SC&A RESPONSE TO NIOSH WHITE PAPER FOR GSI APPENDIX BB REVIEW

 Prepared by

 Robert Anigstein 

S. Cohen & Associates 

November 8, 2008 

On October 31, 2008, NIOSH issued a report titled “White Paper for GSI Appendix BB 

Review.” The white paper updates the analyses originally presented in Battelle-TBD-6000 

(Scherpelz 2006), as well as “Appendix BB: General Steel Industries” (Allen and Glover 2007) 

to that report. The white paper addresses two principal topics. One is the use of film badge 

dosimetry data to revise the exposure matrix for workers at the General Steel Industries (GSI) 

steel foundry at Granite City, IL, during the covered period of January 1, 1953 to June 30, 1964. 

The second is a critical review of the SC&A (2008) review of Appendix BB, first issued on 

March 17, 2008, with corrected pages issued on March 20, and a redacted version, cleared under 

the Privacy Act, issued on April 21. 

Review of Film Badge Dosimetry Data 

We have performed a limited review of the NIOSH analysis of the film badge dosimetry data 

obtained from Landauer, the vendor who supplied and processed the film badges. The dosimetry 

records furnished to us by NIOSH begin with a summary report for the first 3 months of 1964. 

This is followed by the first weekly report for the week that begins on Monday, January 6, 1964. 

There are presumably 130 weekly reports that span the period from January 6, 1964 to June 30, 

1966, the end of covered activities. Each weekly report includes a control badge that is not 

assigned a badge number. This badge is normally stored in a location away from, or shielded 

from, any radiation sources. It is used to check on any accidental exposures of the badges for 

that week before they were issued to the monitored individuals or after they were retrieved from 

these individuals. Badge 1 is named “Betatron Ctl.” 

According to our observation of the film badge reports, as confirmed by a former official of 

Landauer, each badge number is unique to the monitored individual. An examination of the 

reports for the covered period at GSI shows the highest assigned badge was number 93. Thus, 

there were at most 92 monitored individuals during this period.1 

According to the dosimetry reports, the program began in November 1963. However, no reports 

were furnished for the weeks prior to January 6, 1964. As it happens, the film badge dosimetry 

program began at approximately the same time that the new betatron was installed at the GSI 

Granite City foundry. According to the white paper, 6,999 badge readings were recorded 

through June 30, 1966.2 The vast majority of these readings were reported as M, meaning that 

1 It is possible that the actual number was smaller, since some badges may never have been assigned to any 

workers. 

2 The authors of the white paper mistakenly interpreted the first quarterly report as a report for the week 

beginning January 1, 1964. They may have thus added these results to the total. 

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the results were below the reporting level of 10 mrem.3 According to NIOSH, there are only 22 

reported readings of 10 mrem or greater (all values are reported in increments of 10 mrem). 

Because the PDF files containing the optically scanned reports furnished by NIOSH are of 

limited legibility (a number of the 1964 reports are totally illegible), we were not able to 

completely reproduce the NIOSH analyses of these data. We were able to perform a somewhat 

limited analysis, however, primarily based on the cumulative doses reported for each individual 

at the end of various monitoring periods. We did confirm that 22 individuals received 

cumulative doses of 10 mrem or greater during the covered period. We also determined that at 

least one individual received his dose during two or more separate weeks. In another case, a 

badge number first appears on the report for a given week, with no name and a 1-week dose of 

M. No cumulative doses are listed for any badge in that report. The same entries for this badge 

number appear on the reports for the next two weeks. The report for the following week lists a 

name for this badge number, but a blank field appears in place of the 1-week dose. The next 

week the individual has a 1-week dose of M, but a cumulative dose of 40 mrem for the calendar 

quarter, which is listed as the permanent lifetime dose on later reports on this worker. 

Consequently, based on this one individual, there is some question about the relevance of the 

reported cumulative doses to exposures at GSI. 

