REPORT TO THE ADVISORY BOARD ON RADIATION AND 

WORKER HEALTH 

National Institute of Occupational Safety and Health 

Audit of Case #PIID* from the Bethlehem Steel Facility 

Contract No. 200-2004-03805 Task Order No. 4 

SCA-TR-TASK4-CNPIID* 

Prepared by 

John Mauro, PhD CHP S. Cohen & Associates 6858 Old Dominion Road, Suite 301 

McLean, Virginia 22101 

February 2005 

NOTICE: This information is protected by Privacy Act 5 USC §552a; disclosure to any third party 

without the written consent of the individual to whom the information pertains is strictly prohibited. 
S. Cohen & Associates: 

Technical Support for the Advisory Board on Radiation 

& Worker Health Review of NIOSH Dose 

Reconstruction Program 

AUDIT OF CASE #PIID* FROM THE 

BETHLEHEM STEEL FACILITY 

Task Manager: ___________________ Date: 02/04/05 

Hans Behling, PhD, MPH 

Project Manager: _________________ Date: 02/04/05 

John Mauro, PhD, CHP 

Document No. 

SCA-TR-TASK4-CNPIID* 

Effective Date: February 4, 2005 

Revision No. 1 

Page 2 of 14 

 Supersedes: 

Draft Rev. 0 
TABLE OF CONTENTS 

Summary ....................................................................................................... 4 

1.0 Introduction........................................................................................ 6 

2.0 Summary of Doses.............................................................. 8 

3.0 Independent Reproduction and Review of Selected NIOSH Derived 

Doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

3.1 Internal Dose from Inhalation ........................................... 10 

3.2 External 

Exposures..................................................................................... 12 

3.2.1 External Exposures to Uranium Sources........................... 12 

3.2.2 External Annual Doses to the Liver due to Submersion in Air 

Containing Uranium Dust ............................................................ 13 

3.2.3 External doses to Liver due to Routine, Work-Related Medical XRay Examinations........................................................................... 13 

3.2.4 Other Sources of External Exposure .................................. 13 

3.3 Conclusions ........................................................................ 13 

References .................................................................................... 14 
SUMMARY 

This report presents the results of an independent audit of a dose reconstruction 

performed by the National Institute of Occupational Safety and Health (NIOSH) for an 

energy employee (Case #PIID*) that worked at the Bethlehem Steel Corporation as a 

PIID* from PIID*, through PIID*, except for military service from PIID*, to PIID* . 

This time period includes the time period (1949 to 1952) when the Bethlehem Steel 

facility in Lackawanna, New York, was under contract with the Atomic Energy 

Commission (AEC) to develop rolling mill pass schedules for the rolling of 5-inch 

natural uranium billets into 1.5-inch rods to be used in nuclear reactors. As a result of 

employment at the facility during and following the uranium rolling operations, the 

worker likely experienced internal exposures due to the inhalation of airborne particles of 

uranium oxide, and external exposure from working in the vicinity of the uranium billets, 

rods, and residual uranium. In addition, the worker is believed to have had routine x-rays 

as part of Bethlehem Steel’s medical surveillance program. The worker was not provided 

with film badge or thermoluminescent dosimeters (TLDs) to measure external exposures, 

nor were bioassays performed to estimate internal exposures. As a result, exposures 

experienced by the worker were estimated using the exposure matrix provided in the site 

profile or technical background document (TBD) prepared by NIOSH for the Bethlehem 

Steel plant (ORAUT-TKBS-0001, March 31, 2003). 

In PIID*, the energy employee was diagnosed with liver cancer. Table 1 summarizes 

the results of NIOSH’s reconstruction of the doses to the energy employee’s liver for the 

purpose of deriving the probability of causation (POC) using IREP. Table 1 also 

presents the results of the audit. The results of the audit are expressed in terms of 

whether we found the exposures to have been derived in a scientifically valid and 

claimant-favorable manner. 
 

