ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller & Associates I MJW Corporation

Page 1 of 19

Document Title:

Internal Dosimetry Coworker Data 

for K-25

Document Number: ORAUT-OTIB-0035

Revision: 00 PC-1 

Effective Date: 07/21/2006

Type of Document: OTIB

Supersedes: None

Subject Expert: Robert N. Cherry

Document Owner

Approval: Signature on File Approval Date: 08/05/2005

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 08/04/2005

Richard E. Toohey, Project Director

Approval: Signature on File Approval Date: 08/09/2005

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE REPLACE THE PRIOR REVISION. 

PLEASE DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-OTIB-0035 Revision No. 00 PC-1 Effective Date: 07/21/2006 Page 2 of 19

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

04/21/2005 00-A New technical information bulletin for assignment of K-25 internal 

doses based on coworker bioassay data. Initiated by Robert N. 

Cherry.

06/10/2005 00-B Incorporates internal review comments. Initiated by Robert N. 

Cherry.

07/19/2005 00-C Incorporates NIOSH review comments. Initiated by Robert N. 

Cherry.

08/09/2005 00 First approved issue. Initiated by Robert N. Cherry.

07/21/2006 00 PC-1 Approved page change revision to add updated language to Section 

1.0 on pages 5 and 6. Details were added to page 6 in Section 2.0. 

The date in Section 5.1 and in Table 5.1 on page 8 was changed 

from 1948 to 1945. Attachment C, Estimate of Intake Rates for 

1945-1947 was added to pages 18 and 19. Incorporates internal and 

NIOSH formal review comments on pages 6, 7, 8, and 9 in Sections 

2.0, 4.0, 5.1, and 5.2 respectively. No sections were deleted. This 

revision results in no change to the assigned dose and no PER is 

required. Training required: As determined by the Task Manager. 

Initiated by Thomas R. LaBone. Approval:

Document Owner:

John M. Byrne, Task 3 Manager

Signature on File____________________________ 07/12/2006

Edward F. Maher, Task 5 Manager

Signature on File____________________________ 07/12/2006

Kate Kimpan, Project Director

Signature on File____________________________ 07/20/2006

James W. Neton, Associate Director for Science

Signature on File____________________________ 07/21/2006
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 3 of 19

TABLE OF CONTENTS

SECTION TITLE 

1.0 Purpose ...................................................................................................................................

PAGE

5

2.0 Overview..................................................................................................................................6

3.0 Data .........................................................................................................................................6

 3.1 Selected Bioassay Data ...................................................................................................7

 3.2 Analysis ...........................................................................................................................7

4.0 Intake Modeling........................................................................................................................7

 4.1 Bioassay Fitting ...............................................................................................................7

 4.2 Material Types ................................................................................................................. 8

 4.2.1 Uranium.................................................................................................................8

 4.2.2 Technetium-99 ......................................................................................................8

5.0 Assignment of Intakes and Doses ............................................................................................8

5.1 Intake Rate Summary.......................................................................................................8

5.2 Contribution from Contaminants in Recycled Uranium .....................................................9

5.3 Dose Assignment .............................................................................................................9

References ........................................................................................................................................10

 A Tables...............................................................................................................................11

 B Figures .............................................................................................................................

Attachments

10

ATTACHMENT C, Estimate of Intake Rates for 1945-1947................................................................. 10
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 4 of 19

LIST OF TABLES

TABLE TITLE

5-1 Derived uranium intake rate, 1945 to 1978...............................................................................

PAGE

8

5-2 Derived 99Tc intake rates..........................................................................................................8

A-1 Summary of annual uranium urinary excretion rate analyses, 1948 to 1988........................... 11

A-2 Summary of annual 99Tc urinary excretion rate analyses, 1978 to 1988................................. 12

LIST OF FIGURES

FIGURE TITLE

B-1 Predicted uranium bioassay results calculated using IMBA-derived U intake 

rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 50th-percentile, Type F ............................................................

