Draft White Paper 

EVOLUTION OF DOSE RECONSTRUCTION APPROACH AT DOW 

MADISON AND USE OF SURROGATE DATA 

Contract No. 200-2009-28555 

Prepared by 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, VA 22182 

 March 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 White Paper – Dow Madison 2 SC&A – March 9, 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. 

At the February 5, 2010, meeting of the SEC Issues Work Group, SC&A was tasked by 

Chairman Melius to prepare an outline to insure that all the relevant points related to Special 

Exposure Cohort (SEC) issues at Dow Madison had been addressed. Based on the discussion at 

the meeting, SC&A determined that this request has two parts. The first is to delineate the extent 

to which surrogate data are used for dose reconstruction, based on the most recent NIOSH 

position presented in Appendix C of Battelle-TBD-6000, and the second is to summarize the 

extent to which SC&A’s findings (based on its August 24, 2009, review of Appendix C) have 

been addressed. These two items are covered in separate brief white papers. This white paper 

describes SC&A’s understanding of the extent to which surrogate data are proposed to be used at 

Dow Madison, based on the material provided in Appendix C to TBD-6000. Table 1 

summarizes the extent of proposed surrogate data usage for dose reconstruction. The ensuing 

paragraphs expand upon this summary. 

Table 1. Proposed Usage of Surrogate Data for Dose Reconstruction at Dow Madison 

Based on Appendix C to Battelle-TBD-6000 

Exposure Period Source Term Is Surrogate Data Used? 

Operating Internal Uranium Yes 

Operating External Uranium Yes 

Operating Internal Thorium Dose reconstruction not feasible 

Operating External Thorium Yes 

Residual Internal Uranium Yes 

Residual External Uranium Yes 

Residual Internal Thorium No 

Residual External Thorium Yes 

Residual Thoron No 

BACKGROUND 

In its Petition Evaluation Report for SEC-00079, dated April 13, 2007, NIOSH concluded the 

following (NIOSH 2007a): 

NIOSH has documented herein that it cannot complete the dose reconstructions 

related to this petition where doses resulted from exposure to thoriumcontaining materials. The basis of this finding is specified in this report, which 

demonstrates that NIOSH does not have access to sufficient information to 

estimate with sufficient accuracy either the maximum radiation dose incurred by 

any member of the class or to estimate such radiation doses more precisely than a 

maximum dose estimate. Members of this class at the Dow Chemical Company 

site in Madison, Illinois, may have received unmonitored internal and external 

radiological exposures from thorium radionuclides at the plant. NIOSH lacks 

sufficient information, which includes sufficient personnel and workplace 

monitoring data and radiological source term information, to allow NIOSH to 

estimate the potential total internal thorium exposures to which the proposed class 

may have been exposed. 
Draft White Paper – Dow Madison 3 SC&A – March 9, 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. 

With the data currently available to NIOSH, it is feasible to reconstruct with 

sufficient accuracy the external and internal doses resulting from exposure to 

uranium metal during the Dow Madison AWE operational period (January 1, 1957 

through December 31, 1960), and during the residual radiation period (January 1, 

1961 through December 31, 1998). NIOSH also considers the reconstruction of 

medical dose for Dow Madison workers to be feasible. 

After the Petition Evaluation Report was issued, NIOSH obtained about 700 pages of additional 

information from Dow. Based on this new documentation, NIOSH issued Addendum 1 to the 

Petition Evaluation Report (NIOSH 2007b). In Addendum 1, NIOSH concluded that the 

additional information did not provide sufficient data to change its original conclusion 

regarding the infeasibility of reconstructing internal Th doses during the operating period. 

NIOSH further concluded that sufficient information was available to conduct a bounding 

estimate of external doses from thorium exposure during the operating period. 

