DISCLAIMER; This is a working document provided by the Centers for Disease Control and Prevention (CDC) 

technical support contractor, SC&A, for use in discussions with the National Institute for Occupational Safety and 

Health (NIOSH) and the Advisory Board on Radiation and Worker Health (ABRWH), including its Working Groups 

or Subcommittees. Documents produced by SC&A, such as memorandum, white paper, draft or working documents 

are not final NIOSH or ABRWH products or positions, unless specifically marked as such. This document prepared 

by SC&A represents its preliminary evaluation on technical issues.

NOTICE: This document 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. 

MEMORANDUM

TO: Metals and Controls Corporation Work Group 

FROM: SC&A, Inc.

DATE: September 17, 2018 

SUBJECT: Response to NIOSH White Paper on M&C dated April 23, 2018 

Introduction 

This memorandum presents SC&A’s review of the National Institute for Occupational Safety 

and Health (NIOSH) white paper, Metals and Controls Corp. Subsurface Exposure Model, dated 

April 23, 2018. Since this is a review of a white paper addressing subjects intended to support 

Advisory Board on Radiation and Worker Health (Advisory Board) deliberations regarding the 

granting or denial of a Special Exposure Cohort (SEC) petition, as opposed to a site profile 

review, the main questions addressed in this review emphasize whether there are scientifically 

sound and claimant-favorable data and information that can be used to support an SEC 

determination, and not whether the specific scientific methods and assumptions employed can be 

improved. These subjects are generally reserved for site profile reviews and entail a much more 

detailed analysis of the models and assumptions and the specific data used as input to the 

models. Nevertheless, where feasible, this report also addresses what is often referred to as site 

profile issues. 

SC&A agrees with the description of the material provided in the paper’s introduction, including 

the summary of the results of the worker interviews conducted on October 24–26, 2017, and the 

description of the November 8, 2017, teleconference. It is noteworthy that the Introduction refers 

to newly found monitoring data obtained on February 6, 2018, and February 13, 2018, that was 

collected by Creative Pollution Solutions (CPS) in the early to mid-1990s in support of 

characterizing the radiological condition at the facility prior to initiating and during site 

remediation. These data are directly applicable to the characterization of the subsurface 

environment in the 1990s and are being used in support of dose reconstructions associated with 

M&C maintenance and refurbishment activities during the residual period. SC&A reviewed

these data and confirmed that we also made use of these data to assess their usefulness and 

applicability. As discussed in more detail below, although we believe that the data can be used to 

reconstruct subsurface exposures to Metals and Controls Corporation (M&C) workers, we do not 

agree with the methods and assumption used in the white paper to reconstruct these doses.

Inside Building 10

Evidence suggests that in Building 10 portions of the concrete floors were removed, subsurface 

gravel and dirt were removed, and maintenance and repurposing activities periodically took 
Memo – Response to April 2018 M&C White Paper 2 SC&A – September 17, 2018 

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place during the residual period. Some of this work involved cutting and replacing subsurface 

drainage lines and conduits, handling subsurface soil, and removing debris clogging the 

subsurface lines, primarily by “snaking” the lines. 

In September 1995, a radiological survey of the subsurface drains in the affected areas of 

Buildings 4 and 10 was performed to determine the concentrations, distribution, and inventory of 

uranium present in the drainage system as a result of historical nuclear materials processing 

(Weston 1996). SC&A reviewed the NIOSH model of subsurface areas below Building 10 that

specifically focuses on the subsurface drain lines. Although the white paper references use of soil 

samples, the 44 samples used in the modeling are volumetric samples taken from inside the 

pipes. This material is better characterized as sludge or sediment. Soil samples would be 

inappropriate to use in this instance because the integrity of the pipes was compromised, and thus 

removal of the pipes, or snaking of pipes, would result in the material inside of the pipes 

becoming exposed and potentially airborne. 

SC&A reviewed the NIOSH modeling file and found that NIOSH accurately calculated the 

geometric mean of the pipe samples to be 147.12 picocuries per gram (pCi/g) and a geometric 

standard deviation of 7.68. However, SC&A does not believe this value is appropriate to use for 

the modeling of subsurface material intakes. 

