Defense Threat Reduction Agency

8725 John J. Kingman Road, MS-6201

Fort Belvoir, VA 22060-6201

Technical Basis for Expedited Processing 

of Radiation Dose Assessments 

for NTPR Hiroshima and Nagasaki Participants

DISTRIBUTION A. Approved for public release: distribution is unlimited.

November 2015

Prepared by:

Leidos, Inc.

Alexandria, VA

DTRA-TR-15-044

TECHNICAL REPORT
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4. TITLE AND SUBTITLE

Technical Basis for Expedited Processing of Radiation Dose 

Assessments for NTPR Hiroshima and Nagasaki Participants

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

McKenzie-Carter, Michael and Egbert, Stephen.

5d. PROJECT NUMBER

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7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

Leidos, Inc., Alexandria, VA

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REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

Nuclear Technology Department, Attn: Dr. Blake 

Defense Threat Reduction Agency 

8725 John J. Kingman Road, Mail Stop 6201 

Fort Belvoir, VA 22060-6201

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DTRA J9-NTSN

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DTRA-TR-15-044

12. DISTRIBUTION AVAILABILITY STATEMENT

DISTRIBUTION A. Approved for public release: distribution is unlimited.

13. SUPPLEMENTARY NOTES

14. ABSTRACT

This report provides the technical basis for development and use of radiation doses for use in expedited processing 

of Radiation Dose Assessments (RDAs) for Hiroshima and Nagasaki (H&N) veterans in the Nuclear Test Personnel 

Review (NTPR) Program. The report describes the general nature of RDAs currently conducted for H&N veterans, 

and the approach used to define three expedited processing groups (EPGs) to include virtually all H&N veterans, 

including occupation forces and prisoners of war in or near Hiroshima or Nagasaki, Japan in 1945–1946. The report 

discusses the technical methods and assumptions used for estimating “maximized doses” and upper-bound external, 

internal, skin, and eye lens doses for each EPG. The results of the dose assessment for each EPG are presented 

and discussed.

15. SUBJECT TERMS

Nuclear Test Personnel Review, Hiroshima, Nagasaki, Radiation Dose Assessment, Expedited Processing

16. SECURITY CLASSIFICATION OF: 17. LIMITATION 

OF ABSTRACT

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18. NUMBER

OF PAGES

54 Pages

19a. NAME OF RESPONSIBLE PERSON 

Paul K. Blake, PhD

a. REPORT

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b. ABSTRACT

 

c. THIS PAGE

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19b. TELEPONE NUMBER (Include area code ) 

 (703) 767-3433
2015-11-16

UNIT CONVERSION TABLE

U.S. customary units to and from international units of measurement*

U.S. Customary Units Multiply by International Units

Divide by†

Length/Area/Volume

inch (in) 2.54 × 10–2 meter (m)

foot (ft) 3.048 × 10–1 meter (m)

yard (yd) 9.144 × 10–1 meter (m)

mile (mi, international) 1.609 344 × 103 meter (m)

mile (nmi, nautical, U.S.) 1.852 × 103 meter (m)

barn (b) 1 × 10–28 square meter (m2)

gallon (gal, U.S. liquid) 3.785 412 × 10–3 cubic meter (m3)

cubic foot (ft3) 2.831 685 × 10–2 cubic meter (m3)

Mass/Density

pound (lb) 4.535 924 × 10–1 kilogram (kg)

unified atomic mass unit (amu) 1.660 539 × 10–27 kilogram (kg)

pound-mass per cubic foot (lb ft–3) 1.601 846 × 101 kilogram per cubic meter (kg m–3)

pound-force (lbf avoirdupois) 4.448 222 newton (N)

Energy/Work/Power

electron volt (eV) 1.602 177 × 10–19 joule (J)

erg 1 × 10–7 joule (J)

kiloton (kt) (TNT equivalent) 4.184 × 1012 joule (J)

British thermal unit (Btu) 

(thermochemical) 1.054 350 × 103 joule (J)

foot-pound-force (ft lbf) 1.355 818 joule (J)

calorie (cal) (thermochemical) 4.184 joule (J)

Pressure

atmosphere (atm) 1.013 250 × 105 pascal (Pa)

pound force per square inch (psi) 6.984 757 × 103 pascal (Pa)

Temperature

degree Fahrenheit (oF) [T(oF) − 32]/1.8 degree Celsius (oC)

degree Fahrenheit (oF) [T(oF) + 459.67]/1.8 kelvin (K)

Radiation

curie (Ci) [activity of radionuclides] 3.7 × 1010 per second (s

–1

) [becquerel (Bq)]

roentgen (R) [air exposure] 2.579 760 × 10–4 coulomb per kilogram (C kg–1)

rad [absorbed dose] 1 × 10–2 joule per kilogram (J kg–1) [gray (Gy)]

rem [equivalent and effective dose] 1 × 10–2 joule per kilogram (J kg–1) [sievert (Sv)] *

Specific details regarding the implementation of SI units may be viewed at http://www.bipm.org/en/si/. †

Multiply the U.S. customary unit by the factor to get the international unit. Divide the international unit by the factor to get the 

U.S. customary unit.
i

DTRA-TR-15-044: Technical Basis for Expedited Processing of Radiation Dose 

Assessments for NTPR Hiroshima and Nagasaki Participants

Table of Contents

List of Figures........................................................................................................................... iii

List of Tables............................................................................................................................ iv

Executive Summary ....................................................................................................................v

Section 1. Introduction................................................................................................................1

Section 2. Background Information.............................................................................................2

2.1 NTPR Expedited Processing and Doses................................................................2

2.2 General Nature of H&N RDAs.............................................................................2

Section 3. Approach for H&N Expedited Processing Doses........................................................4

3.1 General Approach for EPG Dose Assessments.....................................................4

3.2 Methodology for Determining Composition of H&N EPGs..................................4

3.3 General Assumptions for H&N EPG Dose Calculations.......................................8

3.4 General EPG Exclusions Based on Participant Scenarios .....................................9

3.5 Organ and Skin EPG Exclusions Based on Limiting Doses..................................9

Section 4. Expedited Processing Doses for Hiroshima Participants ...........................................11

4.1 Description of the Hiroshima EPG .....................................................................11

4.2 Highest-Dose Cohort Scenario for Hiroshima EPG ............................................11

4.3 Hiroshima EPG Scenario and Parameter Assumptions .......................................12

4.4 Summary of Hiroshima EPG Doses and Upper Bounds......................................13

4.4.1. Hiroshima EPG Organ Doses ........................................................................13

4.4.2. Hiroshima EPG Skin Doses...........................................................................13

4.4.3. Hiroshima EPG Eye (lens) Dose....................................................................13

4.5 Organ and Skin Site Exclusions for the Hiroshima EPG.....................................13

Section 5. Expedited Processing Doses for Nagasaki Participants.............................................17

5.1 Description of the Nagasaki EPG .......................................................................17

5.2 Highest-Dose Cohort Scenario for the Nagasaki EPG.........................................18

5.3 Nagasaki EPG Scenario and Parameter Assumptions .........................................19

5.4 Summary of Nagasaki EPG Doses and Upper Bounds........................................20
ii

5.4.1. Nagasaki EPG Organ Doses..........................................................................20

5.4.2. Nagasaki EPG Skin Doses.............................................................................21

5.4.3. Nagasaki EPG Eye (lens) Dose......................................................................21

5.5 Organ and Skin Site Exclusions for the Nagasaki EPG.......................................22

Section 6. Expedited Processing Doses for Prisoner of War Claimants......................................23

6.1 Description of the POW EPG.............................................................................23

6.2 Highest-Dose Cohort Scenario for the POW EPG ..............................................23

6.3 POW EPG Scenario and Parameter Assumptions...............................................24

6.4 Summary of POW EPG Doses and Upper Bounds .............................................25

6.4.1. POW EPG Organ Doses................................................................................25

6.4.2. POW EPG Skin Doses...................................................................................27

6.4.3. POW EPG Eye (lens) Dose ...........................................................................28

6.5 Organ and Skin Site Exclusions for the POW EPG.............................................28

Section 7. References................................................................................................................30

Appendix A. Weathering Effects of Rainfall on Fallout Exposure Rates....................................32

A-1. Introduction .......................................................................................................32

A-2. Weathering Model and Rainfall Data .................................................................32

A-3. Effects of Weathering on Exposure Rates...........................................................34

A-4. Impacts of Weathering on EPG Doses................................................................35

Appendix B. Parameter Values for H&N EPG Skin Dose Assessments.....................................38

B-1. Parameters used in Contaminated Soil Groundshine Pathway.............................38

B-2. Parameters Used in Dermal Contamination Pathway..........................................40

B-2.1. Parameters for Dermal Contamination by Resuspended Contaminant ......40

B-2.2. Parameters for Dermal Contamination by Descending Fallout .................41

B-2.3. Summary of Interception and Retention Fractions....................................42

B-3. Parameters Used in Clothing Contamination Pathway........................................42

Abbreviations, Acronyms, and Unit Symbols............................................................................44
iii

List of Figures

Figure A-1. Daily and total rainfall at Hiroshima and Nagasaki during the three months 

following the bombings..........................................................................................34

Figure A-2. Comparison of modeled fallout exposure rates for the Hiroshima EPG...................36

Figure A-3. Comparison of modeled fallout exposure rates for the Nagasaki EPG.....................36

Figure A-4. Comparison of modeled fallout exposure rates for the POW EPG ..........................37
iv

List of Tables

Table 1. Composition of EPGs for Hiroshima and Nagasaki participants....................................7

Table 2. Hiroshima participant categories and numbers of individuals......................................11

Table 3. Maximized exposure pathways for the Hiroshima EPG...............................................13

Table 4. Hiroshima EPG external and internal organ doses and upper bounds ..........................14

Table 5. Hiroshima EPG TOD and applicable LD values .........................................................15

Table 6. Hiroshima EPG total external skin doses and LD values.............................................16

Table 7. Nagasaki participant categories and numbers of individuals........................................17

Table 8. Maximized exposure pathways for the Nagasaki EPG ................................................19

Table 9. Nagasaki EPG external and internal organ doses and upper bounds ............................20

Table 10. Nagasaki EPG TOD and applicable LD values .........................................................21

Table 11. Nagasaki EPG total external skin doses and LD values.............................................22

Table 12. Maximized exposure pathways for the POW EPG ....................................................25

Table 13. POW EPG external and internal organ doses and upper bounds................................26

Table 14. POW EPG TOD and applicable LD values...............................................................27

Table 15. POW EPG total external skin doses and LD values...................................................28

Table A-1. Rainfall periods and amounts used in weathering calculations ................................33

Table B-1. Beta-to-gamma dose ratios for bare skin exposures to mixed fission products at the

Pacific Proving Ground ..........................................................................................39

Table B-2. Modification factors for light clothing.....................................................................39

Table B-3. Standard heights and corresponding parameter values.............................................40

Table B-4. Summary of factors in the calculation of the effective retention fraction for 

resuspended contaminants.......................................................................................41

Table B-5. Summary of factors in the calculation of the effective interception and retention 

fraction for descending fallout ................................................................................42

Table B-6. Interception and retention fractions.........................................................................43
v

Executive Summary

Expedited processing of Nuclear Test Personnel Review program radiation dose 

assessments (RDAs) is an option for certain claims from the Department of Veterans Affairs that 

require a radiation dose reconstruction. This process allows for timely processing of claims from 

many veterans, while ensuring that an individual veteran’s assigned dose is greater than his 

actual dose. Claims that are limited to potential exposures associated with participation as World 

War II Prisoners of War (POW) in Japan or as a member of the post-war occupation forces in the 

vicinity of Hiroshima and Nagasaki (H&N), Japan, have just recently been included in expedited 

processing procedures. This technical report was prepared to describe and document the 

technical basis for radiation doses suitable for use in expedited processing of H&N1claims.

The technical basis for H&N expedited processing doses involves the development and 

analysis of three large Expedited Processing Groups (EPGs) to include essentially all H&N 

participants. Each EPG includes individuals who share fundamental aspects of a generic

exposure scenario, and who can therefore be grouped for purposes of a bounding radiation dose 

assessment. The three H&N EPGs consist of one EPG for approximately 154,000 Hiroshima 

participants, a second EPG for approximately 122,000 Nagasaki participants, and a third EPG for 

approximately 3,000 POWs. The H&N EPGs were developed in a manner similar to that used

for EPGs previously developed for participants in U.S. atmospheric nuclear tests conducted at 

the Pacific Proving Ground and the Nevada Test Site. The organ, skin, and eye (lens) doses 

calculated for each H&N EPG are based on high-sided and maximized parameter values and 

assumptions, and their upper bounds are higher than any realistically-calculated upper-bound 

doses for any member of one of the EPGs. Consequently, the resulting EPG doses described in 

this report are suitable for use in the expedited processing of the claim for any H&N participant 

that can be included in one of the H&N EPGs.

For assignment to a veteran, upper-bound total organ and skin doses must not only 

clearly bound the veteran’s actual dose, but also must be well below the dose that could result in 

a service-connected decision. In order to judge if doses were well below a dose resulting in a 

service-connected determination, limiting doses (LDs) were identified for all cancer types for 

organs and three skin cancer types. The LD value is the radiation dose that results in a 

probability of causation of 40 percent for an organ or skin cancer. The majority of upper-bound 

radiation doses calculated for 20 internal organs and 11 skin sites for each H&N EPG are less 

than the applicable LDs, and are thus suitable for use as the basis for expedited processing. 

