Status of SRS Work Group Review of 

Savannah River Site SEC Evaluation for 

Subcontractor CTWs, 1991–2007

Bob Barton, CHP

Advisory Board on Radiation and Worker Health

April 20, 2023
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SRS status: SEC-00103 review for subCTWs

 July 12, 2021: Board recommendation of Special Exposure Cohort 

(SEC) class for subcontractor construction trade workers (CTWs), 

1972–1990 (Oct. 12, 2021, Federal Register designation date) 

(ABRWH, 2021)

 April 22, 2022: SC&A issued “Focused Review of ORAUT-RPRT0092, Revision 00, and Remaining Petition SEC-00103 Evaluation 

Report Period: 1991–2007” (SC&A, 2022)

 November 22, 2022 (SC&A receipt January 5, 2023): NIOSH 

issued response to SC&A’s focused review (NIOSH, 2022)

 March 22, 2023: Savannah River Site (SRS) Work Group meeting
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Original SEC question before work group

 Deficiencies in permit-driven, job-specific bioassay program 

identified in the late 1990s

 Only 21% compliance with job-specific bioassay requirements in 

1997

 Transient short-term subcontractors are the most likely (but not sole 

group) affected by the job-specific bioassay program

 Former worker interviews indicate that some subcontractors were 

brought in to do the work with higher exposure potential (NIOSH, 

2017)

 Key Question: Did deficiencies exist in the completeness of the 

job-specific bioassay program during years 1972–2007 that would 

preclude formulation of a representative co-exposure model?
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Designated SEC, 1972–1990

 ABRWH recommendation letter, July 12, 2021:

– “All construction trade employees of Department of Energy 

subcontractors [excluding employees of the following prime contractors 

who worked at the Savannah River Site in Aiken, South Carolina, 

during the specified time periods: E. I. du Pont de Nemours and 

Company, October 1, 1972, through March 31, 1989; and 

Westinghouse Savannah River Company, April 1, 1989 through 

December 31, 1990], who worked at the Savannah River Site from 

October 1, 1972 through December 31, 1990, for a number of work 

days aggregating at least 250 work days, occurring either solely under 

this employment or in combination with work days within the 

parameters established for one or more other classes of employees 

included in the Special Exposure Cohort.”
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ABRWH SEC basis (1972–1990)

 ABRWH recommendation letter, July 12, 2021: 

– “Subcontractor construction trades workers [CTWs] conducted a broad 

range of work activities . . . . They may have worked in highcontamination and high-airborne radioactivity areas and may have 

been utilized for short-term high-exposure work tasks.”

– “Subcontractor construction trades workers may have been ‘transient’ 

and not have worked for long periods at SRS and also may have been 

intermittently tasked with nonroutine radiological jobs under work 

permits, and thus were not likely enrolled in the routine (including 

termination) bioassay monitoring program.”
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ABRWH SEC finding (1972–1990)

 ABRWH recommendation letter, July 12, 2021:

– “The Board finds there to be insufficient information, including a 

lack of job-specific radio-bioassay monitoring data for 

subcontractor construction trades workers, and assurance of 

workplace monitoring and source term data, to enable NIOSH to 

estimate with sufficient accuracy all potential internal doses from 

radionuclides associated with fuel handling, reactor operations, fuel 

reprocessing, and/or research activities, to which the proposed class 

may have been exposed during the time period in question” 

(emphasis added).
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When did information become “sufficient” to 

enable DR with sufficient accuracy?

 Remaining SEC period for subcontractor CTWs: 1991–2007

 In its 2022 focused review, SC&A examined the following 

information for sufficiency based on prior SEC designation:

– Westinghouse Savannah River Company Radiological Work Permit 

(RWP) and job-specific bioassay policies, procedures, and practices, 

and their implementation (trending numbers, percentages)

– Assurance of workplace monitoring (data completeness: degree to 

which job-specific bioassays submitted)

– Representativeness of scope and matching of radionuclides in RPRT0092 sampling

 NIOSH delivered its response paper in November 2022
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SC&A conclusion 1: Sampling premise is not 

sufficiently grounded in historical SRS practices

NIOSH response

 Transition between SRS 

operating contractors led to 

increasing RWP job-specific 

bioassays by procedure vs. RWP 

forms. 

 Absence of bioassay 

requirements on RWPs is 

irrelevant.

Work group discussion

 Agreement that RWPs were 

evolving during implementation 

phase in early to mid-1990s. 

 Disagreement persists on how 

bioassay performance rate should 

be calculated based on RPRT- 0092 data. 

