Draft White Paper 

FEASIBILITY OF INTERNAL DOSE RECONSTRUCTION WITH 

SUFFICIENT ACCURACY AT THE NEVADA TEST SITE DURING THE 

UNDERGROUND TESTING PERIOD: 

A REVIEW OF THE NIOSH POSITION PAPER “NIOSH REVIEW OF 

THE SEC-00084 NEVADA TEST SITE EVALUATION REPORT: 

INTERNAL DOSIMETRY ISSUES ANALYSIS” 

Contract Number 200-2009-28555 

Prepared by 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, Virginia 22182 

Saliant, Inc. 

5579 Catholic Church Road 

Jefferson, Maryland 21755 

January 2010 

Disclaimer 

This document is made available in accordance with the unanimous desire of the Advisory Board on 

Radiation and Worker Health (ABRWH) to maintain all possible openness in its deliberations. However, 

the ABRWH and its contractor, SC&A, caution the reader that at the time of its release, this report is predecisional and has not been reviewed by the Board for factual accuracy or applicability within the 

requirements of 42 CFR 82. This implies that once reviewed by the ABRWH, the Board’s position may 

differ from the report’s conclusions. Thus, the reader should be cautioned that this report is for 

information only and that premature interpretations regarding its conclusions are unwarranted.
Draft – Review of NIOSH Position Paper 2 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

TABLE OF CONTENTS 

Summary..........................................................................................................................................4 

List of Principal Findings.....................................................................................................4 

Purpose of the Report...........................................................................................................5 

Rationale of NTS Bioassay Sampling Program (NIOSH Issue 1).......................................6 

Data Gaps (NIOSH Issue 2).................................................................................................6 

Campaign-Driven Bioassay Program (NIOSH Issue 3) ......................................................7 

Radionuclide Coverage (NIOSH Issue 4)............................................................................7 

Other Key SC&A Findings..................................................................................................8 

1.0 Introduction..........................................................................................................................9 

1.1 Background..............................................................................................................9 

1.2 NIOSH 2009 Review of the Electronic Internal Dosimetry Data..........................10 

1.3 Framework for This Report ...................................................................................11 

2.0 Analysis of the Data...........................................................................................................13 

3.0 Results................................................................................................................................15 

3.1 Plutonium...............................................................................................................16 

3.2 Gamma...................................................................................................................19 

3.3 Beta ........................................................................................................................22 

3.4 Tritium ...................................................................................................................26 

3.5 Statistical Analysis Regarding Monitoring Pattern................................................28 

3.6 Other Radionuclides...............................................................................................35 

3.7 Quality of Data.......................................................................................................36 

4.0 Comparison with Prior SC&A Results..............................................................................38 

4.1 Data Adequacy – Quantity.....................................................................................38 

4.2 Quality of Data.......................................................................................................40 

4.3 Potential Exposures to Above-ground Releases of Fission and Activation 

Products..................................................................................................................42 

5.0 Conclusions Regarding Internal Dose Reconstruction Feasibility ....................................46 

5.1 Rationale of NTS Bioassay Sampling Program.....................................................46 

5.2 Data Gaps...............................................................................................................47 

5.3 Chronic and Episodic Exposure.............................................................................48 

5.4 Radionuclide Coverage..........................................................................................49 

5.5 Period of this Analysis and Period of the Recommended SEC.............................49 

5.6 Partial Internal Dose Estimation ............................................................................50 

6.0 References..........................................................................................................................51 
Draft – Review of NIOSH Position Paper 3 SC&A – January 12, 2010 

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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

LIST OF FIGURES 

Figure 3-1: Workers Sampled for Plutonium by Year..............................................................17 

Figure 3-2: Rank-Ordered Plutonium-239 Concentration in Urine..........................................18 

Figure 3-3: Rank-Ordered Pu-239 Concentration in Urine – Expanded Horizontal Axis........18 

Figure 3-4: Rank-Ordered 50th Percentile Concentration in Urine by Year for All 

Monitored Workers................................................................................................19 

Figure 3-5: Number of Workers Sampled for Gamma by Year...............................................21 

Figure 3-6: Rank-Ordered Gamma Concentration in Urine .....................................................21 

Figure 3-7: Rank-Ordered 50th Percentile Concentration in Urine by Year for All 

Monitored Workers................................................................................................22 

Figure 3-8: Number of Workers Sampled for Beta/GFP by Year............................................24 

Figure 3-9: Rank-Ordered Beta/GFP Concentration in Urine ..................................................24 

Figure 3-10: Rank-Ordered Beta/GFP Concentration in Urine – 

Expanded Horizontal Axis.....................................................................................25 

Figure 3-11: Rank-Ordered 50th Percentile Concentration in Urine by Year for 

All Monitored Workers..........................................................................................25 

Figure 3-12: Number of Workers Sampled for Tritium by Year................................................27 

Figure 3-13: Rank-Ordered Tritium Concentration in Urine......................................................27 

Figure 3-14: Rank-Ordered 50th Percentile Concentration in Urine by Year for 

All Monitored Workers..........................................................................................28 

Figure 3-15: Pu-239 Biosamples by Claimant Job Type............................................................30 

Figure 3-16: Percentile Plot of Pu-239 Biosamples by Claimant Job Type ...............................31 

Figure 3-17: Normal Score Plot of Pu-239 Biosamples by Claimant Job Type.........................31 

Figure 3-18: Normal Score Plot of Gross Gamma Biosamples by Claimant Job Type .............32 

Figure 3-19: Normal Score Plot of Gross Beta Biosamples by Claimant Job Type...................32 

Figure 3-20: Normal Score Plot of Tritium Biosamples by Claimant Job Type ........................33 

Figure 3-21: Percentile Plot of Pu-239 Biosamples for RadSafe Claimants by Decade ............33 

Figure 3-22: Normal Score Plot of Pu-239 Biosamples for RadSafe Claimants by Decade......34 

Figure 3-23: Percentile Plot of Pu-239 Biosamples for Security Claimants by Decade ............34 

Figure 3-24: Normal Score Plot of Pu-239 Biosamples for Security Claimants by Decade ......35 
Draft – Review of NIOSH Position Paper 4 SC&A – January 12, 2010 

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However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

SUMMARY 

LIST OF PRINCIPAL FINDINGS 

Finding 1 (Overall finding): Based on the analysis in this report and that presented in prior 

SC&A reports on internal exposure monitoring (SC&A 2008, SC&A 2009), SC&A concurs with 

NIOSH’s overall conclusion that internal dose reconstruction for Nevada Test Site (NTS) 

workers from January 1, 1963, to December 31, 1992, with sufficient accuracy is infeasible. 

SC&A also examined each of the points that led NIOSH to conclude that dose reconstruction 

with sufficient accuracy was not feasible. That review led SC&A to conclude that NIOSH’s 

finding is robust. 

Finding 2: The fact that many or most RadSafe personnel were monitored throughout the 

Special Exposure Cohort (SEC) period does not provide an adequate basis for constructing a 

coworker model for other workers with exposure potential, even for those radionuclides for 

which there are monitoring data in all periods. 

Finding 3: Given that the frequency of monitoring was inadequate and that information about 

timing and context of bioassay sampling is not available, it is not possible to bound fission 

product doses with the available NTS data. 

Finding 4: The inability to sort out monitoring done for routine exposures from that done for 

episodic exposures makes data interpretation very complex. Specifically, the available data do 

not lend themselves to creating a reliable coworker model to estimate doses with sufficient 

accuracy. 

Finding 5: NTS had a variety of exposure scenarios, from episodic to routine, and a large 

number of radionuclides to which exposure was possible. For most of these radionuclides, data 

are very scant to non-existent. Hence, for these unmeasured radionuclides, unmonitored workers 

include essentially all NTS workers. 

Finding 6: The electronic database contains data that are similar to the previously analyzed 

data. Only the RadSafe group seems to have been consistently monitored in the monitoring 

types for which most data are available. Given the large number of workers whose data have 

now been reviewed, it is highly unlikely that further review of NTS internal dosimetry data will 

reveal a different sampling pattern. 

Finding 7: The electronic database indicates that the RadSafe group, the only one with 

consistent monitoring data for four types of bioassay (plutonium, gamma, beta, and tritium), 

cannot be assumed to be among the job types with the highest exposure potential. On the 

contrary, there are indications that other (variable) job types may have had higher exposure 

potential, depending on the radionuclides being monitored. Hence, there is no job type with 

adequate data that can be used to construct a coworker model that would estimate doses with 

sufficient accuracy. 
Draft – Review of NIOSH Position Paper 5 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

PURPOSE OF THE REPORT 

The purpose of this report is to review the technical basis of the NIOSH SEC recommendation in 

its report of November 25, 2009 (NIOSH 2009), regarding SEC Petition SEC-00084. This 

petition asks NIOSH to include Department of Energy (DOE) and contractor and subcontractor 

employees at NTS during the underground testing period (starting in 1963) in the SEC. In the 

report under review here (NIOSH 2009), NIOSH made a recommendation that NTS workers 

from January 1, 1963, to December 31, 1992, be added to the SEC, based on its conclusion that it 

cannot reconstruct internal doses for all members of the proposed class (p. 5). 

SC&A’s prior analysis of available internal dosimetry data (SC&A 2008, SC&A 2009) indicated 

that many workers were not monitored at all or were monitored very infrequently, even in the 

categories where the total number of bioassay samples was large. Only the RadSafe group of 

workers had bioassay monitoring data for plutonium, gamma, beta [or Gross Fission Products 

(GFP)], and tritium in all relevant periods analyzed, while miners had tritium data. Security 

workers appeared to have been routinely monitored in the 1980s. SC&A also raised significant 

issues regarding the quality of plutonium and gamma bioassay data in various years until about 

1987. 

In its November 2009 report re-evaluating the feasibility of internal dose reconstruction with 

sufficient accuracy, as required by 42 CFR 83, which governs SEC petitions, NIOSH examined a 

large electronic database that had not previously been reviewed in the NTS SEC context. 

NIOSH concluded that it was not possible to bound internal doses with sufficient accuracy, and 

recommended that NTS workers between January 1, 1963, and December 31, 1992, with more 

than 250 days of relevant employment be added to the SEC class. 

In this report, SC&A has reviewed the NIOSH November 2009 report. The aim was to review 

the robustness of NIOSH’s conclusion and the underlying reasons for this conclusion. A 

necessary part of that process was to review whether the electronic database was similar to or 

different from the prior data reviewed by SC&A in the two reports cited above, and whether the 

electronic database provided any new insights as to the ability to reconstruct doses. 

Finding 1 (Overall finding): Based on the analysis in this report and that presented in prior 

SC&A reports on internal exposure monitoring (SC&A 2008, SC&A 2009), SC&A concurs with 

NIOSH’s overall conclusion that internal dose reconstruction for NTS workers from January 1, 

1963, to December 31, 1992, with sufficient accuracy is infeasible. SC&A also examined each 

of the points that led NIOSH to conclude that dose reconstruction with sufficient accuracy was 

not feasible. That review led SC&A to conclude that NIOSH’s finding is robust. 

The summary of SC&A’s review of NIOSH’s four reasons for concluding that internal dose 

reconstruction with sufficient accuracy was infeasible for the SEC period is provided below. 
Draft – Review of NIOSH Position Paper 6 SC&A – January 12, 2010 

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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

RATIONALE OF NTS BIOASSAY SAMPLING PROGRAM (NIOSH ISSUE 1) 

NIOSH found that there was insufficient documentation “to describe a consistent rationale 

behind the collection of personnel bioassay sampling or to indicate that sampling occurred 

consistently in the situations where it was required.” As a result, “NIOSH cannot conclusively 

determine that doses to all of these potentially exposed individuals were detected by the bioassay 

program” (NIOSH 2009, p. 3). 

SC&A’s analysis shows that several groups other than RadSafe, the most intensively monitored 

job type, and security personnel, monitored from the 1980s onward, had significant exposure 

potential. There is evidence that some groups had greater exposure potential than the RadSafe 

group, but the data are too sparse for a definitive conclusion for all periods examined. A 

definitive comparison is also rendered difficult by the fact that sampling in some cases appears to 

have been routine, in other cases a mixture of routine and incident-driven, while in yet other 

cases, it seems to be mainly incident-driven. Therefore, the fact that many or most RadSafe 

personnel were monitored throughout the SEC period does not provide an adequate basis for 

constructing a coworker model for other workers with exposure potential, even for those 

radionuclides for which there are monitoring data in all periods. This conclusion is rendered 

even more robust by the fact that the sparseness of the data makes a reliable comparison between 

RadSafe and other groups of workers difficult or impossible in most cases. 

Finding 2: The fact that many or most RadSafe personnel were monitored throughout the SEC 

period does not provide an adequate basis for constructing a coworker model for other workers 

with exposure potential, even for those radionuclides for which there are monitoring data in all 

periods. 

DATA GAPS (NIOSH ISSUE 2) 

NIOSH statement: 

NIOSH has identified data gaps that exist in the electronically available bioassay 

data for certain nuclides and time periods... that impact NIOSH’s ability to bound 

the internal dose. 