 

 

 

 

 

 

 

 

 

Table 1. Summary of Internal and External Exposure to the Liver as Estimated by 

NIOSH, Along with the Audit Results (The values reported here are the modes of a 

triangular distribution) 

Exposure Scenario NIOSH Derived 

Annual Doses (rem) 

Scientifically 

Valid? 

Claimant 

Favorable? 

Internal exposure from inhalation (alpha) during 

operations 

About 0.2 during 

AEC operations * * 

Internal exposures from ingestion (alpha) during 

operations ND** 

Internal exposure from inhalation (alpha) of residual 

resuspended particles following the conclusion of 

operations 

ND 

External exposures during operations (PIID*) 

Ground surface contamination (chronic) ND 

Natural Uranium Source 30-250 keV (chronic) 0.10 Yes Yes 

Natural Uranium Source >250 keV (chronic) 0.11 Yes Yes 

 Submersion in airborne plume (chronic) Negligible Yes NA 

Diagnostic x-rays (acute) 0.022 Yes Not necessarily 

Chronic external exposure to residual contamination 

following the conclusion of AEC operations in 

PIID* 

ND 

* This audit reveals that there are some aspects of the methods used by NIOSH to 

reconstruct the doses to the liver of this worker that do not appear to be entirely 

scientifically valid or claimant favorable. However, since the claimant was compensated, 

our findings are of interest more from a theoretical, rather than a practical, perspective. 

** ND refers to Not Determined because the uranium dust inhalation doses alone were 

sufficient to consider the dose reconstruction complete. 
1.0 INTRODUCTION 

This report presents the results of an independent audit of a dose reconstruction 

performed by the National Institute of Occupational Safety and Health (NIOSH) for an 

energy employee that worked at the Bethlehem Steel facility in Lackawanna, New York. 

This audit is one of several dose reconstruction audits being performed by S. Cohen & 

Associates (SC&A, Inc.) on behalf of the Advisory Board on Radiation and Worker 

Health. 

This audit report makes extensive use of the findings provided in a separate report 

prepared by SC&A entitled Review of NIOSH Site Profile for Bethlehem Steel Plant, 

Lackawanna, NY (SCA-TR-TASK1-001, October 2004). The review of the site profile 

prepared by SC&A is currently being reviewed by NIOSH. We expect that NIOSH will 

provide comments on the SC&A site profile review that, upon consideration by SC&A, 

may affect the findings of this audit report. 

Part one of this audit report presents a summary of our understanding of the doses 

derived by NIOSH, along with a brief description of the basic approach and assumptions 

employed by NIOSH to derive the doses. This material is extracted directly from the final 

dose reconstruction report published by NIOSH for this case, along with supporting 

documentation, including the technical basis document for the Bethlehem Steel facility 

(ORAUT-TKBS-0001, March 31, 2003). This section of the report summarizes our 

understanding of the methods used by NIOSH to reconstruct the doses to workers, and 

also serves as a baseline for the discussion and review provided in Section 3 of this 

report. 

Part two of the audit process (provided in Section 3 of this report) consists of an attempt 

to independently reproduce doses derived by NIOSH and a discussion regarding the 

validity of the methods employed. The doses selected for review are based on the 

judgment of the auditors as to the importance of the particular doses to the totality of the 

doses experienced by the energy employee. The reason for this step in the audit process 

is to provide the author, NIOSH, and the Advisory Board with a level of assurance that 

the auditors understand how NIOSH went about deriving the doses provided in their dose 

reconstruction report. In the process of attempting to reproduce the NIOSH derived 

doses, we also provide a critical review of the fundamental data, information, models, 

and assumptions used by NIOSH to perform the dose reconstruction. This review draws 

heavily from a draft review of the TBD prepared by SC&A and submitted to the Board in 

October 2004.1

 This part of the audit explores the degree to which the data are adequate 

to support the dose reconstruction, and whether the models and assumptions adopted by 

