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 report has been reviewed to identify and redact any information that is protected by the Privacy Act 

5 U.S.C. § 552a and has been cleared for distribution.

MEMORANDUM

TO: Advisory Board on Radiation and Worker Health, Work Group on Carborundum Company 

FROM: Robert Anigstein and John Mauro, SC&A 

DATE: November 10, 2016 

SUBJECT: Review of NIOSH Use of Surrogate Data in the SEC Evaluation Report for Carborundum 

On October 27, 2016, Thomas Tomes (NIOSH/DCAS) issued a memorandum titled “Use of Surrogate 

Data at the Carborundum Company” (Tomes 2016). In an email message on the same day, Ted Katz, 

Designated Federal Official to the Advisory Board on Radiation and Worker Health (ABRWH), asked 

SC&A to review this report (Katz 2016). 

Tomes (2016) reviewed the use of surrogate data from TBD-6000 (Allen 2011) in the SEC Evaluation 

Report for Carborundum (ER) (Jessen and Scalsky 2015) in order to determine if the use of these data 

satisfied the criteria specified in OCAS-IG-004 (OCAS 2008). Since SC&A is the technical support 

contractor to the Advisory Board, we deemed it appropriate to determine if the use of surrogate data 

conformed to the board’s own criteria (ABRWH 2010). 

Advisory Board Criteria for the Use of Surrogate Data 

We first list the five criteria for use of surrogate data, as stated by the Advisory Board (ABRWH 2010). 

Criterion 1: Hierarchy of Data

It should be assumed that the usual hierarchy of data would apply to dose reconstructions 

for that site (individual worker monitoring data followed by co-worker data followed by 

workplace monitoring data such as area sampling followed by process and source term 

data). This hierarchy should be considered when evaluating the potential use of surrogate 

data. Surrogate data should only be used to replace data if the surrogate data have some 

distinct advantages over the available data and then only after the appropriate adjustments 

have been made to reflect the uncertainty inherent in this substitution. 

Criterion 2: Exclusivity Constraints1

[In situations where] there are no or very little monitoring data available . . . the use of 

the surrogate data as the basis for individual dose reconstruction would need to be 

stringently justified. This judgment needs to take into account not only the amount of 

 

1 Only the relevant text from Criterion 2 is quoted here.
Memo – Use of Surrogate Data for Carborundum 2 SC&A – November 10, 2016

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surrogate data being relied on relative to data from the site but also the quality and 

completeness of that surrogate data.

Criterion 3: Site or Process Similarities

One of the key criteria for judging the appropriateness of the use of surrogate data would 

be the similarities between the site (or sites) where the data were generated and the site 

where the surrogate data are being utilized. The application of any surrogate data to an 

individual dose reconstruction at a site should include a careful review of the rationale for 

utilizing that source of data. Factors that could be considered include, but are not limited 

to, similarity of the production processes, presence or absence of conditions that might 

affect exposure, and monitoring methods employed at the site(s). The potential 

availability of other sources of surrogate data needs to be considered and the selection of 

the surrogate data used for dose reconstruction justified. Some of the questions to be 

considered where appropriate are:

• Are there other sources of surrogate data that were not used?

• Do these other potential sources contradict or undermine the application of the data 

from the selected site?

• Are there adequate data characterizing the site being used that would help support its 

application to other sites?

• Do the surrogate data reflect the type of operations and work practices in use at the 

facilities in question?

Surrogate data should not be used if the equivalence of working conditions, source terms, 

and processes of the surrogate facility to the one for which dose reconstructions are being 

done cannot be established with reasonable scientific or technical certainty as outlined 

here. 

Criterion 4: Temporal Considerations 

Consideration also needs to be given to the period in question, since working conditions 

and processes varied in different periods. Surrogate data should belong in the same 

general period as the period for which doses are sought to be reconstructed unless it can 

be demonstrated that the working conditions, procedures, monitoring methods, and 

(perhaps) legal requirements were comparable to the period in question. 

Criterion 5: Plausibility 

The manner in which the surrogate data are to be used must be “plausible” with regard to 

the reasonableness of the assumptions made. The plausibility determination should 

address issues of: 

• Scientific plausibility. Are the assumed models (e.g., bioassay, concentration 

gradients) scientifically appropriate? Have the models been validated (where feasible) 

using actual monitoring data collected in a similar situation?
Memo – Use of Surrogate Data for Carborundum 3 SC&A – November 10, 2016

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• Workplace plausibility. Are the assumed processes and procedures (including 

monitoring) plausible for the facility in question? Have all of the factors that could 

significantly impact exposure been taken into account? Is adequate information 

available about the facility in order to be able to make a fair assessment?

