SEC Petition Evaluation Report 

SEC-00012-2 

Report Rev # Draft 2 Report Submittal Date __________ 

Petition Administrative Summary 

Petition Under Evaluation 

Petition # Petition 

Type 

Submittal Date DOE/AWE Facility Name 

SEC-00012 83.13 07-21-2004 Mallinckrodt 

Feasible to Estimate Doses with Sufficient Accuracy? 

Single class Multiple classes Determination Established for All Classes? 

Yes No Yes No X Yes No X 

Initial Class Definition 

The entire uranium division of Mallinckrodt Chemical Works (1942-1957) 

Proposed Class Definitions (Abbreviated) 

(1) All Department of Energy (DOE), DOE contractors, or subcontractors, or Atomic Weapons Employer 

(AWE) employees who worked in the Uranium Division at the Mallinckrodt Destrehan Street facility during 

the period from 1946 through 1948. (2) All DOE, DOE contractors, or subcontractors, or AWE employees who 

worked in the Uranium Division at the Mallinckrodt Destrehan Street facility during the period from 1949 

through 1957. 

Related Petition Summary Information 

SEC Petition Tracking #(s) Petition Type DOE/AWE Facility Name Petition Status 

NA NA NA NA 

Related Evaluation Report Information 

Report Title DOE/AWE Facility Name 

SEC Petition Evaluation Report SEC-00012-1 Mallinckrodt 

Lead Technical Evaluator: Signature on File 

LaVon B. Rutherford Date 

Peer Review Completed By: Signature on File 

James W. Neton Date 

SEC Petition Evaluation Approved By: Signature on File 

Larry J. Elliott Date 
 

Evaluation Summary 

This evaluation report by the National Institute for Occupational Safety and Health (NIOSH) covers a 

subset of the employees proposed as a class for addition to the Special Exposure Cohort (SEC) in SEC 

Petition No. 12, qualified on November 24, 2004. Although the petition requested NIOSH to consider 

all workers within the Uranium Division at the Mallinckrodt Destrehan Street facility in St. Louis, 

Missouri, over the entire period of operation from 1942 through 1957, this evaluation is limited to 

those Uranium Division employees working from 1946 through 1957. An evaluation of workers 

employed from 1942 through 1945 has been performed and documented in SEC Petition Evaluation 

Report SEC-00012-1. The current evaluation addresses all Uranium Division workers including those 

employed directly or under contract by the Manhattan Engineering District /Atomic Energy 

Commission (MED/AEC) for radioactive material processing or for research. 

This evaluation report addresses the feasibility of estimating radiation doses with sufficient accuracy 

(i.e., the feasibility of dose reconstruction) and the evidence concerning the possible health 

endangerment for members of two classes that cover the 1946-1957 time period. As discussed below, 

these two factors, the feasibility of dose reconstruction and health endangerment, govern decisions by 

the Department of Health and Human Services (HHS) on whether or not to designate a class of 

employees for addition to the SEC and the definition of such classes. 

Feasibility of Dose Reconstruction 

The feasibility determination for the class of employees covered by this evaluation report is governed 

by 42 C.F.R. § 83.13(c)(1). Under this regulation, NIOSH must establish whether or not it has access 

to sufficient information to either estimate the maximum radiation dose that could have been incurred 

under plausible circumstances by any member of the class, or to estimate the radiation doses of 

members of the class more precisely than a maximum dose estimate. If NIOSH were to have access 

to the information sufficient for either case, then dose reconstruction would be feasible. 

NIOSH has established in this evaluation that it does not have access to sufficient information to 

estimate the maximum radiation doses incurred by employees of Mallinckrodt working during the 

period from 1946 through 1948. NIOSH has queried all recognized and currently known sources of 

data concerning the operations at the facility. The majority of the data identified is summarized in 

NIOSH’s Technical Basis Document (TBD) for the facility, Technical Basis Document: Basis for 

Development of an Exposure Matrix for the Mallinckrodt Chemical Company St. Louis Downtown 

Site, St. Louis, Missouri, Period of Operation: 1942-1958. There are limited workplace and worker 

monitoring data available for the 1946-1948 period, prior to the establishment of a formal health 

physics program, and some of the worker monitoring data are documented as unreliable. 

Furthermore, NIOSH has reviewed documents that raise serious questions concerning the integrity of 

the handling and reporting of monitoring data at Mallinckrodt. These circumstances, taken together, 

do not provide NIOSH with reasonable means to validate dose estimates based on monitoring data. In 

addition, although NIOSH has substantial information on radiological sources and processes during 

this period at Mallinckrodt, the variety of these sources and the diversity of processes involving these 

sources limit the ability of NIOSH to use this information, independently of monitoring data, to 

estimate maximum doses for employees who worked during the time period. As a result, NIOSH 

finds that it is not feasible to estimate doses to employees at Mallinckrodt with sufficient accuracy 

from 1946 through 1948, and proposes establishing a class comprising employees of this time period. 