According to the white paper, 89 individuals were monitored during the covered period. This is 

consistent with our observation that there were 92 badges, not including the betatron control, 

some of which may never have been assigned to individual workers. If this total is correct, we 

agree that 67 of these workers may not have received any recorded dose, since we found only 22 

individuals with such doses. Our observation is based on spot checks of cumulative doses at 

various times, and may not include workers who were removed from the monitoring program 

between such times. 

The white paper attempted to apply several statistical methods to the dosimetry data. In the one 

that was finally adopted, the authors assigned a dose of 10 mrem to every reading reported as M. 

They then calculated an average weekly dose for each of these individuals. Since only 10 

monitored workers received doses greater than 10 mrem, the 79 other workers were assigned 

average weekly doses of 10 mrem. We calculated the maximum average weekly dose of the 

workers to be approximately 35 mrem. 

The authors of the white paper calculated a mean weekly dose to the 89 workers of 10.35 mrem 

(listed as mr in the white paper) with a standard deviation of 2.75 mrem.4

 They then use these 

values to estimate a 95th percentile weekly dose of 14.87 mrem. We have reproduced the 

calculated values of the mean and the standard deviation. However, we note that the calculation 

of the 95th percentile dose is valid only for data that has a normal distribution. 

3 In some cases, the field for reporting the weekly reading is blank. We do not know if these blank fields are 

included in the 6,999 reading cited by NIOSH. 

4 The dosimetry data is reported by Landauer in units of mrem, which is how the film badges were calibrated. 

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y = 0.8358x + 10.338 

R2

 = 0.0958 

0 

5 

10 

15 

20 

25 

30 

35 

40 

Dose (mrem) 

Dose 

95th Percentile 

Regression Line 

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 

Normal Score 

3 

SC&A Analysis of Film Badge Dosimetry Data 

To determine the goodness of fit of the data to a normal distribution, we constructed a normal 

score plot of the average weekly doses to the 89 individuals, as calculated by NIOSH. This plot 

is shown in Figure 1. The horizontal axis in this figure is the normal score or z-score, which 

measures the number of standard deviations the value is from the center of the distribution. The 

assigned values form a horizontal line at 10 mrem. The regression line fits closely to these 

values, due to the large leverage of values on the left side of the figure. The extreme high value 

on the right lies far from the regression line in this case. The red vertical line marks the location 

of the 95th percentile. 

The R2

 for this regression is 0.096, indicating that the normal distribution provides a very poor fit 

to the distribution of values. In this case, a large majority of the data points lie close to the 

regression line, but the normal distribution provides a poor fit to the values in the upper tail of 

the distribution. 

Figure 1. Normal Score Plot of Average Weekly Doses to Individuals 

We next tried to fit a lognormal distribution to the same data, as shown in Figure 2. The R2

 for 

this regression is 0.115, which indicates that the lognormal distribution is a slightly better fit than 

the normal. However, neither fit satisfy the criterion specified by Brackett (2005) in OTIB-0019: 

“A value [of R2

] greater than 0.9 indicates a very good fit; however, values as low as 0.7 are 

acceptable, and even lower values may be acceptable if no better equation seems appropriate.” 

Values of 0.096 or 0.115 are completely outside the acceptable range. This is despite the fact 

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y = 0.0461x + 2.3218 

R2

 = 0.1151 

2 

2.5 

3 

3.5 

4 

Log dose (mrem) 

Dose 

95th Percentile 

Regression Line 

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 

Normal Score 

3 

 

that a rank-ordered data, such as those used to construct these plots, yield an R2 with an inherent 

upward bias. Consequently, neither an assumed normal nor a lognormal distribution appear to 

constitute a scientifically valid basis for assigning doses to GSI workers. 