Use of Surrogate Data in the SEC Evaluation Report for Carborundum

External Exposure to Penetrating Radiation from Uranium Metal during the First Operational Period

Tomes (2016) cited three instances in which surrogate data from TBD-6000 were used in the ER. We 

first discuss the estimate of doses from external exposure to penetrating radiation from uranium metal 

during the first operational period (June 1, 1943, to September 27, 1943). Neither Tomes nor the ER cite 

the actual external doses used to estimate doses during this period. Tomes states: 

As provided in the ER section 5.1.1, the source term for the 1943 work at Carborundum 

is well known. The work was limited to natural uranium metal slugs, which are included 

in the various shapes of metal evaluated [in] TBD-6000. The source terms are similar.

However, this is not the source term specified in the ER, which states: 

In the absence of personnel-specific external dosimetry records during the first 

operational period, external dose from uranium will be estimated using the data found in 

the TBD, Site Profiles for Atomic Weapons Employers That Worked Uranium Metals. . . . 

Specifically, the section of Tables 7.8 and 7.9 pertaining to pre-1951 dose rate for 

“Machining” should be used. 

Tables 7.8 and 7.9 list intakes of uranium dust by inhalation and ingestion, respectively, not external 

doses. External doses to workers in various job categories are listed in the Excel file “Carborundum 

Methodology 2015-07-23 FINAL.xlsx” (henceforth referred to as “Methodology.xlsx”), which is one of 

three documents that present the proposed prescriptions of the National Institute for Occupational Safety 

and Health (NIOSH) for dose reconstructions (DRs) for Carborundum workers and are available on the 

Division of Compensation Analysis and Support (DCAS) restricted website. These doses correspond to 

those listed in Table 6.4 of TBD-6000 for machining operations prior to 1951. The major component of 

these doses is exposure to uranium metal. The default source—the basis for the values in Table 6.4—is a 

rectangular uranium ingot with dimensions of 24 Η 16 Η 4 inches thick (60.96 Η 40.64 Η 10.16 cm) 

(Anderson and Hertel 2005). Such an ingot has a mass of 477 kg (1,052 lb), as listed in Table 1 of the 

present memo.

Table 1. Dose Rates at 1 Foot from Various Shapes of Natural Uranium Metal 

Shape Mass (kg) Dose rate at 1 ft 

(mrem h-1) 

Specific dose rate at 1 ft 

(mrem h-1 kg-1) 

Ingot 477.0 2.08 0.00436

Slug 2.032 0.0524 0.0258

Plate 3.118 0.231 0.0741

Source: Anderson and Hertel 2005
Memo – Use of Surrogate Data for Carborundum 4 SC&A – November 10, 2016

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Reviewing the use of these data against the five criteria presented above, we draw the following 

conclusions: 

• The external dose rates satisfy the hierarchy-of-data criterion, since there are no site-specific 

radiation measurements for the uranium machining operations at Carborundum. 

• The external dose rates satisfy the exclusivity constraints for the same reason given above.

• The external dose rates do not satisfy the site-or-process-similarities criterion. Although the dose 

rates modeled for TBD-6000 result from exposures to natural uranium metal, which is presumed 

to have been the radiation source at Carborundum in 1943, the size and shape of the metal is 

quite different. According to the ER, the uranium was assumed to be in the form of Clinton 

slugs, which were described as cylinders, 1.1 inches (2.79 cm) in diameter by 4 inches (10.16cm) 

long. Since uranium has a density of 18.95 g/cm2

, the slugs would have had a mass of 1.18 kg 

(~2.6 lb), far less than the rectangular ingot. 

• The temporal-considerations criterion is not applicable, since the calculations that are the basis of 

the TBD-6000 model would not change with time. 

• The external dose rates do not satisfy the plausibility criterion. Since the total mass of uranium 

shipped to Carborundum was ~30 lb, assuming that the radiation levels were the same as those 

from a 1,052-lb ingot is implausible.