 NIOSH contends that addressing 

RWPs and bioassay requirements 

on RWPs is not necessary for coexposure modeling.
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SC&A conclusion 2: Results for direct and 

effective monitoring may be overstated

NIOSH response

 Agrees that definition of 

“monitored” in RPRT-0092 is 

not applied consistently and all 

radionuclides were not 

addressed. 

 These tallies were updated, but 

NIOSH conclusion that a coexposure model can be 

constructed has not changed.

Work group discussion

 Addressed NIOSH’s concern 

that 80% matching threshold 

cited in SC&A review is 

“arbitrary.”

 It was pointed out that such 

subjective benchmarks for 

comparison had been used 

before by both SC&A and 

NIOSH.
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SC&A conclusion 3: Generalized matching is 

not sufficient

NIOSH response

 For co-exposure modeling, 

coworkers used for effective 

monitoring matches need only 

have the same or higher 

exposure potential. 

 SC&A’s criteria of same RWP, 

same date, same time, same 

craft seen as far too restrictive.

Work group discussion

 SC&A presented the 

clarification that co-exposure 

matching for the purposes of 

RPRT-0092 (on an individual 

subCTW level) is different than 

that for co-exposure modeling 

for the entire site (general 

population) and that different 

crafts could be used if apparent 

that there was equal or greater 

potential for exposure.
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SC&A conclusion 4: RWP-specified, jobspecific bioassay data are incomplete

NIOSH response

 Noncompliance uncertainties are 

unknown. 

 Noncompliance does not prevent 

development of co-exposure models.

 If the samples prescribed by site internal 

dosimetrist when a suspected intake 

occurred are part of NIOSH’s co- exposure database, this is evidence that 

a bounding co-exposure model could be 

constructed.

Work group discussion

 NIOSH to provide “TRACK” database 

from SRS containing bioassay samples.

 Work group members clarified that these 

data (for cause, “special” bioassays) 

would be relevant to co-exposure model, 

but not to job-specific bioassay data 

completeness and representativeness 

review. 

 NIOSH to corroborate site internal 

dosimetrist interview statements. 

 Exposure data review for subCTWs 

proposed.
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SC&A conclusion 5: Feasibility of co-exposure model 

needs to be balanced

 NIOSH response: Agree.

 Work Group discussion:

– SC&A underscored that there has been no shift in its review focus: 

Both feasibility of dose reconstruction and feasibility of co-exposure 

modeling are predicated on demonstrating data completeness and 

representativeness, as called for by DCAS-IG-006. 

– SC&A’s weight-of-evidence review seeks to balance job-specific 

bioassay data completeness and program assurance information as a 

basis for the work group’s judgment on a suitable SEC cutoff milestone 

within 1991–2007.
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Summary of work group actions

 Work group requested that NIOSH provide:

– Independent corroboration of LaBone interview statements about 5Q1.1-506 

interpretation and special monitoring programs

– TRACK database, to verify inclusion of the most-highly-exposed workers in bioassay 

dataset by sometime in 1991

 Work group requested that SC&A work with NIOSH to propose framework 

for conducting analysis of exposure distribution for subcontractor CTWs at 

SRS for post-1990 period.

 SC&A will complete and issue its formal response to NIOSH’s response 

paper.

 Work group review of prime contractor employees remains to be 

determined for the full 1972–2007 qualified evaluation report period and 

will be addressed following this current review of subCTWs.
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References

Advisory Board on Radiation and Worker Health. (2021, July 12). Correspondence 

from Henry A. Anderson III, Chair, to Xavier Becerra, Secretary, Department of 

Health and Human Services. 

https://www.cdc.gov/niosh/ocas/pdfs/abrwh/secrecs/bdrecsrs-103b-508.pdf

National Institute for Occupational Safety and Health. (2017, September 29). 

Analysis of CTWs vs. subcontractor CTWs [Email communication to J. Melius and 

B. Clawson, ABRWH].

National Institute for Occupational Safety and Health. (2022). Response to SC&A’s 

“Focused review of ORAUT-RPRT-0092, revision 00, and remaining petition SEC- 00103 evaluation report period: 1991–2007” [Response paper]. 

https://www.cdc.gov/niosh/ocas/pdfs/dps/dc-orrprt92r0-sec103-508.pdf

SC&A, Inc. (2022). Focused review of ORAUT-RPRT-0092, revision 00, and 

remaining petition SEC-00103 evaluation report period: 1991–2007 (SC&A-TR2022-SEC001, rev. 0). https://www.cdc.gov/niosh/ocas/pdfs/abrwh/scarpts/scasrsorrprt92r0sec103-r0-508.pdf