PAGE

13

B-2 Predicted uranium bioassay results calculated using IMBA-derived U intake 

rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 84th-percentile, Type F ............................................................ 13

B-3 Predicted uranium bioassay results calculated using IMBA-derived U intake 

rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 50th-percentile, Type M ........................................................... 14

B-4 Predicted uranium bioassay results calculated using IMBA-derived U intake 

rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 84th-percentile, Type M ........................................................... 14

B-5 Predicted uranium bioassay results calculated using IMBA-derived U intake 

rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 50th-percentile, Type S ........................................................... 15

B-6 Predicted uranium bioassay results calculated using IMBA-derived U intake 

rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 84th-percentile, Type S ........................................................... 15

B-7 Predicted technetium-99 bioassay results calculated using IMBA-derived 

99Tc intake rates (line) compared with uranium bioassay results (dots), 

January 1, 1978, to December 31, 1988, 50th-percentile, Type F .......................................... 16

B-8 Predicted technetium-99 bioassay results calculated using IMBA-derived 

99Tc intake rates (line) compared with uranium bioassay results (dots), 

January 1, 1978, to December 31, 1988, 84th-percentile, Type F .......................................... 16

B-9 Predicted technetium-99 bioassay results calculated using IMBA-derived 

99Tc intake rates (line) compared with uranium bioassay results (dots), 

January 1, 1978, to December 31, 1988, 50th-percentile, Type M ......................................... 17

B-10 Predicted technetium-99 bioassay results calculated using IMBA-derived 

99Tc intake rates (line) compared with uranium bioassay results (dots), 

January 1, 1978, to December 31, 1988, 84th-percentile, Type M ......................................... 17

C-1 Median Urine Concentration (dpm/100 mL) and Geometric Standard 

Deviation for K-25 Workers for 1948-1988 ............................................................................. 17

C-2 Normal Probability Plot of the Median Urine Concentration.................................................... 17
Document No. ORAUT-OTIB-0035 Revision No. 00 PC-1 Effective Date: 07/21/2006 Page 5 of 19

1.0 PURPOSE

Technical Information Bulletins (TIBs) are not official determinations made by the National Institute for 

Occupational Safety and Health (NIOSH) but are rather working documents that provide historical 

background information and guidance to assist in the preparation of dose reconstructions at particular 

sites or categories of sites. They will be revised in the event additional relevant information is 

obtained. TIBs may be used to assist the NIOSH staff in the completion of individual work required for 

each dose reconstruction.

In this document, the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy [DOE] facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act [EEOICPA; 42 U.S.C. § 7384l(5) and (12)]. 

EEOICPA defines a DOE facility as “any building, structure, or premise, including the grounds upon 

which such building, structure, or premise is located ... in which operations are, or have been, 

conducted by, or on behalf of, the Department of Energy (except for buildings, structures, premises, 

grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program)” [42 U.S.C. § 

7384l(12)]. Accordingly, except for the exclusion for the Naval Nuclear Propulsion Program noted 

above, any facility that performs or performed DOE operations of any nature whatsoever is a DOE 

facility encompassed by EEOICPA.

For employees of DOE or its contractors with cancer, the DOE facility definition only determines 

eligibility for a dose reconstruction, which is a prerequisite to a compensation decision (except for 

members of the Special Exposure Cohort). The compensation decision for cancer claimants is based 

on a section of the statute entitled “Exposure in the Performance of Duty.” That provision [42 U.S.C. § 

7384n(b)] says that an individual with cancer “shall be determined to have sustained that cancer in the 

performance of duty for purposes of the compensation program if, and only if, the cancer ... was at 

least as likely as not related to employment at the facility [where the employee worked], as 

determined in accordance with the POC [probability of causation1

As noted above, the statute includes a definition of a DOE facility that excludes “buildings, structures, 

premises, grounds, or operations covered by Executive Order No. 12344, dated February 1, 1982 (42 

U.S.C. 7158 note), pertaining to the Naval Nuclear Propulsion Program” [42 U.S.C. § 7384l(12)]. 