NIOSH to perform the dose reconstruction are scientifically sound and claimant 

favorable. Areas where the methods are found to meet these criteria, or are deemed to be 

inadequate with regard to these criteria, are identified and discussed. The report is not 

exhaustive in the review of these matters, but is limited to those areas of inquiry that are 

judged by the reviewers to be significant with respect to the dose reconstruction and the 

derivation of the probability of causation (POC). 
 1

 SC&A’s review of the Bethlehem Steel TBD was delivered to the Advisory Board in draft form 

in October 2004. The report is entitled Review of the NIOSH Site Profile for Bethlehem Steel Plant, 

Lackawanna, NY, Contract No. 200-2004-03805, Task Order No. 1, SCA-TR-TASK1-001, October 2004. 

The Board has not yet officially accepted the report, and NIOSH has not yet had an opportunity to respond 

to the SC&A’s findings. 

Methods employed by NIOSH that are found to be either scientifically inappropriate or 

not necessarily clamant favorable are identified, but no attempt is made to correct these 

deficiencies and redo the dose calculations. It is assumed that NIOSH and the Advisory 

Board will have an opportunity to consider the results of this audit and determine whether 

a revision of the dose reconstruction is needed, and if so, how to go about making the 

necessary revisions. 

2.0 SUMMARY OF DOSES 

The energy employee worked at the Bethlehem Steel Corporation as a PIID* from PIID*, 

through PIID*, except for military service from PIID*, to PIID*. This time period 

includes the time period (1949 to 1952) when the Bethlehem Steel facility in 

Lackawanna, New York, was under contract with the Atomic Energy Commission (AEC) 

to develop rolling mill pass schedules for the rolling of 5-inch natural uranium billets into 

1.5-inch rods to be used in nuclear reactors. In PIID*, following employment, the energy 

employee was diagnosed with liver cancer. Table 2 presents the results of NIOSH’s 

reconstruction of the doses to the energy employee’s liver for the purpose of deriving the 

probability of causation (POC) using IREP. 

The notations used in Table 2 to present the doses include the year in which the dose was 

received by the organ of interest, the statistical distribution that was used, and the key 

parameters for the distribution. For example, for exposure period number 1 in Table 2 

(PIID*), internal exposure of the liver to alpha emitters is assumed to have a triangular 

distribution with a minimum of 0, a mode of 5.20E-4, and a maximum of 0.369 rem due 

to the inhalation of uranium dust. A discussion of various types of statistical distributions 

and other parameters used as input to NIOSH-IREP is provided in NIOSH (2002). The 

internal dose to the organ of interest was determined by NIOSH to have a range of 0 to 

31.8 rem, with a mode of 0.045 rem. The worker was also assumed to have an external 

photon dose of 0.27 to 1.18 rem to the liver. Based on these reconstructed doses, the 

POC was determined to be greater than 50% and the claimant was compensated. 

The final dose reconstruction report and the technical basis document (TBD) provide 

detailed descriptions of the methods and assumptions used by NIOSH to derive the doses 

presented in Table 2. As may be noted, Table 2 presents doses in terms of annual doses to 

the liver due to internal alpha exposure resulting from the inhalation, and external 

exposure from working in the vicinity of uranium billets and rods, and also from periodic 

x-ray examinations. None of the dose estimates are based on the use of dosimeters worn 

by the energy employee, such as film badges or thermoluminescent dosimeters TLDs, 

which, if used, would have provided a generally reliable method for determining external 

doses to the organ of concern. In addition, none of the dose estimates are based on 

bioassay data, such as urine or fecal analysis, or whole-body counting, which would have 
provided a generally reliable basis for estimating internal doses to most organs from the 

inhalation and/or ingestion of uranium. Instead, the doses were derived indirectly, using 

the generic methodologies described in the TBD. 
Table 2. Doses to the Liver of the Employee as Derived by NIOSH for Use as Input 

to IREP for the Purpose of Deriving Probability of Causation 

Table below has been deleted – please see hard copy #5 
3.0 INDEPENDENT REPRODUCTION AND REVIEW OF 