In January 2008, the U.S. Department of Energy (DOE) provided information to the Department 

of Labor (DOL) that some Mg-Th alloys could have been purchased by Mallinckrodt for atomic 

weapons applications (DOE 2008). Prior to this, it was assumed that exposures to thorium only 

need be considered during the operational period, since Mg-Th alloys were presumed to be 

produced for strictly commercial purposes during the operational period when some special 

uranium fabrication had been done by Dow to support the weapons program (January 1, 1957, 

through December 31, 1960). Previously, only uranium exposures had been considered during 

the residual radiation period (initially defined as January 1, 1961, through December 31, 1998). 

In response to the DOL information, NIOSH prepared Addendum 2 to the Dow Madison SEC 

Petition Evaluation Report to address the new DOE information that Mg-Th alloys had been used 

in weapons (NIOSH 2008a). One consequence of the new DOE information was that thorium 

exposures from weapons material production would need to be evaluated during the residual 

radioactivity period. NIOSH also updated the end date for the residual radioactivity period to 

October 31, 2006, and concluded that thorium doses during the residual radioactivity period 

could be reconstructed with sufficient accuracy. 

Subsequent to the publication of these three petition evaluation review reports, NIOSH released 

Appendix C to TBD-6000 (Battelle 2006) on September 8, 2008, which specifically deals with 

the Dow Madison site. Appendix C tabulates and consolidates data and guidance that can be used to 

calculate internal (inhalation and ingestion) and external doses from uranium exposures during both 

the operating and residual periods. Appendix C also provides data that can be used to calculate 

external thorium exposures during the operating period and both external and internal (inhalation, 

ingestion, and thoron) exposures during the residual period. In Appendix C, the end of the residual 

period was defined as July 31, 2000, for uranium and November 30, 2007, for thorium.

 

Operating Period Summary – January 1, 1957, through December 31, 1960 

Since Dow Madison workers during this period have been added to the SEC, the only concerns 

revolve around the ability to conduct dose reconstructions for workers with non-presumptive 
Draft White Paper – Dow Madison 4 SC&A – March 9, 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. 

cancers. NIOSH originally determined in the SEC Petition Evaluation Review Report for SEC00079 that internal and external uranium doses can be calculated using sources such as ORAUTOTIB-0004, Estimating the Maximum Plausible Dose to Workers at Atomic Weapons Employer 

Facilities (ORAUT 2006). It should be noted that ORAUT-OTIB-0004 relies on surrogate data. 

External exposures are modeled with MCNP or MicroShield® for a worker standing near a large 

mass of uranium metal. Inhalation exposures are based on measurements of air concentrations 

made at various Atomic Weapons Employer (AWE) facilities. 

Subsequently in Appendix C, NIOSH refined its guidance regarding uranium dose 

reconstruction. For external exposures, they cited the generic guidance in TBD-6000 to calculate 

photon doses. These surrogate data were derived from MCNP calculations using uranium shapes 

typical of those handled at AWE facilities. For internal uranium exposures during 1957 and 

1958, NIOSH used surrogate data from Table 7.2 of TBD-6000, which summarizes information 

on air concentrations associated with extrusion at various AWE facilities. Similarly for 1959 and 

1960, NIOSH used surrogate data from Table 7.7 of TBD-6000, which summarizes information 

on air concentrations associated with rod straightening at various AWE facilities. 

Based on the additional information provided by Dow and examined by NIOSH in Addendum 1, 

NIOSH concluded that it was still not feasible to evaluate thorium internal doses, but the new 

data provided sufficient information for a bounding reconstruction of external Th doses (NIOSH 

2007b, p. 3). The ability to bound external dose was based on additional direct radiation 

readings, coupled with film badge results from the Dow Bay City facility, where the same 

operations were performed (NIOSH 2007b, p. 4). It appears that film badge monitoring was not 

used at Dow Madison, but was used at Dow Bay City for a single 13-day period. It was 

NIOSH’s position in Addendum 1 that use of the direct radiation measurements at Dow 

Madison, together with the surrogate data from Bay City, provided sufficient data to bound the 

external exposures. 