The extensive analysis done by SC&A in two prior reports (SC&A 2008, SC&A 2009), as well 

as the present report, confirms NIOSH’s analysis regarding the scant data for radionuclides like 

plutonium. The large fraction of positive bioassay results in all four bioassay monitoring 

categories that were examined indicate significant internal exposure potential even for groups 

that had scant monitoring data, contrary to the assumption that the monitored workers were 

among those with the highest exposure potential. 

The problem of the low frequency of monitoring in most cases is compounded by the lack of the 

information on time and context of sampling that is needed to interpret gamma and beta bioassay 

data. Frequent sampling and knowledge of time could make it possible to use gamma and beta 

bioassay data to bound fission product dose. However, these conditions are not fulfilled by the 

available NTS data. 
Draft – Review of NIOSH Position Paper 7 SC&A – January 12, 2010 

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Finding 3: Given that the frequency of monitoring was inadequate, and that information about 

timing and context of bioassay sampling is not available, it is not possible to bound fission 

product doses with the available NTS data. 

CAMPAIGN-DRIVEN BIOASSAY PROGRAM (NIOSH ISSUE 3) 

NIOSH’s review of the electronic database led to their conclusion that the bioassay sampling 

program was “campaign driven,” so that “a coworker model that is useful in reconstructing 

chronic intake scenarios would not necessarily be representative of the exposure patterns for the 

NTS workforce” (NIOSH 2009, p. 4). 

SC&A’s statistical analysis indicates that much of the sampling at NTS was campaign-driven or 

incident-driven. However, in some cases, it seems to be a mixture of incident-driven and routine 

monitoring, while in a couple of cases, it seems to be mainly routine monitoring. To the extent 

that the limited quantity of data enable an analysis, the data in most cases do not fit the usual 

lognormal distribution that characterizes a routine sampling protocol. SC&A also notes that, 

besides samples on the same day, the same workers sometimes had many or most samples in a 

year taken in a short period. For instance, one worker had [redacted] plutonium samples in 

1964, and [redacted] of them were in a 16-day period [redacted]. To complicate interpretation, 

this worker also had [redacted] samples taken on exactly the same dates in the next year. In 

neither case do the sample collection dates correspond to test dates or the day immediately after a 

test.1

Furthermore, NTS personnel also had the potential for routine exposure. Examples include 

activities in contaminated areas of the test site outside the context of the activities following a 

specific test, waste site workers, and laboratory workers. 

Finding 4: The inability to sort out monitoring done for routine exposures from that done for 

episodic exposures makes data interpretation very complex. Specifically, the available data do 

not lend themselves to creating a reliable coworker model to estimate doses with sufficient 

accuracy. 

RADIONUCLIDE COVERAGE (NIOSH ISSUE 4) 

NIOSH found that, given the variety of radionuclides and exposure patterns, it would be 

complicated “to definitively establish the relative mixture of the exposure source-term” for 

workers with no bioassay records (NIOSH 2009, p. 4). 

All three datasets analyzed by SC&A (the NIOSH group of 100 in Table 7-1 of NIOSH 2007, the 

120 workers in 6 job types in SC&A 2008 and SC&A 2009, and the electronic database) indicate 

that monitoring for plutonium for most job types and most periods was sparse. This is even more 

so in the case of americium and uranium data. SC&A has found no bioassay data for thorium or 

 1

 The data referred to for this claimant, a [redacted] group worker, can be found on the [redacted] 

worksheet of the plutonium data spreadsheet on the O-Drive. The list of nuclear tests and their dates can be found in 

DOE 2000. 
Draft – Review of NIOSH Position Paper 8 SC&A – January 12, 2010 

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radionuclide-specific fission product data other than very sparse data for Sr-90, I-131, I-133, and 

I-135. 

Finding 5: NTS had a variety of exposure scenarios, from episodic to routine, and a large 

number of radionuclides to which exposure was possible. For most of these radionuclides, data 

are very scant to non-existent. Hence, for these unmeasured radionuclides, unmonitored workers 

include essentially all NTS workers. 

OTHER KEY SC&A FINDINGS 

SC&A compared the electronic database to the data from prior analyses of internal dosimetry 

data by period and job type (SC&A 2008, SC&A 2009). 

Finding 6: The electronic database contains data that is similar to the previously analyzed data. 

Only the RadSafe group seems to have been consistently monitored in the monitoring types for 

which most data are available. Given the large number of workers whose data have now been 

reviewed, it is highly unlikely that further review of NTS internal dosimetry data will reveal a 

different sampling pattern. 

Finding 7: The electronic database indicates that the RadSafe group, the only one with 

consistent monitoring data for four types of bioassay (plutonium, gamma, beta, and tritium), 

cannot be assumed to be among the job types with the highest exposure potential. On the 

contrary, there are indications that other (variable) job types may have had higher exposure 

potential, depending on the radionuclides being monitored. Hence, there is no job type with 

adequate data that can be used to construct a coworker model that would estimate doses with 

sufficient accuracy. 

Finally, we note that this report relates only to a review of NIOSH 2009 insofar as it concerns 

SEC Petition SEC-00084. SC&A has not examined the period starting January 1, 1993, about 

which there is also a discussion in NIOSH 2009.
Draft – Review of NIOSH Position Paper 9 SC&A – January 12, 2010 

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However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

1.0 INTRODUCTION 

The purpose of this report is to review the technical basis of the National Institute for 

Occupational Safety and Health (NIOSH) Special Exposure Cohort (SEC) recommendation in its 

report of November 25, 2009 (NIOSH 2009), regarding SEC Petition SEC-00084. This petition 

asks NIOSH to include Department of Energy (DOE) and contractor and subcontractor 

employees at Nevada Test Site (NTS) during the underground testing period (starting in 1963) in 

the SEC. In the report under review here (NIOSH 2009), NIOSH made a recommendation that 

NTS workers from January 1, 1963, to December 31, 1992, be added to the SEC, based on its 

conclusion that it cannot reconstruct internal doses for all members of the proposed class with 

sufficient accuracy (p. 5). 

1.1 BACKGROUND 

According to NIOSH, only about one-third of the workers at NTS have some bioassay data 

(NIOSH 2007, p. 15 and p. 35), necessitating a coworker model for the rest of the workers and 

possibly for some monitored workers who did not have data for some radionuclides for which 

they had exposure potential. In its report evaluating Petition SEC-00084, NIOSH stated that it 

had adequate data to reconstruct internal doses of unmonitored workers by constructing a 

coworker model based on data of 100 workers (NIOSH 2007, p. 36 and Table 7-1). The 100 

workers were selected based on (1) “significant” cumulative external dose, and (2) the 

assumption that it was “most likely that significant internal exposure would be associated with 

significant external exposure” (NIOSH 2007, p. 35). 

SC&A reviewed dosimetry data for the NIOSH group of 100 workers in Table 7-1 of the NIOSH 

Evaluation Report (NIOSH 2007), as well as data for a sample of 120 claimants, consisting of 20 

workers drawn at random in each of 6 job types. SC&A’s analysis was provided to the Advisory 

Board’s Nevada Test Site Work Group in two reports (SC&A 2008, SC&A 2009). The 

conclusions of the two SC&A reports may be summarized as follows: 

(1) Data for valid comparisons between the RadSafe group and the other workers are sparse 

to non-existent in most categories, such as for plutonium and gross fission products, and 

for most worker groups and periods (see also SC&A 2008). (Note: The periods used 

were 1963–1967, 1968–1970, 1971–1980, and 1981–1992.) Hence, it is not clear that 

RadSafe group data, the only group with data in all periods, could be used to create a 

coworker model. Moreover, the data indicate that miners had a higher exposure potential 

for tritium than the RadSafe group. 

(2) The 95th percentile value of the NIOSH-100 plutonium bioassay data for the RadSafe 

worker group (and the whole group of 100 workers) is almost 6 times lower than the 

corresponding value of the SC&A RadSafe Group, indicating that the NIOSH group of 

100 workers was not representative of the RadSafe workers or of NTS workers with the 

highest plutonium exposure potential. 
Draft – Review of NIOSH Position Paper 10 SC&A – January 12, 2010 

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(3) There are inconsistencies in plutonium and gamma bioassay data that raise questions 

about the quality of these data. These data quality and consistency issues are not 

addressed in the Evaluation Report. 

(4) Cumulative external exposure of the group of 100 in Table 7-1 of NIOSH 2007 does not 

appear to be correlated with internal exposure potential, as reflected in the highest 

bioassay results or in the frequency of bioassay monitoring. Moreover, a large portion of 

the cumulative external exposure for this group was experienced prior to the SEC period 

under consideration. 

(5) Table 7-1 over-represents tunnel workers compared to workers in the Flats, where most 

of the tests were conducted. 

For the above reasons, SC&A concluded that NIOSH’s selection of the 100 workers in Table 7-1 

is inappropriate for the construction of an internal exposure coworker model for NTS workers. 

SC&A also concluded that NIOSH had not demonstrated the feasibility of a coworker model for 

unmonitored NTS workers (SC&A 2008, pp. 8–9). 

During a Work Group meeting to discuss these findings, NIOSH agreed that the issue of internal 

dose needed to be revisited. NIOSH subsequently examined a large electronic database to 

determine whether it had sufficient data to build a reliable coworker model that would meet the 

requirements of 42 CFR 83, the regulation governing additions to the SEC. NIOSH’s analysis 

and findings were reported in its November 2009 report (NIOSH 2009). 

1.2 NIOSH 2009 REVIEW OF THE ELECTRONIC INTERNAL DOSIMETRY DATA 

NIOSH’s central conclusion was as follows: 

As presented in this position paper, NIOSH believes that there is insufficient 

information to adequately support bounding internal dose (reconstructing 

internal dose with sufficient accuracy) for the portion of the SEC00084-NTS 

worker class who worked during the period of testing from 1963 through 1992. 

[NIOSH 2009, p. 4] 

NIOSH’s conclusion regarding internal doses during the period was based on four findings: 

1. NIOSH has identified exposure scenarios involving varying job titles/duties 

and work activities, such as drill-backs, post-test work activities, and 

construction or other soil disturbing activities in areas that had been 

contaminated by previous tests. Prior to 1993, no source documentation 

could be located to confirm the rationale behind why bioassay samples were 

collected. Because of this, NIOSH cannot conclusively determine that doses 

to all of these potentially exposed individuals were detected by the bioassay 

program. 

 A review of the available data indicates a large number of radiological 

technicians and security personnel were routinely sampled. Other job 
Draft – Review of NIOSH Position Paper 11 SC&A – January 12, 2010 

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titles/duties are also represented but a substantial fraction of the ‘other’ 

group of bioassay samples appears to have been collected on a more event or 

incident-driven basis. Although NIOSH does have access to site procedures 

and directives, NIOSH has not located sufficient documented evidence, other 

than anecdotal, to describe a consistent rationale behind the collection of 

personnel bioassay sampling or to indicate that sampling occurred 

consistently in the situations where it was required. 

2. NIOSH has identified data gaps that exist in the electronically available 

bioassay data for certain nuclides and time periods... that impact NIOSH’s 

ability to bound the internal dose... 

3. The nature of work at the NTS site and the large geographic area over which 

this work was conducted presents a unique challenge for bounding the 

internal doses at NTS. Unlike many production sites (i.e., SRS, Rocky Flats, 

Fernald, etc.), the NTS was primarily engaged in shorter-term campaigndriven activities that were separated by large distances, and there appears to 

be a direct relationship between campaigns and bioassay sampling. The 

concept of a campaign-driven bioassay sampling program is further 

supported by the fact that many of the periodic bioassay samples appear to 

have been collected on the same day. Because of the episodic nature of the 

exposures at NTS, a coworker model that is useful in reconstructing chronic 

intake scenarios would not necessarily be representative of the exposure 

patterns for the NTS workforce. 

4. The reconstruction of internal doses at NTS is also complicated by the variety 

of the radionuclides to which workers may have been exposed. As indicated 

in the NTS site profile, the potential nuclide source-term included, but is not 

limited to, plutonium, americium, uranium, thorium, radium, iodine, and other 

fission products. For workers with no bioassay records, and who had the 

potential for exposure, NIOSH would have to definitively establish the relative 

mixture of the exposure source-term. 

NIOSH also stated that due to the end of testing in 1992, the promulgation of 10 CFR 835, and a 

documentable policy to adhere to it, NTS internal doses can be reconstructed from 1993 onward. 

Since SC&A’s mandate from the Work Group in the present review extended only to matters 

related to the SEC petition, we have not reviewed the analysis or documentation underlying 

NIOSH’s conclusion regarding the period starting in 1993. 

1.3 FRAMEWORK FOR THIS REPORT 

SC&A focused its review of NIOSH 2009 on the contents of the electronic database, which was 

analyzed to address the following questions: 
Draft – Review of NIOSH Position Paper 12 SC&A – January 12, 2010 

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• Was the pattern of monitoring revealed by the electronic database similar to or different 

from that observed by SC&A in its prior analysis referred to above (see SC&A 2008 and 

SC&A 2009)? 

• Were there more data in the various worker categories and periods that would allow the 

identification of a group of workers who were at the highest exposure potential in the 

different categories of radionuclides for which data are necessary to estimate doses? 

• Did the quality of data issues persist, or were they resolved by the new data?

• Did any new issues emerge regarding internal dose reconstruction not previously 

identified in the prior SC&A reports? 