Exceptions include skin doses for cases involving certain skin site/cancer combinations for 

individuals in all three H&N EPGs. In addition, claims for members of the POW EPG involving 

cancers of the thyroid are not recommended for expedited processing based on the comparison of 

the POW EPG thyroid total organ dose to the thyroid LD.

 1 The use of “H&N” in this report generally refers to all H&N occupation forces, including occupation troops, 

POWs, veterans passing through Hiroshima or Nagasaki, and ship-based personnel at either location. Specific 

definitions of H&N participants are provided in 38 CFR 3.309 (VA, 2015) and apply throughout this report. 
vi

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1

Section 1.

Introduction

Since 2008, the Nuclear Test Personnel Review (NTPR) program has used an approved

procedure to expedite the processing of radiation dose assessments (RDAs) for certain claims

submitted by the Department of Veterans Affairs (VA) for atmospheric nuclear weapons testing 

veterans with qualifying participant exposure scenarios. Qualifying claims may be expedited 

using Standard Operating Procedure (SOP) RA02 (DTRA, 2015a), by assigning pre-determined,

group-based, upper-bound dose estimates to veteran claimants. The use of expedited processing 

procedures allows for timely processing of large numbers of claims while ensuring that an

individual veteran’s assigned dose is greater than his actual dose. 

Veteran claims that involve potential radiation exposure only in the vicinity of Hiroshima 

or Nagasaki, Japan, in 1945 or 1946 are not included in the expedited processing procedure of 

SOP RA02 or its predecessors (DTRA, 2015a). These Hiroshima and Nagasaki (H&N2) claims 

primarily involve participation as a World War II Prisoner of War (POW) or as a member of the 

post-war occupation forces in the vicinity of Hiroshima and Nagasaki. Approximately 280,000 

individuals have been identified as potential members of one of these participant groups. Without 

expedited processing for H&N claims, preparation of veteran-specific exposure scenarios and 

dose estimates was necessary for DTRA to process the claims. This resulted in additional 

processing time with no added benefit to claimants. 

To address expedited processing for H&N claims, DTRA recently prepared a draft 

version of SOP RA05 (DTRA, 2015b). That Draft SOP is similar to RA02 in that it includes the 

assignment of pre-determined, group-based, upper-bound dose estimates to H&N veteran 

claimants. The basis for the pre-determined doses was established in McKenzie-Carter (2014), 

which initially described the approach and technical basis to support expedited processing of

claims involving H&N exposure scenarios. The purpose of the current report is to further 

describe relevant participation details of various H&N military units, and to document in more 

detail the methodology for the estimation of upper-bound external and internal radiation doses to 

internal organs, and external doses to the skin and the lens of the eye using maximized H&N 

exposure scenarios. The approach described in this report generally follows the approach used

previously for development of the technical basis for expedited processing of claims involving

participation in U.S. atmospheric nuclear tests conducted primarily at the Pacific Proving Ground 

(PPG) and the Nevada Test Site (NTS) (Case et al., 2011a; Case et al., 2011b). Consequently, the 

doses described herein are suitable for use in the expedited processing of H&N claims.

 2 The use of “H&N” in this report generally refers to all H&N occupation forces, including occupation troops, 

POWs, veterans passing through Hiroshima or Nagasaki, and ship-based personnel at either location. Specific 

definitions of H&N participants are provided in 38 CFR 3.309 (VA, 2015) and apply throughout this report.
2

Section 2.

Background Information

This section describes the types of doses used for expedited processing of PPG and NTS 

cases, and the general nature of H&N RDAs as currently prepared in the NTPR program. These 

are provided as background information on the expedited processing framework and to provide a 

context for the dose analyses described in this report.

2.1 NTPR Expedited Processing and Doses

There are two different sets of doses utilized in the expedited processing SOP for NTS 

and PPG cases (DTRA, 2015a). The two sets of doses are designated as Expedited Processing 

(“XP”) doses and Expedited Processing Group (“EPG”) doses. The XP doses are defined for two 

broad scenario categories, i.e., for PPG participants and NTS participants (DTRA, 2015a). They 

are based on distributions of doses from the NTPR database of full RDAs as described in Case et 

al. (2011a), and are judged to bound actual veteran doses. The XP doses are used for assignment 

to veterans in expedited processing of PPG and NTS claims. Claims involving H&N scenarios

are assigned XP doses only if those claims also involve participation in a PPG or NTS operation, 

and other criteria are met (DTRA, 2015a). In contrast, the EPG doses consist of sets of scenariobased doses that were developed specifically for use in expedited processing of RDAs. Doses 

were estimated for 32 defined exposure groups participating in various operational series at 

either PPG or NTS, based on similarity of activities and exposure pathways (Case et al., 2011a).

The EPG upper-bound doses are also judged to bound actual veteran doses, but rather than being

used for assignment to veterans, EPG doses are used in the expedited processing SOP to help 

ensure that XP dose assignments are appropriate. 

In an effort to produce a set of XP doses for H&N claims, a review of the NTPR database 

was conducted to characterize the range of upper-bound doses for completed H&N RDAs. 

Because of the low number of RDAs, and the format of the database entries, not enough 

information was available to develop a set of H&N XP doses. Therefore, EPG upper-bound 

doses corresponding to maximized H&N exposure scenarios were developed to support 

expedited processing of H&N claims. Because of the use of EPGs and EPG doses, the technical 

information and the maximized doses contained in this report are suitable for use in expedited 

processing of H&N claims. The specific use of these doses will be addressed in a new revision of 

NTPR SOP RA05 (DTRA, 2015b).

2.2 General Nature of H&N RDAs

The standard methods used for H&N RDAs form the foundation for development of the 

technical basis for full expedited processing of NTPR H&N claims. Standard RDA analyses for

H&N cases are conducted somewhat differently than the analyses for other NTPR cases, as 

described in the NTPR/RDA SOP Manual (DTRA, 2008, Appendix A-1). This is due to the very 

limited information that is available to characterize the H&N radiation environments and 

participant activities, which is in contrast to what is available for most PPG and NTS

participants. Consequently, H&N exposure scenarios are not customized for various participating 

units to account for specific locations, radiation environments, or activities conducted. The 

standard H&N RDA analyses require only the specification of known or assumed arrival and 
3

departure dates, generic daily durations of exposure, breathing rate, and identification of the 

affected organ(s). Values for all other exposure scenario parameters are generic (not specific to a 

veteran or a unit) and are generally very high-sided. For example, almost all H&N RDA dose 

estimates are based on no more than two measured radiation exposure rates at each general 

location (i.e., two measurements for Hiroshima and two for Nagasaki). The standard assumption 

in H&N RDAs is that the entire time a veteran spent in any contaminated area was in an area at 

which one of these levels was measured. In reality, these areas of relatively high radiation levels 

were very small (approximately 0.04 square miles (mi2

). In addition, measurable contamination 

levels were recorded over only 50 percent of the Hiroshima built-up area and only 14 percent of 

Nagasaki’s (McRaney and McGahan, 1980). Similar to participants at Hiroshima and Nagasaki, 

dose estimates for POWs are based on a maximum measured exposure rate, from a location 

approximately 25 mi downwind of Nagasaki on the Shimabara Peninsula. This location is

approximately 20 mi upwind of the nearest POW camp (at Kumamoto) and is also well away 

from all other known POW camps in Japan with surviving POWs (McRaney, 1987).

Another important example of a high-sided scenario assumption used in H&N RDAs is 

that all Nagasaki participants were assumed to ingest 2 liters per day (L d−1) of contaminated 

water from the Nishiyama Reservoir. This assumption is based on the knowledge that this 

reservoir was one of four reservoirs that provided drinking water to Nagasaki City. The assumed 

activity concentration of the reservoir water is based on the fallout surface activity estimated for 

the land surface near Nishiyama Reservoir, and includes a factor to account for potential 

additions of fallout entrained in runoff from the catchment area surrounding the reservoir. The 

calculated reservoir water activity concentration does not incorporate any dilution that would 

result from additions of rain or inflow of runoff water over the period of dose assessment. 

(DTRA, 2008, Appendix A-1)

Because of the lack of scenario-specific information for H&N case analyses and the 

resulting use of very high-sided default parameter values, H&N RDA doses are much more 

conservative than standard NTPR RDAs as completed for most PPG and NTS participants. In 

addition, few details are available to characterize exposure scenarios for most H&N participants, 

and consequently there are no distinct H&N cohort scenarios. These high-siding characteristics 

are reflected in the technical approach to dose estimation for H&N EPGs, as well as in the 

specific EPG organ, skin, and lens of the eye doses, as described in the following section.
4

Section 3.

Approach for H&N Expedited Processing Doses

As described above, neither XP nor EPG doses are available in SOP RA02 for use in 

NTPR processing of H&N claims. Consequently, H&N EPG doses have been developed for use 

in expedited processing of these claims, and are described in this report. The EPG doses are 

based on the approved NTPR standard methods and use the same general approach as was used 

in the development of EPG doses for PPG and NTS veterans, as described below.

3.1 General Approach for EPG Dose Assessments

The general approach for EPG dose assessments was established previously by the 

process used to develop EPG scenarios and doses for PPG and NTS participants (Case et al., 

2011a). The basic steps of the process are listed below.

1) Identify EPG cohorts (simultaneously identify specific exclusion activities)

2) Select a “highest-dose” cohort

3) Modify exposure pathway doses by combining pathway doses from multiple cohorts

4) Replace parameter values with limiting plausible values where possible

5) Calculate EPG doses for each pathway and upper-bound EPG doses using NTPR 

standard methods supplemented by additional high-sided assumptions

For PPG and NTS EPG development, the above steps were applied using the wide variety 

of cohort exposure scenarios for PPG and NTS participants. For each cohort, potential exposure 

pathways, radiation environments, and participant activities were based on cohort-specific 

assumptions and parameter values to develop reasonably high-sided estimates of cohort doses. 

This resulted in EPG doses that satisfied the criteria that they are based on dose-maximizing

parameter values and assumptions, and that their upper bounds be higher than any realistically 

calculated veteran’s upper-bound doses, while simultaneously maximizing the number of 

participants included in each EPG. (Case et al., 2011a; Case et al., 2011b)

3.2 Methodology for Determining Composition of H&N EPGs

Because of the very high-sided and generic nature of H&N RDA analyses (Section 2.2), 

the general EPG steps listed above could not be rigorously applied for the development of H&N 

EPGs. For example, an H&N “cohort” was necessarily described more loosely than those 

defined for PPG and NTS, because activities of most participants are not well-documented in the 

available military records. Therefore, H&N cohorts could not be based on well-defined scenarios 

of participation activities and exposures of their members. However, it was still possible to 

develop a basis for H&N EPG development that was more broadly defined than what is used for 

typical H&N RDA doses, and that relied on categories that would be useful to the NTPR 

program in processing participation and dose requests from the VA. Consequently, following the 

five numbered steps above, the general approach to development of H&N EPGs is described 

below.

1) Initial large groupings of participants at both Hiroshima and Nagasaki were made, based 

on very general criteria such as time-frame of participation, and assigned location (e.g., 
5

on land or on a ship). The list below shows the five participant categories that were 

identified for both Hiroshima and Nagasaki. 

• Occupation troops: Individuals assigned to units responsible for the occupation of 

Hiroshima or Nagasaki during the period August 6, 1945 through early July, 1946. 

Occupation troops were assigned to units within the organizational structure at each 

location and were responsible for establishing control of Japan, ensuring compliance 

with the surrender terms, and conducting activities related to demilitarization, 

rehabilitation of the infrastructure or deactivation and conversion of war plants or 

materials. Activities did not include cleanup of any areas or rebuilding any facilities. 

(VA, 2015; Gladeck and Johnson, 1996; McRaney and McGahan, 1980)

• Ship-based personnel: These individuals were assigned to ships that were in or near 

the harbor during the occupation period. Responsibilities assigned to these ships 

included mine sweeping, harbor patrols, loading of POWs for repatriation, ferrying 

duties, and possibly some shore-based duties. 

• Enroute personnel: Individuals that passed through Hiroshima or Nagasaki before or 

during the occupation period while enroute to or from other locations in Japan.

• POWs: Individuals that were interned as a prisoner of war within 75 mi of Hiroshima 

or 150 mi of Nagasaki, Japan during World War II and had the opportunity for 

radiological exposure comparable to that of the Occupation troops at any time during 

the occupation period.

• Other personnel: Participants that are not obviously in any other H&N participant 

category. This primarily includes pre-occupation forces present in Japan as early as 

approximately September 8, 1945, and those remaining beyond the end of the 

occupation periods. Also included are aircrew members participating on or after 

August 6 or August 9, 1945, and any participants not assigned to a military unit 

within the organizational structure of occupation forces at each location.

Within each of these large groups, “cohorts” were identified based on criteria such as 

arrival/departure dates, geographic area of responsibility, location of POW camp, and 

assigned ship. 

2) Similar criteria as those for cohort identification (Step #1) were then used to identify the 

most likely highest-dose cohort within each group. This determination was later 

confirmed on the basis of scoping dose calculations. 