While this definition contains an exclusion with respect to the Naval Nuclear Propulsion Program, the 

section of EEOICPA that deals with the compensation decision for covered employees with cancer 

[i.e., 42 U.S.C. § 7384n(b), entitled “Exposure in the Performance of Duty”] does not contain such an 

exclusion. Therefore, the statute requires NIOSH to include all occupationally derived radiation 

exposures at covered facilities in its dose reconstructions for employees at DOE facilities, including 

radiation exposures related to the Naval Nuclear Propulsion Program. As a result, all internal and 

external dosimetry monitoring results are considered valid for use in dose reconstruction. No efforts 

are made to determine the eligibility of any fraction of total measured exposure for inclusion in dose 

reconstruction. NIOSH, however, does not consider the following exposures to be occupationally 

derived:

] guidelines established under 

subsection (c) ...” [42 U.S.C. § 7384n(b)]. Neither the statute nor the probability of causation 

guidelines (nor the dose reconstruction regulation) define “performance of duty” for DOE employees 

with a covered cancer or restrict the “duty” to nuclear weapons work.

 

1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the POC. 
Document No. ORAUT-OTIB-0035 Revision No. 00 PC-1 Effective Date: 07/21/2006 Page 6 of 19

• Radiation from naturally occurring radon present in conventional structures

• Radiation from diagnostic X-rays received in the treatment of work-related injuries

The purpose of this TIB is to provide information for the application of K-25 coworker data in 

estimating unmonitored internal exposures. Some employees were not monitored for internal ionizing 

radiation exposure during the course of their employment at a U.S. Department of Energy (DOE)2

2.0 OVERVIEW

facility, or the records of such monitoring are incomplete or unavailable. In such cases, data from 

monitored coworkers may be used to estimate an individual’s possible exposure.

Analysis of Coworker Bioassay Data for Internal Dose Assignment (ORAUT 2004a) describes the 

general process used to analyze bioassay data for assigning doses to individuals based on coworker 

results. Coworker Data Exposure Profile Development (ORAUT 2004b) describes the approach and 

processes to be used to develop reasonable exposure profiles based on available dosimetric 

information for workers at DOE sites.

Bioassay results were obtained from the Oak Ridge Institute for Science and Education (ORISE) 

Center for Epidemiologic Research (CER) Dosimetry Database, which contains urinalysis records 

from the K-25 site for 1948 to 1988. ORISE obtained these data from K-25 to conduct an 

epidemiological study of site workers. The urinalysis results, labeled “gross alpha,” are in units of 

disintegrations per minute per 100 mL (dpm/100 mL). Results labeled “Uranium” were also available 

that included units of mass rather than activity concentration. It is not possible to convert mass 

concentration to activity concentration accurately for dose assessment purposes without knowing the 

isotopic abundances. Therefore, only the gross alpha data were used because these data were 

adequate and complete.

A statistical analysis of the gross alpha data was performed in accordance with ORAUT (2004a). The 

resultant values were input to the Integrated Modules for Bioassay Analysis (IMBA) ExpertTM OCASEdition computer software (ACJ 2004), and a fit to the data was performed to obtain intake rates for 

assigning dose distributions.

Technetium-99 bioassay results were similarly obtained from the ORISE CER Dosimetry Database, 

which contains 99Tc urinalysis records from the K-25 site for 1978 to 1988. During these years, 

operations with purified 99Tc were conducted which could result in intakes of 99Tc without 

commensurate intakes of uranium. The 99Tc urinalysis results are in units of dpm/mL. A statistical 

analysis of these data was performed in accordance with ORAUT (2004a). The resultant values were 

input to IMBA, and a fit to the data was performed to obtain intake rates for assigning dose 

distributions.

An analysis of the urinary excretion data for 1948-1988 was used to develop the most probable 

urinary excretion rate for 1945-1947, when there were no direct bioassay measurements. This 

analysis, which is detailed in Attachment C, concludes that the chronic intake rates calculated for 

1948-1988 are appropriate for use in 1945-1947.