2
 
NIOSH has defined a separate class of employees covering those who worked at Mallinckrodt from 

1949 through 1957, for which the scope and variety of monitoring data differ substantially from those 

of the earlier period. Beginning in 1949, Mallinckrodt established an operational program of radiation 

monitoring of employees and of work areas. This monitoring program was conducted with oversight 

from the Atomic Energy Commission’s Health and Safety Laboratory (HASL), which possessed 

recognized expertise in monitoring radiation exposure in the workplace. Moreover, there is sufficient 

information from the various monitoring activities, together with information on radiological sources 

and processes, to validate dose estimates. This ability to validate dose estimates using independent 

data, and the substantial extent of the radiological source, process, and monitoring data available, 

would ordinarily provide assurance that NIOSH dose reconstructions would provide reasonable 

estimates of dose for the purposes of the Energy Employees Occupational Illness Compensation Act 

(EEOICPA), as provided for under 42 C.F.R. pt. 82 and NIOSH internal procedures for implementing 

its dose reconstruction program. On the other hand, any documentation that raises questions 

concerning the integrity of data management or reporting at Mallinckrodt helps sustain the lack of 

credibility accorded by the Mallinckrodt claimant population to the government concerning the 

employees’ radiological exposures at Mallinckrodt and concerning the dose reconstruction program 

under EEOICPA. For this reason, although NIOSH believes that it has a sufficient scientific and 

technical basis to estimate radiation doses incurred by employees of Mallinckrodt working from 1949 

through 1957, NIOSH has not decided whether or not its basis for dose reconstruction is viable for the 

purposes of this compensation program. NIOSH will, however, seek advice from the Advisory Board 

on Radiation and Worker Health (“the Board”) concerning this matter. Specifically, NIOSH will ask 

the Board to provide advice on how to weigh the scientific and technical evidentiary basis in support 

of a positive feasibility determination against the evidentiary basis for concern about the integrity of 

the monitoring activities at Mallinckrodt during this late period. The Board’s advice concerning this 

and similar weight-of-the-evidence determinations involving data reliability will also be taken into 

consideration in light of the potential for such matters to arise in future Cohort petitions. 

Health Endangerment 

The health endangerment determination for the classes of employees covered by this evaluation report 

is governed by 42 C.F.R. § 83.13(c)(3). Under this regulation, if it is not feasible to estimate with 

sufficient accuracy radiation doses for members of the class, NIOSH must also determine that there is 

a reasonable likelihood that such radiation doses may have endangered the health of members of the 

class. The regulation requires NIOSH to assume that any duration of unprotected exposure may have 

endangered the health of members of a class when it has been established that the class may have been 

exposed to radiation during a discrete incident likely to have involved levels of exposure similarly 

high to those occurring during nuclear criticality incidents. If the occurrence of such an exceptionally 

high level exposure has not been established and it is not feasible to estimate radiation doses for 

members of the class, then NIOSH is required to specify that health was endangered for those workers 

who were employed for a number of work days aggregating at least 250 work days within the 

parameters established for the class or in combination with work days within the parameters 

established for one or more other classes of employees in the SEC. 

The NIOSH evaluation did not identify any evidence from the petitioners or from other resources that 

would establish that either of the classes defined above were exposed to radiation during a discrete 

incident likely to have involved exceptionally high level exposures, as described above. NIOSH is not 

aware of any report of such an occurrence at the facility. Evidence presented by the petitioner and 

3
 
 

obtained by NIOSH characterizes the hazard as episodic inhalations of radionuclides that cumulatively 

resulted in chronic exposures. NIOSH has determined that it is reasonably likely that such exposures 

may have endangered the health of Mallinckrodt workers covered by the proposed class definitions 

provided in section 9.0 of this evaluation. Consequently, NIOSH has specified that health was 

endangered for those workers covered by this evaluation who were employed for a number of work 

days aggregating at least 250 work days within the parameters established for these classes or in 

combination with work days within the parameters established for one or more other classes of 

employees in the SEC. 

Proposed Class Definitions 

This evaluation defines one class of employees for which NIOSH has established that it cannot 

estimate radiation doses with sufficient accuracy and whose health may have been endangered by such 

radiation doses. This class includes employees of DOE or DOE contractors or subcontractors 

employed by the Uranium Division of Mallinckrodt during the period from 1946 through 1948 and 

whom were employed for a number of work days aggregating at least 250 work days, occurring either 

solely under this employment, or in combination with work days of employment occurring within the 

parameters (excluding aggregate work day requirements) established for other classes of employees 

included in the SEC. 

The evaluation defines a second class of employees which includes employees of DOE or DOE 

contractors or subcontractors employed by the Uranium Division of Mallinckrodt during the period 

from 1949 through 1957 and whom were employed for a number of work days aggregating at least 

250 work days, occurring either solely under this employment, or in combination with work days of 

employment occurring within the parameters (excluding aggregate work day requirements) 

established for other classes of employees included in the SEC. For this class, HHS will obtain the 

advice of the Board concerning the matter of data reliability, as discussed above, as well as the advice 

of the Board as generally provided for under 42 C.F.R. § 83.15. 

This evaluation, in conjunction with SEC Evaluation Report Petition SEC-00012-1 (1942-1945), 

completes the NIOSH evaluation of SEC Petition No. 12, which covered all workers within the 

Uranium Division of the Mallinckrodt Destrehan Street facility in St. Louis, Missouri, over the entire 

period of operation from 1942 through 1957. 