3) Modification of the exposure pathway doses was considered; however, modifications 

were not made because pathways and associated doses were generally shared by all 

related cohorts. 

4) Only a limited replacement of RDA default parameter values was accomplished because 

most parameter values were already at or above maximum reasonable values.

5) The existing H&N RDA standard methods were then used to calculate external, internal,

skin, and eye lens doses and upper bounds for the highest-dose cohort for each group.
6

Following a review of the potential exposure scenarios and performing scoping dose

calculations for the five participant categories listed above for Hiroshima and Nagasaki

participants, it was possible to further combine several of these groups.

For Hiroshima and Nagasaki participants, respectively, a review of known and likely 

participant activities allowed for the determination that individuals in the Occupation troops, 

Ship-based personnel, Enroute personnel, and Other personnel categories could be combined into 

a single EPG for each location. Although general activities of members of these groups may have 

been different, their activities that may have resulted in exposure to residual radiation were likely 

similar. Furthermore, the sources of potential radiation exposure of members of these groups 

were similar. In addition, the following characteristics of specific categories were included in the 

considerations for final grouping:

• Ship-based personnel had no sources of exposure while on-board ship (including 

consumption of seawater [McRaney, 1993]), so all potential exposures were the same 

as or less than the Occupation troops. 

• Enroute personnel, by definition, would have spent much less time in Hiroshima or 

Nagasaki than Occupation troops, and also less time in potentially contaminated 

areas.

• Other personnel includes individuals who were often present for only a short period 

(e.g., pre-occupation and POW recovery participants), and therefore had generally 

less potential for exposures.

• The potential doses for POWs repatriated through Hiroshima were determined to be 

bounded by POW doses calculated for POWs repatriated through Nagasaki, and so all 

POWs were combined into a single POW EPG.

The identification, evaluation, and final grouping of participant categories resulted in the 

three EPGs described below and evaluated in this technical report: two primary EPGs which 

include most H&N participants, and a single EPG for POWs. These three EPGs are intended to 

cover all individuals that are confirmed by the NTPR program as participants of the occupation 

of Hiroshima or Nagasaki, or as former prisoners of war in Japan (VA, 2015). The EPGs are

listed below (with participant categories included as indicated), and are also shown in Table 1.

• Hiroshima EPG: includes Occupation troops, Ship-based personnel, Enroute

personnel, and most Other personnel

• Nagasaki EPG: includes Occupation troops, Ship-based personnel, Enroute

personnel, and most Other personnel

• POW EPG: includes most POWs that were interned or worked near Hiroshima or 

Nagasaki prior to or during the occupation period
7

Table 1. Composition of EPGs for Hiroshima and Nagasaki participants

Participant

Category*

H&N Expedited Processing Groups

Hiroshima Nagasaki Prisoners of War

Occupation troops

Occupation troops in the vicinity of

Hiroshima from early September, 

1945 through July, 1946

Occupation troops present in the 

vicinity of Nagasaki, Nishiyama 

Reservoir, or nearby POW Camps

during the period early September, 

1945 to July, 1946

n/a

Ship-based personnel

Ship-based personnel near Hiroshima 

Harbor or City any time from early 

September, 1945 through July, 1946

Ship-based personnel in the vicinity of

Nagasaki Harbor or City for any length 

of time from early September, 1945 to 

July, 1946

n/a

Enroute personnel

Individuals passing through 

Hiroshima any number of times from 

early September, 1945 through July,

1946

Individuals passing through or near 

Nagasaki any number of times from 

early September, 1945 through July, 

1946

n/a

Other personnel†

Any participant not in any other 

category present near Hiroshima on 

August 6, 1945 or for any length of 

time from early September, 1945 

through July, 1946 

Any participants not in another 

category that were present in the 

vicinity of Nagasaki or nearby areas on 

August 9, 1945 or from early 

September, 1945 to July, 1946

n/a

POWs n/a n/a

POWs that were interned or worked 

near Hiroshima or Nagasaki for any 

period following August 6, 1945, or 

were repatriated through Nagasaki * All H&N participants (VA, 2015), fall into one of the Categories listed as defined in Section 3 unless generally or specifically excluded. † The Other personnel participant category includes individuals conducting pre-occupation activities, POW recovery teams, aircrew members (including bomb 

delivery aircraft), and members of other units such as 509 Composite Group, the Manhattan Project Atomic Bomb Investigation Group, and the Strategic 

Bombing Survey. 
8

3.3 General Assumptions for H&N EPG Dose Calculations

Following the determination of the three H&N EPGs, upper-bound external and internal 

doses were calculated for each EPG. Organ doses from external and internal exposure pathways 

were calculated, as well as external doses to the skin and lens of the eye. Except where noted, the 

dose calculations were based on default assumptions used for H&N RDAs, using NTPR standard 

methods (DTRA, 2008; DTRA, 2010). Key general assumptions used for the dose calculations in 

each of the EPGs are described below.

• Exposure rates assumed for the entire areas of contamination in and near Hiroshima and 

Nagasaki were based on the survey results of the Naval Medical Research Institute (NMRI) 

for each location. The highest values from NMRI surveys were used and were assumed to be 

applicable to the entire area of contamination at each location. The NMRI results were used 

rather than other measurements (e.g., those made by the Manhattan Engineer District), 

because the NMRI measurements were made at a height of 1 meter (m) and should be 

representative of whole-body exposure (McRaney and McGahan, 1980).

• Measured and modeled exposure rates for in situ (fixed) soil activation were assumed to be 

unaffected by weathering. These exposure rates were assumed to be reduced only by 

radiological decay, from the times of the detonations to the end of each EPG exposure 

scenario.

• Measured and modeled exposure rates for deposited fallout were assumed to be reduced by 

the combined effects of radiological decay and weathering. Radiological decay was assumed 

over the time from the detonation to the end of each EPG exposure scenario. The effects of 

weathering by rainfall were assumed to occur from the time of deposition to the date of the 

relevant measurement for each EPG exposure scenario. Weathering effects are not normally 

included in NTPR RDAs but are included in the EPG dose calculations to help ensure that 

high-sided doses are estimated (see additional discussion in Appendix A).

• Daily duration in contaminated areas for every day of participation in the areas of Hiroshima 

and Nagasaki was assumed to be either 8 hours per day (h d−1) in the vicinity of ground zero 

(GZ), or 4 h d−1 in areas of fallout, whichever assumption produced the highest dose. 

• Exposure rates in the vicinity of GZ were assumed to be entirely due to fixed, in situ soil 

activation products (McRaney and McGahan, 1980; Kerr et al., 2015). 

• The area of Hiroshima fallout was assumed to be in the Koi River/Takasu vicinity, and 

Nagasaki fallout was assumed to have been deposited in the vicinity of the Nishiyama 

Reservoir and areas further to the east. Fallout3 was assumed to consist of weapon-specific 

 3 Measurements verify that weapon debris including fission products were in the Hiroshima and Nagasaki fallout at 

these locations (Kerr et al., 2015; McRaney and McGahan, 1980). A mechanism for downwind deposition of lofted 

activated soil and building material has also been suggested (Kerr et al., 2015). Although the heights of both 

detonations were well above the height at which significant masses of surface material were pulled up into the cloud, 

some activated soil and building materials were lofted into the lower portions of the clouds (dust pedestals and 

stems). However, because characterizations of lofted material have not been accomplished, in addition to the 

speculative status of potential deposition of lofted material in outlying areas, activated soil is not considered as a 

component of fallout in this analysis.
9

bomb debris, fission products, actinides, and activated case material. (McRaney and 

McGahan, 1980).

• Although fallout is not known to have fallen on any POW camps, POWs were assumed to be 

in a fallout-contaminated area 24 hours each day. This assumption is based on a fallout 

measurement made downwind of Nagasaki, in the direction of a POW camp near Kumamoto.

• All time that participants were assumed to spend in a contaminated area was assumed to be

outdoors, with no shielding by buildings or other structures.

• To model the suspension of in situ neutron-induced soil activation products in the vicinity of 

GZ, a constant suspension factor of 10−4

m

−1

was used.

• To model the resuspension of fallout, the standard method time-dependent resuspension 

factor algorithm used for PPG and NTS radiation dose assessments was used (DTRA, 2010).

• External skin and eye doses from gamma and beta radiation from contamination in or on the 

ground (ground shine) were calculated for a representative set of body skin sites for all EPGs. 

Doses for these sites were calculated assuming both uncovered (bare) skin and skin covered 

by a layer of clothing (see Appendix B). The calculation of doses for covered skin sites for 

Hiroshima and Nagasaki occupation forces is not normally conducted in standard RDAs.

• External skin doses due to dermal and clothing contamination were calculated for the POW

EPG, because POWs were assumed to have been exposed to descending fallout.

• For purposes of skin and eye dose calculations, individuals in all H&N EPGs were assumed 

to be sitting on the ground for one-half of each period spent in a fallout-contaminated area.

• Uncertainty factors of 3 and 10 were used to obtain upper-bound external and internal 

doses, respectively.

The NTPR default assumptions and parameter values were supplemented by additional 

EPG-specific assumptions and values in order to help ensure that final upper-bound EPG doses 

were bounding for all members of each EPG. The EPG-specific assumptions are described in 

subsequent sections for each EPG.

3.4 General EPG Exclusions Based on Participant Scenarios

The following individuals/activities are generally excluded from the expedited processing 

groups, based on the potential for exposure scenarios that may exceed the assumed EPG scenario 

conditions.

• Personnel permanently assigned to Radiation Safety (RadSafe) duties

• Individuals with unique exposures not normally encountered by Hiroshima and Nagasaki 

participants that could lead to increased exposure (e.g., routine consumption of local 

food)

3.5 Organ and Skin EPG Exclusions Based on Limiting Doses

Some organ or skin doses calculated for H&N EPGs using the conservative methodology 

described in the following sections could be near or above the level that could result in serviceconnected determinations. To be useful, upper-bound doses that result from the EPG approach 
10

described in this technical report must be well below the dose that could result in serviceconnected determinations. Consistent with the previous EPG analyses (Case et al., 2011a), this 

report defines “well below the dose that could result in compensation” as the dose that produces 

a probability of causation for cancers of 40 percent at the upper 99 percent credibility limit for 

exposure at age 18 years, and diagnosis of cancer at either age 50 years or after an appropriate 

elapsed time following exposure. This dose is defined as the “Limiting Dose” (LD) for each 

organ or skin cancer, and is used to compare with upper-bound doses resulting from the EPG 

methodologies.

Values for LDs for internal organs have previously been determined using NIOSH-IREP 

(NIOSH, 2014) and are tabulated in Case et al. (2011a). Because LD values for skin cancers are 

not known to be documented elsewhere, NIOSH-IREP was used to calculate LD values 

specifically for this report for each of the three skin cancer models available in NIOSH-IREP. 

Skin cancer LDs were determined using input to NIOSH-IREP that is consistent with the LDs 

documented in Case et al. (2011a), i.e., gamma doses entered as acute doses from photons with 

energy > 250 keV, beta doses from electrons with energy > 15 keV, exposure at age 18 years, 

and attained age of 50 years. Furthermore, the LDs for skin cancers vary according to the 

ethnicity of an individual. The values in this report were estimated using the Ethnic Origin 

choice of “White-Non-Hispanic” in NIOSH-IREP. The LDs estimated using an Ethnic Origin 

choice of “Black” in NIOSH-IREP are about 90 percent (melanoma), and about 50 percent (basal 

cell and squamous cell carcinoma) of the values listed for White-Non-Hispanic. (NIOSH, 2014)

For each EPG, Total Organ Doses (TODs) were calculated by adding the upper-bound 

external dose and the upper-bound internal doses (alpha and beta+gamma) for 20 standard 

organs, and then rounding up to two significant digits. Upper-bound skin doses (beta+gamma) 

were also calculated for 11 representative skin sites and the lens of the eye. Any TOD or upperbound skin or eye lens dose that exceeds the applicable LD or other applicable reference dose4 is 

not recommended for use in expedited processing of a specific veteran’s claim. In addition, any 

organs or skin cancers that do not have associated LDs listed in this report are not recommended 

for expedited processing unless surrogate organs exist. The TODs and upper-bound skin doses 

that exceed the applicable LD are identified as necessary in subsequent sections.

Some NTPR standard organs are used as surrogate organs for more than one tissue or

organ, some of which have different LDs. For example, liver is the surrogate organ for both 

gallbladder (LD = 11 rem) and liver (LD = 7.7 rem). Similarly, ET Region is the surrogate organ 

for esophagus (LD = 22 rem), larynx (LD = 67 rem), and several tissues and organs in the oral 

cavity such as tongue, parotid gland, and pharynx (LD = 66 rem). In these cases, the lowest of 

these multiple LDs for any standard organ is the LD that is compared to the H&N EPG dose for 

each NTPR standard organ in subsequent sections. For example, the LD used for liver is 7.7 rem 

(the lower of 11 and 7.7 rem), and the LD used for ET Region is 22 rem (the lowest of 22, 66, 

and 67 rem). (Case et al., 2011a)

 4 By definition, LDs are applicable only to cancers. However, doses that are similar to LDs have been identified for 

certain non-cancer conditions. This includes a thyroid dose range of 25–36 rem for thyroid nodular disease, and an 

eye lens dose of 28 rem for posterior subcapsular cataracts. (DTRA, 2015a)
11

Section 4.

