ORAU Team

Dose Reconstruction Project for NIOSH

Technical Information Bulletin – Use of Coworker 

Dosimetry Data For External Dose Assignment

Document Number:

ORAUT-OTIB-0020

Effective Date: 12/29/2004

Revision No.: 00

Controlled Copy No.: ______

Page 1 of 6

Subject Expert: Steven E. Merwin

Document Owner

Approval: Signature on File Date: 12/20/2004

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Date: 12/21/2004

Richard E. Toohey, Project Director

Approval: Signature on File Date: 12/29/2004

James W. Neton, Associate Director for Science

Supersedes:

None
Effective Date: 12/29/2004 Revision No.: 00 Document No. ORAUT-OTIB-0020 Page 2 of 6

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 11/30/2004 00-A New technical information bulletin to provide 

general information to allow ORAU Team dose 

reconstructors to assign doses to workers at DOE 

sites who have no or limited monitoring data, 

based on site coworker external dosimetry data. 

Initiated by Steven E. Merwin.

Draft 12/14/2004 00-B Incorporates internal review comments. Initiated 

by Steven E. Merwin.

Draft 12/16/2004 00-C Incorporates NIOSH review comments. Initiated 

by Steven E. Merwin.

12/29/2004 12/29/2004 00 First approved issue. Initiated by Steven E. 

Merwin.
Effective Date: 12/29/2004 Revision No.: 00 Document No. ORAUT-OTIB-0020 Page 3 of 6

1.0

The purpose of this Technical Information Bulletin (TIB) is to provide general information to allow 

ORAU Team dose reconstructors to assign doses to workers at DOE sites who have little or no 

individual monitoring data, based on site coworker external dosimetry data. This TIB is to be used in 

conjunction with separate TIBs or other approved documents that provide site-specific coworker data.

PURPOSE

2.0

The ORAU Team is conducting a series of coworker data studies to permit dose reconstructors to 

complete certain cases for which external and/or internal monitoring data are unavailable or 

incomplete. Coworkers are considered to be workers at a site (potentially grouped by work location, 

job description, or other appropriate category) whose measured doses are considered representative 

of those received by one or more claimants with no individual monitoring data. 

BACKGROUND

Cases without individual external monitoring data may fall into one of several categories, including:

• the worker was unmonitored and, even by today’s standards, did not need to be monitored 

(e.g., a non-radiological worker).

• the worker was unmonitored, but by today’s standards would have been monitored.

• the worker may have been monitored but the data are not available to the dose reconstructor.

• the worker may have partial information, but the available information is insufficient to permit a 

dose reconstruction to occur.

Some cases with little or no individual monitoring data can be processed in the absence of completed 

coworker studies, most notably those falling under the first category listed above. For example, nonradiological workers with no potential for workplace radiation exposures may be assigned on-site 

ambient doses. Even some cases falling under the second and third categories above do not require 

coworker studies, e.g., radiological workers who may in some cases be assigned reasonable upper 

limits provided that the total probability of causation (POC) is less than 45%. Regarding the last 

category above, if sufficient information is available, a prorated dose could be assigned in certain 

circumstances. Note, however, that many of the cases without external monitoring data that can be 

processed using one of these types of approaches have already been processed at this point in the 

program. 

3.0

The general approach to applying coworker data for cases with little or no individual external 

monitoring data involves two phases. The first phase (Phase I) permits cases to be processed when 

a “best and final” estimate of dose is not required for claim determination. This approach supports the 

statement included in most dose reconstruction reports that “NIOSH has determined that further 

research and analysis will not produce a level of radiation dose resulting in a probability of causation 

of 50% or 

GENERAL APPROACH

greater [for a low POC case] or less

The second phase (Phase II) of the external coworker data approach facilitates the assignment of 

“best and final estimates” of dose, when necessary. This phase involves fitting the available data to 

[for a high POC case]. Section 7.0 of this TIB outlines 

the methodology for analyzing external coworker data such that dose reconstructors can complete the 

external dose reconstruction portion of cases for which Phase I applies.
Effective Date: 12/29/2004 Revision No.: 00 Document No. ORAUT-OTIB-0020 Page 4 of 6

one or more dose distributions defined in a manner consistent with input parameters required by 

IREP. Section 8.0 of this TIB outlines the methodology for analyzing external coworker data such that 

dose reconstructors can complete the external dose reconstruction portion of cases for which Phase II 

applies. 

The actual coworker data sets and distributions to be applied for both Phase I and Phase II are 

provided in separate, site-specific TIBs. These TIBs also provide information on the sources of the 

site data, validation of the data, and conversion of the data into annual doses to be applied in dose 

reconstructions.

4.0

In parallel with the development of site-specific TIBs that document the external coworker data sets 

and distributions to be used in dose reconstructions, cases not yet completed are being screened to 

identify those cases requiring external coworker data to facilitate case processing. As described 

previously, some cases with little or no individual monitoring data have been processed using 

methods not dependent on coworker data. Cases requiring coworker data will be processed using 

either a Phase I approach as described in Section 7.0 (such cases typically will clearly have a high or 

low POC and will not require the application of internal coworker data) or a Phase II approach as 

described in Section 8.0 (most such cases requiring this approach for external dose assignment will 

require a similar “best and final estimate” approach for internal dose assignment).

APPLICATIONS AND LIMITATIONS

5.0

1. NIOSH (National Institute for Occupational Safety and Health), External Dose Reconstruction 

Implementation Guideline, Rev. 0, OCAS-IG-001, Office of Compensation Analysis and Support, 

Cincinnati, Ohio, 2002.