• Was NIOSH’s overall technical analysis sustained by SC&A’s prior analysis of the data 

and SC&A’s review and analysis of the electronic database? 

• Were NIOSH’s conclusions regarding lack of sufficient data to reconstruct internal doses 

with sufficient accuracy robust? 

It should be noted that SC&A worked from a set of Excel® spreadsheets prepared by NIOSH 

from the original database, which are in an older format. The references to the “electronic 

database” or “electronic data” in this report are to these Excel spreadsheets. SC&A did not 

attempt to verify the completeness or quality of the transcription of the original database to the 

multiple Excel spreadsheet format. Some observations on the issue of completeness and quality 

of the data in the electronic database, as reflected in the spreadsheets, are provided in this 

analysis.
Draft – Review of NIOSH Position Paper 13 SC&A – January 12, 2010 

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2.0 ANALYSIS OF THE DATA 

In order to analyze the monitoring practices of the six job types identified in SC&A’s previous 

analyses (SC&A 2008, SC&A 2009), a connection had to be made between the workers 

contained in the new database and their job titles. Since the electronic database does not contain 

job classification information, only the subset of employees in the database who were claimants 

could be analyzed by job title. This occurs because job title data are only available in the 

NIOSH claimant database and not in the additional electronic bioassay database provided to and 

recently reviewed by NIOSH. The social security numbers (SSNs) for each worker in the 

database were matched to the SSNs listed for NTS claimants on NOCTS to determine which data 

entries represented the job titles that matched the six titles analyzed in SC&A 2008 and SC&A 

2009. 

The electronic database provided monitoring results for seven different radionuclides—

americium, beta/gross fission products, gamma, plutonium, strontium, tritium, and uranium. 

Three of these radionuclides (americium, strontium, and uranium) had very sparse data and 

therefore could not provide substantial insight into the monitoring practices associated with these 

contaminants. Therefore, these three radionuclides could not be analyzed in the same depth as 

the other four; however, they are discussed briefly in Section 3.6. 

The vast majority of data entries were urinalysis samples given in the units of microcurie per cc 

(MI/cc); however, other bioassay types and units were also occasionally listed. For example, 

several data entries were listed as whole-body scans that did not have an associated result 

included. In addition, many urinalysis samples were given in units other than MI/cc, such as 

total microcurie, disintegrations per minute, millicurie/cc. In order to analyze the magnitude of 

the bioassay entries for various categories of workers, the data had to be normalized to a 

consistent set of units and bioassay types. Furthermore, while whole-body counts are listed in 

the electronic database as having been performed, it does not contain any actual measurements. 

Therefore, all non-urinalysis samples were removed for the purposes of characterizing the 

magnitude of the intakes experienced by the workers and comparing them to previously 

compiled data.2

 Urinalysis samples that could not be converted to MI/cc, or reasonably assumed 

to be in these units, were removed. Any data entries designated as ‘Less than’ or ‘Not 

Detectable’ were assumed to be zero. Blank entries with no indication that the sample was ‘not 

detectable’ or ‘less than’ were removed, because there was insufficient evidence that the sample 

was ever analyzed. It is important to note that the removal of samples was only for the purposes 

of analyzing the ‘concentration in urine,’ and does not apply when characterizing the total 

number of samples, number of workers sampled, and frequency of monitoring for the designated 

worker categories and time periods. It also should be noted that only a small proportion of the 

data, less than 9% for the 4 major radionuclides, had to be removed in this way. The largest 

percentage of samples removed occurred for plutonium (15.35%), which is a result of the large 

number of whole-body scans included in this dataset (accounting for roughly 12.5% of the data 

entries). The 3 remaining radionuclides had approximately 5%, 8%, and 10% of their samples 

2

 The number of whole-body counts listed in the electronic database is noted in this analysis to provide an 

idea of the relative magnitude of urine bioassay data used to whole-body counting data that could not be used, since 

no measurements were available in the electronic database for these counts. 
Draft – Review of NIOSH Position Paper 14 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

removed for beta, tritium, and gamma, respectively. So the analysis provided here is based on 

the vast majority of monitoring data in the electronic database. 

The data for claimants as compiled by SC&A from the electronic database and NIOSH’s 

NOCTS database for claimants are available in spreadsheets on the O-Drive for NIOSH and the 

Board. The original spreadsheets compiled by NIOSH are also available on the O-Drive. All 

these data contain names and SSNs of workers and are protected by the Privacy Act.
Draft – Review of NIOSH Position Paper 15 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

3.0 RESULTS 

The following subsections present the bioassay data for the claimants in the electronic database, 

sorted by job category for the four main monitoring categories: 

• Plutonium

• Gamma 

• Beta (Gross Fission Products) 

• Tritium

Each subsection contains a set of tables that show an overview of the data (how many samples, 

how many workers sampled, etc.); data characteristics (number of positive, negative, zero, less 

than, blank, and non-detectable results); number of samples by designated period; and the 

number of samples per worker given as a rank order at the 50th, 75th, and 95th percentiles. In 

addition to the tables, three chart types are presented that show the number of workers monitored 

in any given year; the rank ordered concentration in urine for all workers in the database, as well 

as the identified job types, with data from all timeframes group together; and finally the rank 

ordered 50th percentile concentration in urine for all workers as a function of year. 

These tables and charts are designed to enable a comparison with previously analyzed data in 

these four bioassay and six job categories. For instance, the samples by period show that the 

RadSafe group was the most consistently monitored, and the security group was also monitored 

in the 1980s and early 1990s. Furthermore, the cumulative distribution functions for each 

bioassay group in charts labeled “Rank-Ordered [Bioassay type] Concentration in Urine,” are 

designed to provide an overview of the relative magnitudes of the bioassay measurements for the 

various groups of workers. These charts are discussed in terms of their implications for a 

coworker model in Section 4. In reviewing them, it must be kept in mind that these charts of 

rank-ordered bioassay measurements contain no separation of values by period. A parsing by 

period is important. The last figure in each set shows that, for the most part, bioassay results in 

the early part of the SEC period (roughly the decade starting in 1963) are generally higher than 

those in later periods. 

However, in most cases, the data are too sparse to construct cumulative distribution functions by 

period that would allow comparison of bioassay results by job type. Hence, the rank-ordered 

charts by job type show all data for each job type without regard to period. These charts allow 

one to determine the probability that the bioassay measurement will be less than a particular 

amount for a given type of bioassay. For instance, the rank ordering of gamma bioassay by job 

type shows that there is a 60% probability that the bioassay value for the RadSafe job type will 

be less than about 1.2 × 10-7 MI/cc, while that for laborers is considerably higher at about 1 × 

10-6 MI/cc. This would usually indicate a greater exposure potential for laborers relative to 

RadSafe workers. However, as we will see below, the interpretation of much of the NTS 

bioassay data is rendered complex by the presence in many situations of a large number of shortlived radionuclides, and by the apparent incident-driven nature of much of the sampling. 
Draft – Review of NIOSH Position Paper 16 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

3.1 PLUTONIUM 

Table 3-1: Overview of Plutonium Data 

Claims 

Plutonium Data 

RadSafe Laborers Welders Wireman Miners Security All Claimant 

Pu 

All Workers 

in Database

Data Overview 

Total Samples 468 18 [redacted] [redacted] 25 227 952 9,273 

# Individuals 40 [redacted] [redacted] [redacted] 15 29 144 2,518 

Urine Samples 430 

(91.88%) 

14 

(77.78%) 

[redacted]

(100.00%) – 19 

(76.00%) 

178 

(78.41%) 

826 

(86.76%) 

8,116 

(87.52%) 

Whole-Body 

Counts 

38 

(8.12%) 

[redacted]

(22.22%) – [redacted](100.00%)

[redacted]

(24.00%) 

49 

(21.59%) 

126 

(13.24%) 

1,157 

(12.48%) 

Pu-239 467 

(99.79%) 

18 

(100.00%) 

[redacted]

(71.43%) 

[redacted]

(100.00%)

24 

(96.00%) 

220 

(96.92%) 

933 

(98.00%) Not Counted

Pu-238 [redacted]

(0.21%) – [redacted](28.57%) – [redacted](4.00%) 

[redacted]

(3.08%) 

19 

(2.00%) Not Counted

Data Characteristics 

Number of Positive 

Results 

361 

(77.14%) 

12 

(66.67%) 

[redacted]

(57.14%) – 13 

(52.00%) 

160 

(70.48%) 

694 

(72.90%) 

6,598 

(71.15%) 

Number of Results 

Listed as 

‘Less than’3

38 

(8.12%) – – – [redacted]

(16.00%) – 60 

(6.30%) 

509 

(5.49%) 

Number of 

Negative Results 

26 

(5.56%) 

[redacted]

(11.11%) 

[redacted]

(42.86%) – [redacted](8.00%) 

13 

(5.73%) 

60 

(6.30%) 

831 

(8.96%) 

Number of Zero 

Results 

[redacted]

(1.07%) – – – – [redacted](2.20%) 

12 

(1.26%) 

167 

(1.80%) 

Number of Results 

listed as 

‘No Detectable’ 

– – – – – – – [redacted]

Number of Blank 

Results 

38 

(8.12%) 

[redacted]

(22.22%) – [redacted](100.00%)

[redacted]

(24.00%) 

49 

(21.59%) 

126 

(13.24%) 

1,167 

(12.58%) 

# of Samples by Period

Total Samples 468 18 [redacted] [redacted] 25 227 952 9,273 

1963–1967 10 

(2.14%) – – – – – 10 

(1.05%) 

133 

(1.43%) 

1968–1970 44 

(9.40%) – [redacted]

(28.57%) – [redacted](32.00%) 

[redacted]

(1.76%) 

92 

(9.66%) 

741 

(7.99%) 

1971–1980 226 

(48.29%) 

[redacted]

(16.67%) – – [redacted](32.00%) 

25 

(11.01%) 

354 

(37.18%) 

2,756 

(29.72%) 

1981–1992 188 

(40.17%) 

15 

(83.33%) 

[redacted]

(71.43%) 

[redacted]

(100.00%)

[redacted]

(36.00%) 

198 

(87.22%) 

496 

(52.10%) 

5,643 

(60.85%) 

 3

 These data entries appear with an ‘LT’ in the detection column and either a zero or a blank entry in the 

analyze amount column. This applies to all four radionuclide types except where noted for gamma. 
Draft – Review of NIOSH Position Paper 17 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

Claims 

Table 3-1: Overview of Plutonium Data 

Plutonium Data 

RadSafe Laborers Welders Wireman Miners Security All Claimant 

Pu 

All Workers 

in Database

Rank Ordered Percentile of Samples per Claimant/Worker

# Individuals 40 [redacted] [redacted] [redacted] 15 29 144 2,518 

50th Percentile 

# Samples 10 [redacted] [redacted] – [redacted] 7.5 [redacted] [redacted]

75th Percentile 

# Samples 17 [redacted] [redacted] – [redacted] 11 [redacted] [redacted]

95th Percentile 

# Samples 29 [redacted] [redacted] – [redacted] 14.1 23.6 13 

Maximum 

# Samples 30 [redacted] [redacted] [redacted] [redacted] 16 30 31 

Workers Sampled for Plutonium by Year

0

100

200

300

400

500

600

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

Year

Number of Workers Sampled in Year

Figure 3-1: Workers Sampled for Plutonium by Year 
Rank Ordered Pu-239 Concentration in Urine

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.00E-12 1.00E-11 1.00E-10 1.00E-09

Concentration (MI/cc)

Rank Order

All Claimants

RadSafe

Laborers

Welders

Miners

Security

All Workers

Figure 3-2: Rank-Ordered Plutonium-239 Concentration in Urine 

Rank Ordered Pu-239 Concentration in Urine

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.00E-11 2.00E-11 3.00E-11 4.00E-11 5.00E-11 6.00E-11 7.00E-11 8.00E-11 9.00E-11 1.00E-10

Concentration (MI/cc)

Rank Order

All Claimants

RadSafe

Laborers

Welders

Miners

Security

All Workers

Figure 3-3: Rank-Ordered Pu-239 Concentration in Urine – Expanded Horizontal Axis 

Draft – Review of NIOSH Position Paper 18 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
Rank Ordered 50th Percentile Concentration in Urine by Year 

for All Monitored Workers

1.00E-12

1.00E-11

1.00E-10

1.00E-09

1.00E-08

1.00E-07

1.00E-06

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

Year

Concentration in Urine

Figure 3-4: Rank-Ordered 50th Percentile Concentration in Urine by Year for All 

Monitored Workers 

3.2 GAMMA 

Table 3-2: Overview of Gamma Data 

Claims 

Gamma Data 

RadSafe Laborers Welders Wireman Miners Security 

All 

Claimant 

Gamma 

All Workers 

in Database 

Data Overview 

Total Samples 2658 153 47 15 407 875 5343 46,767 

# Individuals 46 24 12 10 47 35 280 5,093 

Urine Samples 2627 

(98.83%) 

139 

(90.85%) 

46 

(97.87%) 

14 

(93.33%) 

384 

(94.35%) 

834 

(95.31%) 

5209 

(97.49%) 

45,404 

(97.09%) 

Whole-Body Counts 31 

(1.17%) 

14 

(9.15%) 

[redacted]

(2.13%) 

[redacted]

(6.67%) 