Figure 2. Lognormal Score Plot of Average Weekly Doses to Individuals 

NIOSH Review of SC&A Report on Appendix BB 

Location of Betatron Operator 

In their review of the SC&A (2008) report on Appendix BB, the authors of the white paper point 

out inconsistencies which they have perceived in our analyses. The first perceived inconsistency 

is the location of the betatron operator in between radiographic exposures.5 In calculating the 

exposure to residual radiation from the betatron apparatus, we assumed that, during the short 

shots, in which the betatron target was 6 ft from the casting, the worker was at a fixed distance of 

3 ft—halfway between the internal betatron target and the casting—while during the long shots, 

in which the betatron was 9 ft from the casting, the worker moved over a range of 3–6 ft from the 

target. Although the actual movements of the operator were certainly more complex than 

represented by this simple model, we believe these to be reasonable, upper-bound assumptions. 

However, in calculating the radiation from the activated metal, we followed NIOSH/OCAS 

procedures regarding the distance from the metal. In OTIB-0004, Anderson and Bloom (2006) 

5 There were a number of betatron operators employed by GSI during the covered period. The betatron 

operator discussed in this report is a hypothetical construct used to model bounding exposures—it does not represent 

any actual individual. 

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provide guidance for estimating the maximum plausible dose to workers at Atomic Weapons 

Employers (AWEs). These authors assume that the worker is exposed for 8 h/d to uranium metal 

in the anteroposterior (AP) orientation at a distance of 1 ft. In Battelle-TBD-6000, Scherpelz 

(2006) recommends that an operator be assumed to spend 8 h/d at 1 ft from the metal, while a 

general laborer spends 8 h/d at a distance of 1 m. In Appendix BB, Allen and Glover (2007) 

assumed that the betatron operator spent one-half of the setup time at 1 ft from the metal and the 

other half at 1 m. We retained the last assumption in our original analysis. 

While we certainly agree that the assumptions we used in calculating the exposures from the two 

sources appear to be inconsistent, they are not illogical. The assumptions about the distance 

from the betatron are reasonable and claimant favorable and should not be changed, absent more 

precise information. Changing the distance from the metal would make the dose reconstructions 

inconsistent with those used for other AWEs, raising issues of fairness. We wish to emphasize 

that our analyses represent bounding calculations—if the distances from the metal are reasonable 

for other AWEs, they should be also used in these instances. 

However, the results of our analyses render these issues moot. As discussed in our report, the 

limiting weekly exposure is of a betatron operator exclusively occupied with radiographing steel. 

His exposure, based on a time-weighted average of long and short shots, is 33.5 mR/shift from 

all sources. If the exposure from the activated metal were completely ignored in the calculation, 

his exposure would be reduced to 33.0 mR/shift. Thus, if the exposure to the steel were 

recalculated to account for greater distances, the exposure would be between 33.0 and 

33.5 mR/shift, an insignificant difference from the original calculation. 

The distance from the metal takes on special significance in calculating the doses from beta 

radiation to the skin and other superficial organs. In these cases, the assumption that the worker 

was at a greater distance from the metal, even if it placed him nearer to the betatron, may not be 

claimant favorable. Since we do not know a priori which organs will be the targets of dose 

reconstructions, it is not possible to definitively state which worker location would be most 

claimant favorable. We therefore suggest that the apparently inconsistent positions are not 

unreasonable. 

Time of Onset of Exposure to Residual Radiation from Betatron 

The authors of the white paper take issue with our calculation of the time-integrated exposure to 

the residual radiation from the betatron, claiming that the assumption that the exposure starts at t 

= 0 is inconsistent with the calculation of the exposure to the activated metal, which starts 5 s 

after the beam is turned off. The reason for this apparent discrepancy is that the initial exposure 

rate of 15 mR/h at a distance of 6 ft from the betatron target, reported by Schuetz (2007), was 

measured under conditions similar to those experienced by the betatron operator. As stated in 

section 2.2.3 of our report, “[he] estimated . . . that [the] initial reading was taken within 5–10 s 

after the beam was turned off.” Consequently, the initial exposure rate corresponds to the 

moment the operator reached the betatron, so no additional decay time needs to be considered. 