In consultation with the Division of Energy Employees Occupational Illness Compensation, 

Department of Labor, NIOSH has determined that Plants 1, 2, 4, 6, and 7 are functionally equivalent 

to that portion of the Mallinckrodt Destrehan Street facility known as the Uranium Division, and has 

therefore proposed class definitions that utilize that designation. 

4
 
 

 

 

1.0 Purpose 

The purpose of this report is to provide an evaluation of the feasibility of reconstructing the doses for 

a subset of the employees proposed as a class in SEC Petition 00012 at the Mallinckrodt Destrehan 

Street facility in St. Louis, Missouri. Although the petition requested NIOSH to consider all workers 

within the Uranium Division at the Mallinckrodt Destrehan Street facility in St. Louis, Missouri, over 

the entire period of operation from 1942 through 1957, this evaluation is limited to those Uranium 

Division employees working from 1946 through 1957. An evaluation of workers employed from 

1942 through 1945 has been performed and documented in SEC Petition Evaluation Report SEC00012-1. 

This evaluation was conducted in accordance with the requirements of 42 C.F.R. pt. 83 and the 

guidance contained in NIOSH’s Internal Procedures for SEC Evaluations, OCAS-PR-004. It provides 

information and analyses germane to considering a petition for adding a class of employees to the 

SEC. It does not provide any determinations concerning the feasibility of dose reconstruction for any 

individual energy employee who might require a dose reconstruction from NIOSH. 

2.0 Introduction 

Title 42 of the Code of Federal Regulations (C.F.R.), Part 83, Procedures for Designating Classes of 

Employees as Members of the Special Exposure Cohort Under the Energy Employees Occupational 

Illness Compensation Program Act of 2000, requires NIOSH to evaluate qualified petitions requesting 

HHS to add a class of employees to the SEC. The evaluation is intended to provide a fair, sciencebased determination of whether or not it is feasible to estimate with sufficient accuracy the radiation 

doses of the class of employees through NIOSH dose reconstructions1 . If it is not feasible, the 

evaluation is further required to make a determination with respect to the health endangerment of the 

class of employees. 

NIOSH is required to document the evaluation in a report, which is provided to the petitioners and to 

the Board. The Board will consider the NIOSH evaluation report, together with the petition and any 

comments of the petitioner(s), to make recommendations to the Secretary of HHS on whether or not to 

add one or more classes of employees to the SEC. Once NIOSH has received and considered the 

advice of the Board, the Director of NIOSH will propose decisions on behalf of HHS. The Secretary 

of HHS will make final decisions, taking into account the NIOSH evaluation, the advice of the Board, 

and the proposed decision issued by NIOSH. As part of this final decision process, the petitioner(s) 

may seek a review of certain types of proposed decisions issued by NIOSH.2 

This NIOSH report provides a summary of the methods and findings of the NIOSH SEC petition 

evaluation for Uranium Division workers at the Mallinckrodt Destrehan Street facility in St. Louis, 

Missouri, during the 1946 through 1957 period of operation. The Uranium Division conducted 

radioactive material processing and related research for the MED/AEC. 

1

 NIOSH dose reconstructions under EEOICPA are performed using the methods promulgated under 42 C.F.R. pt. 82 and 

the detailed implementation guidelines available at www.cdc.gov/niosh/ocas. 

2 See 42 C.F.R. pt. 83 for a full description of the procedures summarized here. Additional internal procedures are
 

available at www.cdc.gov/niosh/ocas. 

5
 
3.0 Initial Class Definition and Petition Basis 

A Special Exposure Cohort Petition - Form B (Form B) was received from the petitioners, with 

attached supporting documentation via fax, on July 15, 2004. A supplemental fax containing four 

additional items was received on September 30, 2004. Several phone conversations were conducted 

with the petitioner for clarification purposes to ensure that the correct worker class was evaluated in 

this petition. An evaluation of the entire set of information provided in Form B and the supplemental 

fax was conducted by a health physicist assigned to the petition. This evaluation is documented and 

maintained in the project record. The information supplied by the petitioners that qualified the 

petition for further evaluation is given here: 

•	 Document A1 (Basis for Development of an Exposure Matrix for the Mallinckrodt Chemical 

Company St. Louis Downtown Site, St. Louis, Missouri, Period of Operation: 1942-1958., 

ORAUT-TKBS-0005, page 60), monitoring records may be limited or do not exist. 

•	 Document A2 (ORAUT-TKBS-0005, page 58), monitoring records may be limited or do not 

exist. 

•	 Document A3 (ORAUT-TKBS-0005, page 39-40), monitoring records may be limited or do 

not exist. 

•	 Document A4 (Mallinckrodt Chemical Works (MCW) document from petitioner’s private 

archive), monitoring records are limited or do not exist. 

•	 Document A6 (ORAUT-TKBS-0005, page 25), monitoring records may be limited or do not 

exist. 

•	 Document A7 (ORAUT-TKBS-0005, page 41-43), monitoring records may limited or do not 

exist. 

•	 Document A8 (consisted of two letters associated with Thomas F. Mancuso, MD), medical 

monitoring records may have been lost or destroyed. 

