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final NIOSH or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document 

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National Institute for Occupational Safety and Health Division of Compensation Analysis and Support

DEPARTMENT OF HEALTH & HUMAN SERVICES

Memorandum

DCAS External Memorandum 

Division of Compensation Analysis & Support 

To: Metals and Controls (M&C) Special Exposure Cohort (SEC) Working 

 Group 

From: Peter Darnell, DCAS Health Physicist

Subject: NIOSH Response to the SC&A review of the NIOSH White Paper dated April 23, 2018 

Date: October 18, 2018

NIOSH Response to the SC&A review of the NIOSH White Paper dated 

April 23, 2018

General Discussion

The following update is provided for the M&C SEC Working Group. NIOSH received SC&A’s review 

of the M&C white paper (WP) dated April 23, 2018. NIOSH will provide a new WP to accommodate 

SC&A’s review and recommendations. In addition, the WP will describe and model exposures to M&C 

personnel who performed maintenance type work in the Building 10 ceiling area, on the roof, or on the 

HVAC system. While the planned date for completion of this WP is December 2018, NIOSH will 

submit the WP as soon as practical. 

Currently, NIOSH has completed its initial review of the WP and is working to complete comment 

resolution. NIOSH is compiling sample data for the areas outside Building 10 to better analyze data in 

support of the exposure models. The revision to the Evaluation Report (ER) is ongoing. NIOSH plans no 

new data captures or interviews before completing the WP or its revision of the ER. The remainder of 

this document briefly addresses SC&A comments on the NIOSH WP dated April 23, 2018. NIOSH 

plans no revision of this WP. NIOSH anticipates submitting more detailed comment resolutions and 

model updates in the WP scheduled for December 2018. 
This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in 

discussions with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not 

final NIOSH or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document 

represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to 

identify and redact any information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

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NIOSH Responses to the SC&A Memo 

SC&A’s Recommendation 1

NIOSH should consider a more bounding concentration of uranium in soil for the purpose of 

reconstructing internal exposures to M&C workers involved in subsurface activities beneath 

Building 10. 

NIOSH response 

In its summary before this recommendation, SC&A discussed Weston data and its bearing on the 

bounding estimate. NIOSH didn't use the type of radiological controls and doses assigned by 

Weston to determine the bounding uranium concentration in the surrounding soil. However, 

NIOSH originally proposed the 50th percentile. The new WP uses the 95th percentile for air and 

other dose models.

SC&A provided several bullet point comments:

The values from CPS 1993, page 21, and Sowell 1985 (SRDB 94371) pages 69 and 90, represent 

single samples rather than average values like the rest of the aggregated data. The single CPS 

1993 value comes from discussion of the maximum value in text. No measurement records could 

be located to support the value. 

SC&A questions why Table 4 and Table 11 values from Sowell 1985 (SRDB 94371) were not 

used in the assessment. The samples represent surface soil sampling from the Building 12 burial 

area and areas outside Building 10, respectively. Other surface samples were used in the 

analysis from similar locations.

The values used in the modeling from Site Research Database (SRDB) 165968 (CPS n.d., pp. 7–

20) represent diluted averages. NIOSH took the arithmetic average of total uranium (pCi/g) at

each depth of the grid location and then took the arithmetic average of each depth in that grid

location to come up with an average of the averages. An example of this calculation technique is

shown below. These values were then input into the main outdoor model where they are further

aggregated by a geometric mean. Although this aggregation technique results in a modestly

lower dose, depending on the location it is not mathematically defensible.

NIOSH response 

NIOSH anticipates that the data analysis discussion in the new WP will address the first 2 bullet 

points. The difference between averages used by SC&A versus those used by NIOSH varies at a 

maximum of about 7%. NIOSH will review the compiled sample data and present our findings in 

the new WP. With the decision to use the 95th percentile for areas outside Bldg. 10 subsurface
This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in 

discussions with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not 

final NIOSH or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document 

represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to 

identify and redact any information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

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models, the difference in the averages may not be consequential. NIOSH and SC&A agree that 

sufficient documentation exists to establish a bounding distribution of radiological materials 

found in the soils in and around the burial ground on site. 

