SEC Petition Evaluation Report Supplement

SEC Petition SEC-00020 

Report Rev # 0 Supplement Submittal Date: 01-18-2006 

Petition Administrative Summary

Petition Under Evaluation 

Petition # Petition 

Type 

Submittal Date DOE/AWE Facility Name

SEC-00020 83.13 01-03-2005 Pacific Proving Ground (PPG) 

Feasible to Estimate Doses with Sufficient Accuracy? 

Single Class Multiple Classes Determination Established for All Classes 

Yes No X Yes No Yes X No

Initial Class Definition 

All scientists and scientific couriers employed at Enewetak Atoll during Operation HARDTACK I, from July 1, 

1958 through August 31, 1958. 

Proposed Class Definition 

All employees of DOE, DOE contractors, or subcontractors employed at the PPG from 1946 through 1962 who 

were monitored or should have been monitored for exposure to ionizing radiation as a result of nuclear weapons 

testing at the PPG. 

Related Petition Summary Information 

SEC Petition Tracking #(s) Petition Type DOE/AWE Facility Name Petition Status 

None

Related Evaluation Report Information 

Report Title DOE/AWE Facility Name

None

Lead Technical Evaluator: Signature on File 1/19/2006 

LaVon Rutherford Date 

Reviewed By: Signature on File 1/19/2006 

James W. Neton Date 

Signature on File Supplement Approved By: 1/19/2006 

Larry J. Elliott Date 
SEC-0020, Pacific Proving Ground 

Supplement to SEC Evaluation Report 

Discussion of comments received from the Defense Threat Reduction Agency

In a letter dated December 22, 2005, the Defense Threat Reduction Agency (DTRA) 

provided comments to NIOSH on Special Exposure Cohort (SEC) Petition Evaluation 

Report-0020. The proposed class definition for this petition included all Department of 

Energy (DOE) employees and DOE contractors or subcontractors employed at the Pacific 

Proving Ground (PPG) from 1946 through 19621

. In their letter, DTRA expressed 

concern that NIOSH’s decision to add this class of workers to the SEC was based on 

“serious misconceptions” about the operating status of the Nuclear Test Personnel 

Review (NTPR) program which DTRA administers under the Department of Defense 

(DOD). In addition, DTRA expressed concern that NIOSH’s SEC Petition Evaluation 

Report-0020 contained “several misrepresentations” of a National Research Council 

(NRC) report that presented the results of a Congressionally mandated review of the 

NTPR program (NRC 2003). A copy of the letter is provided in Attachment A. 

The “serious misconceptions” that NIOSH has of the operating status of the NTPR 

program are believed by DTRA to unfairly cast doubt on the credibility of the NTPR’s

dose reconstruction process and also might errantly influence NIOSH’s conclusion that 

internal doses for the defined class could not be estimated with sufficient accuracy. 

NIOSH regrets any negative inference to the credibility of the DTRA program that might 

be implicitly drawn from this conclusion. SEC Petition Evaluation Report-0020 was not 

intended to cast doubt on the integrity of the DTRA process for reconstructing doses 

under the framework of their governing regulations. Rather, it was written solely for the 

purpose of deciding if NIOSH could reconstruct doses to civilian participants employed 

at the Pacific Proving Ground (PPG) in accordance with EEOICPA and with sufficient 

accuracy as specified in the requirements of NIOSH’s governing regulation. As indicated 

in SEC Petition Evaluation Report-0020, the procedures governing this decision are 

outlined in 42 C.F.R. pt. 83, which states in part that a dose reconstruction can be 

estimated with sufficient accuracy if: 

NIOSH has established that it has access to sufficient information to estimate the 

maximum radiation dose for every type of cancer for which radiation doses are 

reconstructed, that could have been incurred in plausible circumstances by any 

member of the class... 

As described in SEC Petition Evaluation Report-0020, NIOSH’s judgment was that it 

could not estimate the maximum internal radiation dose for every type of cancer that 

 

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 To ensure that only those participants who were actually exposed to radiation are covered under this class, 

NIOSH has modified the definition to read: All employees of DOE, DOE contractors, or subcontractors 

employed at the PPG from 1946 through 1962 who were monitored or should have been monitored for 

exposure to ionizing radiation (see discussion below). 

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could have been incurred by civilian employees at the PPG. This conclusion was reached 

after a careful evaluation of the available monitoring data and a comparison of these data 

against the dose reconstruction process outlined in the dose reconstruction regulation, 42 

C.F.R. pt. 82. The rule describes a hierarchical approach to the use of existing data 

sources to reconstruct doses. These are, in order of decreasing preference: individual 

monitoring data; 2) area monitoring data; and 3) process and source-term information. 

As indicated in the evaluation report, NIOSH did not find bioassay data suitable for 

reconstructing internal doses to civilian employees at the PPG. Further, there were 

insufficient sources of air monitoring data to put credible upper bounds on the internal 

doses experienced by this class of workers. 

Given that individual bioassay and area monitoring data were determined to be 

inadequate, NIOSH reviewed the source-term technique that DTRA employs to 

reconstruct internal doses for claimants under the NTPR program. This review was 

conducted with the intent of determining the applicability of this technique to dose 

reconstructions under the EEOICPA. After an on-site visit with DTRA contractor 

personnel, and the review of several example dose reconstructions, NIOSH learned that 

internal doses reconstructed under the NTPR program were based on a computer model 

that relates a measured external dose to an intake of radioactive material2

. This is, in 

effect, a source-term model in which a measured external dose is used to estimate the 

activity and composition of the radioactive material deposited in the vicinity of the test

participant. Once the activity and the composition of the material in the air or on the 

ground are estimated, the inhalation intake can be estimated by applying appropriate 

factors. The individual’s fifty year committed internal dose is then estimated using the 

methodology contained in ICRP publication 30. 