•	 Document A9 (letter from M. G. Mason to Thomas F. Mancuso, MD), monitoring records may 

have been falsified. 

•	 Document A11 (document sent to Thomas F. Mancuso, MD), monitoring records may be 

limited or do not exist. 

•	 First paragraph via fax, September 30, 2004, monitoring records may be limited or do not 

exist. 

•	 Second paragraph via fax, September 30, 2004, monitoring records may be limited or do not 

exist. 

Based upon the evaluation of the supporting documents, the petitioners for SEC Petition 00012 were 

notified that the petition “qualified” for formal evaluation on November 24, 2004. [The Federal 

Register notice was made December 20, 2004 and is located at 69 FR 75984.] The worker class 

provided by the petitioners included: 

All employees that worked in the Uranium Division at the Mallinckrodt Destrehan Street 

facility in St Louis, Missouri from 1942-1957. 

6
 
 

 

4.0 Data Resources 

NIOSH identified and reviewed data resources to determine the availability of information relevant to 

determining the feasibility of dose reconstruction for the class of employees covered by the petition. 

This included determining the availability of information on personal monitoring, area monitoring, 

industrial process, and radiation source materials. The following sections identify the resources 

identified and reviewed. 

Site Profile or Technical Basis Documents 

NIOSH reviewed portions of the site profile issued on October 24, 2003 for the facility covered by the 

petition: Technical Basis Document: Basis for Development of an Exposure Matrix for the 

Mallinckrodt Chemical Company St. Louis Downtown Site, St. Louis, Missouri, Period of Operation: 

1942-1958. The TBD provides process history information, personal and area monitoring data, 

radiation source descriptions, references to primary documents relevant to the radiological operations 

at the facility, and methods to reconstruct dose. An August 2004 draft revision of this TBD has also 

been utilized to a limited extent in this evaluation. Presentation of material or information from the 

draft revision will be appropriately cited. 

Previous Dose Reconstructions 

NIOSH reviewed its dose reconstruction database, NIOSH OCAS Claims Tracking System (NOCTS), 

to identify dose reconstruction cases under EEOICPA that might provide information relevant to the 

petition evaluation. NIOSH reviewed each case to determine whether NIOSH had been able to obtain 

internal and/or external personal monitoring records on the employee or area monitoring data that 

could be used in the place of personal data. The following table summarizes the results of that search. 

7
 
Summary of NOCTS Claims and Available Monitoring Data 

Applicable to Mallinckrodt Workers (1946-1957) 

Year 

Total 

Number of 

Claimantsb 

1946 101 1947 123 1948 128 1949 137 1950 162 1951 175 1952 180 1953 189 1954 197 1955 205 1956 222 1957 259 

Breath Radon 

# of Claimants 

Monitored 

N/A N/A 

25 29 32 74 53 72 75 38 

N/A 

1 

Urinalysis 

# of 

Claimants 

Monitored 

N/A N/A 

62 67 79 83 96 

100 109 119 

98 

112 

U Dust 

Exposure 

Recordsa 

# of 

Claimants 

records 

6 3 

7 

70 31 92 

101 

45 42 

121 

N/A 

N/A 

External 

Monitoring 

# of 

Claimants 

Monitored 

9 

33 

70 71 84 93 

101 104 108 123 

136 

136 

N/A – None Available a Based on breathing zone dust sampling measurements, results were used to calculate time weighted daily average exposu

regularly assigned employee job categories. “Number of Claimants Records” data column refers to the number of emploassigned these dust concentration exposure values based on known job duties. 

b Number of claimants with a work history in this year as of 12/04. 

8
NIOSH and ORAU Research Documents and Databases 

NIOSH and Oak Ridge Associated Universities (ORAU) site research databases were reviewed for 

documents to support the evaluation of the petitioning class. The documents identified for review 

from this search are listed in Attachment 1. They include information on dust studies, radon 

sampling, dose rate surveys, film badge records, urinalysis data, the radiological control program, 

medical monitoring, feed materials and process description information. The information from these 

documents relevant to the petitioning class is summarized in section 5.0 of this report. Monitoring 

data compiled into databases by ORAU’s Center for Epidemiological Research (CER) group were 

also reviewed. These data are also summarized in section 5.0 of this report. 

Documentation and/or affidavits provided by the Petitioners 

In qualifying and evaluating the petition, NIOSH reviewed the following documents submitted or 

referenced by the petitioners: 

1) Letter from Denise Brock (Petitioner) to the Honorable Tommy Thompson, dated July 17, 

2004. 

2) NIOSH TBD on the facility, issued October 24, 2003: (various sections of the document are 

referenced in the petition). 

3) Mallinckrodt Chemical Works, Subject: Concerning the Grouping of Death Certificate Cards 

into Exposed vs. Unexposed Groups, M. E. Mason, August 1975. 

4) Urine Samples – Mallinckrodt Chemical Works dated September 20, 1951. 

5) Letter from Knowlton J. Caplan to W. B. Harris Subject: Techniques of Radon Breath 

Sampling dated January 8, 1951. 

6) Letter from Thomas F. Mancuso to Sidney Marks concerning the possible destruction of 

Medical Records dated September 12, 1972. 