According to TBD-6000: “For an individual site, there may be information on which shape applied to a 

site’s operations . . . . However, for the generic case, a worst-case assumption should be made, which is 

that all work was done with a uranium metal slab.” Since site-specific information is available, there is 

no need to use a worst-case assumption. NIOSH should use such information and reasonable 

assumptions regarding the quantity and form of the uranium metal handled and processed at 

Carborundum. For instance, NIOSH could consider basing the dose rates on the uranium slug, one of the 

shapes listed in TBD-6000, Table 6.1. This slug was modeled as a hollow cylinder, with an inner radius 

of 1.041 cm, an outer radius of 2.108 cm, and a length of 10.16 cm (Anderson and Hertel 2005). Such a 

slug has a mass of 2.03 kg (~4.5 lb) and resembles the Clinton slug far more than does the rectangular 

ingot. The dose rate at a distance of 1 ft from the surface of the slug is listed in Table 6.1 as 0.0524 

mrem/h, vs. 2.08 mrem/h for the ingot. A bounding case would be an array of seven slugs, with a total 

mass of ~31 lb. An upper bound of the dose rate at 1 foot could be estimated as 7 times the dose rate 

from one slug, or 0.367 mrem/h, which is 18% of the rate from the rectangular ingot. Such a dose rate 

could be substituted for the values of the “Metal whole body dose” listed in TBD-6000, Table 6.4, to 

calculate the doses entered in “Methodology.xlsx.” Dose rates from penetrating radiation at 1 m from 

the metal could be calculated in a similar manner. 

External Exposure to Penetrating Radiation from Uranium during the Second Operational Period 

A second instance of the use of surrogate data is the estimate of doses from external exposure to 

penetrating radiation from uranium during the second operational period. “Methodology.xlsx” used the 

TBD-6000 external dose rates based on the rectangular uranium ingot. However, the mass of this ingot 

far exceeds the actual amount of uranium handled at Carborundum during this period. Table 5-2 of the 

ER summarized the uranium operations during this period, including quantities of uranium in various 
Memo – Use of Surrogate Data for Carborundum 5 SC&A – November 10, 2016

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batches of uranium products. The maximum quantity cited in this table was in a request for 10 lb 

(4.5 kg) of uranium shot. Another entry refers to batches ranging from about 30 g to 6 lb (2.7 kg). All 

other batches listed in this table fall into this range. 

Applying the five criteria to the use of surrogate data from TBD-6000 to represent external doses during 

this period, we again conclude that the external dose rates do not satisfy the site-or-process-similarities 

criterion, nor the plausibility criterion, for the reasons discussed previously. The other three criteria are 

either satisfied or inapplicable, as discussed earlier.

Although no single shape or quantity can be used to describe the uranium processed or handled during 

this period, NIOSH could elect to use the dose rates from a uranium plate, shown in Table 1 of this 

memo, to bound the external exposures to uranium. The mass of the plate, ~3.1 kg (6.9 lb) is consistent 

with the largest single batch of uranium cited in the ER and only slightly less than the 10 lb of uranium 

shot requested by Carborundum. This shape also has the highest specific dose rate (dose rate per unit 

mass of uranium metal) of the shapes listed in Table 1, as well as of all other shapes modeled by 

Anderson and Hertel (2005). Consequently, use of this shape to represent the external dose rates from 

the largest batch of uranium processed at Carborundum would yield a plausible yet claimant-favorable 

upper bound, given the limited amount of uranium handled at this site. 

Intakes of Uranium Aerosols during the First Operational Period

According to the ER: “Internal doses from uranium intakes during the first operational period are 

estimated using the data from the pre-1951 ‘Machining’ operation in Tables 7.8 and 7.9 of the Technical 

Basis Document: Site Profiles for Atomic Weapons Employers That Worked Uranium Metals.” We note 

that the operator is assigned an intake of 43,632 dpm per calendar day as the median of a lognormal 

distribution with a GSD of 5. The arithmetic mean of this distribution is 159,323 dpm per calendar day, 

which corresponds to an average breathing zone concentration of 20,192 dpm/m3. 

Reviewing the use of these data against the five criteria presented above, we draw the following 

conclusions: 

• The internal doses satisfy the hierarchy-of-data criterion, since there are no site-specific airborne 

dust measurements for the uranium machining operations at Carborundum. 

• The internal doses satisfy the exclusivity constraints for the same reason.

• The internal doses satisfy the site-and-process-similarities criterion: Uranium machining 

operations at Carborundum involved centerless grinding. Harris and Kingsley (1959), in 

reporting airborne uranium concentrations generated by this process, stated that, “without 

ventilation, breathing zone concentrations as high as 13,000 [dpm/m3] have been recorded.”