23 

(5.65%) 

41 

(4.69%) 

134 

(2.51%) 

1,363 

(2.91%) 

Draft – Review of NIOSH Position Paper 19 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
Draft – Review of NIOSH Position Paper 20 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

Claims 

Table 3-2: Overview of Gamma Data 

Gamma Data 

RadSafe Laborers Welders Wireman Miners Security 

All 

Claimant 

Gamma 

All Workers 

in Database 

Data Characteristics 

Number of Positive 

Results 

1928 

(72.54%) 

94 

(61.44%) 

41 

(87.23%) 

11 

(73.33%) 

322 

(79.12%) 

286 

(32.69%) 

3561 

(66.65%) 

30,629 

(65.49%) 

Number of Results 

Listed as 

‘Less than’* 

70 

(2.63%) – – – [redacted]

(1.47%) – 100 

(1.87%) 

786 

(1.68%) 

Number of Negative 

Results – – – – – – – – 

Number of Zero 

Results 

219 

(8.24%) 

11 

(7.19%) 

[redacted]

(6.38%) – 18 

(4.42%) 

150 

(17.14%) 

476 

(8.91%) 

5,037 

(10.77%) 

Number of Results 

listed as 

‘No Detectable’ 

410 

(15.43%) 

34 

(22.22%) 

[redacted]

(4.26%) 

[redacted]

(20.00%) 

36 

(8.85%) 

398 

(45.49%) 

1070 

(20.03%) 

8,932 

(19.10%) 

Number of Blank 

Results 

31 

(1.17%) 

14 

(9.15%) 

[redacted]

(2.13%) 

[redacted]

(6.67%) 

25 

(6.14%) 

41 

(4.69%) 

136 

(2.55%) 

1,383 

(2.96%) 

# of Samples by Period 

Total Samples 2,658 153 47 15 407 875 5,343 46,767 

1963–1967 204 

(7.67%) 

31 

(20.26%) 

11 

(23.40%) 

[redacted]

(13.33%) 

72 

(17.69%) 

[redacted]

(0.46%) 

489 

(9.15%) 

4,916 

(10.51%) 

1968–1970 306 

(11.51%) 

12 

(7.84%) 

[redacted]

(4.26%) – 36 

(8.85%) 

[redacted]

(0.23%) 

502 

(9.40%) 

3,503 

(7.49%) 

1971–1980 1,065 

(40.07%) 

41 

(26.80%) 

[redacted]

(10.64%) 

[redacted]

(40.00%) 

149 

(36.61%) 

32 

(3.66%) 

1,740 

(32.57%) 

10,200 

(21.81%) 

1981–1992 1,083 

(40.74%) 

69 

(45.10%) 

29 

(61.70%) 

[redacted]

(46.67%) 

150 

(36.86%) 

837 

(95.66%) 

2,612 

(48.89%) 

28,148 

(60.19%) 

Rank Ordered Percentile of Samples per Claimant/Worker 

# Individuals 46 24 12 10 47 35 280 5,093 

50th Percentile 

# Samples 34 [redacted] [redacted] [redacted] [redacted] 24.5 [redacted] [redacted]

75th Percentile 

# Samples 85 [redacted] [redacted] [redacted] 10.25 37.25 22 [redacted]

95th Percentile 

# Samples 180.9 20 12.2 [redacted] 27.3 45.75 85 39 

Maximum 

# Samples 234 36 17 [redacted] 38 52 234 234 

* One entry had internally inconsistent information. It was listed as ‘LT’ in the “detection” column and as a 

positive result in the “analyze amount” column. We chose to count this entry towards the positive results and not 

the ‘less than’ result totals. This was the only instance of a positive result associated with a ‘less than’ tag for any 

of the four major radionuclides. 
Number of Workers Sampled for Gamma by Year

0

100

200

300

400

500

600

700

800

900

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

Year

Number of Workers Sampled

Figure 3-5: Number of Workers Sampled for Gamma by Year 

Rank Ordered Gamma Concentration in Urine

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02

Concentration (MI/cc)

Rank Order

All Claimants

RadSafe

Laborers

Welders

Wireman

Miners

Security

All Workers

Figure 3-6: Rank-Ordered Gamma Concentration in Urine 

Draft – Review of NIOSH Position Paper 21 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
Rank Ordered 50th Percentile Concentration in Urine by Year 

for All Monitored Workers

1.00E-08

1.00E-07

1.00E-06

1.00E-05

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

Year

Concentration in Urine (MI/cc)

Figure 3-7: Rank-Ordered 50th Percentile Concentration in Urine by Year for All 

Monitored Workers 

3.3 BETA 

Table 3-3: Overview of Beta Data 

Claims 

Beta Data 

RadSafe Laborers Welders Wireman Miners Security 

All 

Claimant 

Beta 

All Workers 

in Database

Data Overview 

Total Samples 1,173 44 12 [redacted] 42 597 2,362 22,308 

# Individuals 40 [redacted] [redacted] [redacted] 14 29 138 2,671 

Urine Samples 1,157 

(98.64%) 

44 

(100.00%) 

11 

(91.67%) 

[redacted]

(50.00%) 

39 

(92.86%) 

591 

(98.99%) 

2,327 

(98.52%) 

21,949 

(98.39%)4

Whole-Body 

Counts 

16 

(1.36%) – [redacted]

(8.33%) 

[redacted]

(50.00%) 

[redacted]

(7.14%) 

[redacted]

(1.01%) 

35 

(1.48%) 

358 

(1.60%) 

 

Draft – Review of NIOSH Position Paper 22 SC&A – January 12, 2010 

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However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

4

 There was also one wound swab included in the database for beta. 
Draft – Review of NIOSH Position Paper 23 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

Claims 

Table 3-3: Overview of Beta Data 

Beta Data 

RadSafe Laborers Welders Wireman Miners Security 

All 

Claimant 

Beta 

All Workers 

in Database

Data Characteristics 

Number of Positive 

Results 

1,137 

(96.93%) 

43 

(97.73%) 

11 

(91.67%) 

[redacted]

(50.00%) 

36 

(85.71%) 

585 

(97.99%) 

2,292 

(97.04%) 

20,946 

(93.89%) 

Number of Results 

Listed as 

‘Less than’ 

17 

(1.45%) – – – – – 21 (0.89%) 

135 

(0.61%) 

Number of 

Negative Results 

[redacted]

(0.26%) 

[redacted]

(2.27%) – – [redacted](2.38%) 

[redacted]

(0.84%) 

10 

(0.42%) 

180 

(0.81%) 

Number of Zero 

Results – – – – – – – – 

Number of Results 

listed as 

‘No Detectable’ 

– – – – – [redacted]

(0.17%) 

[redacted]

(0.04%) [redacted]

Number of Blank 

Results 

16 

(1.36%) – [redacted]

(8.33%) 

[redacted]

(50.00%) 

[redacted]

(11.90%) 

[redacted]

(1.01%) 

38 

(1.61%) 

1,041 

(4.67%) 

# of Samples by Period 

Total Samples 1,173 44 12 [redacted] 42 597 2,362 22,308 

1963–1967 37 

(3.15%) 

[redacted]

(6.82%) – – [redacted](7.14%) – 59 

(2.50%) 

1,148 

(5.15%) 

1968–1970 112 

(9.55%) – – – [redacted]

(9.52%) – 169 

(7.15%) 

1,120 

(5.02%) 

1971–1980 497 

(42.37%) – – [redacted]

(50.00%) 

18 

(42.86%) 

[redacted]

(0.67%) 

685 

(29.00%) 

4,614 

(20.68%) 

1981–1992 527 

(44.93%) 

41 

(93.18%) 

12 

(100.00%) 

[redacted]

(50.00%) 

17 

(40.48%) 

593 

(99.33%) 

1,449 

(61.35%) 

15,426 

(69.15%) 

Rank Ordered Percentile of Samples per Worker 

# Individuals 40 [redacted] [redacted] [redacted] 14 29 138 2,671 

50th Percentile 

# Samples 22 [redacted] [redacted] [redacted] [redacted] 21.5 10 [redacted]

75th Percentile 

# Samples 50 10.75 [redacted] [redacted] [redacted] 27.75 26 10 

95th Percentile 

# Samples 69 17.75 10 [redacted] [redacted] 35.75 58.1 32 

Maximum 

# Samples 77 20 11 [redacted] 10 45 77 88 
Number of Workers Sampled for Beta/GFP by Year

0

100

200

300

400

500

600

700

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

Year

Number of Workers

Figure 3-8: Number of Workers Sampled for Beta/GFP by Year 

Rank Ordered Beta/GFP Concentration in Urine

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.00E-10 1.00E-09 1.00E-08 1.00E-07 1.00E-06

Concentration (MI/cc)

Rank Order

All Claimants

RadSafe

Laborers

Welders

Wireman

Miners

Security

All Workers

Figure 3-9: Rank-Ordered Beta/GFP Concentration in Urine 

Draft – Review of NIOSH Position Paper 24 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
Rank Ordered Beta/GFP Concentration in Urine

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.00E-09 2.00E-09 3.00E-09 4.00E-09 5.00E-09 6.00E-09 7.00E-09 8.00E-09 9.00E-09 1.00E-08

Concentration (MI/cc)

Rank Order

All Claimants

RadSafe

Laborers

Welders

Wireman

Miners

Security

All Workers

Figure 3-10: Rank-Ordered Beta/GFP Concentration in Urine – 

Expanded Horizontal Axis 

Rank Ordered 50th Percentile Concentration in Urine by Year 

for All Monitored Workers

0.00E+00

5.00E-09

1.00E-08

1.50E-08

2.00E-08

2.50E-08

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

Year

Concentration in Urine

Figure 3-11: Rank-Ordered 50th Percentile Concentration in Urine by Year for 

All Monitored Workers 

Draft – Review of NIOSH Position Paper 25 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
Draft – Review of NIOSH Position Paper 26 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

3.4 TRITIUM 

Table 3-4: Overview of Tritium Data 

Claims 

Tritium Data 

RadSafe Laborers Welders Wireman Miners Security All Claimant 

Pu

All Workers 

in Database 

Data Overview 

Total Samples 1,985 221 39 37 822 826 4,977 42,748 

# Individuals 13 17 [redacted] 13 50 34 244 4,724 

Urine Samples 1,900 

(95.72%) 

207 

(93.67%) 

35 

(89.74%) 

31 

(83.78%) 

762 

(92.70%) 

764 

(92.49%) 

4,673 

(93.89%) 

40,253 

(94.16%) 

Whole-Body 

Counts 

85 

(4.28%) 

14 

(6.33%) 

[redacted]

(10.26%) 

[redacted]

(16.22%) 

60 

(7.30%) 

62 

(7.51%) 

304 

(6.11%) 

2,495 

(5.84%) 

Data Characteristics 

Number of 

Positive Results 

1,718 

(86.55%) 

202 

(91.40%) 

29 

(74.36%) 

28 

(75.68%) 

722 

(87.83%) 

755 

(91.40%) 

4,320 

(86.80%) 

36,199 

(84.68%) 

Number of 

Results Listed as 

‘Less than’ 

148 

(7.46%) 

[redacted]

(1.36%) 

[redacted]

(5.13%) 

[redacted]

(5.41%) 

23 

(2.80%) 

[redacted]

(0.36%) 

276 

(5.55%) 

2,448 

(5.73%) 

Number of 

Negative Results 

21 

(1.06%) 

[redacted]

(0.45%) 

[redacted]

(10.26%) – [redacted](0.12%) 

[redacted]

(0.73%) 

41 

(0.82%) 

602 

(1.41%) 

Number of Zero 

Results 

13 

(0.65%) – – – [redacted]

(0.24%) – 19 

(0.38%) 

135 

(0.32%) 

Number of 

Results listed as 

‘No Detectable’ 

– – – – – – – [redacted]

Number of Blank 

Results 

85 

(4.28%) 

15 

(6.79%) 

[redacted]

(10.26%) 

[redacted]

(18.92%) 

74 

(9.00%) 

62 

(7.51%) 

321 

(6.45%) 

3,361 

(7.86%) 

# of Samples by Period 

Total Samples 1,985 221 39 37 822 826 4,977 42,748 

1963–1967 42 

(2.12%) 

[redacted]

(2.71%) 

[redacted]

(5.13%) 

[redacted]

(8.11%) 

57 

(6.93%) 

[redacted]

(0.36%) 

179 

(3.60%) 

2,753 

(6.44%) 

1968–1970 167 

(8.41%) 

[redacted]

(3.62%) – – 48 

(5.88%) 

[redacted]

(0.12%) 

322 

(6.47%) 

2,616 

(6.12%) 

1971–1980 923 

(46.50%) 

69 

(31.22%) 

[redacted]

(15.38%) 

28 

(75.68%) 

393 

(47.81%) 

35 

(4.24%) 

1,929 

(38.76%) 

11,108 

(25.98%) 

1981–1992 853 

(42.97%) 

138 

(62.44%) 

31 

(79.49%) 

[redacted]

(16.22%) 

324 

(39.42%) 

787 

(95.28%) 

2,547 

(51.18%) 

26,271 

(61.46%) 

Rank Ordered Percentile of Samples per Worker 

# Individuals 13 17 [redacted] 13 50 34 244 4,724 

50th Percentile 

# Samples 18 [redacted] [redacted] [redacted] [redacted] 22 [redacted] [redacted]

75th Percentile 

# Samples 28.5 10.25 5.25 [redacted] 15 38.5 26 [redacted]

95th Percentile 

# Samples 118.7 40.5 12.3 7.7 84.5 43 83.8 40 

Maximum 

# Samples 120 100 15 [redacted] 110 48 138 162 
Number of Workers Sampled for Tritium per Year

0

100

200

300

400

500

600

700

800

900

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

Year

Number of Workers Sampled

Figure 3-12: Number of Workers Sampled for Tritium by Year 

Rank Ordered Tritium Concentration in Urine

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.00E-08 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01

Concentration (MI/cc)

Rank Order

All Claimants

Radsafe

Laborers

Welders

Wireman

Miners

Security

All Workers

Figure 3-13: Rank-Ordered Tritium Concentration in Urine

Draft – Review of NIOSH Position Paper 27 SC&A – January 12, 2010 

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However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
Rank Ordered 50th Percentile Concentration in Urine by Year 

for All Monitored Workers

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

Year

Concentration in Urine (MI/cc)

Figure 3-14: Rank-Ordered 50th Percentile Concentration in Urine by Year for 

All Monitored Workers 

3.5 STATISTICAL ANALYSIS REGARDING MONITORING PATTERN 

Figure 3-15 contains a plot of the plutonium-239 biosamples in the electronic database that were 

matched to a claimant and hence, to a job type. Only Pu-239 samples are included in this plot.5 

The plot shows samples for five groups of claimants; RadSafe workers, security workers, miners, 

laborers and welders.6

 The number of samples in each job category is shown in the key in 

parentheses. While the samples from the RadSafe worker claimants span the entire period, the 

samples from security worker claimants are almost all in the period after 1980. The small 

number of samples from miners and laborers are scattered throughout the time period. The 

[redacted] in this dataset had samples only in the late 1980s and early 1990s. 