7) Interim Report: MCW Evaluation of Dust Exposure, Plant 4 and Plant 6 dated October 3, 

1972. 

8) Document untitled, undated, and unknown origin identified as “Gaps in Present State of 

Knowledge.” 

9) Mallinckrodt’s Uranium Operations for the U.S. Government: MED and AEC unknown date. 

10) Memorandum from Merril Eisenbud to W. E. Kelley dated January 31, 1951 (Cover letter to 

“An Estimate of Cumulative Multiple Exposures to Radioactive Materials”). 

11) Document entitled “An Estimate of Cumulative Multiple Exposures to Radioactive Materials” 

dated November 20, 1950. 

12) Document entitled “Some Observations on Uranium Exposures within the Nuclear Industry,” 

A.F. Becher, Consultant, ERDA Health and Mortality Study, undated. 

13) Transcript of the “Oral History of Merril Eisenbud,” United States Department of Energy 

Office of Human Radiation Experiments May 1995. 

These documents were reviewed as to the relevance to the petitioning class. The information from 

these documents relevant to the petitioning class has been summarized in sections 5.0, 6.0, and 7.0 of 

this report. 

9
 
 

5.0 Summary of Radiological Operations Relevant to the Class 

The following two subsections summarize the radiological operations at the Mallinckrodt facility. The 

focus is on the processes and source materials utilized from 1946-1957. Some information on earlier 

plant activities is also provided as an aid to following the transition into the later plant processes. To 

this end, it should be noted that although the processing history of Plants 1 and 2 have been included 

in the descriptions, work at both plants reportedly ended in late 1945 or early in 1946 time frame 

(Mason, 1977). The actual levels of activity occurring within Plants 1 and 2 in early 1946, just prior 

to their closure are relevant to this petition class but are not discussed. The short period with respect to 

the class and the activities would not have provided the maximum exposures of concern during this 

operating period. 

The principal source of information for these sections is the Mallinckrodt TBD Rev.0 and information 

obtained in developing the draft revision to the TBD. This draft revision of the TBD is a significant 

update to the initial revision and contains more detailed process and source descriptions. It presents 

available information regarding the identity and quantities of each radionuclide of concern, as well as 

information describing the process through which the radiation exposures of concern may have 

occurred and the physical environment in which they may have occurred. A detailed discussion of 

Mallinckrodt processes is discussed in Fuel for the Atomic Age – Completion Report on St. Louis Area 

Uranium Processing Operations, 1942 – 1967. 

5.1 Process Description 

The following table (from the TBD) presents a summary chronology of the radiological operations at 

the Mallinckrodt facility from 1942 – 1958. Brief plant-specific process descriptions follow. 

10
 
 

 

 

 

Summary Chronology of Operations at the Mallinckrodt St. Louis Downtown Site 

April 1942 Plant 2 was used to develop a batch process using ether to extract uranium as UO3 from milled ore and then to 

convert the UO3 to UO2. Plant 1 was used for developmental work. 

October 1942 Plant 4 was converted for use in the UO2→UF4→U metal process. The ore→UO2 operations continued in Plant 2, 

while miscellaneous activities related to R&D work continued in Plant 1. 

April 1943 Production of UF4 from UO2 began in Plant 4. 

1944 Experimental extraction of uranium using pitchblende ores began in Plant 1. 

1945 At some point in 1945 or early 1946, uranium operations at Plant 1 ceased. Plant 2 was apparently still used for 

some metallurgical-type work. Pitchblende ore began to arrive at the site in greater than research-level quantities in 

about May 1945. 

1946 Plant 6 began operation in early 1946, with all ore→UO2 production operations shifted there. Uranium operations 

at Plant 2 ceased in early 1946, the work (including UO3 milling) apparently shifting to Plant 6. Only Plants 4 and 6 

were in operation. 

1946-1947 AEC acquires SLAPS in 1946 and Mallinckrodt residues begin to be sent there for storage in about 1947. 

1947-1951 Decontamination of Plants 1 and 2, with unrestricted release to Mallinckrodt in 1951. 

1948-1949 K-65 residue is brought back from SLAPS for reprocessing. After about 1949, no more K-65 residue is sent to 

SLAPS, only low-radium residues. 

1949–1950 In 1949-1950, major improvements were made in dust control at Plants 4 and 6, with the latter shut down during 

part of 1949-1950 for this. Ore milling at Plant 6 stopped in 1950. 

October 1950 Plant 6E operations began. The UF4→U metal work shifted there from Plant 4, with the UO2→UF4 work remaining 

at Plant 4. Plant 4 was also modified for metallurgical-R&D work and became known as the Pilot Plant; some 

metal production (derbies, dingots) continued to take place there for experimental purposes. 

1951 Plant 7 operations began in the first half of 1951. At that time, some UF4 production work continued until perhaps 

1952 at Plant 4, while the UO3-to-UO2 production at Plant 6 seems to have ended completely. Instead, UO3 was 

sent to Plant 7 to be converted in a continuous process to UF4. Some recovery and storage operations also shifted to 

Plant 7. 

1952-1953 At some point, the continuous UO3-to-UF4 process began in Plant 7, after which time Plant 6 made only UO3. 