SC&A Discussion of Occupancy Rates

SC&A agrees that there is considerable uncertainty in this value. There is ample evidence from 

the interviews that many different people were involved in subsurface work in any given year 

and, therefore, it is unlikely that any single individual was involved in all subsurface activities. 

Hence, we believe that the approach used by NIOSH with respect to the 1 month-per-year 

assumption may benefit from further Work Group deliberation. 

NIOSH response 

NIOSH has updated the approach to occupancy rates in the new WP. The occupancy rate was 

doubled to account for both subsurface and roof work. The dose for the remainder of the year for 

these workers will be as outlined in the revised ER. 

SC&A Discussion of Dust Loading

Hence, there is substantial agreement between the dust loading used in the white paper and 

those used by SC&A in its review of the SEC petition ER.

NIOSH agrees with this assessment.

SC&A Discussion of Inhalation Rate and Recommendation 2

NIOSH should consider adopting an inhalation rate commensurate with elevated breathing rates 

induced by physical exertion while individuals are involved with subsurface work.

SC&A’s discussion before Recommendation 2 included: As a claimant-favorable assumption, 

SC&A’s petition ER review used a breathing rate of 2.5 m3/h, which is the recommended 

breathing rate for adult males engaging in moderate activities, including “heavy indoor cleanup 

[and] performance of major indoor repairs and alterations” in the U.S. Environmental 

Protection Agency (EPA) Exposure Factors Handbook (1997). Although it is unlikely that any 

individual respired at this rate during the entirety of their subsurface work, this rate bounds 

potential intakes.

NIOSH response

During its review, NIOSH determined that this rate substantially over-estimates intake. NIOSH 

requests SC&A provide the data used to arrive at this recommendation. 
This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in 

discussions with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not 

final NIOSH or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document 

represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to 

identify and redact any information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

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SC&A Discussion of Ingestion

SC&A cited NUREG/CR-5512 and found that the 50 mg/day value comes from a 1990 study by 

Calabrese et al. that found conservative adult soil ingestions in residential scenario are 50 

mg/day. 

SC&A also cited a section of the NUREG that states ”... workers are assumed to ingest 10 mg of 

loose surface contamination...”

SC&A further states: This value is inconsistent with the value of 50 mg/day NIOSH used in the 

white paper. The difference appears to be the assumption of working conditions. Therefore, this 

subject requires further discussion.

NIOSH response

NIOSH used massed-based volumetric samples to model the exposures associated with soils and 

sediments (i.e., subsurface work). NIOSH believes it is inappropriate to apply the NUREG 

surface contamination method, referenced by SC&A, to the exposures associated with subsurface 

work. However, other exposures, including those associated with the ceiling/roof work are based 

on surface contamination levels. In these cases, NIOSH believes the NUREG surface 

contamination method is appropriate for use.

SC&A Discussion of External Exposures

The white paper continues to make use of film badge data collected during the Atomic Weapons 

Employer period as the basis for reconstructing external exposures during the residual period. 

SC&A notes that the SEC petition ER already intends to use the 1967 dosimetry data at the 95th

percentile plus accommodations for potential missed dose for production workers. The proposed 

model in the white paper for subsurface workers assigning one third of the quarterly GM of the 

1967 results to account for one month of subsurface work will effectively reduce the dose 

assigned to subsurface workers in comparison to other production workers. This is 

unacceptable, given the additional exposure risks for subsurface workers. Neither model takes 

source term depletion into account. 

NIOSH response

The WP uses 2/3 the quarterly dose for workers assigned to maintenance work. This dose is 

assigned in addition to the residual dose assigned to co-located worker dose for the remaining 10 

months of the year. There is no reduction of dose because standard cleaning and environmental 

reduction factors at the site may have less effect on the source term at maintenance work 

locations. Regarding the revised ER’s use of the 95th percentile, NIOSH will assign doses not 
This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in 

discussions with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not 

final NIOSH or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document 

represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to 

identify and redact any information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

 Page 5 of 5

associated with maintenance work based on the geometric mean and account for source term 

depletion for non-maintenance exposures. NIOSH provides additional details in our F2 and O5 

Issues Matrix responses (https://www.cdc.gov/niosh/ocas/pdfs/dps/dc-metcontimsec236-101218-

508.pdf ).

__ ____ 

[Signature on File]

Peter Darnell, CHP, RRPT 

Division of Compensation Analysis and Support