Expedited Processing Doses for Hiroshima Participants

4.1 Description of the Hiroshima EPG

The Hiroshima EPG consists of U.S. forces that were present in or near Hiroshima, Japan 

for any length of time, primarily from September 8, 1945 to July 1, 1946. Also included are 

aircrew members that were airborne over Hiroshima on or after August 6, 1945 (McRaney and 

Weitz, 1980). The date of September 8, 1945 corresponds to the approximate date of initial 

landings of a POW recovery team, at a location more than 100 mi east of Hiroshima near

Wakayama, Japan (Kerr, 1980). Occupation troops first landed near Hiroshima 28 days later, on 

October 6, 1945. The end date of July 1, 1946 corresponds to the latest reasonable departure date 

found in the NTPR participant database (NTPR, 2013a).

Approximately 154,000 individuals are listed as Hiroshima participants in the NTPR 

participant database; a breakout of this population is shown in Table 2. (NTPR, 2013a).

Table 2. Hiroshima participant categories and numbers of individuals

Category

Approximate Number 

of Individuals Comments

Occupation troops 37,100 Over 400 named units

Ship-based

personnel 67,400 Includes over 500 ships, comprising U.S. military, Liberty, Victory, and merchant ships

Enroute personnel 48,800 Individuals passing through the Hiroshima 

area, generally short stay times

Other personnel 300

Includes, for example, members of the 509 

Composite Group, Manhattan Project Atomic 

Bomb Investigation Group, and unidentified 

unit affiliations

There are no specific exclusions for the Hiroshima EPG. Therefore, all individuals 

described in Table 2. other than those with general exclusions (Section 3.4) are considered to be 

included in the Hiroshima EPG. However, there are certain EPG/organ combinations that may 

not be appropriate for expedited processing based on the Hiroshima EPG doses in this report, as

identified in a subsequent section.

4.2 Highest-Dose Cohort Scenario for Hiroshima EPG

Military units responsible for the occupation of western Honshu (including Hiroshima) 

were initially from the 41st Division, followed by units of the 24th Division. The 162nd Infantry 
12

Regiment and the 186th Infantry Regiment (41st Division) landed near Hiroshima over

October 6–7, 1945, and were responsible for the occupation of the Hiroshima area until early 

December, 1945. These troops were billeted at the Kure Submarine Base (11 mi southeast of 

Hiroshima) or at a bivouac location at Kaidaichi, about 5 mi southeast of the center of 

Hiroshima. In early December, 1945, the 34th Infantry Regiment (24th Division), replaced the 

162nd and 186th Regiments of the 41st Division in the Hiroshima area. Only one Company of the

34th Regiment was in the immediate vicinity of Hiroshima, and that Company was quartered on a 

small island in the river delta just south of Hiroshima. On March 6, 1946, the 34th Regiment was 

relieved of its responsibilities by Australian troops. The arrival of the Australian troops ended the 

U.S. occupation responsibilities at Hiroshima (McRaney and McGahan, 1980). 

Using previous dose estimates (DTRA, 2008; McRaney and McGahan, 1980), 

supplemented with current calculations based on the arrival/departure dates and areas of 

responsibility among the military units described above that were present at or near Hiroshima 

during the occupation period, the highest-dose unit was determined to be a generic unit of the 

34th Regiment present in the Hiroshima area from early December, 1945, until March 6, 1946. 

Certain elements of the exposure scenario for the 34th Regiment were maximized for the EPG 

dose analysis as described below.

4.3 Hiroshima EPG Scenario and Parameter Assumptions 

To estimate upper-bound doses for the Hiroshima EPG, calculations were accomplished

using NTPR standard methods including the general assumptions and parameter values described 

in Section 3.3. Additional specific parameter values used in the Hiroshima EPG dose assessment 

include the following (DTRA, 2008, Appendix A-1).

• The highest iso-contour exposure rate of 0.069 milliroentgen per hour (mR h−1) measured in 

Hiroshima on November 1, 1945 by a team from the NMRI is used as the basis for the 

exposure rate for entire time in the vicinity of GZ. This exposure rate was assumed to be due 

to in situ neutron-induced soil activation products.

• The highest exposure rate of 0.042 mR h−1 measured in the Koi River/Takasu area west of 

Hiroshima on November 1, 1945 by the NMRI team is used as the basis for the exposure rate 

for the entire time near Koi River/Takasu. This exposure rate was assumed to be due to 

fallout deposited in the area.

Two additional maximizing assumptions were incorporated into the Hiroshima EPG 

assessment. Based on a review of the NTPR participant database (NTPR, 2013a), the duration of 

participation near Hiroshima was extended to span the longest reasonable duration for any 

Hiroshima participant. Also, the assumed breathing rate of participants is 2 m3 h−1, based on the 

assumption of personnel activities consisting of a mix of 50 percent light activity and 50 percent 

moderate activity (Case et al., 2011b). These assumptions, which maximize the EPG dose 

calculations as compared to the standard Hiroshima RDA calculations, are further specified in 

Table 3. 
13

Table 3. Maximized exposure pathways for the Hiroshima EPG

Exposure Pathway Basis for Exposure Pathway Maximizing Factor

EXTERNAL and INTERNAL

Duration of participation Participants were assumed to 

have been present in the 

vicinity of Hiroshima.

Participation is from Sep 8, 1945 

through Jul 1, 1946 (296 days) instead 

of the more typical duration of 30–60 

days.

INTERNAL

Inhalation of suspended 

or resuspended 

contaminants

Participants may have inhaled 

suspended soil activation 

products in vicinity of GZ or

fallout in the Koi/Takasu area.

Breathing rate is 2 m3 h−1 instead of the 

NTPR RDA default value of 1.2 m3 h−1.

4.4 Summary of Hiroshima EPG Doses and Upper Bounds

4.4.1. Hiroshima EPG Organ Doses

The external and internal and corresponding upper-bound doses for the Hiroshima EPG 

were calculated for the standard NTPR organs using the assumptions and parameter values 

described above. The resulting doses are shown in Table 4. The Hiroshima EPG TODs for

standard organs and comparison with applicable LDs are shown in Table 5. All TODs in Table 5

are less than the applicable LD by more than an order of magnitude.

4.4.2. Hiroshima EPG Skin Doses

Skin doses were calculated for 11 representative skin sites for members of the Hiroshima 

EPG using the assumptions and parameter values described above. A summary of these skin 

doses, corresponding upper-bound doses, and comparisons with LD values for three skin cancers 

are shown in Table 6. With the exception of the dose for uncovered skin on the foot or ankle, 

total upper-bound skin doses for all skin sites in Table 6 are less than all LDs. 

4.4.3. Hiroshima EPG Eye (lens) Dose

External doses for the lens of the eye were calculated for the Hiroshima EPG using the 

assumptions and parameter values described above. The resulting total upper-bound external 

dose (beta plus gamma) to the lens of the eye is 0.23 rem. This dose is well below the dose of 

28 rem judged to be “as likely as not” to result in posterior subcapsular cataracts (DTRA, 2015a).

4.5 Organ and Skin Site Exclusions for the Hiroshima EPG

To determine organ and skin exclusions, EPG TODs and total upper-bound skin doses 

were compared with the LD values as described above. Based on this comparison, certain claims 

involving skin cancers are not recommended for EPG processing based on the EPG doses. 

Specifically, the upper-bound skin dose calculated for bare skin on the foot or ankle should not 

be assigned in expedited processing of claims involving malignant melanoma or basal cell 

carcinoma.
14

Table 4. Hiroshima EPG external and internal organ doses and upper bounds

External Source External Dose (rem) External Upper-bound

Dose (rem)

Residual gamma radiation 0.074 0.22

NTPR Standard Organ

Internal Dose (rem) Internal Upper-bound

Dose (rem)

Alpha* Beta+Gamma Alpha* Beta+Gamma

Adrenals - 0.005 - 0.051

Bone surface - 0.003 0.001 0.026

Brain - 0.001 - 0.010

Breast - 0.005 - 0.051

Stomach wall - 0.003 - 0.032

Small intestine wall - 0.002 - 0.024

Upper large intestine wall - 0.004 - 0.038

Lower large intestine wall - 0.007 - 0.069

Kidneys - 0.002 - 0.025

Liver - 0.005 - 0.053

Extra-thoracic region - 0.033 - 0.34

Lung - 0.064 - 0.64

Muscle - 0.003 - 0.026

Pancreas - 0.004 - 0.041

Red marrow - 0.003 - 0.032

Spleen - 0.004 - 0.041

Testes - 0.001 - 0.009

Thymus - 0.006 - 0.060

Thyroid - 0.002 - 0.025

Urinary bladder wall - 0.001 - 0.013

* A dash indicates that the calculated dose is less than 0.001 rem.
15

Table 5. Hiroshima EPG TOD and applicable LD values

NTPR Standard Organ

Total Organ Dose*

(rem)

Limiting Dose†

(rem)

Adrenals 0.28 30

Bone surface 0.25 32

Brain 0.24 30

Breast 0.28 36

Stomach wall 0.26 18

Small intestine wall 0.25 44

Upper large intestine wall 0.26 26

Lower large intestine wall 0.29 26

Kidneys 0.25 31

Liver 0.28 7.7

Extra-thoracic region 0.57 22

Lung 0.87 30

Muscle 0.25 34

Pancreas 0.27 61

Red marrow 0.26 14

Spleen 0.27 44

Testes 0.23 41

Thymus 0.29 41

Thyroid 0.25 5.1

Urinary bladder wall 0.24 33

* TODs are calculated by adding the upper-bound external dose and the upper-bound internal 

doses (alpha and beta+gamma) from Table 4, and rounding up to two significant digits.

† The LDs correspond to a 40 percent probability of causation. Each value shown is the lowest 

LD for any organ for which the indicated NTPR standard organ is used (see Section 3.5).
16

Table 6. Hiroshima EPG total external skin doses and LD values

Skin Site

Total External Dose

(rem)*

Total Upper-bound 

External Dose 

(rem)*

Limiting Dose 

(rem)†

Bare 

Sites

Covered 

Sites

Bare 

Sites

Covered 

Sites MM BCC SCC

foot/ankle 2.5 1.1 7.3 3.1

4.2 4.1 195

calf/shin 1.2 0.65 3.4 2.0

knee 0.66 0.46 2.0 1.4

hand/

mid-thigh 0.48 0.35 1.5 1.1

waist 0.41 0.31 1.3 0.93

forearm 0.41 0.31 1.3 0.93

lower back/

stomach 0.33 0.25 0.97 0.75

upper back/

upper arm/

mid-chest

0.27 0.22 0.81 0.64

neck 0.25 0.20 0.75 0.60

face/nose/

ear/head 0.23 0.19 0.69 0.56

top of head 0.21 0.17 0.63 0.51 * Doses are rounded up with two significant digits displayed.

† LDs correspond to a 40 percent probability of causation for malignant melanoma (MM), basal cell carcinoma 

(BCC), and squamous cell carcinoma (SCC), and were calculated as described in Section 3.5.
17

Section 5.

Expedited Processing Doses for Nagasaki Participants

5.1 Description of the Nagasaki EPG

The Nagasaki EPG consists of most U.S. military participants that were present in or near 

Nagasaki, Japan for any length of time from as early as about September 8, 1945 to early July, 

1946. Also included are aircrew members that were airborne over Nagasaki on or after August 9, 

1945 (McRaney and Weitz, 1980). The date of September 8, 1945 corresponds to the 

approximate date that mine-sweeping operations began in Nagasaki Harbor (McRaney, 1987). A

POW recovery team with a detachment of Marine guards landed at Nagasaki on September 11, 

1945, and an advance party of Occupation troops landed near Nagasaki on September 16, 1945;

the remainder of the Nagasaki Occupation troops landed during the period September 23–28, 

1945 (McRaney and McGahan, 1980). The end date of the EPG period corresponds to the latest 

reasonable departure date determined from the documented occupation history, and the latest 

reasonable departure date found in DNA 5512F (McRaney and McGahan, 1980) and the NTPR 

participant database (NTPR, 2013b).

Approximately 122,000 individuals are listed as Nagasaki participants in the NTPR 

participant database; a breakout of this population is shown in Table 7.

Table 7. Nagasaki participant categories and numbers of individuals

Category

Approximate Number 

of Individuals Comments

Occupation troops 14,200 Over 100 named units

Ship-based personnel 106,000

Includes over 350 ships, comprising U.S. 

military, Liberty, Victory, and merchant 

ships

Enroute personnel 20 Individuals passing through the Nagasaki 

area, generally short stay times

Other personnel 1,630

Includes, for example, members of: 

Manhattan Project Atomic Bomb 

Investigation Group; the Strategic Bomb 

Survey Tokyo; Naval Mobile 

Construction Battalions 43 and 70; and 

unidentified unit affiliations

There are no specific exclusions associated with the Nagasaki EPG. However, there are 

certain EPG/organ combinations that may not be appropriate for expedited processing based on

the Nagasaki EPG doses in this report, as identified in a subsequent section.
18

5.2 Highest-Dose Cohort Scenario for the Nagasaki EPG

The occupation of the Nagasaki area was assigned to the 2nd Marine Division, 

5th Amphibious Corps of the Sixth Army. The 2nd Division was organized into several functional 

groups (by task and assigned areas), as follows:

• Support Group (Division troops, Service troops, Engineer troops)

• Regimental Combat Team 2 (RCT-2)

• Regimental Combat Team 6 (RCT-6)

• Regimental Combat Team 8 (RCT-8)

• Artillery Group

• 2nd Tank Battalion

• Marine Observation Squadron #2

The 2nd Division units assigned to each of the above functional groups changed 

somewhat over the course of the occupational period. Most units assigned to the 2nd Division 

experienced large turnover of personnel during the occupation period. Therefore it is very 

unlikely that many 2nd Division personnel remained in the Nagasaki area for the duration of the 

occupation period. Units assigned to areas potentially experiencing fallout (primarily near the 

Nishiyama Reservoir and in the vicinity of Kumamoto) had the potential to accrue the largest 

doses. These units are RCT-2, RCT-8, and the Artillery group as described below.