3.0 DATA

 

2 References to DOE in this document include DOE’s predecessors, the Manhattan Engineer District (1942 to 1946), the 

U.S. Atomic Energy Commission (1947 to 1975), and the Energy Research and Development Administration (1975 to 1977), 

as well as DOE (1977 to the present).
Document No. ORAUT-OTIB-0035 Revision No. 00 PC-1 Effective Date: 07/21/2006 Page 7 of 19

3.1 SELECTED BIOASSAY DATA

Uranium urinalysis data from 1948 to 1988 were extracted from a Microsoft® Access table named 

“tblK25_Urinalysis_rawData” in a subdatabase named “K25_Urinalysis_to_COC_10-8-2004.mdb” in 

the ORISE/CER Dosimetry Database.

Technetium-99 urinalysis data were similarly extracted and analyzed for 1978 to 1988.

3.2 ANALYSIS

Bioassay data were analyzed by year. A lognormal distribution was assumed, and the 50th and 84th 

percentiles were calculated for each year using the method described in ORAUT (2004a).

Many results in the database were listed as less than (<) a value. For 1953 and 1977 through 1988, 

for every record in the “Result” field that contained the less-than symbol followed by a number, that 

number was included in the ranking but not in the fit.

Tables A-1 and A-2 show the uranium and 99Tc statistical analysis results, respectively.

4.0 INTAKE MODELING

Although K-25 operations began in early 1945, uranium bioassay results are not currently available for 

years earlier than 1948. The derivation of intake rates for 1945-1947 is discussed in Attachment 

C.Assumptions

Each result used in the intake calculation was assumed to be normally distributed. A uniform absolute 

error of 1 was applied to all results, thus assigning the same weight to each result. IMBA requires 

results to be in units of activity per day, so all results were normalized to 1400 mL, the volume of urine 

excreted by Reference Man in a 24-hour period.

Because of the nature of work at K-25, a chronic exposure pattern best approximates the true 

exposure conditions for most workers with a potential for intakes. Intakes were assumed to be by way 

of inhalation using a default breathing rate of 1.2 m3

/hr and a 5-μm activity median aerodynamic 

diameter particle size distribution.

The database file for uranium lists all results as activity concentrations. Because a variety of 

enrichments is possible at the K-25 site, 234U was assumed for the IMBA intake modeling. The dose 

coefficients (also referred to as dose conversion factors) in International Commission on Radiological 

Protection (ICRP) Publication 68 for 234U are 7% to 31% larger than those for 235U, 236U, and 238U 

(ICRP 1995). Therefore, use of the 234U dose conversion factor will overestimate doses and is 

therefore a claimant-favorable assumption.

4.1 BIOASSAY FITTING

IMBA was used to fit inhalation intakes to the bioassay results. Data from January 1948 to December 

1988 were fit as one or more chronic intakes.
Document No. ORAUT-OTIB-0035 Revision No. 00 PC-1 Effective Date: 07/21/2006 Page 8 of 19

4.2 MATERIAL TYPES

4.2.1

Uranium urinalysis results were fit in IMBA using types F, M, and S materials to derive intake rates for 

1948 to 1988. The solid lines in Figures B-1 to B-6 show the individual fits to the 50th- and 

84th-percentile excretion rates. The same intake periods were applied for both percentiles because 

the bioassay values modeled followed a similar pattern. 

Uranium

4.2.2

Urinalysis results for 99Tc were fit in IMBA using types F and M materials to derive intake rates for 

1978 to 1988. [Type S material is not considered in ICRP (1995) for 99Tc.] The solid lines in Figures 

B-7 to B-10 show the individual fits to the 50th- and 84th-percentile excretion rates. The same intake 

periods were applied for both percentiles because the values followed a similar pattern. 

Technetium-99

The bioassay data showed a significant change in excretion rate between 1982 and 1983, which 

required different fits for the periods from 1978 to 1982 and from 1983 to 1988.

5.0 ASSIGNMENT OF INTAKES AND DOSES

5.1 INTAKE RATE SUMMARY

The derived 50th- and 84th-percentile uranium excretion data are relatively constant from 1948 to 

1988, as shown in Figures B-1 to B-6. Therefore, a single intake period was assumed. Table 5-1 

summarizes the derived uranium intake rate that produced the fits, including the extrapolated intake 

rates for 1945-1947.