• The temporal-considerations criterion is satisfied. TBD-6000 states, “These results are typical of 

the state of technology in the late 1950s, as surveyed by Harris and Kingsley,” which was about 

15 years earlier. However, since the cited breathing zone concentration was not ameliorated by 

ventilation, it is unlikely that the working conditions at facility surveyed by these authors would 

have been any more favorable to the worker’s health and safety than those at Carborundum in 

1943. NIOSH assigned the operator an intake of 43,632 dpm per calendar day as the median of a 
Memo – Use of Surrogate Data for Carborundum 6 SC&A – November 10, 2016

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lognormal distribution with a GSD of 5. The arithmetic mean of this distribution is 159,323 dpm 

per calendar day, which corresponds to an average breathing zone concentration of 

20,192 dpm/m3

. We find that, given the limited quantity of uranium metal in the present case, the 

values listed in TBD-6000 are sufficiently bounding. 

• The internal dose rates satisfy the plausibility criterion. The average breathing zone 

concentration of 20,192 dpm/m3 is consistent with the concentration of 13,000 dpm/m3 cited by 

Harris and Kingsley, if we allow for uncertainty and variability. 

Conclusions

External Dose Rates from Uranium Metal during First and Second Operational Periods 

We note that neither Tomes (2016) nor the ER explicitly cite the dose rates from external exposure to 

penetrating radiation from uranium metal during first and second operational periods, nor do they 

identify the specific model(s) to be used to determine such dose rates. On the basis of 

“Methodology.xlsx,” we found that these dose rates correspond to the rates listed in Table 6.4 of TBD6000. Those rates, in turn, are based on MCNP calculations of dose rates from a rectangular uranium 

ingot which is much more massive, and results in much higher dose rates, than the quantities of uranium 

metal present at Carborundum during either period. Consequently, we find that the use of these dose 

rates is inconsistent with the Advisory Board’s surrogate data criteria, and with TBD-6000 itself, which 

refers to these dose rates as a worst-case assumption. 

However, this conclusion does not invalidate the conclusion in the ER that NIOSH can reconstruct doses 

from external exposure to uranium metal during the two operational periods. This is a site profile issue 

but not an SEC issue. 

We have suggested acceptable methodologies that NIOSH could employ for this purpose. NIOSH 

should consider the use of such methods when preparing final instructions to dose reconstructors to use 

in estimating doses to former Carborundum employees. 

Intakes of Uranium Aerosols during the First Operational Period 

We conclude that use of TBD-6000, Tables 7.8 and 7.9, to estimate intakes of uranium aerosols during 

the first operational period is consistent with the five Advisory Board criteria for the use of surrogate 

data.
Memo – Use of Surrogate Data for Carborundum 7 SC&A – November 10, 2016

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References

Advisory Board on Radiation and Worker Health (ABRWH). 2010. “Criteria for the Use of Surrogate 

Data.” Available at http://www.cdc.gov/niosh/ocas/pdfs/abrwh/proc/abrwh-proc-sd-r0.pdf

Allen, D. 2011. “Site Profile for Atomic Weapons Employers that Worked Uranium Metals,” BattelleTBD-6000, Rev. 1. Available at http://www.cdc.gov/niosh/ocas/pdfs/tbd/bat-6000-r1.pdf

Anderson, J. L., and N. E. Hertel. 2005. “Bremsstrahlung doses from natural uranium ingots.” Radiation 

Protection Dosimetry, 115(1–4), 298–301. 

Harris, W. B., and I. Kingsley. 1959. “The Industrial Hygiene of Uranium Fabrication.” A.M.A. Archives 

of Industrial Health, 19, 540–565.

Jessen, K., and E. Scalsky. 2015. “SEC Petition Evaluation Report: Petition SEC-00223 Report,” Rev. 1. 

Available at http://www.cdc.gov/niosh/ocas/pdfs/sec/carbco/carbcoer-223-r1.pdf

Katz, T. 2016. “Review of Surrogate Data Analysis for Carborundum” October 27, 2016, personal email 

to John Stiver, SC&A, Inc., cc: Genevieve Roessler, ABRWH.

Office of Compensation Analysis and Support (OCAS). 2008. “The Use of Data from Other Facilities in 

the Completion of Dose Reconstructions under the Energy Employees Occupational Illness 

Compensation Program Act,” OCAS-IG-004, Rev. 0. Available at 

https://www.cdc.gov/niosh/ocas/pdfs/dr/ocas-ig-004-r0.pdf

Tomes, T. P. 2016. “Use of Surrogate Data at the Carborundum Company,” Memo to Advisory Board 

on Radiation and Worker Health, Work Group on Carborundum Company.