Occupation troops landed at various locations in and near Nagasaki Harbor over the 

period September 23–28, 1945. The initial responsibility for Nagasaki City was assigned to 

RCT-2, which relieved the Marine security guards assigned to the POW recovery operation. The 

RCT-2 zone of occupation responsibility included all of the city of Nagasaki on the east side of 

Nagasaki harbor, as well as the areas east, northeast, and southwest of the city (including the area 

around Nishiyama Reservoir). On September 28, 1945, RCT-2 began sending patrols throughout 

its area of responsibility. RCT-2 operated in its zone of responsibility until October 30–

November 12, 1945, when the elements of RCT-2 moved to areas at and more than 100 mi from 

Nagasaki. During this period of RCT-2’s departure from Nagasaki, the Artillery Group was 

reassigned from Isahaya, approximately 12 mi northeast of Nagasaki, to the areas of 

responsibility vacated by RCT-2, starting as early as November 2, 1945. RCT-8 was also initially 

assigned to Isahaya, and on October 8, 1945 was reassigned to the Kumamoto area where it 

apparently remained until departure. Members of the Artillery Group and limited other 

2nd Division troops remained in the vicinity of Nagasaki until approximately June 26, 1946. 

(McRaney and McGahan, 1980)

The identification of a highest-dose cohort for the Nagasaki EPG is based on the known 

areas of responsibilities of the above functional groups. RCT-2 and the Artillery Group were the 

groups that shared responsibility for the area that included the Nishiyama Reservoir, and RCT-8 

was assigned to Kumamoto for a portion of the occupation period. In general, these three groups 

had the potential for the highest doses from residual radiation because of the assumed fallout 

near Nishiyama Reservoir and Kumamoto. Based on screening calculations accomplished for 

exposure scenarios involving these three groups, the highest-dose cohort was determined to be 

the Artillery Group.
19

5.3 Nagasaki EPG Scenario and Parameter Assumptions 

To estimate upper-bound doses for the Nagasaki EPG, calculations were accomplished

using NTPR standard methods including the general assumptions and parameter values described 

in Section 3.3. Additional specific parameter values used in the Nagasaki EPG dose assessment

include the following (DTRA, 2008, Appendix A-1).

• The highest iso-contour exposure rate of 0.069 mR h−1 measured in Nagasaki on October 21, 

1945 by an NMRI team is used as the basis for the exposure rate for the entire time in the

vicinity of GZ. This exposure rate was assumed to be due to in situ neutron-induced soil 

activation products.

• The highest exposure rate of 1.080 mR h−1 measured near Nishiyama Reservoir on 

October 21, 1945 by an NMRI team is used as the basis for the exposure rate for the entire 

time in the area of Nishiyama Reservoir. This exposure rate was assumed to be due to fallout 

deposited in the area.

• A consumption rate of 2 L d−1 of water from the Nishiyama Reservoir was assumed for all 

participants.

Two additional maximizing assumptions were incorporated into the Nagasaki EPG dose 

assessment. The duration of participation was extended to span the longest reasonable duration 

for any Nagasaki participant in the Artillery Group. The duration was based on the documented 

history of this group (McRaney and McGahan, 1980), and also on a review of the NTPR 

participant database (NTPR, 2013b). Also, the assumed breathing rate is 2 m3 h−1, based on the 

assumption of personnel activities consisting of a mix of 50 percent light activity and 50 percent 

moderate activity (Case et al., 2011b). These assumptions maximize the EPG dose calculations 

as compared to the standard Nagasaki RDA calculations, and are further specified in Table 8.

Table 8. Maximized exposure pathways for the Nagasaki EPG

Exposure Pathway

Basis for Exposure 

Pathway Maximizing Factor

EXTERNAL and INTERNAL

Duration of 

participation

Participants were assumed

to have been present in the 

vicinity of Nagasaki.

Participation is from Sep 24, 1945 through 

Jun 26, 1946 (277 days) instead of a more 

typical 30–60 days.

Daily time in 

contaminated areas

Participants may have been 

present near GZ area or in 

the vicinity of fallout east 

of Nagasaki near 

Nishiyama Reservoir

Sep 24–Nov 2, 1945:

 8 h d−1 in vicinity of GZ

Nov 2, 1945–Jun 26, 1946:

 8 h d−1 in vicinity of GZ, or*

 4 h d−1 in vicinity of Nishiyama Reservoir

INTERNAL

Inhalation of 

suspended or 

resuspended 

contaminants

Participants may have 

inhaled suspended soil 

activation products in 

vicinity of GZ or fallout 

near Nishiyama Reservoir.

Breathing rate is 2 m3 h−1 instead of the NTPR 

RDA default value of 1.2 m3 h−1.

* Exposure pathway doses are calculated for each dose location assumption, and the highest of each is selected as 

the dose for each exposure pathway.
20

5.4 Summary of Nagasaki EPG Doses and Upper Bounds

5.4.1. Nagasaki EPG Organ Doses

The external and internal doses and corresponding upper-bound doses for the Nagasaki 

EPG were calculated for the standard NTPR organs using the assumptions and parameter values 

described above. The resulting doses are shown in Table 9. The relatively large internal doses for 

bone surface and liver result primarily from the inhalation of resuspended fallout near the 

Nishiyama Reservoir, whereas the relatively large doses for upper and lower large intestine walls

result primarily from the ingestion of fallout in drinking water assumed to come from the 

Nishiyama Reservoir.

The Nagasaki EPG TODs for standard organs and comparisons with applicable LDs are 

shown in Table 10. All TODs in Table 10 are less than the applicable LD.

Table 9. Nagasaki EPG external and internal organ doses and upper bounds

External Source External Dose (rem)

External Upper-bound

Dose (rem)

Residual gamma radiation 0.25 0.74

NTPR Standard Organ Internal Dose (rem)

Internal Upper-bound

Dose (rem)

Alpha Beta+Gamma Alpha Beta+Gamma

Adrenals 0.003 0.031 0.030 0.32

Bone surface 1.6 0.26 17 2.6

Brain 0.003 0.023 0.030 0.24

Breast 0.003 0.025 0.030 0.25

Stomach wall 0.003 0.090 0.031 0.90

Small intestine wall 0.003 0.19 0.032 1.9

Upper large intestine wall 0.004 0.83 0.043 8.4

Lower large intestine wall 0.007 2.3 0.068 23

Kidneys 0.007 0.036 0.070 0.36

Liver 0.40 0.047 3.6 0.47

Extra-thoracic region 0.012 0.050 0.12 0.50

Lung 0.024 0.15 0.25 1.6

Muscle 0.003 0.030 0.030 0.31

Pancreas 0.003 0.033 0.030 0.33

Red marrow 0.080 0.13 0.81 1.3

Spleen 0.003 0.030 0.030 0.31

Testes 0.023 0.030 0.23 0.29

Thymus 0.003 0.030 0.030 0.27

Thyroid 0.003 0.22 0.030 2.3

Urinary bladder wall 0.003 0.046 0.030 0.47
21

Table 10. Nagasaki EPG TOD and applicable LD values

NTPR Standard Organ

Total Organ Dose*

(rem)

Limiting Dose†

(rem)

Adrenals 1.1 30

Bone surface 21 32

Brain 1.1 30

Breast 1.1 36

Stomach wall 1.7 18

Small intestine wall 2.7 44

Upper large intestine wall 9.2 26

Lower large intestine wall 24 26

Kidneys 1.2 31

Liver 4.9 7.7

Extra-thoracic region 1.4 22

Lung 2.6 30

Muscle 1.1 34

Pancreas 1.1 61

Red marrow 2.9 14

Spleen 1.1 44

Testes 1.3 41

Thymus 1.1 41

Thyroid 3.1 5.1

Urinary bladder wall 1.3 33

* TODs are calculated by adding the upper-bound external dose and the upper-bound internal 

doses (alpha and beta+gamma) from Table 9, and rounding up to two significant digits. † The LDs correspond to a 40 percent probability of causation. Each value shown is the lowest 

LD for any disease for which the indicated NTPR standard organ is used (see Section 3.5).

5.4.2. Nagasaki EPG Skin Doses

Skin doses were calculated for 11 representative skin sites for members of the Nagasaki EPG

using the assumptions and parameter values described above. A summary of these skin doses, 

corresponding upper-bound doses, and comparisons with LD values are shown in Table 11.

5.4.3. Nagasaki EPG Eye (lens) Dose

External doses for the lens of the eye were calculated for the Nagasaki EPG using the 

assumptions and parameter values described above. The resulting total upper-bound external 

dose (beta plus gamma) to the lens of the eye is 1.8 rem. This dose is well below the dose of 

28 rem judged to be “as likely as not” to result in posterior subcapsular cataracts (DTRA, 2015a).
22

Table 11. Nagasaki EPG total external skin doses and LD values

Skin Site

Total External 

Dose (rem)*

Total Upper-bound 

External Dose 

(rem)*

Limiting Dose 

(rem)†

Bare 

Sites

Covered 

Sites

Bare 

Sites

Covered 

Sites MM BCC SCC

foot/ankle 23 9.4 68 28

4.2 4.1 195

calf/shin 11 5.9 31 18

knee 6.0 4.1 18 13

hand/

mid-thigh 4.5 3.3 14 9.7

waist 3.9 3.0 12 8.8

forearm 3.9 3.0 12 8.8

lower back/

stomach 3.2 2.5 9.5 7.3

upper back/

upper arm/

mid-chest

2.8 2.2 8.2 6.4

neck 2.6 2.1 7.7 6.1

face/nose/

ear/head 2.4 2.0 7.2 5.8

top of head 2.2 1.8 6.6 5.3 * Doses are rounded up with two significant digits displayed.

† LDs correspond to a 40 percent probability of causation for malignant melanoma (MM), basal cell carcinoma 

(BCC), and squamous cell carcinoma (SCC), and were calculated as described in Section 3.5.

5.5 Organ and Skin Site Exclusions for the Nagasaki EPG

To determine organ and skin exclusions, EPG TODs and total upper-bound skin doses 

were compared with the LD values as described above. Based on this comparison, certain claims 

involving skin cancers are not recommended for EPG processing based on the EPG doses. 

Specifically, all of the upper-bound skin doses are greater than the LDs for malignant melanoma 

and basal cell carcinoma and should not be assigned in expedited processing of claims involving 

these skin cancers.
23

Section 6.

Expedited Processing Doses for Prisoner of War Claimants

6.1 Description of the POW EPG

The H&N POW EPG consists of POWs that were interned or worked in Japan near 

Hiroshima or Nagasaki starting on or before August 6, 1945. Most of these POWs were 

evacuated from Japan via Hiroshima or Nagasaki before the end of September, 1945 (McRaney 

and McGahan, 1980). There are approximately 3,000 POWs identified in the NTPR database 

(NTPR, 2013a; NTPR, 2013b), although McRaney (1987) indicates a total of about 3,700 POWs 

were evacuated from the two locations. The NTPR database contains about 500 POWs that 

passed through Hiroshima and about 2,400 POWs that passed through Nagasaki.

The only specific exclusion for the POW EPG is for any individual that worked in 

Hiroshima or Nagasaki during the period between the bombings of these cities and the arrival of 

the U.S. military personnel in early September, 1945.

6.2 Highest-Dose Cohort Scenario for the POW EPG

At the time of the bombings, numerous POW camps were located in Japan, including a 

considerable number of camps on western Honshu, Kyushu, and Shikoku within 100 mi of

Hiroshima and/or Nagasaki. The closest camps to Hiroshima and Nagasaki with surviving U.S. 