SELECTED 

NIOSH DERIVED DOSES 

This section presents the results of IMBA calculations that attempt to reproduce selected 

doses derived by NIOSH. In so doing, we will have confirmed that we understand how 

NIOSH performed the dose reconstruction and that the calculations are correct, given 

the models and assumptions employed by NIOSH. In the process of attempting to 

reproduce the doses, we also discuss and critically review the data, models, and 

assumptions employed by NIOSH to reconstruct the doses. 

3.1 INTERNAL DOSE FROM INHALATION 

As indicated in Table 2, the annual alpha doses to the liver were determined by NIOSH 

to build up to a peak mode of 2.82E-3 rem in PIID*, with a minimum of 0 and a 

maximum of 2 rem. After PIID*, after AEC rolling operations ceased in PIID*, the 

annual alpha doses to the liver gradually decline due to gradual clearance of the uranium 

from the liver. In this section, the annual alpha dose delivered to the liver is checked by 

reviewing the source documents and by performing IMBA calculations. 

The starting point for this analysis is a description of the rolling operations and how 

workers were exposed to airborne particles of uranium. Uranium billets were shipped to 

Bethlehem Steel by freight cars, in which the billets were stored on site until the rolling 

operations were initiated. Since the facility was fully involved in rolling steel billets, 

uranium rolling operations at Bethlehem Steel took place only on weekends. Table 1 of 

the TBD presents NIOSH’s estimate of the dates when experimental and production 

rollings took place, along with an estimate of the number of billets that were rolled. In 

general, uranium rollings occurred on weekends, and during the week, the workers 

returned to their normal activities, which involved rolling steel billets. 

During the rolling operations, airborne uranium dust was generated primarily as a result 

of the oxidation and flaking of uranium particles as the billets were processed through the 

rollers. NIOSH performed a review of uranium dust loading measurements made at the 

Bethlehem Steel facility and another similar facility, Simonds Saw. Based on a review of 

these air-sampling data, NIOSH concluded that the amount of air-sampling data was very 

limited, making it difficult to construct a reliable characterization of the airborne uranium 

dust concentrations at the facility as a function of time and work location. Because of 

these uncertainties, NIOSH elected to construct two alternative distributions of the 

airborne uranium dust concentrations at the Bethlehem Steel facility. One distribution 

was considered a lower-bound estimate of the range of dust loadings throughout the 

facility, and the other was considered an upper-bound estimate of the uranium dust 

loadings throughout the facility. The lower-bound distribution was used as a basis for 

quickly determining whether a claimant should be compensated; i.e., if the reconstructed 

doses using the lower-bound distribution were determined to be compensable, the 

analysis was considered complete. However, if the use of the lower-bound distribution 
 

 

 

 

 

 

yielded doses that were not compensable, then the upper bound distribution was used as 

the basis for rejecting a claim. 

The dose reconstruction undergoing review in this report is for a worker whose claim was 

granted. As a result, the focus of attention of this review is the lower-end radionuclide 

concentration distribution employed by NIOSH, as provided in Table 2a of the TBD, and 

which is reproduced here as Table 3. 

Table 3. Internal Exposure Matrix - Lower Bound 

(Reproduced from Table 2a of the TBD) 

Work 

period Air Concentration (dpm/m3) Breathing Rate (m3/hr)* Hours Annual Intake (pCi)

 Min Mode Max Light/heavy Min Mode Max 

PIID* 0 140 4,900 1.2/1.7 120 0 9.16E3 4.54E5 

PIID* 0 140 4,900 1.2/1.7 120 0 9.16E3 4.54E5 

PIID* 0 140 4,900 1.2/1.7 130 0 9.93E3 4.92E5 

PIID* 0 140 4,900 1.2/1.7 110 0 8.40E3 4.17E5 

* The breathing rate of 1.2 m3/hr was used to calculate the minimum and mode 

intake. The breathing rate of 1.7m3/hr was used to calculate the maximum intake. 