NIOSH did not address external Th exposures during the operating period in Addendum 2. 

 

In Appendix C, NIOSH noted that a more prescriptive approach to external exposure had been 

presented in Attachment 2 of Addendum 2 for the residual period. In Addendum 2, NIOSH 

stated that, “The highest recorded exposure rate (0.7 mr/hr at one foot) was obtained near the 

thorium storage area and scrap bins, where AWE era materials were stored” (NIOSH 2008a, 

p. 31). This was equivalent to an annual exposure of 1,400 mrem/yr. This assumes that an 

operator spends 100% of his time 1 foot from the highest observed Th photon source and is 

based on measured data at Dow Madison. 

If NIOSH had applied the same exposure scenario as recommended in TBD-6000 (i.e., 50% of 

the time at 1 foot), the annual external dose would have been 700 mrem for the operating 

period. Instead, for Appendix C, NIOSH selected surrogate data from film badge measurements 

made during a 13-day period at Bay City. The 95th percentile annual dose was 1,095 mrem, 

yielding a more claimant-favorable result than using the measured data from Dow Madison. The 

beta dose at all distances was assumed to be equal to the gamma dose at 1 foot. NIOSH does not 
Draft White Paper – Dow Madison 5 SC&A – March 9, 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. 

provide the reasoning for using surrogate data rather than measured data for external Th 

exposure. 

Thus, any dose reconstructions for non-presumptive cancers in the operating period would rely 

largely on surrogate data, supplemented in the case of Th with direct radiation measurements. 

Residual Period Summary – January 1, 1961, through October 31, 2006 

NIOSH concluded, in the initial petition evaluation review report for Dow Madison, that it was 

feasible to calculate internal and external doses for uranium during the residual period (NIOSH 

2007a). NIOSH stated that, “Potential internal doses received from inhalation and/or ingestion 

of re-suspended uranium during the residual contamination period can be reconstructed, as 

indicated by the model dose reconstructions covering the period January 1, 1957 through 

December 31, 1998.” NIOSH provided no citations to support that position. NIOSH made the 

same statement with regard to external doses during the residual period (NIOSH 2007a, 

Section 6.2). No new uranium information was provided in either Addendum 1 or Addendum 2. 

In the initial petition evaluation review report and Addendum 1, NIOSH did not consider 

thorium exposures during the residual period, because it was presumed that all Mg-Th alloy 

production during the operations period was related to applications not involving atomic 

weapons. However, based on more recent information about the possible use of Dow Mg-Th 

alloys in atomic weapons, Th exposures during the residual period were examined in 

Addendum 2. Inhalation exposures from dust were modeled using an exponential decay function 

and air sampling measurements taken prior to the beginning of the residual period on January 1, 

1961, and a bounding sample taken during final cleanup in 2006. Thoron exposures were 

similarly modeled. External exposures were based on the assumption that, “The highest 

recorded exposure rate (0.7 mr/hr at one foot) was obtained near the thorium storage area and 

scrap bins, where AWE era materials were stored” (NIOSH 2008a, p. 31). 

In Appendix C of TBD-6000, NIOSH proposed the same exponential decay approach to Th 

internal exposures as was presented in Attachment 2 to Addendum 2. To calculate external 

doses from Th, it was assumed during the first year of the residual period that doses were based 

on the surrogate film badge data from Bay City. External exposures were then assumed to decay 

at the same exponential rate as internal exposures. NIOSH notes that, “The external estimate is 

considered a bounding estimate because the majority of the external dose recorded on the film 

badges likely came from the in-process thorium material itself rather than residual 

contamination” (Battelle 2006, Appendix C, p. 7). 