Table 5-1. Derived uranium intake rate, 1945 to 1988. 

Type F material Type M material Type S material

50th 

percentile

(dpm/d)

84th 

percentile

(dpm/d)

Geometric 

standard 

deviation

50th 

percentile

(dpm/d)

84th 

percentile

(dpm/d)

Geometric 

standard 

deviation

50th 

percentile

(dpm/d)

84th 

percentile

(dpm/d)

Geometric 

standard 

deviation

21.5 76.2 3.54 88.3 313 3.54 990 3,460 3.50

The derived 50th- and 84th-percentile 99Tc excretion data are relatively constant from 1978 to 1982 

and, at lower rates, from 1983 to 1988, as shown in Figures B-7 to B-10. Therefore, two intake 

periods were assumed. Table 5-2 summarizes the derived 99Tc intake rates that produced the fits. 

Although the modeling resulted in lower GSDs, a GSD of 3 is assigned to all of the Tc-99 intakes for 

1978 through 1988 to adequately account for uncertainty in the biokinetic modeling.

Table 5-2. Derived 99Tc intake rates. 

Years

Type F material Type M material

50th 

percentile

(dpm/d)

84th 

percentile

(dpm/d)

Geometric 

standard 

deviation

50th 

percentile

(dpm/d)

84th 

percentile

(dpm/d)

Geometric 

standard 

deviation

1978–1982 13,900 24,900 3.0 15,570 27,860 3.0

1983–1988 3,160 6,890 3.0 3,420 7,499 3.0
Document No. ORAUT-OTIB-0035 Revision No. 00 PC-1 Effective Date: 07/21/2006 Page 9 of 19

5.2 CONTRIBUTION FROM CONTAMINANTS IN RECYCLED URANIUM

Spent fuel from fission reactors was processed throughout the DOE complex to recover uranium for 

recycling. Because the uranium streams at K-25 contained recycled uranium at various times, the 

dose from the added constituents, including plutonium, neptunium, and 99Tc, must be included during 

dose reconstruction. ORAUT (2004c) provides information about recycled uranium at K-25.

Results of bioassays analyzed specifically for 99Tc are available for 1978 to 1988, as noted above. 

These bioassays could have been performed for workers on decontamination efforts because “99Tc 

was concentrated at K-25 for purposes of recovery and removal” (ORAUT 2004d). 

Intake rates derived from these 99Tc bioassay results will be used for 99Tc from 1978 to 1988 rather 

than the assumed 99Tc ratio of contaminant concentration in uranium. All other years will use the 99Tc 

ratio as outlined in ORAUT (2004c).”

5.3 DOSE ASSIGNMENT

Doses to be assigned to individuals are calculated from the 50th-percentile intake rates. Dose 

reconstructors should select the material type that results in the largest probability of causation.

A comparison shows that intake rates derived assuming type S material are much greater than the 

intake rates derived assuming type M or type F materials for all periods. However, because type S 

material remains in the lungs for an extended period while types F and M materials are transferred to 

systemic organs, it is necessary to compare the annual doses on a case-by-case basis to determine 

which will deliver the largest dose to the organ of interest.

Recycled uranium contaminants, when appropriate for the period, should also be included in the 

above comparison. 

The lognormal distribution is selected in the NIOSH Interactive RadioEpidemiological Program 

(NIOSH-IREP), with the calculated dose entered as Parameter 1 and the associated geometric 

standard deviation as Parameter 2. The geometric standard deviation is associated with the intake, 

so it is applied to all annual doses determined from the intake period.
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 10 of 19

REFERENCES

ICRP (International Commission on Radiological Protection), 1959, Report of ICRP Committee II on 

Permissible Dose for Internal Radiation, Publication 2, Pergamon Press, Oxford, England.

ICRP (International Commission on Radiological Protection), 1995, Dose Coefficients for Intakes of 

Radionuclides by Workers, Publication 68, Pergamon Press, Oxford, England.