REFERENCES

6.0

External dosimetry data for DOE sites are potentially available from several sources. These include 

the Center for Epidemiologic Research (CER) databases maintained by Oak Ridge Associated 

Universities (ORAU), the Comprehensive Epidemiologic Data Resource (CEDR) databases 

maintained by the Department of Energy, other data sets maintained by the Department of Energy, 

and data maintained by the sites themselves. Additionally, claimant data submitted by DOE sites to 

NIOSH as part of the EEOICPA Subtitle B program provide a useful subset of site-wide data.

DEVELOPMENT OF SITE COWORKER DATA SETS AND DISTRIBUTIONS 

Development of site-specific data summaries and distributions involve a careful examination of the 

various data sources with the objective of identifying the most complete and accurate data set 

available. Prior to the analysis of the selected data and the development of summary statistics and 

dose distributions, a sampling of the data are compared to claim-specific data submitted to NIOSH by 

the DOE sites. This comparison helps verify the accuracy and completeness of the site data selected 

for use in coworker studies since the data submitted to NIOSH are often more detailed than the sitewide data sets (e.g., individual badge data are typically provided to NIOSH, while the site-wide data 

often represent annual summarized data). The comparison also provides information needed to 

adjust the site-wide data sets to account for missed dose, partial year data, etc. (discussed later in 

this section). Should significant issues arise during the course of this comparison that shed doubt on 

the accuracy or completeness of the site data selected for analysis, additional evaluations will take 

place to ensure that a valid data set has been selected.
Effective Date: 12/29/2004 Revision No.: 00 Document No. ORAUT-OTIB-0020 Page 5 of 6

The specific data sets selected for a particular site and the rationale for their selection are 

documented in site-specific coworker data TIBs titled “External Coworker Dosimetry Data for the 

[DOE Site].” Prior to publication of these site-specific TIBs, the data are subjected to an independent 

and separately documented validation process. 

Once coworker data have been selected to represent a particular site, the data are analyzed for the 

purpose of developing summary statistics and dose distributions. Summary statistics are developed 

to support coworker data Phase I dose reconstructions as described generally in Section 7.0, and 

dose distributions are developed to support coworker data Phase II dose reconstructions as described 

generally in Section 8.0. The Phase I summary statistics are developed initially, and the Phase II 

dose distributions are developed later and documented in a revision to the site-specific TIB (Note: the 

timing of the revision and the effort expended depend on the expected benefit for completing dose 

reconstructions; for example, if the monitoring program and data reporting are sufficiently robust for a 

particular site such that external dose distributions are expected to be necessary for only a few cases, 

development of Phase II dose distributions may be delayed). 

The site-specific external coworker dosimetry data TIBs provide information on adjustments to the 

data necessary to develop annual doses and distributions for use in dose reconstructions. For 

example, partial-year dosimetry data included in the site data must be extrapolated to provide annual 

values that represent the doses that would have been received for a full year of employment for all 

monitored employees. The objective is to provide data on the annual doses received by employees 

had they been monitored for a full year; dose reconstructors may then prorate the data for individual 

cases, as appropriate, to account for partial years of employment. 

The site dosimetry data also require adjustment to account for missed dose based on the badge 

exchange frequency and the dosimeter limit of detection (LOD). For example, the median annual 

reported dose might be zero at a particular site and in a particular year, but it would be inappropriate 

to assign a dose of zero as a median value because of the potential for missed dose, which must be 

included in the dose estimates to claimants.1

 Specific information on the incorporation of missed dose 

in the site coworker data is provided in the site-specific TIBs. 

Site-specific adjustments to the dose summaries and distributions based on technical considerations 

(e.g., dosimeter underresponse) must be incorporated by the dose reconstructor based on the site 

Technical Basis Documents (TBDs).

7.0

Data are presented in site-specific external coworker TIBs as 50th-percentile, 95th-percentile, and 

99th-percentile annual doses for monitored workers. These percentiles may be used by dose 

reconstructors for likely high or likely low POC cases using the guidance presented below. If a case 

cannot be processed successfully using any of these approaches, the instructions in Section 8.0 must 

be applied.

PHASE I – USE OF SITE COWORKER DATA SETS FOR CASES NOT REQUIRING 

BEST ESTIMATES

Likely High POC Cases

The 50th-percentile values may be used for cases for which individual monitoring data do not exist, if 

the dose reconstructor believes, based on a review of all pertinent information, that the energy 

employee was likely to have received doses greater than the median dose received by monitored 

workers at the site. The data should be prorated, as appropriate, to account for partial years of 

employment or portions of employment that did not involve the potential for radiation exposure.
Effective Date: 12/29/2004 Revision No.: 00 Document No. ORAUT-OTIB-0020 Page 6 of 6

Likely Low POC Cases

The 50th-percentile values may be used for cases for which individual monitoring data do not exist, if 

the dose reconstructor believes, based on a review of all pertinent information, that the energy 

employee was likely to have received doses substantially less than the median dose

The 95th-percentile values may be used for cases for which individual monitoring data do not exist, if 

the dose reconstructor believes, based on a review of all pertinent information, that the energy 

employee was likely to have received doses 

received by 

monitored workers at the site. Note that for unmonitored employees who were not potentially 

exposed to workplace radiation sources (e.g., non-radiological workers), it may be appropriate to 

assign only external on-site ambient dose and not unmonitored dose based on coworker studies—

refer to the site Occupational Environmental TBD.

not substantially above the median dose

The 99th-percentile values may be used for cases for which individual monitoring data do not exist, if 

the dose reconstructor believes, based on a review of all pertinent information, that the energy 

employee was likely to have received doses 

received by 

monitored workers at the site.

approaching the highest doses 

8.0

received by monitored 

workers at the site.

Reserved

PHASE II – USE OF SITE COWORKER DATA DISTRIBUTIONS FOR CASES 

REQUIRING BEST ESTIMATES