In the case of the activated metal, the exposure rates are based on MCNPX simulations, which 

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begin at the moment the beam is turned off; therefore, the 5-s delay, which allows time for the 

operator to reach the casting, is appropriate in that case. 

Railroad Track Exposure Scenario 

The white paper questions the applicability of the scenario in which the casting was radiographed 

while on the railroad track and the limit switches on the betatron were overridden by reversing 

the head of the instrument. As stated in the white paper: 

The operators went on to indicate that this was not done until the supervisor 

present in the early 1960s left the company and was replaced by another. This 

supervisor left the company on 6/30/1966 which is the last day of the uranium 

work. This information indicates the railroad shots occurred after the covered 

period. 

Although this supervisor did in fact remain at GSI until 1966, he had been promoted and moved 

to another division not involved with betatron operations at an earlier time. According to the 

workers interviewed at the meeting in Collinsville, IL, on October 9, 2007, a later supervisor 

ordered the betatron operator to override the limit switches. The Landauer film badge dosimetry 

reports for 1964 list the name of the earlier supervisor on weekly reports through the week of 

November 9. No listing of his name was found on any later report. Thus, it appears most likely 

that he was transferred to his new position by the end of that week, if not sooner. Having been 

issued a film badge, it is highly unlikely that he would continue being involved with betatron 

operation but not be monitored. Furthermore, the name of the later supervisor is first found on 

the report for the week of January 4, 1965. However, that report indicates that there were nine 

previous reports for this individual, beginning in November 1964. Thus, it would appear he 

started work in the betatron at about the same time the previous supervisor left that facility. 

Therefore, the practice modeled in our scenario may have taken place during at least part of the 

covered period (i.e., November 1964–June 30, 1966). 

Output of Old Betatron 

The next issue raised in the white paper concerns the output of the old betatron. The authors are 

incorrect in stating that “SC&A used a betatron output of 250 R/min from both the new and old 

betatron machines.” As stated in section 2.1.3 of our report, we used MCNPX to calculate the 

electron beam current in the new betatron, based on a beam energy of 25 MeV and an output of 

250 R/min. We then assumed the same current for the old betatron, which operated at 24 MeV, 

and used MCNPX to calculate the resulting photon and neutron emissions. These emissions are 

lower due to the lower beam energy. We recognize that the old betatron may have had a lower 

beam current. However, since the beam current of the old machine is not known and the actual 

exposure rate was not well documented and changed over the years of operation at GSI, we made 

the claimant-favorable assumption that the beam current was the same as in the new machine. 

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Different Assumptions for Beta and Photon/Neutron Dose Calculations 

The white paper discusses an apparent inconsistency between the calculation of doses from beta 

rays and from photons and neutrons. The authors are correct in stating that the beta dose 

calculations took account of the uranium radiography, while the photon and neutron dose models 

did not. This apparent discrepancy is resolved in sections 2.6.2 and 3.2.9 of our report. As 

stated in the former section: “Since the Mallinckrodt purchase orders specified that the work 

was to be performed on the day shift Monday through Friday, we assume that the same operator 

could have performed all the uranium radiography during a given year.” As stated in section 

3.2.9: “Since we calculated a slightly higher exposure per shift for the radiography of steel than 

of uranium, the frequency of uranium radiography does not affect the maximum annual 

exposure, which we assumed to be that of an operator on the evening or night shift, when no 

uranium radiography was supposed to take place.” Thus, the beta dose was to a worker on the 

weekday day shift, while the photon and neutron doses were to a worker on the evening or night 

shift. Depending on the organ in question, either the beta dose or the photon and neutron doses 

predominate; therefore, both scenarios are needed to perform a claimant-favorable dose 

reconstruction. 