ORAUT (Oak Ridge Associated Universities Team), 2004a, Analysis of Coworker Bioassay Data for 

Internal Dose Assignment, ORAUT-OTIB-0019, Rev. 00, Oak Ridge, Tennessee.

ORAUT (Oak Ridge Associated Universities Team), 2004b, Coworker Data Exposure Profile 

Development, ORAUT-PLAN-0014, Rev. 00, Oak Ridge, Tennessee.

ORAUT (Oak Ridge Associated Universities Team), 2004c, Technical Basis Document for the K-25 

Site – Site Description, ORAUT-TKBS-0009-2, Rev. 00, Oak Ridge, Tennessee.

ORAUT (Oak Ridge Associated Universities Team), 2004d, Technical Basis Document for the K-25 

Site – Occupational External Dose, ORAUT-TKBS-0009-6, Rev. 00, Oak Ridge, Tennessee.
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 11 of 19

ATTACHMENT A: TABLES

Table A-1. Summary of annual uranium urinary excretion rate analyses, 1948 to 

1988. 

Year

50th percentile

(dpm/100 mL)

84th percentile

(dpm/100 mL)

1948 0.450 1.134

1949 0.239 0.827

1950 0.430 1.233

1951 0.210 0.769

1952 0.173 1.372

1953 0.378 1.577

1954 0.256 1.184

1955 0.280 1.256

1956 0.332 1.342

1957 0.519 1.994

1958 0.420 1.666

1959 0.331 1.524

1960 0.359 2.081

1961 0.567 2.867

1962 0.572 2.355

1963 0.502 1.790

1964 0.623 1.803

1965 0.740 2.922

1966 0.393 1.330

1967 0.284 1.022

1968 0.199 1.027

1969 0.381 1.406

1970 0.352 1.341

1971 0.399 1.782

1972 0.495 1.798

1973 0.645 2.187

1974 0.424 1.409

1975 0.542 1.782

1976 0.265 0.981

1977 0.327 1.510

1978 0.159 0.767

1979 0.258 0.896

1980 0.405 1.139

1981 0.506 1.296

1982 0.506 1.166

1983 0.605 1.397

1984 0.610 1.809

1985 0.581 2.322

1986 0.657 1.643

1987 0.517 1.181

1988 0.648 1.166
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 12 of 19

Table A-2. Summary of annual 99Tc urinary 

excretion rate analyses, 1978 to 1988. 

Year

50th percentile

(dpm/mL)

84th percentile

(dpm/mL)

1978 2.804 4.602

1979 1.682 3.821

1980 0.961 2.384

1981 3.086 5.264

1982 2.444 3.560

1983 0.691 1.462

1984 0.661 1.714

1985 0.002 0.066

1986 0.553 1.000

1987 0.157 0.464

1988 0.428 0.788
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 13 of 19

ATTACHMENT B: FIGURES

Figure B-1. Predicted uranium bioassay results calculated using IMBA-derived U 

intake rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 50th-percentile, Type F. 

Figure B-2. Predicted uranium bioassay results calculated using IMBA-derived U 

intake rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 84th-percentile, Type F. 
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 14 of 19

Figure B-3. Predicted uranium bioassay results calculated using IMBA-derived U 

intake rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 50th-percentile, Type M. 

Figure B-4. Predicted uranium bioassay results calculated using IMBA-derived U 

intake rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 84th-percentile, Type M. 
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 15 of 19

Figure B-5. Predicted uranium bioassay results calculated using IMBA-derived U 

intake rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 50th-percentile, Type S. 

Figure B-6. Predicted uranium bioassay results calculated using IMBA-derived U 

intake rates (line) compared with uranium bioassay results (dots), January 1, 

1948, to December 31, 1988, 84th-percentile, Type S. 
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 16 of 19

Figure B-7. Predicted technetium-99 bioassay results calculated using IMBAderived 99Tc intake rates (line) compared with uranium bioassay results (dots), 

January 1, 1978, to December 31, 1988, 50th-percentile, Type F. 