1954 The Ore Room and K-65 sampling operations in Plant 6 appear to have ended by about August 1954, possibly with 

the shipment of the last of the pitchblende ore (which would have been processed into at least 1955). It is not clear 

when the various Plant 6 pilot plant(s) began, but a 1954 start appears reasonable. Also, the Plant 6E Slag 

Separation Plant started in the first half of 1954. Some reversion of UF4 to UO2 and UO3 was done in Plant 7. 

1955 In 1955, thorium extraction from AM-7 residue began in Plant 7E and slag processing began in the Slag Separation 

Plant (Bldg. 701, part of Plant 7). Also, processing of residues to extract thorium began in early 1955 and the 

processing of a small amount of "enriched uranium" was done at Plant 7 early in 1955. Predigestion ore grinding 

ceased. Processing of high-grade pitchblende ore ceased and concentrates became the principal feed material. 

1955 or 1956 In late 1955 or early 1956, dingots began to be produced in Plant 4, with derby production only intermittent; both 

were for experimental purposes. 

Late 1956 All operations at Plant 4 ceased. 

1957–1958 In 1957, all regular site operations ceased, except for some Plant 7 activities that continued until July 1958. Other 

post processing and shutdown-related activities may have continued into 1958. 

Plant 1 

Plant 1 conducted laboratory scale developmental work for the operations in Plants 2 and 4. Processes 

were tested on a pilot scale within Plant 1 prior to the full scale operations in Plants 2 and 4. Research 

and development work on pitchblende ores (also known as Belgian Congo Ores, which contained high 

concentrations of uranium and substantial radium content) began in 1944. Related laboratory work 

that occurred in Building 25-2 and Building K1-E contained the Pilot Plant to test the pitchblende ore 

extraction methods. Plant 1 also included the engineering and administrative offices for uranium 

processing operations at the facility. MED/AEC operations in Plant 1 were terminated in the late 

1945/early 1946 timeframe and transferred to Plant 6. 

11
 
 

 

Plant 2 

Plant 2 began uranium refining operations (production of UO2 from ore concentrates that were 

originally received from other facilities) in April of 1942, and by July 1942, the Plant attained a 

production rate of 1 ton of UO2 per day. African and Canadian ores were also milled onsite and 

converted to black oxides. Most significant with respect to exposures with potential to deliver 

substantial internal radiation doses, the process in Plant 2 involved batch operations which 

necessitated bulk transfer of the materials from building to building during the refining process. This 

process, as tested in Plant 1, required manual scooping of uranium products and waste products, 

which had potential to produce and aerosolize substantial quantities of radioactive dusts. A 

continuous flow process to replace this manual batch operation was pilot tested in Plant 2 in 1945, but 

not implemented for production until operations were transferred to Plant 6 in 1945-1946. 

To produce UO2, ore concentrates were digested in nitric acid to produce uranyl nitrate. The uranyl 

nitrate was purified by using an ether extraction process. The uranyl nitrate was then converted to 

UO3 through denitrification and oxidized to UO2 using furnaces. Certain locations of Plant 2 served 

as a warehouse to store incoming feed materials, outgoing product, and tanks of process liquids. In 

1945 an annex to one of the buildings in Plant 2 was constructed to serve as a pilot plant for the 

continuous extraction process that was to replace the manual batch process. All Plant 2 MED/AEC 

operations were terminated in early 1946 and transferred to Plant 6. 

Plant 4

 In October 1942, Plant 4 was converted from a lumber sash and door works to a uranium refinery to 

convert UO2 into uranium tetrafluoride (UF4) and then into uranium metal. In mid-1943, the 

production of UF4 commenced in Plant 4 using UO2 from Plant 2. The production of UF4 occurred in 

Building 400 and the conversion of UF4 into uranium metal occurred in Buildings 400 and 401B. 

Plant 4 operations, similarly to those of Plants 1 and 2, included substantial manual manipulation of 

radioactive materials with the potential to produce and aerosolize substantial quantities of radioactive 

dusts. 

The principal production of metal moved from Plant 4 to Plant 6E in 1950 although some metal was 

still produced in Plant 4 and some UF4 was still produced there until perhaps early 1953. After the 

development of a continuous furnace process, UO2-to-UF4 production moved to Building 705 of Plant 

7 in late 1951. In about 1950 or 1951, Plant 4 was refitted as an experimental development and a 

metallurgical pilot plant processing uranium metal and was then referred to as the “Pilot Plant.” The 

"dingot" metal production process was developed and conducted at Plant 4 in the mid-1950s along 

with sporadic ordinary metal "derby" production on a developmental basis. Plant 4 was used until 

1956. 

Plants 6 and 6E 

In 1945-1946, Plant 6 was constructed to increase production and safety in the production process. 

Plant 6 was referred to as the refinery and contained the laboratories and offices which were relocated 

from Plant 2. The buildings associated with the Plant 2 operations included Building 110, 110A, 104, 

and 111. In 1946, the ore to UO2 production was permanently moved to Plant 6. Incoming ore (by 

rail) was stored in Building 110 prior to processing. Building 104 housed the continuous flow process 

12
 
equipment (which replaced the batch process from Plant 2). Buildings 110A and 111 contained the 

offices and laboratories where uranium ore assays were performed. 