POWs were 6 mi or more from the cities. The liberation and rapid evacuation of American and 

allied POWs from these camps was a priority mission soon after the end of World War II. The 

port city of Wakayama (160 mi east of Hiroshima) was used to evacuate all POWs from western 

Honshu and the island of Shikoku. POWs in camps in these areas were processed at Wakayama 

and were embarked on evacuation ships from September 12–15, 1945. Nagasaki was the 

processing center for the evacuation for POWs in camps on Kyushu. The first trainload of POWs 

arrived at the Nagasaki processing center about 2 mi south of the Nagasaki ground zero on 

September 13, 1945. The Nagasaki center processed three trainloads of POWs per day, and all 

POWs were evacuated via Nagasaki by September 23, 1945. (McRaney and McGahan, 1980; 

McRaney, 1987)

Downwind fallout from the Hiroshima detonation was not detected in the direction of any 

POW camps. Light fallout from the Nagasaki detonation occurred at considerable distances east 

of Nagasaki, in the general direction of several POW camps. Readings above background were 

recorded by an NMRI survey approximately 25 miles east of the Nagasaki GZ, and fallout was 

detected by Japanese scientists in Kumamoto but no levels were reported. Based on the 

prevailing winds, the POW camp at Kumamoto is the most likely camp for any significant 

fallout. An NMRI measurement on Shimabara Peninsula, at a location about 25 miles downwind 

from Nagasaki, was assumed to apply to the camp near Kumamoto. The Kumamoto POW camp 

is across the Shimabara Bay from the measurement location, about 20 mi further downwind from

the measurement location. Based on the possibility of fallout occurring, the POWs at the 

Kumamoto POW camp form the highest-dose cohort for the POW EPG. Exposure pathways for 

POWs include exposure to fallout at the camp, and exposure to residual radiation while enroute 

to evacuation processing centers. (McRaney, 1987)
24

6.3 POW EPG Scenario and Parameter Assumptions 

POWs did not accrue doses from neutrons or initial gamma radiation. This is because all 

POW camps with surviving American POWs were located at least 6 mi from the ground zero of 

either detonation, and at this distance radiation levels from initial radiations were undetectable 

(DTRA, 2010). In addition, no POWs that were in Hiroshima or Nagasaki at the time of the 

bombings are known to have survived the detonations. (DTRA, 2008; McRaney, 1987) 

To estimate upper-bound doses for the POW EPG, calculations were conducted using 

NTPR standard methods, including the general assumptions and parameter values described in 

Section 3.3. Additional specific parameter values used in the POW EPG dose assessment are 

listed below (DTRA, 2008, Appendix A-1; DTRA, 2010). Additional details on the skin dose 

methodology used are included in Appendix B.

• The highest exposure rate of 0.020 mR h−1 measured by an NMRI team on October 21, 1945 

at a location on the Shimabara Peninsula about 20 mi upwind of the Kumamoto POW Camp 

is used as the basis for the exposure rate for the entire time POWs spent in the Kumamoto

POW Camp area. This exposure rate was assumed to be due to fallout from the Nagasaki 

weapon deposited in the area of the Kumamoto POW Camp, based on the prevailing winds 

on August 9, 1945.

• The highest iso-contour exposure rate of 0.069 mR h−1 measured in Nagasaki on October 21, 

1945 by an NMRI team at a location near Nagasaki GZ is used as the basis for the exposure 

rate for the one day POWs were assumed to be in the Nagasaki area for repatriation. This 

exposure rate was assumed to be due to neutron-induced soil activation products.

• Members of the POW EPG were assumed to inhale descending fallout near Kumamoto

between H+7 and H+8; the doses for this pathway are estimated using the high-sided 

simplification described in NTPR Standard Method ID01 (DTRA, 2010).

• Members of the POW EPG were assumed to have ingested fallout that was deposited on a 

9-inch diameter dinner plate over a 15-minute period during the 1-hour period of descending 

fallout.

• Skin and clothing contamination doses are included from both descending and resuspended 

fallout, with the assumption that contamination remains on the skin or clothing for 12 hours 

prior to washing off. The skin dose conversion factor used for dermal contamination is 

900 rad h−1 per Ci m

−2. For skin covered by a layer of clothing, a clothing modification factor 

of 0.4 was assumed, and the rounded skin dose conversion factor used is 400 rad h−1

per Ci m−2 (DTRA, 2007, ED04).

Several additional maximizing assumptions were incorporated into the POW EPG dose 

assessment. The maximum duration at the Kumamoto POW camp was assumed, with the further 

assumption that a full day was spent in Nagasaki. Also, the assumed breathing rate is 2 m3 h−1, 

used for consistency with the other H&N EPG analyses. These assumptions, which maximize the 

EPG dose calculations as compared to the standard POW RDA calculations, are further specified

in Table 12.
25

Table 12. Maximized exposure pathways for the POW EPG

Exposure Pathway Basis for Exposure Pathway Maximizing Factor

EXTERNAL and INTERNAL

Duration of 

participation

EPG members were assumed to

have been present at the

Kumamoto POW Camp.

Maximum post-detonation time at 

Kumamoto POW Camp, from Aug 9–

Sep 22, 1945 (44 days), plus one full 

day in Nagasaki on the last day of POW 

processing (Sep 23, 1945)

Daily time in 

contaminated areas

EPG members may have been 

present in the vicinity of fallout 

near the Kumamoto POW Camp.

Aug 9–Sep 22, 1945: 24 h d−1 in vicinity 

of fallout near Kumamoto POW Camp;

Sep 23, 1945: 8 h d−1 in vicinity of

Nagasaki GZ

INTERNAL

Inhalation of suspended 

or resuspended 

contaminants

EPG members may have inhaled 

fallout near Kumamoto and 

suspended soil activation 

products for one day while 

passing through Nagasaki.

Individuals were assumed to inhale 

suspended soil activation products while 

in Nagasaki.

Breathing rate is 2 m3 h−1 instead of the 

NTPR RDA default value of 1.2 m3 h−1.

6.4 Summary of POW EPG Doses and Upper Bounds

6.4.1. POW EPG Organ Doses

The external and internal organ doses and corresponding upper-bound organ doses for the 

H&N POW EPG were calculated for the standard NTPR organs using the assumptions and 

parameter values described above. The resulting doses are shown in Table 13. The relatively 

large internal alpha dose for bone surface is primarily due to the inhalation of resuspended 

fallout. The three relatively large internal beta+gamma doses (for upper and lower large intestine 

wall, and thyroid) result primarily from the internal dose due to the ingestion of fallout deposited 

on a plate. 

The POW EPG TODs for standard organs and comparisons with applicable LDs are 

shown in Table 14. Except for thyroid, all TODs in Table 14 are less than the applicable LD.
26

Table 13. POW EPG external and internal organ doses and upper bounds

External Source External Dose (rem)

External Upper-bound

Dose (rem)

Residual gamma radiation 0.74 2.2

NTPR Standard Organ

Internal Dose (rem) Internal Upper-bound

Dose (rem)

Alpha* Beta+Gamma Alpha Beta+Gamma

Adrenals - 0.007 0.004 0.074

Bone surface 0.20 0.029 2.0 0.30

Brain - 0.004 0.004 0.040

Breast - 0.004 0.004 0.044

Stomach wall - 0.16 0.004 1.6

Small intestine wall - 0.24 0.004 2.4

Upper large intestine wall - 0.74 0.004 7.4

Lower large intestine wall - 1.1 0.004 12

Kidneys 0.001 0.019 0.009 0.20

Liver 0.043 0.017 0.43 0.18

Extra-thoracic region 0.002 0.15 0.020 1.5

Lung 0.004 0.17 0.043 1.7

Muscle - 0.008 0.004 0.078

Pancreas - 0.011 0.004 0.11

Red marrow 0.010 0.016 0.097 0.17

Spleen - 0.008 0.004 0.085

Testes 0.003 0.006 0.028 0.060

Thymus - 0.005 0.004 0.053

Thyroid - 1.7 0.004 18

Urinary bladder wall - 0.048 0.004 0.48

* A dash indicates that the calculated dose is less than 0.001 rem.
27

Table 14. POW EPG TOD and applicable LD values

NTPR Standard Organ

Total Organ Dose*

(rem)

Limiting Dose†

(rem)

Adrenals 2.3 30

Bone surface 4.6 32

Brain 2.3 30

Breast 2.3 36

Stomach wall 3.9 18

Small intestine wall 4.7 44

Upper large intestine wall 9.7 26

Lower large intestine wall 15 26

Kidneys 2.5 31

Liver 2.9 7.7

Extra-thoracic region 3.8 22

Lung 4.0 30

Muscle 2.3 34

Pancreas 2.4 61

Red marrow 2.5 14

Spleen 2.3 44

Testes 2.3 41

Thymus 2.3 41

Thyroid 21 5.1

Urinary bladder wall 2.7 33

* TODs are calculated by adding the upper-bound external dose and the upper-bound internal 

doses (alpha and beta+gamma) from Table 13, and rounding up to two significant digits.

† The LDs correspond to a 40 percent probability of causation. Each value shown is the lowest 

LD for any disease for which the indicated NTPR standard organ is used (see Section 3.5).

6.4.2. POW EPG Skin Doses

Skin doses were calculated for 11 representative skin sites (both covered and bare) for 

members of the H&N POW EPG using the assumptions and parameter values described 

previously. A summary of total skin doses, corresponding upper-bound doses, and comparisons 

with LD values are shown in Table 15. As described above, the H&N POW EPG skin doses 

include doses from skin and clothing contamination, and some body sites exhibit high 

interception and retention fractions for descending and resuspended fallout (Appendix B). In 

addition, higher uncertainty factors are associated with these doses as compared to ground shine 

doses. These characteristics can result in large upper-bound doses, as noted in Table 15.
28

Table 15. POW EPG total external skin doses and LD values

Skin Site

Total External 

Dose (rem)*

Total Upperbound External 

Dose (rem)*

Limiting Dose 

(rem)†

Bare 

Sites

Covered 

Sites

Bare 

Sites

Covered 

Sites MM BCC SCC

foot/ankle ‡ 53 ‡ 160

4.2 4.1 195

calf/shin 52 31 170 95

knee 43 22 150 72

hand/

mid-thigh 44 18 170 70

waist ‡ 17 ‡ 66

forearm 36 16 140 58

lower back/

stomach 21 14 130 62

upper back/

upper arm/

mid-chest

20 13 130 60

neck ‡ 12 ‡ 59

face/nose/

ear/head 11 12 45 58

top of head 58 11 ‡ 57 * Doses are rounded up with two significant digits displayed.

† LDs correspond to a 40 percent probability of causation for malignant melanoma (MM), basal cell carcinoma 

(BCC), and squamous cell carcinoma (SCC), and were calculated as described in Section 3.5. ‡

These doses are greater than the LD for all three skin cancers.

6.4.3. POW EPG Eye (lens) Dose

External doses for the lens of the eye were calculated for the POW EPG using the 

assumptions and parameter values described above. The resulting total upper-bound external 

dose (beta plus gamma) to the lens of the eye is 4.1 rem. This dose is well below the dose of 

28 rem judged to be “as likely as not” to result in posterior subcapsular cataracts (DTRA, 2015a).

6.5 Organ and Skin Site Exclusions for the POW EPG

To determine organ and skin exclusions, POW EPG TODs and total upper-bound skin 

doses were compared with the LD values as described above. Based on this comparison, certain 

claims are not recommended for POW expedited processing based on the EPG doses. 

Specifically, the thyroid TOD should not be assigned in expedited processing of claims involving 

thyroid cancers. In addition, all of the upper-bound skin doses are greater than the LDs for 

malignant melanoma and basal cell carcinoma and should not be assigned in expedited 
29

processing of claims involving these skin cancers for any skin site. Finally, several upper-bound 

skin doses are greater than all LDs as indicated in Table 15.
30

Section 7.

References

Apostoaei, A.I. and D.C. Kocher, 2010. Radiation Doses to Skin from Dermal Contamination. 

DTRA-TR-09-16, SENES Oak Ridge. Oak Ridge, TN. October.

Case, D. R., Chehata, M., Dunavant, J. D., Egbert, S. D., Mason, C. L., McKenzie-Carter, M. A., 

Singer, H. A., and Weitz, R. L., 2011a. A Technical Approach to Expedited Processing of 

NTPR Radiation Dose Assessments. DTRA-TR-10-29, Defense Threat Reduction 

Agency. Fort Belvoir, VA. October 17.

Case, D. R., Chehata, M., Dunavant, J. D., Mason, C. L., McKenzie-Carter, M. A., Singer, H. A., 

and Weitz, R. L., 2011b. Compendium of Proposed NTPR Expedited Processing Groups. 

DTRA-TR-11-01, Defense Threat Reduction Agency. Fort Belvoir, VA. November 30.

DTRA (Defense Threat Reduction Agency), 2007. Standard Operating Procedures Manual for 

Radiation Dose Assessment, Revision 1.0. Defense Threat Reduction Agency, Fort 

Belvoir, VA. October 31.

DTRA (Defense Threat Reduction Agency), 2008. Standard Operating Procedures Manual for 

Radiation Dose Assessment, Revision 1.2. DTRA-SOP-10-01, Defense Threat Reduction 

Agency, Fort Belvoir, VA. October 31.

DTRA (Defense Threat Reduction Agency), 2010. Standard Operating Procedures Manual for 

Radiation Dose Assessment, Revision 1.3/1.3a. DTRA-SOP-10-01, Defense Threat 

Reduction Agency, Fort Belvoir, VA. January 31/March 31.

DTRA (Defense Threat Reduction Agency), 2015a. Expedited Processing of Radiation Dose 

Assessments for Atmospheric Nuclear Weapons Testing Veterans, NTPR Standard 

Operating Procedure RA02, Revision 2.2, Defense Threat Reduction Agency, Fort 

Belvoir, VA. June 30.

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Assessments for NTPR Hiroshima and Nagasaki Veterans, NTPR Standard Operating

Procedure RA05, Draft Revision 1.1, Defense Threat Reduction Agency, Fort Belvoir, 

VA. June 23.