Figure B-8. Predicted technetium-99 bioassay results calculated using IMBAderived 99Tc intake rates (line) compared with uranium bioassay results (dots), 

January 1, 1978, to December 31, 1988, 84th-percentile, Type F. 
Document No. ORAUT-OTIB-0035 Revision No. 00 Effective Date: 08/09/2005 Page 17 of 19

Figure B-9. Predicted technetium-99 bioassay results calculated using IMBAderived 99Tc intake rates (line) compared with uranium bioassay results (dots), 

January 1, 1978, to December 31, 1988, 50th-percentile, Type M. 

Figure B-10. Predicted technetium-99 bioassay results calculated using IMBAderived 99Tc intake rates (line) compared with uranium bioassay results (dots), 

January 1, 1978, to December 31, 1988, 84th-percentile, Type M. 
Document No. ORAUT-OTIB-0035 Revision No. 00 PC-1 Effective Date: 07/21/2006 Page 18 of 19

Attachment C: Estimate of Intake Rates for 1945-1947

There are no urine bioassay results available for K-25 during the period of 1945-1947 from which to 

calculate intake rates. One approach to estimate the intake rates during 1945-1947 would be to 

examine the relationship between a parameter like uranium production levels and urine 

concentrations during 1948-1988, when there were bioassay data. Then, the urine concentrations 

during 1945-1947 could be inferred from the production levels during that period. However, there 

does not appear to be any parameter available to perform such an analysis. An alternative approach 

is to examine how the urine concentrations varied from 1948-1988 and assume that the urine 

concentrations varied in a similar fashion during 1945-1947. 

The median urine concentration (dpm/100 mL) and geometric standard deviation (GSD) for the urine 

samples analyzed in each year are shown in the plot below. The median urine concentrations are 

relatively constant, i.e., the slope of the line fit to the data is close to zero.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1940 1950 1960 1970 1980 1990

Year

Median and GSD 

Median

GSD

Figure C-1. The median urine concentration (dpm/100 mL) and geometric standard 

deviation for K-25 workers for 1948-1988.

Thus, the flat excretion rate expected from a chronic intake of soluble uranium fits the urinary 

excretion data quite nicely (see Figure B-1 through B-4 above). One can reasonably extrapolate the 

line of best-fit back to 1945, which gives basically the same intake rate for 1945-1947 as predicted for 

1948-1988. 

The median concentrations for the 1948-1988 period are normally distributed, as shown on the normal 

probability plot below. This plot demonstrates that whatever was making the median urinary excretion 

level vary from year to year was predictable in probabilistic sense. In other words, if it is assumed that 

the same (seemingly) random forces that were at work from 1948-1988 were also at work from 1945-

1947, then the urinary excretion rate during 1945-1947 can be predicted with a given probability.
Document No. ORAUT-OTIB-0035 Revision No. 00 PC-1 Effective Date: 07/21/2006 Page 19 of 19

y = 0.1606x + 0.4278

R2

 = 0.9871

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0

Z Score

Median of Annual Urine Data

(dpm/100 mL)

Figure C-2. Normal probability plot of the median urine concentration.

Based on this analysis, the best estimate of the urinary excretion during 1945-1947 is the mean of 

about 6 dpm/1.4 L (0.43 dpm/100 mL) from the plot above. By no coincidence, this also happens to 

be urine concentration predicted by the line of best fit for the Type F and M uranium on the IMBA 

plots, and the asymptote of the Type S uranium (the predicted excretion is not flat).

A third way of looking at the available information is to examine the 1948-1988 urine data for 120 of 

the workers who were working at K-25 from 1945-1947 and see if they appeared to be typical workers 

during 1948-1988 (uranium urine results consistent with the total population). A review of the urine 

data confirms the fact that they were indeed typical workers from 1948-1988, which supports the 

belief that they would have been typical workers during 1945-1947.

In conclusion, the available information supports the view that the best available estimates of the 

intake rates during 1945-1947 are the intake rates estimated for 1948-1988.