Safety concerns had been recognized by MED and Mallinckrodt as early as 1944 and 1945. 

Subsequently, Plant 6 was designed for continuous operations with less manual operations as 

compared to the earlier batch processing. It was felt with this new design exposures would be 

significantly reduced. However, with the increased production rate and the increased use of the 

pitchblende ore, workers were exposed to significant dust, radon, and external doses. These safety 

concerns were identified by MED and Mallinckrodt in 1948 and further engineering controls were 

implemented in 1949. These improvements were regarded as an interim measure, however. 

Mallinckrodt and AEC agreed to build a new pair of plants that were located at the Destrehan Street 

site. 

The first was Plant 6E, the new metal plant, which was constructed from early 1948 to June 1950, 

began startup operations in June 1950, and went into operation in July 1950. Metal production (UF4­

to-U metal) operations at Plant 4 moved to Plant 6E, which was from then on referred to in records as 

"the metal plant.” Metal production took place in Building 116. 

Plants 7 and 7E 

The second new plant was Plant 7, the green salt plant, which was constructed from November 1950 

to March 1951 and was turned over to Mallinckrodt for operation in March 1951. At Plant 7, a 

continuous process replaced the batch-type process used at Plant 4 and the UO3-to-UO2 production 

process at Plant 6. 

Uranium metal recovery and some storage operations were moved to Plant 7 in 1952. Some reversion 

of UF4 to UO2 or UO3 was done in 1953 and perhaps into 1954. Some time in 1954 or in the late 

1950’s machining of nuclear reactor core elements was done on a temporary basis in a fabrication 

facility in Building 700. In 1955, very low enrichment uranium (probably only a small amount) as 

UF4 was processed at Plant 7 and in August 1956, about 5.5 kg of 20%-enriched uranium was 

processed, presumably in Plant 7. 

Plant 7E, whose sole building (712) was constructed as a temporary facility in 1954-1955 and which 

was regarded administratively as part of Plant 7, was used from 1955-1957 to process pitchblende 

raffinate (solids removed during uranium refining by wet filtration) to produce a concentrated thorium 

solution by an acid digestion process similar to the uranium ore digestion. The concentrate was sent 

to the Mound site for further processing. 

5.2 Radiological Source Materials 

The following subsections summarize information on source materials with potential to produce 

radiological exposures. The site TBD provides a significant amount of information concerning the 

history of radioactive material use at Mallinckrodt and plant operations. Note the information and 

Table given in Section 5.1 provide approximate time periods and building locations when/where 

materials were being processed. 

13
 
 

5.2.1 Uranium Ores 

The uranium ores processed at Mallinckrodt came from both domestic and foreign mine/mill sources 

and uranium content varied significantly, as did other radiologically significant daughter products. 

Pitchblende ores containing both high levels of uranium and Ra-226 and Th-230 (progeny of uranium) 

began to be processed in Plant 1 in about July 1944. The laboratory for the testing of radium 

extraction methods was set up in Building 25-2 and the pilot plant in Building K-1E. By the end of 

1944, Mallinckrodt had obtained sufficient data to begin the engineering design of a pitchblende ore 

refinery. The Ra-226 (in radioactive equilibrium with its progeny) constitutes a significant gamma 

radiation source and thus produced most of the external whole-body penetrating dose received by the 

workers, while Th-234 and Pa-234, both beta emitters, would have produced primarily skin and 

extremity dose. In addition, storage and processing of ores released radon and radioactive dusts, 

potentially resulting in internal doses to the lung and other tissues due to inhalation. The levels of 

radon releases would have correlated closely to the radium content of the ore and its derivatives. 

Radium was removed from the ore during the digestion/dissolution/extraction steps conducted during 

refinery operations and therefore principal exposures to radium (and radon) occurred in ore and 

raffinate storage areas and early extraction phases. The concentration of radium and other daughters 

present at any given time in the ore, the processed uranium, and the processing residue, depended on 

the initial concentration of uranium in the ore, the levels of radiation doses received by workers would 

have depended, in part, on the particular uranium ore being processed at a particular time and what 

process was being conducted. 

5.2.2 Uranium Products 

In 1942, there was potential for workers at the facility to have direct contact with uranium in the form 

of U3O8 when mixing it with nitric acid for digestion (MED 1942). When the pitchblende ore 

processing commenced in Plant 1 in July 1944, it was handled in smaller batch quantities. Due to the 

higher radium content, Mallinckrodt confined the materials to a limited area to prevent their spread 

into other plant areas. Plant 6 began operating in 1946 and took over the refining operations and 

handling of pitchblende ores. Pitchblende ores were processed at the site until sometime in 1955. As 

discussed in section 4.0, plant 6 was designed for continuous operations with less manual operations 

as compared to the earlier batch processing. It was felt with this new design exposures would be 

significantly reduced. However, with the increased production rate and the increased use of the 

pitchblende ore, workers were exposed to significant levels of dust, radon, and external doses. 