SUMMARY 

NIOSH’s approach to dose reconstruction has undergone a series of refinements since the 

Petition Evaluation Report for SEC-00079 was issued. This evolution, which ended with the 

publication of Appendix C to TBD-6000, is summarized in Table 2. It can be seen that use of 

surrogate data is proposed for all source terms except for thoron exposures and internal thorium 

exposures during the residual period. Reliance on use of surrogate could possibly be reduced by 
Draft White Paper – Dow Madison 6 SC&A – March 9, 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. 

using direct radiation measurements at Dow Madison, rather than film badge data from Dow Bay 

City. 

Table 2. Evolution of Dose Reconstruction Approach for Dow Madison 

Exposure SEC-00079 

Evaluation Report 

SEC-00079, 

Addendum 1 SEC-00079, Addendum 2 Appendix C 

Operating Period 

U Internal* Doses can be 

reconstructed using 

surrogate data 

sources, such as in 

OTIB-0004. 

Can be reconstructed using 

generic guidance for TBD6000, including air sampling 

from AWE facilities. 

U External* Doses can be 

reconstructed using 

surrogate data 

sources, such as in 

OTIB-0004. 

Can be reconstructed using 

generic guidance for TBD6000, including MCNP 

calculations of doses from 

large U shapes. 

Th Internal Cannot reconstruct. Cannot reconstruct. Cannot reconstruct. Cannot reconstruct. 

Th External* Cannot reconstruct. Can be 

reconstructed using 

direct radiation 

measurements and 

surrogate data from 

Bay City. 

Used surrogate film badge 

data from Bay City. 

(Could have used direct 

radiation measurements from 

Dow Madison.) 

Residual Period 

U Internal Doses can be 

reconstructed, but 

approach not 

presented. 

Assumed resuspension of 

uranium deposited in 1960. 

Uranium deposition based on 

surrogate data from TBD6000 and constant 

resuspension factor of 1E06/m. 

U External Doses can be 

reconstructed, but 

approach not 

presented. 

Used constant surface 

contamination data from 

TBD-6000. (Reported data 

are in error and must be 

corrected.) 

Th Internal Not considered. Not considered. Doses modeled using 

measured data and timedependent exponential 

decay function. 

Doses modeled using 

measured data and timedependent exponential decay 

function. 

Th External Not considered. Not considered. Based on bounding direct 

radiation measurements. 

External exposures assumed 

to decay at the same 

exponential rate as internal 

exposures from initial value 

based on surrogate film badge 

data from Bay City. 

Thoron Not considered. Not considered. Doses modeled using 

measured data (95th

percentile from 1959 data) 

and same time-dependent 

exponential decay function 

as for Th internal. 

Doses modeled using 

measured data (95th percentile 

from corrected 1959 data) and 

same time-dependent 

exponential decay function as 

for Th internal. 

* - Since workers in the operating period were added to SEC, these exposures are only needed for dose reconstructions 

involving non-presumptive cancers. 
Draft White Paper – Dow Madison 7 SC&A – March 9, 2010 

 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. 

NOTICE:

REFERENCES 

Battelle 2006. Site Profiles for Atomic Weapons Employers that Worked Uranium and Thorium 

Metals. Battelle-TBD-6000. Battelle Team Dose Reconstruction Project for NIOSH.

DOE (U.S. Department of Energy) 2008. Letter from Department of Energy to Department of 

Labor, January 8, 2008; SECIS SRDB Document ID: 105199

NIOSH (National Institute for Occupational Safety and Health) 2007a. SEC Petition Evaluation 

Report Petition SEC-00079. April 13, 2007; SRDB Ref ID: 39873.

NIOSH (National Institute for Occupational Safety and Health) 2007b. Addendum 1 to SEC 

Petition Evaluation Report Petition SEC-00079. August 6, 28, 2007 

NIOSH (National Institute for Occupational Safety and Health) 2008a. Addendum 2 to SEC 

Petition Evaluation Report Petition SEC-00079. June 3, 28, 2008. 

ORAUT 2006. Estimating the Maximum Plausible Dose to Workers at Atomic Weapons 

Employer Facilities. ORAUT-OTIB-0004, Revision 03 PC 2. Effective date: December 6, 

2006.