The samples for the five job categories are displayed in a percentile plot in Figure 3-16. A 

similar plot using the normal score of each sample value on the horizontal axis is shown in 

Figure 3-17. NIOSH typically has used the normal score plot to estimate the parameters of a 

lognormal distribution for use in a coworker model. If the plutonium-239 sample values came 

 5

 Plutonium-239 records were identified by the analyte description code values of 06 and 11, as 

documented in Table A-1 of ORAUT 2008b. Many of these records had contradictory comments in the database 

fields titled Comment 1 and Comment 2, indicating Pu-239 in the Comment 1 field and Pu-238 in the Comment 2 

field. In these cases, information in the Comment 2 field was ignored. 

Draft – Review of NIOSH Position Paper 28 SC&A – January 12, 2010 

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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

6

 The sixth category, “wiremen,” could not be included in the analysis in this section, since there was only 

[redacted] in this category in the electronic database with just one plutonium bioassay sample. 
Draft – Review of NIOSH Position Paper 29 SC&A – January 12, 2010 

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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

from a lognormal distribution, the plots in Figure 3-17 would appear as approximately straight 

lines. Although the plot for security workers appears to be approximately linear in the upper half 

of the plot, the plot for the RadSafe workers has a highly non-linear shape, with an extremely 

high upper tail extending to over a factor of 100 times higher than the remainder of the 

distribution. The high tail values may indicate that the plutonium-239 data in the electronic 

database includes incident-related samples, combined with the results from a more routine 

sampling program. 

Normal score plots for gross gamma concentration in urine for claimants in five job categories 

are displayed in Figure 3-18. The plots for all job types except welders have a non-linear shape, 

with upper tails extending much higher than the remainder of the distribution. The high tail 

values may indicate that the gross gamma data in the electronic database have incident-related 

samples included with routine sampling results. Only one matched claimant was identified as a 

[redacted], with samples in a single time period from the late 1980s to the early 1990s. 

Normal score plots for gross beta concentrations in urine are shown in Figure 3-19. Again, the 

plots for all categories of workers except welders have a non-linear shape, with upper tails 

extending much higher than the remainder of the distribution. These high tail values may 

indicate that the gross beta data in the electronic database also include incident-related samples, 

combined with routine sampling results. 

Figure 3-20 contains plots of tritium concentrations in urine for the five categories of workers. 

Although the tritium plots have non-linear shapes, there are no unusual values in the upper tails. 

The tritium data in the electronic database appear to be mainly part of a routine monitoring 

program during the period under consideration. 

The number of Pu-239 biosamples was sufficient to construct plots for the RadSafe and security 

worker claimants by decade. A percentile plot for the RadSafe claimant samples in the 

electronic database by decade from the 1960s to the 1990s is shown in Figure 3-21. Note that 

the plot for the 1960s begins at a percentile value of approximately 80%, since approximately 

80% of the samples’ values were below the minimum detection limit (MDL). Data points below 

the MDL are not shown in this type of graph, but these data points do affect the position in the 

plot of the first sample value that is above the MDL. 

Figure 3-22 contains a normal score plot for the RadSafe claimant samples for the four decades. 

All four decades have nonlinear plots. These distributions do not appear to be lognormal. In the 

1960s, 80% of the samples are below the MDL, while the remaining samples are among the 

highest in the database. In each decade after the 1960s, the upper tails contain high outliers. 

These patterns are indicative of biosamples collected from RadSafe workers involved in highexposure incidents at the site that are combined with samples from a more routine, ongoing 

sampling program. It is also important to note that apart from some samples in the early 1980s, 

possibly incident-driven, the highest bioassay concentrations of plutonium-239 for RadSafe 

workers are in the 1960s, despite the fact that this period had the smallest rate of sampling for 

this group of workers. 
A percentile plot is shown in Figure 3-23 for the security worker claimants. The security worker 

biosamples cover only the 1981–1992 period. The normal score plot for security workers in 

Figure 3-24 is non-linear in the 1980s, although the upper tail is well behaved with no extreme 

outliers. The security worker biosamples appear to be the results of a regular sampling program, 

with no evidence of unusual incidents. The plot for the much smaller number of security worker 

samples in the 1990s begins at over 60%, indicating that well over half of the samples were 

below the MDL. The early 1990s samples may have an approximately lognormal-shaped 

distribution in the upper tail. This indicates that security personnel sampling for plutonium for 

the early 1990s may also have been of the routine variety. This contrasts with indications of 

mixed incident-driven and routine sampling for the RadSafe group. Most other data, except 

tritium, for the rest of the job types indicate either incident-driven sampling or mixed incidentdriven and routine sampling. 

1E-14

1E-13

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

1965 1968 1971 1973 1976 1979 1982 1984 1987 1990 1993

Year

Pu-239 in Urine (?Ci/cc)

RadSafe (398)

Security (165)

Miners (14)

Laborers [redacted]

Welders [redacted]

Figure 3-15: Pu-239 Biosamples by Claimant Job Type 

(Number of Samples Shown in Parentheses)

Draft – Review of NIOSH Position Paper 30 SC&A – January 12, 2010 

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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
1E-13

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

0% 20% 40% 60% 80% 100%

Percentile

Pu-239 in Urine (

μCi/cc)

RadSafe

Security

Miners

Laborers

Welders

Figure 3-16: Percentile Plot of Pu-239 Biosamples by Claimant Job Type 

1E-13

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

-3 -2 -1 0 1 2 3

Normal Score

Pu-239 in Urine (

μCi/cc)

RadSafe

Security

Miners

Laborers

Welders

Figure 3-17: Normal Score Plot of Pu-239 Biosamples by Claimant Job Type 

Draft – Review of NIOSH Position Paper 31 SC&A – January 12, 2010 

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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
1E-09

1E-08

1E-07

1E-06

1E-05

1E-04

1E-03

1E-02

-4 -3 -2 -1 0 1 2 3 4

Normal Score

Gross Gamma in Urine (

μCi/cc)

RadSafe

Security

Miners

Laborers

Welders

Figure 3-18: Normal Score Plot of Gross Gamma Biosamples by Claimant Job Type 

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

-4 -3 -2 -1 0 1 2 3 4

Normal Score

Gross Beta in Urine (

μCi/cc)

RadSafe

Security

Miners

Laborers

Welders

Figure 3-19: Normal Score Plot of Gross Beta Biosamples by Claimant Job Type 

Draft – Review of NIOSH Position Paper 32 SC&A – January 12, 2010 

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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
1E-10

1E-08

1E-06

1E-04

1E-02

1E+00

-4 -3 -2 -1 0 1 2 3 4

Normal Score

Tritium in Urine (

μCi/cc)

RadSafe

Security

Miners

Laborers

Welders

Figure 3-20: Normal Score Plot of Tritium Biosamples by Claimant Job Type 

1E-13

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

0% 20% 40% 60% 80% 100%

Percentile

Pu-239 in Urine (

μCi/cc)

1960s

1970s

1980s

1990s

Figure 3-21: Percentile Plot of Pu-239 Biosamples for RadSafe Claimants by Decade 

Draft – Review of NIOSH Position Paper 33 SC&A – January 12, 2010 

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However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 
1E-13

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

-3 -2 -1 0 1 2 3

Normal Score

Pu-239 in Urine (

μCi/cc)

1960s

1970s

1980s

1990s

Figure 3-22: Normal Score Plot of Pu-239 Biosamples for RadSafe Claimants by Decade 

1E-13

1E-12

1E-11

1E-10

1E-09

0% 20% 40% 60% 80% 100%

Percentile

Pu-239 in Urine (

μCi/cc)

1980s

1990s

Figure 3-23: Percentile Plot of Pu-239 Biosamples for Security Claimants by Decade 

Draft – Review of NIOSH Position Paper 34 SC&A – January 12, 2010 

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1E-13

1E-12

1E-11

1E-10

1E-09

-3 -2 -1 0 1 2 3

Normal Score

Pu-239 in Urine (

μCi/cc)

1980s

1990s

Figure 3-24: Normal Score Plot of Pu-239 Biosamples for Security Claimants by Decade 

3.6 OTHER RADIONUCLIDES 

The four kinds of bioassay data analyzed for adequacy of quantity of data and for certain aspects 

of quality in SC&A 2008 and SC&A 2009 were plutonium, tritium, gamma, and beta. 

(Comments regarding the interpretation of gamma and beta monitoring are provided below.) But 

there were other radionuclides present at NTS for which there are scant or no internal dosimetry 

data. 

NIOSH 2009 also provides some examples of other radionuclides of concern at NTS during the 

SEC period, including “americium, uranium, thorium, radium, iodine, and other fission 

products” (p. 4). The electronic database indicates that data for these radionuclides are very 

sparse to non-existent for all categories of workers during the SEC period. For instance, SC&A 

found 173 uranium entries during the SEC period in the uranium spreadsheet on the O-Drive, 

with 21 of them being labeled as whole-body scans with no associated data.7

 There are even 

fewer entries in the americium spreadsheet (116 entries, of which 20 are “whole-body” entries 

 

Draft – Review of NIOSH Position Paper 35 SC&A – January 12, 2010 

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7

 The fact that there are no whole-body counting data in the electronic database may not mean that there are 

none in the raw DOE records. It appears that the whole-body counting data were not transcribed into the electronic 

database. NIOSH 2009 states that there are “300 bioassay records for uranium up to the year 1992” (p. 3). SC&A 

has not attempted to track down the source of the difference, since both figures would appear to be insufficient, 

especially in light of the fact that Area 3 and Area 5 waste site workers also had potential for exposure to uranium. 

A list of radionuclides to which NTS workers had exposure potential, by period and Area, can be found in ORAUT 

2008a, Table 2-2, pp. 30–32. 
Draft – Review of NIOSH Position Paper 36 SC&A – January 12, 2010 

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with no associated data. The smallest number of entries is in the strontium-90 spreadsheet; 

30 urine samples, with two blank entries and no whole-body count entries. 

SC&A did not locate any data for radioiodines or thorium isotopes in the electronic database, 

though iodine was occasionally noted in the ‘Comment 2’ column of the gamma database. As 

noted below, SC&A did locate a very small number of data points for I-131, I-133, and I-135 in 

its earlier analysis of NTS data. We have not located other fission product-specific monitoring 

data in the electronic database spreadsheets on the O-Drive. 

In its 2008 revision of the NTS Site Profile, NIOSH provided a list of radionuclides to which 

NTS workers had exposure potential by period and area and, in some cases, types of operations 

in particular periods (ORAUT 2008a, Table 2-2, pp. 30–32). The table also lists whether the 

potential was for internal exposure, external exposure, or both. For instance, drill-back 

operations and mine-back operations during the underground testing period created exposure 

potential for I-131, I-133, and I-135, among a host of others. Waste site Areas 3 and 5 had 

exposure potential to a variety of radionuclides, including uranium and thorium isotopes. 

In summary, data for most of the radionuclides during the SEC period, other than the four 

categories described above in Sections 3.1 through 3.4, appear to be scant, if they exist at all. 

3.7 QUALITY OF DATA 

We reviewed the electronic database for any new quality issues that might be indicated, in 

addition to the ones discussed in Attachment B of SC&A 2008. Some observations are set forth 

below: 

• Many data points are accompanied by large error estimates ranging to more than 500%. 