Verification of Rounded Values of Exposures to Uranium 

The final comment in the white paper is on the exposure to uranium listed in table 16 in our 

report. The white paper cites the incorrect value of 0.66 mR/shift listed in the original March 17 

version of our report. This error was due to a faulty link between the table and an Excel 

workbook, which we detected and corrected in an errata sheet sent out on March 20. The correct 

value is 6.8 mR/shift, as stated in our corrected report. The authors of the white paper attempted 

to calculate the exposure rate using the values listed in tables 8 and 9 of our report, and arrived at 

6.56 mR/shift. The values listed in tables 8 and 9 were rounded to two significant figures so as 

not to imply a high degree of precision to our model, while table 16 displays all values with one 

decimal place; however, the actual calculation is based on the precise values. In the following 

verification, we show the values rounded to two decimal places: 

r + r + r + r 11 12 21 22 R = u 2 

RU = total exposure to irradiated uranium
 

= 6.78 mR/shift 

r11 = exposure to delayed radiation from irradiated uranium at 1 ft 

= 11.46 mR/shift 

r12 = exposure to delayed radiation from irradiated uranium at 1 m 

= 1.38 mR/shift 

r21 = exposure to aged natural uranium at 1 ft 

= 0.64 mR/shift 

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r22 = exposure to aged natural uranium at 1 m
 

= 0.08 mR/shift 

As can be verified from the above data, the rounded value of 6.8 mR/shift was correctly 

calculated. 

Conclusions 

As stated in our original report, the calculations of exposures and doses to betatron operators and 

other workers are bounding estimates. The film badge data indicate that, with two exceptions, 

the maximum dose during any one week is less than that predicted by our models. However, 

workers other than radiographers do not appear to have been issued film badges. Furthermore, it 

is not clear that workers using the 60Co source in number 6 building wore film badges. That 

source was in use from at least 1951 (see footnote 5 on page 7), whereas the Landauer film 

badge program did not begin until November 1963. 

Some of these issues are discussed in the SEC petition evaluation report for GSI (Buker et al. 

2008). We read but did not formally review this report. 

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References 

Allen, D., and S. Glover. 2007. “Site Profiles for Atomic Weapons Employers that Worked 

Uranium and Thorium Metals - Appendix BB: General Steel Industries,” Battelle-TBD-6000, 

Appendix BB, Rev. 0. http://www.cdc.gov/niosh/ocas/pdfs/tbd/b-6000-apbb-r0.pdf 

Anderson, J. L., and C. W. Bloom. 2006. “Estimating the Maximum Plausible Dose to Workers 

at Atomic Weapons Employer Facilities,” ORAUT-OTIB-0004, Rev. 03 PC-2. 

http://www.cdc.gov/niosh/ocas/pdfs/tibs/or-t4-r3-p2.pdf 

Brackett, E. M. 2005. “Analysis of Coworker Bioassay Data for Internal Dose Assignment,” 

ORAUT-OTIB-0019, Rev. 01. http://www.cdc.gov/niosh/ocas/pdfs/tibs/or-t19-r1.pdf 

Buker, L., R. Clark, M. Domal, and J. Guido. 2008. “SEC Petition Evaluation Report: Petition 

SEC-00105," Rev 0. http://www.cdc.gov/niosh/ocas/pdfs/sec/gsi/gsier.pdf 

Scherpelz, R. 2006. “Site Profile for Atomic Worker Employers that Worked Uranium and 

Thorium Metals,” Battelle-TBD-6000, Rev. F0. http://www.cdc.gov/niosh/ocas/pdfs/tbd/bat6000-r0.pdf 

Schuetz, J. G. 2007. Letter report to Samuel Glover, NIOSH/OCAS, May 1, 2007.6 

S. Cohen & Associates (SC&A). 2008. “Review of ‘Site Profiles for Atomic Weapons 

Employers That Worked Uranium and Thorium Metals - Appendix BB: General Steel 

Industries,’ Battelle-TBD-6000, Appendix BB, Rev. 0.” 

http://www.cdc.gov/niosh/ocas/pdfs/abrwh/scarpts/scagsireview.pdf 

6

 Mr. Schuetz was under contract with NIOSH for this project. 

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