The pipe samples were taken in 1995. The drainage pipe system under Building 10 does not 

represent a closed system; i.e., the materials in the pipes at the time of sampling is not entirely 

representative of the materials that were there at the end of operations. A major theme that 

emerged throughout the interviews was that the pipes under the building would frequently back 

up and require attention to unclog them. Some instances required the pipes to be snaked, which 

would result in some materials being removed from the pipe. In other instances, the pipes would 

need to be physically replaced. These actions reduced the quantity of materials in the remaining 

pipes and, thus, source term that was available to be sampled in the 1990s. The pipes that would 

require these actions were likely the pipes with the most material in them and are potentially the 

most contaminated areas. The geometric mean of the pipe sampling results does not reasonably 

bound potential exposures to subsurface workers. 

Total uranium concentrations in the subsurface pipes in Building 10 ranged from 9.75 pCi/g to 

53,224.7 pCi/g. The highest value was taken from “location 1” which consisted of two pipes and 

was the basis for the remediation recommendation by Weston: 

During pilot investigations, high readings from the pipe feed line were noted 

and the pipe was excavated and removed to the main lines. The 4-inch CI and 

4-inch VC pipes were opened; a small rod (5 inches long and 1/2-inch in 

diameter) was removed. Significant sediment buildup was identified. The 

sediment blocked at least 90 percent of the CI pipe and 50 percent of the VC 

pipe. This sediment was sampled and shipped for isotopic uranium analysis. It 

should be noted that these findings were the basis for the WESTON

recommendation to perform drain line characterization prior to full-scale 

remediation activities. [Weston 1996, p. 10]
Memo – Response to April 2018 M&C White Paper 3 SC&A – September 17, 2018 

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The location 1 pipe sample represents the hottest sample from any remediation work done on site

and is more than 4 times higher than the next highest sample anywhere on site. No other fuel 

pieces were found on site during remediation. The second highest pipe reading represents the 

upper 95th percentile of total uranium in the pipes, 5,878.1 pCi/g. This sample was taken from 

“location 6,” which was down gradient from “location 1.” 

SC&A notes that selection of a percentile from the sampling to use in modeling is a site profile 

issue rather than an SEC issue. 

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.

Part of this section of the white paper refers to air sampling data collected by Weston during 

cleanup activities in the 1990s, which reveals that the inhalation doses to these workers were

about 20 mrem/quarter committed effective dose equivalent. We presume that this value 

establishes a benchmark that might have applicability to exposure experienced by M&C workers 

involved in subsurface activities earlier in the residual period. SC&A elected not to draw upon 

the dosimetry data collected in support of cleanup work because all the work was performed 

under the direction of a formal radiological health and safety program, and, as stated by the 

petitioners, these data may not be representative of exposures experienced by M&C workers 

because their work was not performed under a radiological safety program and the workers were 

not aware that they might have been working in radioactively contaminated areas. 

Areas Outside of Building 10

This section of the white paper describes contamination levels and potential exposures in outdoor 

areas in the vicinity of Building 10, the waste disposal area in the vicinity of Building 12, and 

other outdoor areas as collected by contractor personnel in 1994 and the early years of the 1990s. 

SC&A reviewed the same source documents cited in the white paper. On May 1, 2018, SC&A 

received the Excel data file documenting the NIOSH calculation. In reviewing this file, SC&A

identified a potential problem with the calculation and asked for clarification from NIOSH. On 

May 2, 2018, NIOSH agreed there was an error in the calculation and modified the supporting 

file. This change affected the outside uranium results in the white paper and caused the 

geometric mean to change from 53.52 to 50.68 pCi/g on page 5, and the air concentration on 

page 8 to change from 1.18E-14 to 1.11E-14 microcuries per milliliter (μCi/ml). 

Using these values as a starting point, SC&A consulted the source documents used in the 

calculation. SC&A found that rather the 292 samples cited in the white paper, significantly more 

data were used in the assessment. Due to the limitations of working with historical data that were 

not gathered specifically for this analysis, it appears NIOSH had to take various steps to 

standardize data generated from various sources in order to complete its analysis. SC&A has the 

following observations concerning the data and their use: 

• 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. 
Memo – Response to April 2018 M&C White Paper 4 SC&A – September 17, 2018 

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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.