• The plutonium data indicate codes for the Pu-239 isotope (codes 6 or 11, ORAUT 2008b, 

Table A-1, p. 68), and the “Comment 1” column affirms that the analyte is Pu-239. 

However, a large number of the “Comment 2” entries are “Pu-238,” while others are 

“Pu-239.” We could not identify a reason for the difference. We have assumed these 

samples to be Pu-239 based on the analysis code. 

• Another new issue is that SC&A could not identify the significance of the notation 

“Hddr_error” in the comment column of the electronic database where the radionuclide is 

normally listed. SC&A raised this issue at the Work Group meeting on December 15, 

2009. However, NIOSH also could not identify its meaning. We have ignored it in this 

analysis. 

It is also clear that the electronic database is incomplete. SC&A pulled out all the claimants in 

the prior datasets analyzed—100 from the group in the NIOSH Evaluation Report (Table 7-1, 

NIOSH 2007) and 120 from the group that SC&A analyzed in addition (SC&A 2008, SC&A 

2009). Overlap between these two datasets was eliminated. 
Draft – Review of NIOSH Position Paper 37 SC&A – January 12, 2010 

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Since each of the spreadsheets in the electronic database only contain those workers who had at 

least one internal monitoring data point for that type of monitoring, we chose all those workers 

from the prior datasets who had any internal monitoring data for that type of analysis to check 

whether their names and/or SSNs were in the electronic database. A complete or near complete 

match of the lists of workers would indicate that the electronic database was likely to include 

almost all workers with some internal dosimetry data. However, as the table below shows, many 

of the workers in the prior SC&A analysis are not in the electronic database: 

Table 3-5: Monitored Claimants Analyzed in SC&A 2008 Found in the 

Electronic Database 

 

Number of Claimants from NIOSH 

100 + SC&A 120 Monitored 

Number (Percentage) Also 

Identified in Electronic Database 

Tritium 87 80 (91.95%) 

Pu 52 44 (84.62%) 

GFP Beta 72 48 (66.67%) 

Gamma 115 89 (77.39%) 

 

For example, during our previous data compilation, we identified 87 claimants from the SC&A 

120 and NIOSH 100 (no overlapping) who had records for tritium monitoring. Of these, 80 (or 

91.95%) also appeared in the spreadsheet for tritium in the electronic database during the SEC 

period. This means that about 8% of the 87 claimants we studied who had tritium monitoring in 

their hardcopy records are not in the electronic database. Other categories have a lower ratio of 

matches. Fully one-third of the 72 workers studied by SC&A in prior reports with GFP/beta 

monitoring data are not in the electronic database. This demonstrates that the electronic database 

does not include a significant number of workers who were monitored. There is no information 

on the basis of the choice for those who were not included in the available documentation 

provided by NIOSH. SC&A has not attempted to make a detailed analysis of this issue, since 

our conclusion that further analysis of more data is highly likely to show the same patterns and 

problems in the data. However, a comment and an example are provided in Section 4. 
Draft – Review of NIOSH Position Paper 38 SC&A – January 12, 2010 

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4.0 COMPARISON WITH PRIOR SC&A RESULTS 

4.1 DATA ADEQUACY – QUANTITY 

The electronic database has about 122,187 bioassay data entries during the SEC period proposed 

by NIOSH, that is, from January 1, 1963 to December 31, 1992. Of these, 121,404 are in the 

SEC period requested in the petition, which ends on September 30, 1992. Almost all of these 

entries fall into the same four categories of data that SC&A had evaluated in its prior reports on 

internal monitoring (SC&A 2008, SC&A 2009); plutonium, gamma, beta (or gross fission 

products), and tritium. As described above, SC&A analyzed the electronic data by job type by 

matching SSNs with NOCTS. The same six job types were selected, in order to make possible a 

comparison of the contents of the electronic database with the earlier data compiled from raw 

DOE records provided to NIOSH. 

The analysis in Sections 3.1 through 3.4 for these four categories of bioassay shows that these 

data closely follow the pattern found in SC&A 2008 and SC&A 2009. For example: 

• RadSafe workers had monitoring data for all periods examined (1963–1967, 1968–1970, 

1971–1980, and 1981–September 30, 1992), though there are fewer data per year in the 

1960s than in the later periods. 

• Security workers had the next largest amount of monitoring data, but it was almost all in 

the 1981–1992 period. 

• The other four job categories had little to no plutonium monitoring data in most of the 

periods. 

• Miners had tritium monitoring data in all periods. The data indicate that miners had the 

greatest exposure potential to tritium compared to the other job types analyzed, including 

the RadSafe category. 

In comparing frequency of monitoring, it must be borne in mind that only workers with some 

monitoring data are found in the electronic database. In contrast, SC&A selected 20 workers at 

random from among claimants. Like the majority of NTS workers, many of them in the laborer, 

welder, and wireman categories, had no bioassay monitoring data. With that caveat in mind, 

SC&A finds that the frequency of monitoring for the six job types and four monitoring types 

analyzed is generally comparable between the electronic database and the earlier SC&A analysis. 

For instance, in the SC&A set of 120, only RadSafe workers averaged more than one plutonium 

sample per worker, except in the first period (1963–1967). Security guards had the vast majority 

of samples in the 1981–1992 period, when they had more than one sample per worker, and few 

to none in the other periods. All four other categories had either zero plutonium bioassay 

samples or much less than one sample per worker in each of the four periods. A similar pattern 

is observed in the electronic database. 

One new feature does emerge from the electronic database due to the much larger amount of data 

in it. An examination of the cumulative distribution functions shown in Section 3 for tritium, 

gamma, and beta bioassay shows that RadSafe worker bioassay readings were generally less than 
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at least one other group of workers. In the case of gamma bioassay data, which are much more 

plentiful than plutonium data, the RadSafe group of workers had lower bioassay readings than 

that of all claimants in the electronic database, and also of welders, wiremen, and miners. 

Plutonium data are far too sparse for a reliable comparison across job types. However, even in 

this case, the few data points prior to 1980s that are available for laborers indicate the potential 

that this group may have had higher exposures than the RadSafe group. 

In these comparisons of cumulative distribution functions shown in Section 3, some limitations 

of the cumulative distribution functions should be kept in mind: 

• The bioassay results generally indicate higher exposures in the 1960s and possibly the 

1970s than in the 1980s and early 1990s. However, a definitive interpretation of relative 

exposures is not possible, since the context of the bioassay (routine monitoring versus 

incident-driven monitoring) is not known. Comparing a higher result derived from an 

incident with one that was a routine sample could be misleading. 

• The cumulative distribution functions of bioassay readings in Sections 3.1 through 3.4 are 

constructed without regard to the periods in which the samples were taken. Comparisons 

of relative exposures are complicated by this fact, and by the tendency of higher bioassay 

results in the early part of the period studied here. In principle, one could construct 

cumulative distribution functions by period. But in the case of NTS bioassay data, there 

are simply not enough data points for most periods and worker types to construct 

meaningful data comparisons that would yield definitive results. 

But even with these caveats in mind, it is clear that a conclusion that the RadSafe group had the 

highest exposure potential is not supported by the data. One cannot even make a less rigorous 

assertion that the RadSafe group was among those with the highest exposure potential. Indeed, 

the cumulative distribution functions, as well as the detailed individual data points, indicate that 

there may not have been a single group that was most exposed to the variety of radionuclides 

present at the NTS. Different groups of workers may have had higher exposures to different 

radionuclides in different periods. The exception may be miners, who may have been the most 

exposed to tritium, assuming that samples were mainly taken on a routine basis, as is indicated 

by the analysis in Section 3.5. Again, a definitive conclusion would require more information 

about whether the samples were routine or incident driven. 

SC&A’s overall conclusions of this comparative analysis regarding data adequacy are as follows: 

(1) All three data sets are similar: All three datasets examined in detail by SC&A—the 

NIOSH group of 100 in Table 7-1 of the Evaluation Report (NIOSH 2007), the 120 

claimants in six job categories analyzed in SC&A 2008, and the more than 170 claimants 

present in the electronic database in the six job categories already studied—exhibit the 

same general characteristics. The sample size is very large, and this conclusion is robust. 

Further study of the data is unwarranted, since it is highly likely to lead to the same 

general results. 
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(2) The RadSafe worker group was the only one with a significant quantity of internal 

monitoring data throughout the SEC period. The available data point to a definitive 

conclusion that, among the groups with exposure potential analyzed here, only the 

RadSafe group had significant monitoring data in all periods for plutonium, gamma, beta, 

and tritium (except possibly 1963–1967 for plutonium). But data for several other 

radionuclides are either not available or very scant, even for the RadSafe group. 

(3) There is no suitable reference group with a demonstrated high relative exposure 

potential to construct a coworker model. Bioassay monitoring data of the RadSafe 

group, which is the only group with data in all periods for plutonium, gamma, beta, and 

tritium, cannot be used to reliably construct a coworker model that could yield bounding 

doses for unmonitored NTS workers. In other words, they cannot be used to reconstruct 

internal dose with sufficient accuracy, as required by 42 CFR 83. There are two reasons 

for this. First, the data for other groups of workers with exposure potential are too scant 

for most groups of workers and most periods to enable a reliable comparison to be made 

of exposure potential of various groups with the RadSafe group. It is essential to have 

adequate data in the various periods, since exposure potential varied by period.8 Second, 

the data in the electronic database analyzed by job type in this report indicate that the 

RadSafe group of workers may not have been among those with the highest exposure 

potential. Indeed, the data indicate that other groups had higher exposure potential, at 

least some of the time. The data also indicate that there may have been no single group 

of workers that had high exposure potential to the various radionuclides at NTS. 

Exposure potential appears to have been a function of job type, period, radionuclide (or 

radionuclide group), and possibly, on a finer grid, individual tests or test series. (This last 

variable has not been examined by SC&A, since data are already too scant in most 

categories on a much coarser grid.) Finally, there is no other group of workers with an 

adequate quantity of data to construct a coworker model that would meet the criterion of 

estimating internal dose with sufficient accuracy. 

The above conclusions point to the central overall conclusion that NTS internal dosimetry data 

are inadequate in quantity to support the construction of a coworker model that would allow 

estimation of internal dose for unmonitored workers with sufficient accuracy for the SEC period. 

4.2 QUALITY OF DATA 

It is very difficult to evaluate which results can be considered positive valid bioassay results, in 

relation to the capacity of measurement in each time period. The citations below are only 

examples; they are not a summary of all findings from a complete analysis for all years in the 

electronic database. SC&A did not consider this necessary, since the electronic database 

presents similar issues to those of interpretation and quality as those described in SC&A 2008, 

Attachment B. 

8

 The choice of starting and ending dates for the various periods is a matter of judgment based on the 

number of tests, venting incidents, and frequency of monitoring. This is discussed in SC&A 2008, p. 6. 
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• Uncertainty regarding the minimum detectable amount (MDA) of plutonium: The 

Pu MDA from the Occupational Internal Dosimetry TBD (ORAUT 2008b) from 1961 to 

1976 was 0.005 dpm/sample (2.25 E-6 μCi/sample), while activities in the electronic 

database are given in μCi/cc. Since the sample size is not always available, converting a 

dpm/sample value to μCi/cc is associated with some uncertainty. 

• Positive results below MDA: The MDA for Pu-239 for 1977–1987 is listed as 

5E-11μCi/mL. In 1969, for example, there are 343 results, 281 of them listed as LT 

(below detection). From the 61 reported positive results, 23 are below the MDA for 

1977–1987. It is unclear how such positive results below the MDA are to be interpreted. 

• Anomalies in reported errors: The reported errors on those 23 results are very high 

(range of 80% to 98.8%). From the 39 results above 5E-11 μCi/mL, 11 had reported 

errors on the range 80% to 98.8%, and 15 had reported errors above 70%. In 1971, all 

reported errors are listed as zeros. In 1972, there were 171 results and only 3 reported 

errors listed as different from zero. Fifty-two results are below the MDA for 1977–1987. 

There are similar issues in plutonium results in 1980. 

• No reported gamma bioassay MDA before 1977: For gamma emitters, the MDA is not 

defined in the Occupational Internal Dosimetry TBD for the years before 1977 (ORAUT 

2008b). 

• Potentially inconsistent gamma MDAs up to 1977: In 1965 the samples that showed a 

reported result had concentrations mostly in the range 2–3 E-6 MI/cc. In 1966, the 

number of samples increased to about 3,000. There were 3 samples with results of the 

order of E-9, one of the order of E-8, 2 of the order of E-7 and about 2,500 in the range of 

1–5 E-6 MI/cc. Should 1.0 E-6 be considered an MDA for the period? In 1970, there are 

a significant number of positive results on the order E-8 MI/cc. Did the MDA change? 

The validity of the gamma results is questionable because of the uncertainties on the 

MDA values. 

Furthermore, as discussed above, the electronic database is incomplete; it may omit some of the 

most intensively monitored workers. For instance, one of the workers most intensively 

monitored for plutonium in 1965 with 13 bioassay samples is not in the electronic database. 