Gladeck, F. and Johnson, A., 1996. For the Record—A History of the Nuclear Test Personnel 

Review Program, 1978 – 1993. JAYCOR (for Defense Nuclear Agency), Alexandria VA. 

March.

Kerr, G. D., 1980. “Defense Nuclear Agency Report dated 5 October 1979 on General Dosage 

Reconstruction, Marine Occcupation (sic) of Japan, 1945–1946.” Intra-Laboratory 

Correspondence from G. D. Kerr to C.R. Richmond. Oak Ridge National Laboratory. 

June 4.

Kerr, G.D., Egbert, S.D., Al-Nabulsi, I., Bailiff, I.K., Beck, H.L., Belukha, I.G., Cockayne, J.E., 

Cullings, H.M., Eckerman, K.F., Granovskaya, E., Grant, E.J., Hoshi, M., Kaul, D.C., 

Kryuchkov, V., Mannis, D., Ohtaki, M., Otani, K., Shinkarev, S., Simon, S.L., Spriggs, 
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G.D., Stepanenko, V.F., Stricklin, D., Weiss, J.F., Weitz, R.L., Woda, C., Worthington, 

P.R., Yamamoto, K., Young, R.W., 2015. “Workshop Report on Atomic Bomb 

Dosimetry – Review of Dose Related Factors for the Evaluation of Exposures to Residual 

Radiation at Hiroshima and Nagasaki,” Health Physics, 109(6):582–600. 

McKenzie-Carter, M. A., 2014. Technical Basis for Expedited Processing of Radiation Dose 

Assessments for NTPR Hiroshima and Nagasaki Participants. NTPR-TM-14-02. Defense 

Threat Reduction Agency, Fort Belvoir, VA. November 14.

McRaney, W., 1987. “Radiation Doses Received by American Prisoners of War in Japan.” 

Memorandum to File. Science Applications International Corporation. April 17.

McRaney, W., 1993. “Radiological Hazard Associated with Use/Consumption of Seawater in the 

Vicinity of Hiroshima and Nagasaki, Japan, During Fall of 1945.” Memorandum to 

DNA/RARP-NTPR (M. Owais). Science Applications International Corporation, 

McLean, VA. August 10.

McRaney, W. and McGahan, J., 1980. Radiation Dose Reconstruction U.S. Occupation Forces 

in Hiroshima and Nagasaki, Japan, 1945-1946. DNA-5512F. Science Applications, Inc. 

McLean, VA. August 6.

McRaney and Weitz, 1980. “Radiation Dose Estimate for Aircrew Members Over 

Hiroshima/Nagasaki, Japan.” Memorandum to File. Science Applications, Inc., McLean, 

VA. November 13.

NIOSH (National Institute of Occupational Safety and Health), 2014. User’s Guide for the 

Interactive RadioEpidemiological Program (NIOSH-IREP). Version 5.7.1, Oak Ridge 

Center for Risk Analysis, July. Available at: https://www.niosh-irep.com/irep_niosh/

NTPR, 2013a. “Hiroshima Units,” E-mail from H. Gaugler (L-3) to M. Chehata (Leidos). L-3 

Communications, Reston, VA. November 1.

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M. McKenzie-Carter (Leidos). L-3 Communications, Reston, VA. November 13.

Takeshita K., 1972. “Residual radiation from the atomic bomb at Hiroshima.” In: Proceedings 

of Hiroshima University–RINMB 13. pp 1-8 (in Japanese).

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In: “Review of Thirty Years Study of Hiroshima and Nagasaki Atomic Bomb Survivors.” 

Journal of Radiation Research, 16(Suppl. 1):24–31. 

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service connection,” Code of Federal Regulations, National Archives and Records 

Administration's Office of the Federal Register and the Government Printing Office, 

Washington DC. July 1.
32

Appendix A.

Weathering Effects of Rainfall on Fallout Exposure Rates

A-1. Introduction

Weathering is defined for this analysis as natural phenomena that act to reduce the 

amount of radioactive contaminants in a specific area over time. These phenomena can include 

processes such as wind, rainfall runoff and infiltration, and flooding. Although soil samples 

taken in the area of Nishiyama Reservoir in 1970 suggested that fission-product contamination in 

undisturbed soil had not been significantly altered by weathering (McRaney and McGahan, 

1980), weathering effects have been postulated to account for inconsistencies found in 

measurements of soil samples from the Nishiyama Reservoir (Kerr et al., 2015). There are no 

known documented weathering effects on exposure rates from fixed soil activation products at 

either Hiroshima or Nagasaki. Because of uncertainties and the likely lower magnitude of 

potential effects on exposure rates from fixed soil activation products, consideration of 

weathering effects in this report is limited to surface-deposited fallout.

The NTPR dose assessment methods and procedures, including those for H&N RDAs, do 

not include explicit consideration of weathering effects (DTRA, 2010). However, the H&N EPG 

exposure scenarios include two key features not typically found in other NTPR dose 

assessments: unique scenario timing, and significant rainfall. H&N EPG exposure scenarios 

begin at times from about 1 month (for the Nagasaki EPG) to 2.5 months (for the POW EPG) 

prior to the dates of relevant measurements, which is much longer than for most NTPR exposure 

scenarios. Because the exposure scenarios begin well before the relevant measurements, the 

measured exposure rates must be back-calculated to obtain the initial exposure rate at the 

beginning of each exposure scenario. In combination with timing considerations, a large amount 

of rainfall occurred in southern Japan during the period from the time fallout was deposited to 

the dates of the relevant measurements. The significant amounts of rainfall that occurred prior to 

the measurements could have resulted in removal of surface-deposited fallout through runoff or 

infiltration, thereby reducing the measured exposure rates more than they would be reduced by 

radioactive decay alone. By accounting for this potential weathering reduction, higher initial 

exposure rates are obtained when the measured exposure rates are back-calculated to the start 

times of the H&N EPG scenarios. Because consideration of weathering prior to the relevant 

measurements would result in higher doses for some H&N EPG scenarios, the weathering effects 

of rainfall on fallout exposure rates are conservatively incorporated into the H&N EPG dose 

assessments.

A-2. Weathering Model and Rainfall Data

The possible effect of rainfall on fallout exposure rates at Hiroshima and Nagasaki has 

been discussed by Takeshita (1972; 1975) and also more recently in Kerr et al. (2015). Based on 

an evaluation of measured exposure rates, a rainfall weathering constant was derived (Takeshita, 

1975) that can be used with the rainfall amounts to estimate the degree of reduction in exposure 

rates due to weathering. This is accomplished using the equation described in Takeshita (1975) 

and Kerr et al. (2015) and shown below. 
33

Im = Iddd × � tm

tddd�

−1.2

× e−kQm (A-1)

where,

Im = Exposure rate at the time of measurement (R h−1)

Iddd = Exposure rate at the time of fallout deposition (R h−1)

tm = Post-detonation time of measurement (h)

tddd = Post-detonation time of fallout deposition (h)

k = Rainfall weathering constant (= 0.001 mm−1)

Qm = Rainfall for entire period of interest (amount [mm] occurring between tdep and tm)

This function can be expressed more generally using the measured exposure rate and 

applicable rainfall amount to back-calculate the estimated exposure rate at any time t as follows:

It = Im × �

tm

t �

1.2

× ek(Qm−Qt) (A-2)

where,

It = Exposure rate at time t (R h−1)

Qt = Rainfall occurring from tdep to time t (mm)

(Qm − Qt) = Rainfall occurring from time t to the time of measurement tm (mm)

The rainfall occurring at Hiroshima and Nagasaki for the three months after the bombings 

is shown in Figure A-1. To simplify the rainfall weathering calculations for this assessment, 

rainfall amounts at Hiroshima (for the Hiroshima EPG), and at Nagasaki (for the Nagasaki and 

POW EPGs) was apportioned into four periods as shown in Table A-1.

Table A-1. Rainfall periods and amounts used in weathering calculations

EPG Period #1* Period #2 Period #3 Period #4 Total†

Hiroshima EPG Aug 6–Sep 5

190 mm

Sep 6–Sep 17 

280 mm

Sep 18–Sep 25 

140 mm

Sep 26–Oct 10 

300 mm

Aug 6–Nov 1

910 mm

Nagasaki and 

POW EPGs

Aug 9–Sep 1

550 mm

Sep 2–Sep 17

275 mm

Sep 18–Oct 2

150 mm

Oct 3–Oct 18

225 mm

Aug 9–Oct 21

1,200 mm

* The dates of the period (all 1945) and the amount of accumulated rainfall during the period (millimeter [mm]) is

shown for each period. For calculation purposes the rainfall accumulated during each period is all assumed to 

occur on the last day of the period. 

† The dates and rainfall for “Total” are for the entire period from fallout deposition to the date of the relevant 

measurement for each detonation and EPG.
34

Figure A-1. Daily and total rainfall at Hiroshima and Nagasaki

during the three months following the bombings

(Takeshita, 1972; Kerr et al., 2015)

A-3. Effects of Weathering on Exposure Rates

Using Equation A-2 and the rainfall amounts in Table A-1, the peak fallout exposure 

rates prior to weathering were calculated. For the POW EPG, the peak exposure rate at 

Kumamoto POW camp (as measured on the Shimabara Peninsula – see main text of this report) 

occurred at H+8, which is the assumed end of fallout deposition. For the Hiroshima and 

Nagasaki EPGs, deposition times are not relevant to this assessment because occupation forces 
35

were not present at early times after the detonations, so the peak fallout exposure rates at 

Koi/Takasu (Hiroshima EPG) and Nishiyama Reservoir (Nagasaki EPG) are arbitrarily assumed 

to have occurred occur at H+1. The peak rates calculated with weathering are larger by factors of 

about 2.5 (Hiroshima EPG) and 3.3 (Nagasaki and POW EPGs) than when calculated using only 

radioactive decay. These factors were calculated using the total rainfall amounts shown in 

Table A-1. For example, for Hiroshima the peak rate is increased by a factor of exp(0.001  910) 

= 2.5. The factors are applicable for all times from the time of the peak exposure rate to the date 

of the first modeled rainfall for each EPG.

Exposure rates calculated for the dates of the beginning of the EPG exposure scenarios 

are also of interest. These exposure rates are larger by factors of about 1.5 (Nagasaki EPG), 

2.0 (Hiroshima EPG), and 3.3 (POW EPG). These factors are based on the amount of rainfall 

occurring from the start of each exposure scenario to the measurement date (see main text of this 

report for the beginning dates of the H&N EPG exposure scenarios). The POW EPG exposure 

scenario started on the day of the Nagasaki detonation, so the factor reflects the total amount of 

rainfall shown in Table A-1 for the POW EPG (1,200 mm). The Nagasaki factor is the lowest of 

the three factors because the amount of rainfall that occurred from the beginning of the Nagasaki 

exposure scenario to the measurement date is the lowest of the three EPGs (375 mm between 

September 24 and October 21, 1945). 

To illustrate the effect of weathering on the exposure rate functions, comparisons of the 

exposure rate functions for each EPG as modeled with and without weathering are shown in 

Figure A-2, Figure A-3, and Figure A-4. The increased peak exposure rates are evident in these 

figures. Also evident in these figures are the marked decreases in exposure rates at the end of 

each of the rainfall periods described in Table A-1. 

A-4. Impacts of Weathering on EPG Doses

Several factors affect the magnitude of the weathering assumptions on estimated EPG 

organ and skin doses. These factors include: rainfall amounts occurring between scenario start 

dates and measurement dates; exposure scenario timing, including whether any portion of the 

exposure scenario occurs after the measurement date; the assumed location(s) of individuals in 

the scenario (GZ or fallout location); and radiological half-lives of radionuclides contributing to 

internal organ doses. 

Organ and skin doses calculated with the weathering exposure rate functions are 

generally higher by a factor of about 3.2 for the POW EPG as compared to doses calculated 

assuming no weathering. Organ and skin doses calculated for the Hiroshima and Nagasaki EPGs 

are affected much less than the POW EPG doses, with increases ranging from zero to increases 

of 1–25 percent.

As described above, weathering by rainfall is considered in the H&N EPG calculations 

for rainfall occurring over the time periods from fallout deposition to the times of the relevant 

measurements. Consideration of the rainfall occurring after the measurements could also reduce 

the calculated doses for members of the Hiroshima and Nagasaki EPGs by further weathering the 

deposited fallout. However, this potential reduction in doses is not accounted for in this analysis 

consistent with NTPR SOP methods (DTRA, 2010).
36

Figure A-2. Comparison of modeled fallout exposure rates for the Hiroshima EPG

Figure A-3. Comparison of modeled fallout exposure rates for the Nagasaki EPG

1 10 100 1000 10000

0.001

0.01

0.1

1

10

100

1000

Post-detonation time (h)

Exposure rate (mR h

−1

)

──── With weathering

─ ─ ─ Without weathering

 Period of exposure scenario

 ▲ Time of measurement

1 10 100 1000 10000

0.1

1

10

100

1000

10000

100000

Post-detonation time (h)

Exposure rate (mR h

−1

)

──── With weathering

─ ─ ─ Without weathering

 Period of exposure scenario

 ▲ Time of measurement
37

Figure A-4. Comparison of modeled fallout exposure rates for the POW EPG

1 10 100 1000 10000

0.01

0.1

1

10

100

Post-detonation time (h)

Exposure rate (mR h

−1

)

──── With weathering

─ ─ ─ Without weathering

 Period of exposure scenario

 ▲ Time of measurement
38

Appendix B.