Example Calculation Derived from SRDB 165968, PDF page 10 

Figure 1. Sample of Subsurface Soil Sample Grid Cell Averages (SRDB 165968, PDF p. 10)

NIOSH method: 

Σ(AAAAAAAAAAAAAAAA)

nnnnnnnn oooo = (185 + 93 + 19 + 61)/4 = 358/4 = 87

Standard Arithmetic Mean:

Σ(ssssssssssss vv vv )

nn nn nn oooo ssssssssssssss = (258 + 30 + 163 + 273 + 307 + 79 + 2 + 2 + 33 + 273 + 149 + 96 +

2 + 2 + 2 + 74 + 18 + 15 + 17 + 63 + 74)/21 = 1932/21 = 92

The current model that uses averages obtained by various averaging methods in combination 

with single measurements requires modification. SC&A suggest a more mathematically valid 
Memo – Response to April 2018 M&C White Paper 5 SC&A – September 17, 2018 

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approach would be to model a distribution of all samples and an additional model where only 

averages are available, and then compare the model distributions. 

With respect to the sources used to support the analysis, SC&A believes there is sufficient 

documentation to establish a bounding distribution of radiological materials found in the soils in 

and around the burial ground on site.

Bounding Exposure Model

This section of the white paper presents the methods used to reconstruct internal doses to M&C 

workers involved in subsurface activities during the residual period using the surrogate data 

described above. Since SC&A gathered and reviewed the same data and worker interview notes, 

the only question that remains is whether we believe that doses can be reconstructed in a 

scientifically sound and claimant favorable manner and, if so, whether NIOSH has performed 

dose reconstructions that we believe to be appropriate for the exposure scenarios and pathway of 

concern. 

Occupancy

One of the issues addressed in this section of the white paper is occupancy times; i.e., the number 

of hours each year that a given worker might be involved in subsurface activities both inside and 

outside Building 10. Based on the interview notes and direct participation in the interviews, 

NIOSH believes that the collective amount of time workers were performing subsurface activity 

in Building 10 during a given year was about 1 month. NIOSH also indicates that subsurface 

workers will also receive assigned residual exposures for the remaining 11 months of each year 

at the same rate as the other workers that did not perform subsurface work. The petitioner 

expressed concerns at the August 23, 2018, Advisory Board meeting that this occupancy factor 

may not capture the full breadth of subsurface work because during the interviews, the 1 month 

was given as an estimate on the total time the floor in Building 10 was disturbed. According to 

the petitioner, this quantity does not reflect times the subsurface pipes were snaked to resolve 

blockages. According to the petitioner, those instances resulted in exposure to subsurface 

materials without breaching the concrete floor of the building. 

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. Further exploration of occupancy 

fractions in Building 10 and the outside areas is a site profile rather than SEC issue.

Dust Loading 

A large portion of the white paper is dedicated to evaluating the airborne dust loading that 

subsurface workers might have experienced. The white paper draws from a number of source 

documents to select a scientifically sound and claimant-favorable dust loading for use in these 

calculations. The white paper gives a default value of 100 micrograms/m3 as suggested in 
Memo – Response to April 2018 M&C White Paper 6 SC&A – September 17, 2018 

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ORAUT-OTIB-0070, Revision 01 (NIOSH 2012), and NUREG/CR-5512, Volume 1 (NRC 

1992). However, the white paper explains that this value may not be entirely applicable to M&C 

activities because the M&C activities were more episodic than the activities addressed in 

ORAUT-OTIB-0070 and NUREG/CR-5512 and likely involved higher dust loading than the 

more chronic exposure scenarios. 

The white paper also cites dust-loading measurements collected during the Mound Plant Canal 

Cleanup project (Taulbee 2018), and as depicted in Figure 1 of the white paper. The white paper 

then evaluates the Mound data against the Advisory Board’s surrogate data criteria and 

concludes that the Mound data satisfy those criteria. On this basis, NIOSH calculated a mean 

dust loading of 7.18E-5 g/m3 (71.8 micrograms/m3) and a 95th percentile value of 2.2E-4 g/m3

(222 micrograms/m3). The mean value was less than the of 100 micrograms/m3 previously 

determined to be insufficient for this application, so NIOSH selected the 95th percentile value 

for use in the white paper. On this basis, NIOSH’s selection of the default dust loading appears 

to be justified. 

To further evaluate the merits of the dust loading calculated by NIOSH, SC&A compared the 

222 micrograms/m3

 value in the white paper to the dust loading values SC&A selected in its 

review of the SEC petition evaluation report (ER) (SC&A 2018). SC&A selected a dust loading 

of 200 micrograms/m3 for its assessment of the internal doses to M&C subsurface workers in 

Building 10. A detailed discussion of the data and basis for this section is provided in 

Appendix D of SC&A’s review of the SEC petition ER. 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. 