In its November paper, NIOSH raised a further issue regarding the quality of data as it pertains to 

the beta/GFP dataset: 

...[T]he bioassay data available to assess fission product exposures are more 

generally listed as gross beta analyses. Given that fission products were the most 

likely source of potential exposure and the makeup of the fission products source 

term was project and time-dependent, this brings into question the ability to 

reconstruct a representative distribution of NTS fission product exposures during 

this time period. [NIOSH 2009, p. 3]

The same problem would apply to gamma bioassay data. The paucity of urine data for specific 

fission products is problematic (of course it would be best to have radionuclide-specific data), 
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but this problem could be largely overcome with regard to bounding doses if there were timely 

measurements of mixed fission products. For example, the dose reconstructor could assign all 

activity labeled as “mixed fission products” or “gross fission products” to the fission product 

(among those likely to present) that would yield the highest dose to the organ of interest. 

Furthermore, given the variety of activities and exposure scenarios at NTS, it is important to 

know the context of the monitoring in relation to the nuclear tests, rocket tests, or other work, 

such as waste handling and disposal. This kind of data is also generally unavailable. Indeed, as 

noted above, some of the monitoring appears to have been incident-driven, while some of it was 

not. Sorting out the data would be very complex, if it is possible at all. 

Since this issue is of some importance in the specific circumstances of NTS and the NIOSH 

recommendation, SC&A examined it in more detail using examples of venting releases. 

4.3 POTENTIAL EXPOSURES TO ABOVE-GROUND RELEASES OF FISSION 

AND ACTIVATION PRODUCTS 

Hundreds of underground tests conducted at the NTS resulted in varying degrees of aboveground contamination with fission and activation products. Some of the releases included large 

quantities of short-lived radionuclides representing potentially high radiation doses from intakes 

during the early hours or days after individual tests, and smaller quantities of radionuclides with 

intermediate or long half-lives representing intake hazards for weeks, months, or years after the 

tests. Releases of activity resulted from containment failure or post-test operations, such as 

drillback activities, purging of gases, or sampling of underground activity. These above-ground 

releases may have been the greatest source of doses to NTS workers as a whole during the period 

1963–1992, but there is a paucity of bioassay data with which to reconstruct doses from intakes 

of the released fission and activation products. 

Releases from underground tests typically included noble gases, particularly Xe-133, Xe-133m, 

Xe-135, Kr-87, and Kr-88, as well as other “volatile” fission products, such as isotopes of iodine 

and ruthenium (DOE 1996). For example, the primary radionuclides identified in releases from 

the tunnel test Door Mist (August 31, 1967) included Ru-103, Ru-106, I-131, I-133, I-135, and 

Xe-135 (DOE 1996). Releases occurred as expected at the tunnel portal and during drillback, 

but there was also unexpected seepage through cables to a cable-splice building. Total releases 

exceeded 106

 Ci. 

A number of underground tests resulted in substantial releases of a variety of fission or activation 

products other than the noble gases, iodines, and rutheniums. For example, identified 

radionuclides in releases from the shaft test TEE (May 7, 1965) included Na-24, Sr-91, Sb-122, 

Sb-124, Te-132, Cs-138, Ba-139, and Ba-140, in addition to I-131, I-132, I-133, I-135, and 

isotopes of Kr and Xe. Rapid releases occurred from a line-of-site pipe at surface ground zero. 

Releases lasting over 4 days occurred from the surface ground zero area (DOE 1996). 

A few surface or near-surface “cratering” tests spread large quantities of many different 

radionuclides over a wide area. Following the Plowshare cratering event Palanquin (April 14, 

1965), the measured concentration of gross beta activity in air at an offsite location was 
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87,000 pCi/m3. Reported concentrations of I-131, I-133, and I-135 in air at an offsite location 

following the test were 12,000 pCi/m3

, 65,000 pCi/m3, and 160,000 pCi/m3, respectively (DOE 

1996). 

Chertok and Lake (1971a and 1971b) studied internal deposition of radionuclides in pigs 

exposed to radioactive fallout from the Plowshare cratering event Schooner (December 8, 1968). 

The pigs were kept in cages in the expected path of the plume, so that they would inhale debris 

and eat food contaminated by the fallout. Radionuclides found in tissues of pigs exposed for 

3 days included W-188/Re-188, Te-132, Au-196, I-131, Ru-103, and As-74. The same 

investigators studied the bioavailability of radionuclides produced by the Plowshare cratering 

events Cabriolet (January 26, 1968) and Buggy (March 12, 1968) by measuring activity in 

excreta of dogs or pigs administered fallout debris in a single oral dose (Chertok and Lake 1970 

and 1971c). The radionuclides detected in excreta included W-187, Au-198, Te-132, I-131, 

Ru-103, Ce-141, Mo-99, Sb-122, and Ba-140/La-140. Radionuclides found to be absorbed into 

blood to a significant extent from the Cabriolet or Buggy fallout were I-131, W-187, Te-132, 

Mo-99, Ru-103, and Sb-122. 

Some unexpected releases of radionuclides, or unexpectedly large quantities of released activity, 

created the potential for dosimetrically significant intake of short-lived radionuclides that are 

usually ignored in dose reconstructions for internally deposited fission products. For example, 

the shaft test Parrot (December 16, 1964) included an initially rapid burst, followed by a 

continuous long-term leakage at a slower rate, with total releases exceeding 2 × 105

 Ci (DOE 

1996). Uncontrolled releases resulted from a crack in a pipe below the surface. The released 

activity was approximately 45% Cs-138 (T1/2 = 32.2 min), 45% Kr-85m (4.5 h), and 10% I-135 

(6.6 hr), along with traces of other iodines. Cesium-138 is a fission product, and is also 

produced by decay of the fission product Xe-138 (T1/2 = 14.2 min). Due to the high mobility of 

Xe-138, its progeny Cs-138 may be found in significant quantities at relatively far distances from 

a nuclear event. 

Table 4-1 lists a number of fission or activation products of potential dosimetric importance that 

were released in large quantities from one or more shaft, tunnel, or cratering tests from late 1963 

(start of the Limited Test Ban Treaty) through 1992 (DOE 1996). These radionuclides, which 

are all beta/gamma emitters, are listed in order of increasing radiological half-life. Only a few of 

these radionuclides were addressed in the NTS bioassay program (e.g., selected radioiodines and 

Sr-90), and reported measurements of those radionuclides are sparse. Some urinary excretion 

data are reported as gross beta or gross fission products, but these measurements were not 

sufficiently frequent or timely to allow estimation of bounding doses for the range of fission 

products to which workers may have been exposed. 

A long delay between collection and analysis of urine samples for gross fission products in some 

cases suggests that monitoring was focused on relatively long-lived fission products, with the 

main exception that short-lived radioiodines, such as I-133 (20.8 hr) and I-135 (6.6 hr), were 

occasionally measured in urine. For example, a urine sample collected from an NTS worker 

(“Worker A”) on January 15, 1965, was analyzed for “gross beta” about 2.5 months after the 

collection date (data from NIOSH’s Excel file for 100 workers). A urine sample collected from 
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another worker (“Worker B”) on February 19, 1965, was analyzed for gross beta about 

1.5 months after the collection date. In both cases, the gross beta measurements would not have 

reflected intakes of radionuclides with half-lives up to several days. 

Table 4-1: Some Radionuclides Other Than Noble Gases Identified in Releases from 

Shaft, Tunnel, or Crater Tests at NTS after August 5, 1963a

Radionuclide Half-life Radionuclide Half-life 

Cs-139 9.27 min Sb-122 2.70 d 

Rb-89 15.2 min Mo-99 2.75 d 

Rb-88 17.8 min Au-198 2.77 d 

Cs-138 32.2 min Te-132 3.25 d 

I-134 52.6 min I-131 8.04 d 

Nb-97 1.20 hr Nd-147 11.0 d 

Ba-139 1.38 hr Ba-140 12.7 d 

As-78 1.51 hr As-74 17.8 d 

La-142 1.54 hr Ce-141 32.5 d 

I-132 2.30 hr Nb-95 35.2 d 

Mn-56 2.58 hr Ru-103 39.3 d 

Sr-92 2.71 hr Sr-89 50.5 d 

Ru-105 4.44 hr Y-91 58.5 d 

I-135 6.61 hr Sb-124 60.2 d 

Sr-91 9.50 hr Zr-95 64.0 d 

Na-24 15.0 hr W-188 69.4 d 

Zr-97 16.9 hr Mn-54 313 d 

I-133 20.8 hr Ru-106 368 d 

W-187 23.9 hr Sr-90 29.1 yr 

Ce-143 1.38 d Cs-137 30.0 yr 

La-140 1.68 d a

Data collected from summaries of individual tests at the NTS (DOE 1996)

Urinary radioiodine data for “Worker B” can be used to illustrate that short-lived fission products 

(say, half-lives less than 1 day) may be important and sometimes the dominant internal emitters 

in persons exposed to fresh fission products. Bioassay data for Worker B (addressed above) 

during the period 1963–1965 are reported only for three brief intervals: June 12–13, 1963; 

October 17–23, 1963; and February 19–20, 1965. Comparison of these dates with dates of 

nuclear tests at the NTS suggests that the purpose of the bioassay measurements during these 

three periods was to assess intake of activity released after underground tests. Measurements of 

I-131 (T1/2 = 8.04 d), I-133 (20.8 hr), and I-135 (6.6 hr) in urine samples collected from 

Worker B on February 19–20 reveal sizable intake of all three radionuclides. The time of 

exposure is not indicated, but there were known releases of radioiodine from shaft tests 

conducted on February 18 and 19, 1965, and releases of unspecified radionuclides from a shaft 

test conducted on February 16, 1965 (DOE 1996). Concentrations of I-133 and I-135 in urine 

were far greater than the concentration of I-131, indicating much higher intakes of the shorterlived isotopes. The estimated intakes of I-133 and I-135 and the resulting thyroid doses depend 

strongly on the time of collection of the urine sample after intake, due to their short half-lives 

and the rapid decline in urinary iodine following intake. Regardless of the time between intake 
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and sample collection, however, the data for Worker B indicate that the dose to the thyroid from 

I-133 was at least an order of magnitude greater than the dose from I-131, which is generally 

assumed to be the most important iodine isotope in the early period following a nuclear event. 

This example shows that it is important to assess the doses to workers from intake of short-lived, 

as well as longer-lived, beta-gamma emitters released by the tests. 

Worker B addressed above is one of the more extensively monitored workers addressed in the 

NIOSH Excel file for 100 workers. Nearly 300 bioassay measurements for this worker were 

made during the period 1963–1990. In addition to limitations in these measurements indicated 

above, the problem arises that there were often long periods (many months) between 

measurements and no apparent systematic monitoring scheme for detecting chronic intake of 

radionuclides or unexpected elevated intakes between nuclear tests. The same problem exists for 

most other workers addressed in the file. This is an important issue for the dose reconstructions 

because of the widespread releases of radionuclides with intermediate or long half-lives over the 

site. Due to such limitations in the database, it is questionable whether reasonable bounding 

doses can be derived, even for many of the most extensively monitored NTS workers. On 

the other hand, the database would allow the derivation of partial, lower-bound doses for 

many workers. 

Of course, even if interpretation of gamma and beta data to reconstruct bounding doses for 

fission products were possible, this would still not solve the problem of insufficiency of data for 

other radionuclides. Finally, as noted in Section 3, the most plentiful data are for a group, 

RadSafe, whose results do not indicate relatively high exposure potential for gamma and beta, 

compared to other groups. For gamma data, the cumulative distribution function for the RadSafe 

group indicates lower bioassay results than those for all workers for the most part (Section 3.2). 
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5.0 CONCLUSIONS REGARDING INTERNAL DOSE 

RECONSTRUCTION FEASIBILITY 

Based on the above analysis and that presented in prior SC&A reports on internal exposure 

monitoring (SC&A 2008, SC&A 2009), SC&A concurs with NIOSH’s overall conclusion that, 

“there is insufficient information to adequately support bounding internal dose (reconstructing 

internal dose with sufficient accuracy) for the portion of the SEC00084-NTS worker class who 

worked during the period of testing from 1963 through 1992” (NIOSH 2009, p. 4). 

SC&A also examined each of the four points that led NIOSH to conclude that dose 

reconstruction with sufficient accuracy was not feasible. They are discussed below. 

5.1 RATIONALE OF NTS BIOASSAY SAMPLING PROGRAM 

NIOSH statement: 

1. NIOSH has identified exposure scenarios involving varying job titles/duties and work 

activities, such as drill-backs, post-test work activities, and construction or other soil 

disturbing activities in areas that had been contaminated by previous tests. Prior to 

1993, no source documentation could be located to confirm the rationale behind why 

bioassay samples were collected. Because of this, NIOSH cannot conclusively 

determine that doses to all of these potentially exposed individuals were detected by 

the bioassay program. 

 A review of the available data indicates a large number of radiological technicians 

and security personnel were routinely sampled. Other job titles/duties are also 

represented but a substantial fraction of the ‘other’ group of bioassay samples 

appears to have been collected on a more event or incident-driven basis. Although 

NIOSH does have access to site procedures and directives, NIOSH has not located 

sufficient documented evidence, other than anecdotal, to describe a consistent 

rationale behind the collection of personnel bioassay sampling or to indicate that 

sampling occurred consistently in the situations where it was required. 