While this model appears to be based on reasonable scientific principles, a number of the 

factors used in this model were brought into question during the NRC review of DTRA’s 

methodology. One of the most significant issues raised in the NRC review was that the: 

Sources and uncertainty in the methods of estimating radionuclide concentrations 

in deposited fallout based on measured external photon exposures have not been 

evaluated, and reliability of methods is not known. 

Although the case is made by DTRA that the NRC report concluded that the uncertainties 

associated with this method are likely to have the greatest impact on participants at the 

Nevada Test Site, the report does not suggest that this uncertainty be ignored for 

participants at the Pacific Proving Ground. 

In SEC Petition Evaluation Report-0020, NIOSH chose to highlight the issues identified 

by the NRC that tended to result in potential underestimates of the internal dose to 

individuals. Although SEC Petition Evaluation Report-0020 acknowledged that there 

were also a number of issues identified in the NRC report that could potentially result in 

 

2

 Although DTRA’s letter indicated that some bioassay and air monitoring are known to exist, NIOSH was 

informed by DTRA contractor personnel that all internal doses under the NTPR program are estimated 

using algorithms that relate the external dose to internal dose. 

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overestimates of the internal dose, they were not specifically identified in the report. 

NIOSH’s SEC regulation, 42 C.F.R. pt. 83, requires that it evaluate the ability to estimate 

the maximum radiation dose for each type of cancer under plausible conditions. Because 

the NRC report provided little or no quantitative judgment regarding the relative 

magnitude of the countervailing effects of the factors that either underestimated or 

overestimated doses, NIOSH did not believe it important to specifically cite every issue 

raised by the NRC. While it might be the case that these effects have a tendency to 

compensate for each other, NIOSH has no quantitative ability to determine this at this 

time. As stated in DTRA’s letter to NIOSH: 

It is important to note that the NRC committee did not question the ability to 

establish credible upper bounds, but rather the credibility of the upper bounds 

that were being estimated at the time of the review. 

Until such time as DTRA completes the research necessary to address the magnitude of 

the effect for each issue, NIOSH does not believe that it can independently establish the 

magnitude of the maximum internal dose to each organ that develops cancer under 

plausible conditions. 

At the time the SEC evaluation report was written, NIOSH was unaware that DTRA 

established interim guidelines for processing of dose reconstructions while the issues 

raised by NRC are researched. These interim guidelines, which were published in letter 

format on July 16, 2003, contain the following (excerpted in part) direction from DTRA 

to their dose reconstruction contractor: 

The following rules of thumb should be applied to upper bound results: 

- apply a factor of 10 times to the internal dose estimate for scenarios not 

identified in the NAS/NRC report as highly uncertain 

- refer internal dose upper bound estimates for highly uncertain scenarios 

to an independent contractor chosen by DTRA 

These rules of thumb, based on our review of the results in the NAS/NRC 

report, are intended to facilitate the processing of VA claims while 

ensuring upper bound estimates are not underestimated. 

NIOSH has not seen any scientific evaluation of the “rules of thumb” put in place by 

DTRA for reconstructing internal dose. While these guidelines may be appropriate for 

making compensation decisions under the NTPR program, NIOSH can not utilize 

guidelines that call for increasing internal doses by a factor of 10, without a detailed 

justification of the scientific basis, which would constitute sufficient accuracy under the 

NIOSH SEC regulation. Under EEOICPA, the establishment of a credible upper bound 

is critical because the decision for compensation is based on a Monte Carlo analysis of 

the distribution of probabilities of causation (PC). The law requires that, of the 

distribution of possible PCs, the 99th percentile be used to determine if the worker’s 

cancer was “at least as likely as not” caused by his/her exposure. As such, any upper 

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bound dose selected for input to the Interactive Radioepidemiology Program (IREP) will 

directly affect the PC at the 99th percentile. 

Based on the above discussion, NIOSH continues to support its position that internal 

doses for civilian employees at the PPG can not be reconstructed at this time with 

sufficient accuracy under the requirements established by the EEOICPA and evaluated 

under 42 C.F.R. pt. 83. 

Change in proposed class definition

The proposed class definition currently contained in SEC Petition Evaluation Report0020 covers all employees of DOE, DOE contractors or subcontractors employed at the 

PPG from 1946 through 1962. After some discussion with Department of Labor 

representatives, and internal deliberation within the Office of Compensation Analysis and 

Support, NIOSH now believes that this definition is too broad in that it potentially 

includes civilians who worked on activities at the PPG, but were not necessarily present 

in the vicinity of radiation and/or contamination generated by a nuclear test. Because of

this, NIOSH has modified the proposed class definition to read: 

All employees of DOE, DOE contractors or subcontractors employed at the PPG from 

1946 through 1962 who were monitored or should have been monitored for exposure to 

ionizing radiation as a result of nuclear weapons testing at the PPG. 

Reference 

NRC 2003 

National Research Council, “A Review of the Dose Reconstruction Program of the 

Defense Threat Reduction Agency” 2003 

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ATTACHMENT A 

Letter from Paul Blake to James Neton, dated December 22, 2005 

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