As an example, the uranium inhalation of 9.16E3 pCi for 1949 was derived as follows: 

(140 dis/min per m3)/(60sec/min) = 2.33 dis/sec per m3 = 63 pCi/m3 

(63 pCi/m3)(1.2 m3/hr)(120 hr/yr) = 9072 pCi/yr 

This value does not exactly match the value in Table 3, but the difference is small and 

it is not considered necessary to further evaluate the reasons for the difference. 

In the TBD, NIOSH explains that the assumptions used to derive the above inhalation 

rates are reasonable because the values represent the lowest, mode, and maximum values 

observed at Bethlehem Steel. However, as described in Section 3.3 of the SC&A review 

of the TBD, we have some concerns with the selection of a triangular distribution for the 

data set, and we believe there are some air samples that were higher than the maximum 

value selected by NIOSH. Nevertheless, since the low-end table is not used to deny 

compensation, these concerns are not important to the audit of this case. On the other 

hand, the number of hours of exposure per year is conservative. For example, Table 1 of 

the TBD indicates that in PIID* and PIID*, there were only 6 and 7 days of rollings, 

respectively. Assuming 10 work hours per day, this would correspond to 60 and 70 hours 

of exposure per year, as opposed to the work hours employed in the TBD (i.e., the TBD 

assumed exposure durations that were approximately twice these values). For the 

purpose of deriving doses to the liver, it was assumed that the uranium was Absorption 

Type M, and the particle size of the airborne dust was assumed to have an AMAD of 5 

micron. These assumptions are claimant favorable. 

Table 2 of this report, which was reproduced directly from the dose reconstruction 
 

 

report, presents the annual alpha doses to the liver for each year as a result of these 

inhalation rates and modeling assumptions. Our independent analysis using IMBA and 

the intake rates in Table 1 of the TBD agrees with the doses provided in Table 2 of this 

report. 

3.2 EXTERNAL EXPOSURES 

NIOSH estimated the external dose using the TBD. Three sources of external exposures 

were explicitly considered, including (1) external exposure to the metallic uranium 

feedstock and rods prior to, during, and following rolling; (2) annual x-ray exposures 

employed as part of the medical surveillance program; and (3) external exposure due to 

submersion to airborne uranium dust. Table 4 summarizes these doses as reported in the 

NIOSH dose reconstruction report. The TBD also estimated the skin and shallow dose, 

but these exposures do not apply to exposure to the liver and are not addressed here. 

Table 4. Summary of External Photon Exposures to the Liver as Reported by 

NIOSH 

Source of Exposure Approximate Annual Organ Doses to Photons (rem) 

Minimum Mode Maximum 

Uranium sources (30-250 keV) 0.01 0.1 0.1 

Uranium sources (<250 keV) 0.06 0.11 0.11 

X-rays 0 0.022 0.086 

Submersion Negligible (<1 mrem) 

This section attempts to reproduce these values and then discusses the degree to 

which these estimated doses are scientifically robust and claimant favorable. 

3.2.1 External Exposures to Uranium Sources 

The external exposure to the liver from external uranium sources were derived by NIOSH 

by assuming the worker was exposed to a semi-infinite plane source of natural uranium. 

The TBD sites several references as the basis for deriving the deep photon dose from this 

exposure setting. Citing reports by Coleman et al. 1983 and U.S. Army 1989, the TBD 

estimated a deep dose rate of 2 mrad/hr at a depth of 1,000 mg/cm2 (i.e., 1 cm depth 

dose). NIOSH further assumed that the 2 mrad/hr deep dose rate from the uranium 

source is evenly divided between photons with energies E=30-250 keV and E=>250 keV, 

and that the exposure orientation was anterior-posterior. 