Inhalation Rate

The white paper does not refer to inhalation rate. According to the interviews, much of the 

subsurface work was done by hand, indicating that the breathing rate was likely elevated, 

compared to the standard breathing rate of 1.2 m3 per hour used in most dose reconstructions. 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. 

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.

Ingestion 

The white paper cites an ingestion rate of 50 mg/workday based on material in Section 6.3.2 of 

NUREG/CR-5512, Volume 1. SC&A reviewed this section of NUREG/CR-5512 and found that 

the 50 mg/day value comes from a literature search that identified a 1990 study by Calabrese et 
Memo – Response to April 2018 M&C White Paper 7 SC&A – September 17, 2018 

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al. that found conservative adult soil ingestions in residential scenario are 50 mg/day. 

NUREG/CR-5512, Volume 1 (NRC 1992, p. 6.14) also states: 

To estimate the potential radiation doses resulting from secondary ingestion, 

adult renovation workers are assumed to ingest 10 mg of loose surface 

contamination per hour of exposure. Workers during routine building occupancy 

are assumed to ingest surface loose contamination at a lesser rate because of the 

general reduction of removable surface contamination in the building. 

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.

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. 

SC&A has remaining concerns (SC&A 2018, Observation 5) about the appropriateness of using 

operational dosimetry to represent the residual period. 

References

Calabrese et al. 1990. E.J. Calabrese, E.J. Stanek, C.E. Gilbert, and R.M. Barnes, “Preliminary 

Adult Soil Ingestion Estimates: Results of a Pilot Study,” Regulatory Toxicology and 

Pharmacology, Vol. 12 (1990), pages 88–95. 

CPS 1993. Texas Instruments Incorporated, Attleboro, Massachusetts, Remediation of the 

Former Radioactive Waste Burial Site (NRC License SNM-23): Final Report, Creative Pollution 

Solutions, Inc. September 1993. [SRDB Ref. ID 24626] 

CPS n.d. Appendix D, Radiological Survey Results, [NIOSH assumes author is CPS based on 

prior work and reports]. No date. [SRDB Ref. ID 165968] 

EPA 1997. Exposure Factors Handbook, Volume I – General Factors, EPA/600/P-95/002Fa, 

U.S. Environmental Protection Agency, Washington, DC. August 1997. Available at 

https://rais.ornl.gov/documents/EFH_Final_1997_EPA600P95002Fa.pdf
Memo – Response to April 2018 M&C White Paper 8 SC&A – September 17, 2018

NOTICE: This document 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.

NIOSH 2012. Dose Reconstruction during Residual Radioactivity Periods at Atomic Weapons 

Employer Facilities, ORAUT-OTIB-0070, Revision 01, National Institute for Occupational 

Safety and Health, Cincinnati, OH. March 5, 2012. [SRDB Ref. ID 108851]

NIOSH 2018. Metals and Controls Corp. Subsurface Exposure Model: White Paper, National 

Institute for Occupational Safety and Health, Cincinnati, OH. April 23, 2018.

NRC 1992. Residual Radioactive Contamination from Decommissioning: Technical Basis for 

Translating Contamination Levels to Annual Total Effective Dose Equivalent, Final Report, 

Volume 1, NUREG/CR-5512, PNL-7994, U.S. Nuclear Regulatory Commission, Washington, 

DC. October 1992. [SRDB Ref. ID 23558]

SC&A 2018. Review of SEC Petition Evaluation Report SEC-00236 Metals and Controls 

Corporation, SCA-TR-2018-SEC001, Revision 0, SC&A, Inc., Arlington, VA. February 12, 

2018.

Sowell 1985. Radiological Survey of the Texas Instruments Site Attleboro, Massachusetts, 

L.L. Sowell, Oak Ridge Associated Universities, Oak Ridge, TN. January 1985. [SRDB Ref.

ID 94371]

Taulbee 2018. Resuspension Factors during Excavation Activities, E-mail correspondence from 

Timothy D. Taulbee, NIOSH, to Jim Neton, NIOSH, et al., Subject: Resuspension Factors during 

Excavation Activities. January 16, 2018. [SRDB Ref. ID 170425]

Weston 1996. Texas Instruments Incorporated Attleboro Facility Building Interiors Remediation

Drainage System Characterization, Roy F. Weston, Inc. January 1996. [SRDB Ref. ID 165965]