Parameter Values for H&N EPG Skin Dose Assessments

The methodology and assumptions used for H&N skin dose assessments are based on 

information contained primarily in NTPR standard methods (DTRA, 2008; DTRA, 2010). Some 

assumptions are based on standard methods that have been revised since the establishment of the 

default H&N assumptions. In addition, skin dose calculations for covered skin sites for 

Hiroshima and Nagasaki occupation forces are not included in the default RDA analyses for 

H&N RDAs. Therefore, this Appendix augments the listing of key assumptions in the main text 

of this report by documenting additional key assumptions used in the skin dose calculations for 

the H&N EPGs.

B-1. Parameters used in Contaminated Soil Groundshine Pathway 

Beta-to-gamma dose ratios are used to calculate the beta skin dose skin from 

contaminated soil for each H&N EPG. Beta-to-gamma dose ratios applicable to bare skin 

exposure of an individual standing upright in an infinite planar field of fission product deposition 

are shown in Table B-1 (DTRA, 2010, SM ED03). These ratios were derived for the PPG, and 

are judged to be appropriate for the similar environment of Japan. In deriving the ratios, it was 

assumed that body self-shielding reduced both 1) the beta dose at any target site on the body by a 

factor of 0.5 from its free-field value, and 2) the gamma dose recorded on a properly worn film 

badge to a value of 0.7 times its free-field value. Beta-to-gamma dose ratios for the 

11 representative body location skin sites for applicable times from Table B-1 are used for each 

EPG: those from approximately 6 hours to 1 month for the POW EPG, and approximately 

1 month to 1 year for the Hiroshima and Nagasaki EPGs. 

As a conservative simplification, constant beta-to-gamma dose ratios for exposure to 

radiations from in situ neutron-induced soil radionuclides are used for all body sites, regardless 

of the post-shot time and distance from the soil: 0.2 for the POW EPG; 0.02 for the Nagasaki 

EPG, and 0.03 for the Hiroshima EPG (DTRA, 2008, Appendix A-1).

Multiplicative modification factors that reduce the beta groundshine dose to account for 

the presence of clothing over the skin are shown in Table B-2 (DTRA, 2010, ED03). The factors 

were derived assuming that the individual is standing upright on an infinite plane of deposited 

fission products, wearing a single layer of clothing that is 28 mg cm−2 in density-thickness. This 

density thickness is representative of “coverall” material. For H&N skin dose analyses for 

deposited fission products, values for 1 month after fission are used as default values (shaded in 

table below). As a conservative simplification, clothing modification factors are not used in the 

assessment of beta skin doses for exposure to in situ neutron-induced soil contaminants because 

these skin doses are typically very small (much smaller than exposure to deposited fission 

products).
39

Table B-1. Beta-to-gamma dose ratios for bare skin exposures to

mixed fission products at the Pacific Proving Ground

Time after Fission Distance from source plane (cm)

1 20 40 80 100 120 160 200

0.5 hour 36.4 24.2 17.7 11.9 10.4 9.1 7.0 5.4

1 hour 32.5 21.4 15.5 10.3 8.9 7.8 5.9 4.5

2 hours 32.0 20.8 15.0 9.9 8.5 7.4 5.5 4.2

4 hours 40.3 25.9 18.5 12.0 10.3 8.9 6.7 5.0

6 hours 51.1 32.6 23.1 14.9 12.7 11.0 8.2 6.2

12 hours 65.6 41.0 28.6 17.8 15.0 12.8 9.3 6.8

1 day 65.1 38.7 25.8 14.9 12.2 10.0 6.8 4.7

2 days 64.4 35.2 22.1 11.8 9.3 7.4 4.7 2.9

3 days 62.8 32.2 19.3 9.8 7.6 6.0 3.6 2.1

1 week 62.3 29.0 16.3 7.7 5.8 4.5 2.5 1.4

2 weeks 65.5 30.5 17.1 8.1 6.2 4.7 2.7 1.6

1 month 72.4 34.7 19.9 9.8 7.6 6.0 3.7 2.2

2 months 85.7 39.8 22.8 11.8 9.5 7.8 5.1 3.3

4 months 90.7 40.4 23.0 12.5 10.5 9.0 6.4 4.4

6 months 94.6 42.5 24.5 13.9 11.9 10.4 7.7 5.5

9 months 116.7 54.5 32.5 19.6 17.2 15.4 11.8 8.8

1 year 166.1 81.2 50.3 31.7 28.2 25.6 20.1 15.2

2 years 494.2 251.9 160.5 104.2 93.6 85.3 68.0 52.3

Table B-2. Modification factors for light clothing

Time after 

fission

Distance from source plane (cm)

1 20 40 80 100 120 160 200

1 hour 0.59 0.74 0.80 0.83 0.84 0.86 0.87 0.87

2 hours 0.59 0.73 0.79 0.84 0.84 0.85 0.87 0.87

6 hours 0.57 0.72 0.78 0.83 0.84 0.85 0.86 0.87

1 day 0.52 0.67 0.73 0.78 0.80 0.81 0.82 0.83

1 week 0.40 0.54 0.66 0.71 0.72 0.74 0.74 0.78

2 weeks 0.40 0.55 0.66 0.71 0.72 0.73 0.77 0.74

1 month 0.41 0.56 0.67 0.73 0.74 0.75 0.78 0.77

1 year 0.42 0.62 0.78 0.86 0.87 0.87 0.88 0.88
40

To illustrate the use of the beta-to-gamma dose ratios applicable to bare skin exposure 

and the clothing modification factors for covered skin sites, values of these parameters applicable 

to the representative skin sites for the “standard height” individual assumed for H&N EPG skin 

dose assessments are shown in Table B-3. The skin site heights listed are based on an 

individual’s height of 172.7 cm (68 inches). (DTRA, 2010, SM ED03)

Table B-3. Standard heights and corresponding parameter values

Skin Site

Standard Heights 

(cm)

Beta-to-gamma 

Dose Ratio*

Clothing 

Modification 

Factor† Standing

Sitting 

(ground)

foot or ankle 1.0 5.1 72.4 0.410

calf or shin 20.3 15.2 34.5 0.562

knee 40.6 15.2 19.7 0.671

hand or mid-thigh 71.1 15.2 12.0 0.717

waist 99.1 14.0 7.7 0.740

forearm 99.1 20.3 7.7 0.740

lower back or stomach 119.4 34.3 6.0 0.750

upper back, upper arm,

or mid-chest 139.7 54.6 4.9 0.765

neck 149.9 64.8 4.3 0.772

face, nose, ear, or head 160.0 74.9 3.7 0.780

top of head 172.7 87.6 3.2 0.777 * Beta-to-gamma dose ratios listed are fission product values applicable to the standard standing heights, 

for a post-detonation time of 1 month.

† Clothing modification factors shown are applicable to the standard standing heights, for a post-shot 

detonation time of 1 month. A single layer of clothing with density thickness of 28 mg cm−2 was 

assumed.

B-2. Parameters Used in Dermal Contamination Pathway 

Skin doses from dermal contamination are included in the skin dose assessment for the 

POW EPG. In addition to the assumptions listed in Section 3.3, other key assumptions are 

described in the following sections. (DTRA, 2010, SM ED04)

B-2.1. Parameters for Dermal Contamination by Resuspended Contaminants 

An effective interception and retention fraction is defined for the fraction of resuspended 

contaminants that is intercepted and retained on skin. The effective interception and retention 

fraction for resuspended contaminants (Fres) is calculated as follows:
41

Fr ri = II i

II ff

× CC × PPr r × Er r × (B-1)

where:

Fr ri = Effective interception and retention fraction for resuspended contaminants at 

skin site i (unitless)

II i = Interception and retention fraction for skin site i (unitless)

II ff = Reference interception and retention fraction for forearm (unitless)

CC = Collection efficiency (unitless) 

PPr r = Particle size factor for resuspended contaminants (unitless)

Er r = Moisture factor for resuspended contaminants (unitless)

= Enrichment factor (unitless)

Values used for parameters in Equation B-1 are listed in Table B-4. The values and a 

discussion of each of these factors are provided in SM ED04 of DTRA (2010). 

Table B-4. Summary of factors in the calculation of the effective retention fraction 

for resuspended contaminants

Parameter Value

Collection Efficiency (CE) 0.02

Interception and retention fraction (IRFi) See values in Table B-6

Particle Size Factor (PSres) 1.0

Moisture Factor for high humidity areas (EMres) 3.0

Enrichment Factor (EF) 1.0

B-2.2. Parameters for Dermal Contamination by Descending Fallout

The effective interception and retention fraction for descending fallout (Fdes) for the POW 

EPG skin dose assessment is calculated as follows:

Fdd i = II i × PPdd × Edd × (B-2)

where:

Fdd i = Effective interception and retention fraction for descending fallout at skin site i

(unitless)

II i = Interception and retention fraction for skin site i (unitless)

PPdd = Particle size factor for descending fallout (unitless)

Edd = Moisture factor for descending fallout (unitless)

= Enrichment factor (unitless)
42

Values used for parameters in Equation B-2 are listed in Table B-5. These values are 

based on information in SM ED04 of DTRA (2007). Discussions of the values and factors are 

provided in DTRA (2007), DTRA (2010), and Apostoaei and Kocher (2010). 

Table B-5. Summary of factors in the calculation of the effective interception

and retention fraction for descending fallout

Parameter Value

Interception and retention fraction (IRFi) See values in Table B-6

Particle Size Factor (PSdes) 3.33

Moisture Factor for high humidity areas (EMdes) 1.0

Enrichment Factor (EF) 1.0

B-2.3. Summary of Interception and Retention Fractions

Using Equation B-1 and the parameter values in Tables B-4 and B-6, the calculation of 

Fres for the POW EPG skin dose assessment is simplified as follows:

Fr ri = II i

0.1

× 0.02 × 1.0 × 3.0 × 1.0

= II i × 0.6

(B-3)

Likewise, using Equation B-2 and the parameter values in Tables B-5 and B-6, the 

calculation of Fdes for the POW EPG skin dose assessment is simplified as follows:

Fdd i = II i × 3.33 × 1.0 × 1.0

= II i × 3.33

(B-4)

A summary of the interception and retention fractions (IRF), and effective interception 

and retention fractions (Fres and Fdes) for the list of representative uncovered skin sites for the 

POW EPG skin dose assessment are shown in Table B-6.

B-3. Parameters Used in Clothing Contamination Pathway 

Skin doses due to clothing contamination by fission products are calculated for the POW 

EPG. In addition to other key assumptions discussed in the main text of this report, the value of 

IRF assumed for covered skin (all sites) is 0.04, based on information in Apostoaei and Kocher 

(2010). Using this value and Equations B-3 and B-4, values of 0.024 and 0.133 are calculated for 

Fres and Fdes, respectively, for all skin sites covered by a layer of clothing.
43

Table B-6. Interception and retention fractions

Bare Skin Site

Interception and 

Retention Fraction 

(IRF)

Effective Interception and 

Retention Fraction

Resuspended 

contaminants 

(Fres)

Descending fallout 

(Fdes)

foot or ankle 1.5* 0.900 5.00

calf or shin 0.1 0.060 0.333

knee 0.1 0.060 0.333

hand or mid-thigh 0.1 0.060 0.333

waist 1.5* 0.900 5.00

forearm 0.1 0.060 0.333

lower back or stomach 0.04 0.024 0.133

upper back, upper arm, 

or mid-chest 0.04 0.024 0.133

neck 1.5* 0.900 5.00

face, nose, ear, or head 0.015 0.009 0.05

top of head 0.17 0.102 0.567 * The bare foot/ankle, waist, and neck were assumed to represent sites that exhibit enhanced collection and 

retention of particles. 
44

Abbreviations, Acronyms, and Unit Symbols

BCC Basal cell carcinoma

Ci curie

cm centimeter (= 0.01 m)

d day

DNA Defense Nuclear Agency

DTRA Defense Threat Reduction Agency

EPG Expedited Processing Group

GZ Ground Zero

h hour

H&N Hiroshima and Nagasaki (locations included in the NTPR program 

for selected personnel during specified time periods)

L liter

LD Limiting Dose

m meter

mg milligram (= 0.001 gram)

mi mile

mm millimeter (= 0.001 m)

MM Malignant melanoma

mR milliroentgen (= 0.001 roentgen, a unit for radiation exposure)

NIOSH-IREP National Institute of Occupational Safety and Health -Interactive 

RadioEpidemiological Program

NMRI Naval Medical Research Institute

NTPR Nuclear Test Personnel Review

NTS Nevada Test Site

POW Prisoner of War

PPG Pacific Proving Ground

rad A unit for radiation absorbed dose

RCT Regimental Combat Team

RDA Radiation Dose Assessment

rem Roentgen Equivalent Man (a unit for equivalent and effective dose)

SCC Squamous cell carcinoma

SM Standard Method

SOP Standard Operation Procedure

TOD Total Organ Dose

VA U.S. Department of Veterans Affairs

XP Expedited processing (NTPR process based on the use of two 

broadly-defined exposure scenarios)