International Commission on Radiological Protection. (2019). Occupational intakes of 

radionuclides: Part 4 (Publication 141). Ann. ICRP, 48(2/3).

Mann, J. R., & Kirchner, R. A. (1967). Evaluation of lung burden following acute inhalation 

exposure to highly insoluble PuO2. Health Physics, 13, 877–882. SRDB Ref. ID 7974 

National Institute for Occupational Safety and Health. (2007). Estimating doses for plutonium 

strongly retained in the lung (ORAUT-OTIB-0049, rev. 01). 

https://www.cdc.gov/niosh/ocas/pdfs/arch/tibs/or-t49-r1.pdf 

National Institute for Occupational Safety and Health. (2010). Estimating doses for plutonium 

strongly retained in the lung (ORAUT-OTIB-0049, rev. 01 PC-2). 

https://www.cdc.gov/niosh/ocas/pdfs/arch/tibs/or-t49-r1-p2.pdf

National Institute for Occupational Safety and Health. (2019). Technical documentation for the 

super S internal dosimetry tool (IDOT_SS) (DCAS-RPT-007, rev. 00). SRDB Ref. ID 178617 

National Institute for Occupational Safety and Health. (2020). Estimating doses for plutonium 

strongly retained in the lung (ORAUT-OTIB-0049, rev. 02).

https://www.cdc.gov/niosh/ocas/pdfs/tibs/or-t49-r2-508.pdf 

Puncher, M., Birchall, A., & Tolmachev, S. Y. (2017). The Mayak worker dosimetry system 

(MWDS 2013): A re-analysis of USTUR case 0269 to determine whether plutonium binds to the 

lungs. Radiat. Prot. Dosim., 176, 50–61.