[NIOSH 2009, p. 3] 

SC&A’s analysis presented above shows conclusively that there were several job types with 

exposure potential; however, most groups examined had little or no data for most periods for 

plutonium and several other radionuclides. Much of the monitoring appears to have been 

incident-driven, as indicated by a lack of lognormal fit in several cases, described above in 

Section 3.5. Furthermore, the bioassay data for several groups of workers indicate that they may 

have had higher exposure potential than RadSafe workers, though given the lack of information 

about monitoring timing and context, it is not possible to definitively establish this. In this kind 

of situation, the fact that many or most RadSafe personnel were monitored does not provide an 

adequate basis for constructing a coworker model for other workers with exposure potential, 

even for those radionuclides for which there are monitoring data in all periods. This conclusion 

is rendered even more robust by the fact that the sparseness of the data makes a robust 

comparison between RadSafe and other groups of workers difficult or impossible in most cases, 

with some exceptions, such as plutonium monitoring comparisons between security and RadSafe 
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personnel in the 1980s, or tritium monitoring comparisons between RadSafe and miner job types. 

To the extent that a comparison is possible, the RadSafe group is not indicated as suitable for 

estimating internal doses with sufficient accuracy under 42 CFR 83. 

5.2 DATA GAPS 

NIOSH statement: 

2. NIOSH has identified data gaps that exist in the electronically available bioassay 

data for certain nuclides and time periods... that impact NIOSH’s ability to bound 

the internal dose. 

• Specific radionuclide analyses for fission products are not available to 

NIOSH. Rather, the bioassay data available to assess fission product 

exposures are more generally listed as gross beta analyses. Given that 

fission products were the most likely source of potential exposure and the 

makeup of the fission products source term was project and timedependent, this brings into question the ability to reconstruct a 

representative distribution of NTS fission product exposures during this 

time period. 

• NIOSH identified only 300 bioassay records for uranium up to the year 

1992. While it may be that there was a limited potential for exposure to 

uranium, and 300 bioassay results could be an appropriate number, 

NIOSH has not located sufficient documentation to support or refute that 

possibility. As is the case with uranium, NIOSH has indentified that the 

number of workers monitored for plutonium appears to be small (e.g., 

fewer than 200 from many years), considering the size of the NTS 

workforce. While it can be argued that few people were monitored 

because of the low potential for exposure, the evidence in the database 

(i.e., a large number of positive Pu results) confirms that there was clearly 

a source-term for plutonium that was capable of producing measurable 

intakes. [NIOSH 2009, pp. 2–3]

The extensive analysis done by SC&A in two prior reports (SC&A 2008, SC&A 2009), as well 

as the present report, confirms NIOSH’s analysis regarding the scant data for radionuclides like 

plutonium with exposure potential. The large fraction of positive bioassay results in all four 

bioassay monitoring categories that were examined indicate significant internal exposure 

potential, contrary to the prior belief that such exposure potential was not significant for most 

groups of workers, or at least that the monitored workers were among those with the highest 

exposure potential. While such a belief may have been the reason for a lack of internal exposure 

monitoring in most periods, it is not sustained by the available data. SC&A also found that the 

notion that external dose would be an indicator of internal exposure potential was not borne out 

by the data for the 100 workers selected for NIOSH’s coworker model in its Evaluation Report 

(NIOSH 2007). 
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In regards to estimating dose from fission products, we have already noted above in Section 4.3, 

that interpretation of beta and gamma bioassay data is problematic and complex, due to the lack 

of data regarding the time and context of the these measurements. 

5.3 CHRONIC AND EPISODIC EXPOSURE 

NIOSH statement: 

3. The nature of work at the NTS site and the large geographic area over which 

this work was conducted presents a unique challenge for bounding the 

internal doses at NTS. Unlike many production sites (i.e., SRS, Rocky Flats, 

Fernald, etc.), the NTS was primarily engaged in shorter-term campaign 

driven activities that were separated by large distances, and there appears to 

be a direct relationship between campaigns and bioassay sampling. The 

concept of a campaign driven bioassay sampling program is further supported 

by the fact that many of the periodic bioassay samples appear to have been 

collected on the same day. Because of the episodic nature of the exposures at 

NTS, a coworker model that is useful in reconstructing chronic intake 

scenarios would not necessarily be representative of the exposure patterns for 

the NTS workforce. [NIOSH 2009, p. 4] 

SC&A’s statistical analysis indicates that much of the sampling at NTS was campaign-driven or 

incident-driven. However, in some cases, it seems to be a mixture of incident-driven and routine 

monitoring, while in a couple of cases, it seems to be mainly routine monitoring. To the extent 

that the limited quantity of data enable an analysis, the data in most cases do not fit the usual 

lognormal distribution that characterizes a routine sampling protocol. SC&A also notes that 

besides samples on the same day, the same workers sometimes had many or most samples in a 

year taken in a short period. For instance, one worker had [redacted] plutonium samples in 

1964, and [redacted] of them were in a 16-day period in [redacted]. To complicate 

interpretation, this worker also had [redacted] samples taken on exactly the same dates in the 

next year. In neither case do the sample collection dates correspond to test dates or the day 

immediately after a test.9

Furthermore, NTS personnel also had potential for routine exposure. Examples include activities 

in contaminated areas of the test site outside of the context of the aftermath of a specific test, 

waste site workers, and laboratory workers. The inability to sort out monitoring done for routine 

exposures from that done for episodic exposures makes data interpretation very complex. 

 9

 The data referred to for this claimant, a [redacted] group worker, can be found on the [redacted] 

worksheet of the plutonium data spreadsheet on the O-Drive. The list of nuclear tests and their dates can be found in 

DOE 2000. 
Draft – Review of NIOSH Position Paper 49 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

5.4 RADIONUCLIDE COVERAGE 

NIOSH statement: 

4. The reconstruction of internal doses at NTS is also complicated by the variety 

of the radionuclides to which workers may have been exposed. As indicated 

in the NTS site profile, the potential nuclide source-term included, but is not 

limited to, plutonium, americium, uranium, thorium, radium, iodine, and other 

fission products. For workers with no bioassay records, and who had the 

potential for exposure, NIOSH would have to definitively establish the relative 

mixture of the exposure source-term. [NIOSH 2009, p. 4] 

All three datasets analyzed by SC&A (the NIOSH group of 100 in Table 7-1 of NIOSH 2007, the 

120 workers in 6 job types in SC&A 2008 and SC&A 2009, and the electronic database) indicate 

that monitoring for plutonium for most job types and most periods was sparse. There was even 

less monitoring of americium and uranium. SC&A has found no bioassay data for thorium. 

Data for specific fission products are very sparse and appear to be limited to a small number of 

samples for Sr-90, I-131, I-132, I-133, and I-135. A compilation of I-131, I-133, and I-135 data 

for workers in the SC&A 120 set can be found in SC&A 2008, Attachment A, starting on 

page 46). For instance, among 120 workers over a period of about 30 years, there were only 30 

I-131 samples in all, of which 12 were for the RadSafe Group and 15 were for the Miners group, 

leaving the other 4 groups essentially unmonitored throughout the SEC period, including during 

the several serious ventings of tests that occurred between 1963 and the end of 1970. Moreover, 

all but one of the miner samples were in the 1980s, while all but two of the RadSafe samples 

were between 1963 and 1970 (SC&A 2008, Table 16, p. 47). 

5.5 PERIOD OF THIS ANALYSIS AND PERIOD OF THE RECOMMENDED SEC 

In the above analysis, SC&A has examined data from January 1, 1963, to September 30, 1992, 

which is the period in SEC Petition SEC-00084 (see NIOSH 2007 and NTS SEC Petition 2007). 

This corresponds to the same period for which an addition to the SEC class is requested in the 

petition (SEC-00084). The period for the above analysis was chosen to maintain comparability 

with the earlier analysis. 

NIOSH has recommended an addition of NTS workers to the SEC class that is slightly broader 

than the SEC period in the petition—from January 1, 1963, to December 31, 1993. The last 

nuclear test at NTS was on September 23, 1992 (DOE 2000, pp. 88–89). Since post-test 

activities would extend for some time after the test, this appears to be a reasonable short 

extension of the SEC period. SC&A did a brief check of the data from October 1, 1992, to 

December 31, 1992, and found it to be consistent with that from the earlier testing period in 

1992. For instance, the frequency of plutonium monitoring between the last 3 months of 1992 

(12 per month in all) was slightly lower than during January 1, 1992, and September 30, 1992 

(nearly 15 per month), when testing was taking place. The gamma bioassay frequency also 

dropped somewhat in the immediate post-test period (86 per month from October to December 

1992, inclusive, compared to 127 per month for the January–September 1992 period). For 
Draft – Review of NIOSH Position Paper 50 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

americium, there were no data at all after August 1983, even though the NTS site profile lists 

exposure potential for this radionuclide as extending to the time of writing (2008) (see Table 2-2 

in ORAUT 2008a, p. 30). 

SC&A has not investigated the period from January 1, 1993 onward, since that is well outside 

the SEC period and outside of the work authorized so far by the Work Group. It should be noted 

here that during the course of the review of the Site Profile and SEC Evaluation Report, NIOSH 

revised its site profile. Most relevant to the present discussion is the fact that NIOSH revised its 

site description (where the radionuclide list and exposure potential in various periods are noted), 

its environmental dose section (relevant for internal dose) and its occupational internal dose 

section in 2008. 

5.6 PARTIAL INTERNAL DOSE ESTIMATION 

Should NTS workers in the underground testing period be added to the SEC class, the issue of 

partial dose reconstructions for cancers not included in the SEC compensation list would remain. 

Much of the NTS bioassay data can be used for estimating partial internal doses for those 

workers who were monitored. For instance, SC&A found no systemic quality issues associated 

with tritium data. There are quality issues associated with plutonium data for up to about 1987 

(SC&A 2008, Attachment B); however, these data could be used for partial dose reconstruction 

for the workers who provided the bioassay samples, provided appropriate caution is observed 

when interpreting results marked “less than” and their relation to the minimum detectable 

amounts specified in the NTS Site Profile. 

For workers who have gamma and mixed fission product monitoring data, a partial dose might 

be estimated on the basis of a likely mixture of the radionuclides present, provided there is a 

specific test or group of tests that is considered to be the likely source of the exposure and the 

urine samples were taken at known times after release of radionuclides to the environment. 

A dose to the thyroid may be estimated in cases where iodine isotopes were measured at known 

times after a test considered the likely source of the radioiodine. 
Draft – Review of NIOSH Position Paper 51 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

6.0 REFERENCES 

10 CFR 835. Department of Energy: Occupational Radiation Protection. On the web at 

http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&tpl=/ecfrbrowse/Title10/10cfr835_main_02.tpl. 

42 CFR 83. Procedures for Designating Classess of Employees as Members of the Special 

Exposure Cohort under the Energy Employees Occupational Illnesses Compensation Program 

Act of 2000, On the web at http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&tpl=/ecfrbrowse/Title42/42cfr83_main_02.tpl. 

Chertok, R. J. and Lake, S. 1970. “Availability in the dog of radionuclides in nuclear debris 

from the plowshare excavation Cabriolet,” Health Phys. 19, 405-409. 

Chertok, R. J. and Lake, S. 1971a. “Biological availability of radionuclides produced by the 

plowshare event Schooner - I. Body distribution in domestic pigs exposed in the field,” Health 

Phys. 20, 317-324. 

Chertok, R. J. and Lake, S. 1971b. “Biological availability of radionuclides produced by the 

plowshare event Schooner - II. Retention and excretion rates in peccaries after a single oral dose 

of debris,” Health Phys. 20, 325-330. 

Chertok, R. J. and Lake, S. 1971c. “Availability in the peccary pig of radionuclides in nuclear 

debris from the plowshare excavation Buggy,” Health Phys. 20, 313-316. 

DOE 1996. Radiological effluents released from U.S. continental tests 1961 through 1992.

DOE/NV-317 (Rev. 1) UC-702. 

DOE 2000. United States Nuclear Tests July 1945 through September 1992, DOE/NV-209-

REV 15, December 2000.

NIOSH 2007. SEC Petition Evaluation Report: Petition SEC-00084, September 25, 2007. 

NIOSH 2009. NIOSH Review of the SEC-00084 Nevada Test Site Evaluation Report: Internal 

Dosimetry Issues Analysis, November 25, 2009. 

NTS SEC Petition 2007. Nevada Test Site Special Exposure Cohort Petition, Petitioners: 

[redacted], Submitted February 5, 2007. 

ORAUT 2008a. Nevada Test Site – Site Description, ORAUT-TKBS-0008-2, Revision 01 

PC-1, May 27, 2008. 

ORAUT 2008b. Nevada Test Site – Occupational Internal Dose, ORAUT-TKBS-0008-5, Rev. 

01, May 28, 2008. 
Draft – Review of NIOSH Position Paper 52 SC&A – January 12, 2010 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

SC&A 2008. Evaluation of Internal Dosimetry Data Selected by NIOSH for Use in the 

Development of a Coworker Model for Workers at the Nevada Test Site (Post 1962), S. Cohen & 

Associates, Vienna, Virginia. October 21, 2008. 

SC&A 2009. Addendum to the October 2008 SC&A Report “Evaluation of Internal Dosimetry 

Data Selected by NIOSH for Use in the Development of a Coworker Model for Workers at the 

Nevada Test Site (Post 1962),” S. Cohen & Associates, Vienna, Virginia. March 2009.