The TBD also cites a report by U.S. AEC 1948b as the basis for assumptions regarding 

exposure time and distance. For the mode, NIOSH assumed the worker was located 1 

meter away from the extended source for 1 hour per 10-hour work shift. For the 

maximum dose, NIOSH assumed the worker was located 0.3 meters from the source for 6 

hours per shift and 1 meter for 4 hours per shift. Based on Table 2b of the TBD, the 

worker is assumed to work about twelve 10-hour shifts per year, and that external 

exposures only occurred during these time periods. 
Based on the above assumptions, the liver doses can be reproduced as follows: 

(2 mrad/hr)(120 hrs/yr)(0.001 rem/mrem)(0.748)/2 + (2 mrad/hr)(120 hrs/yr)(0.001) 

rem/mrem)(0.886)/2 = 0.09 + 0.106 = 0.196 rem/yr 

This value is in close agreement with the value reported by NIOSH for the mode. 

As a means of checking on the 2 mrad/hr 1 cm absorbed dose rate, we ran 

MicroShield to determine the dose rate at a point 1 meter away from an effectively 

infinite slab of natural uranium metal with its short-lived progeny in equilibrium. The 

result of the analysis is a dose rate of 2 mrad/hr, in total agreement with the value 

reported in the TBD. 

With respect to the exposure distances and durations, these certainly appear to be 

claimant favorable, unless the uranium was stored in the immediate vicinity of the 

workers while they were rolling steel during the intervening work week. However, 

there is no indication in the literature that this was the case. Accordingly, it certainly 

appears that the methods used by NIOSH to estimate the liver dose to workers from 

external sources of uranium is scientifically valid and claimant favorable. 

3.2.2 External Annual Doses to the Liver due to Submersion in Air Containing 

Uranium Dust 

NIOSH concluded that this dose was negligible (below 1 mrem/year), and our analysis 

revealed the same result. 

3.2.3 External doses to Liver due to Routine, Work-Related Medical X-Ray 

Examinations 

The 0.022 rem annual dose to the liver from medical examinations of workers at 

Bethlehem Steel, as estimated in the TBD, is somewhat higher than the value of 9.02E-2 

rem for pre-1970 PA x-rays provided in Table 4.0-1 of ORAUT-OTIB-0006 (we are not 

quite sure of the reasons for the small difference between the TBD and the values in 

ORAUT-OTIB-0006, but the differences are too small to be of significance). However, 

in accordance with the guidance provided in ORAUT-OTIB-0006, lacking information 

to the contrary, it would have been more claimant favorable to assume that at least some 

examinations included photofluorography, because such examinations were a matter of 

standard practice prior to 1960. Table 4.0-1 recommends a default pre-1970 

photofluorographic entrance kerma dose of 3,000 mrem, with a corresponding liver dose 

of 0.135 rem per photofluorograph. If the worker had, in fact, received some 

photofluoroscopic examinations, the annual doses to the organ of interest would have 

been substantially greater than the values employed in the dose reconstruction. 
3.2.4 Other Sources of External Exposure 

NIOSH did not address other potential sources of external exposure, such as exposure to 

uranium deposited on surfaces during rollings, in between rollings, and following the 

completion of rollings. However, since the exposures that were explicitly addressed by 

NIOSH were sufficient to result in a probability of causation in excess of 50%, no 

additional analysis was needed. 

3.3 CONCLUSIONS 

We have found that the dose reconstruction is reasonable and appropriate for 

efficiently determining that the worker’s cancer is compensable. 

REFERENCES 

NIOSH 2002, “NIOSH-Interactive Radioepidemiological Program (NIOSH-IREP) 

Technical Documentation,” Final Report. June 18, 2002 

ORAUT-TKBS-0001, Technical Basis Document: Basis for Development of an Exposure 

Matrix for Bethlehem Steel Corporation. March 31, 2003.