Additional controls were implemented to minimize direct personal exposure to the pitchblende ore; 

the ore storage room was divided by brick piers into corridors, with each corridor being wide enough 

to hold stacks of drums four drums wide and two high (MED 1946c). It was thought that this design 

would eliminate the need for workers to pass between or close to ore during the ore storage and 

transfer operations. However, due to the blocking of some corridors and the filling of others with a 

higher quantity of ore drums, workers had to pass close by the ore drums in the crowded corridors 

(MED 1946c). In addition, workers had to handle the barrels manually throughout this period of 

pitchblende operations. 

Once the Ra-226 was removed following the digestion step and the vessel(s) had been vented, the 

gamma dose rates would have been lowered substantially. The radon (which arose from the radium) 

was no longer an issue from this point forward in processing, except for the presence of radiumbearing waste residues. 

14
 
 

There was no information located about processing very low enriched uranium at MCW in the TBD 

(ORAUT, 2004) except for a reference in an AEC air dust study report for Plant 7. The report stated 

that the AEC survey covered "health and safety problems existing during production and processing 

green salt, with the added operation of processing enriched uranium." The panel board operator was 

said to include among his observed duties "charging enriched UF4 into hopper" and "replacing 

enriched material drum and sample bottle" (AEC 1955e). Because there was no further mention of 

any of these activities in later such reports, it appears that this operation may have been performed for 

only a short period of time, e.g., to use up excess UF4 from another site. There is no indication that 

Mallinckrodt itself produced the very low enriched UF4. 

Starting in 1952, some recycling of uranium was done by the AEC and its contractors nationwide 

(ORAUT, 2004). Thus the question arises whether this was done at the Mallinckrodt facilities in St. 

Louis. However, Mallinckrodt (as a company) did not begin to receive recycled uranium until 1962, 

which was after the St. Louis facilities had been shut down and their work had shifted to Fernald and 

Weldon Spring (the latter run by Mallinckrodt) (FUSRAP 2003b). ORNL (1981) stated that in its presurvey review of the site that included interviews with Mallinckrodt old-timers, no indications were 

found that there had ever been any process conducted under AEC contracts involving highly enriched 

uranium. 

5.2.3 Process Residues 

African Metals, which supplied the Belgian Congo Ore used by the facility, required that the facility 

extract and return to it the Ra-226, the Ra-226 progeny, and lead and precious metals (AEC 1967; 

AEC 1949b). Thus the Mallinckrodt process included steps to extract these materials as a separate 

residue, called gangue lead cake or GLC. 

As much as 100 grams of Ra-226 (approximately 100 curies), contained in the GLC residues, was 

produced per month at the facility (AEC 1949b). It is also known that quantities of the residues were 

stored at the site before being transported elsewhere. For example, 200 grams had been transported at 

one time from the facility to Middlesex (AEC 1949b), meaning that this quantity had been in storage 

at the Mallinckrodt site and had to be loaded for transport at one time. The residues were stored in 

drums (FUSRAP 1996). The same storage design and precautions used for the ore were followed for 

the radium-containing waste (MED 1946c). It is not known, however, how much of the residues were 

stored at the facility at any given time. 

5.2.4 Thorium Processing 

In late 1954 or early 1955, a new subplant, called Plant 7E, was established. This was part of what 

was referred to as the Minor Elements Production (ME or MEP) facility that did smaller-scale 

processing and development in Plant 7. The purpose of 7E was to process some of the AM-7 

(pitchblende) residues that had been in storage at the SLAPS site to extract Th-230 (FUSRAP undated 

a; AEC 1967; FUSRAP undated b; FUSRAP 1996). Starting in 1955, the thorium-bearing AM-7 

raffinate residue was brought back from storage at SLAPS, stored at Plant 6, and conveyed by 

dumpster from Plant 6 to Plant 7E as needed (AEC 1955b). The processing was first done on a crash 

basis in early 1955, apparently on a laboratory level (AEC 1955c; ORAU 1991), to produce a solution 

containing several hundred grams of thorium. Mallinckrodt later undertook the process on a pilot 

scale, but insisted on only a limited number of workers and strict safety precautions (ORAU 1991). 

The resulting residue, AM-9, was sent back to SLAPS (AEC 1959). 

15
 
AEC (1955b) described the thorium solution extraction process as follows. The AM-7 was first 

digested in nitric acid in a tank and filtered. The resulting "liquor" was then processed in a tributyl 

phosphate (TBP; a solvent) contactor, forming an aqueous phase and a thorium-bearing TBP phase. 

The TBP phase was treated with hydrofluoric acid, leaving another aqueous phase, a stripped TBP 

phase, and thorium fluoride (apparently in solution). The thorium fluoride was sent to the Hot Lab in 

Plant 6, where it was treated with aluminum nitrate (Al(NO3)3) and a pentaether-ether mixture, 

forming thorium nitrate (Th(NO3)4) and impurities. The thorium nitrate was stripped from the 

impurities, yielding the solution that was sent to Mound. The various waste streams were treated in 

several ways (e.g., the aqueous fractions were treated with lime). This left various cake, slurry, and 

water filtrate forms; the first two types were sent to storage and the latter to the sewer. The main 

residual cake, called AM-9, was sent back to storage at SLAPS. From the beginning of 1955 into 

1957, a total of 350 tons of the AM-7 was processed (AEC 1959; AEC 1967; FUSRAP 1996) (ORAU 

1991 says the processing was performed in 1958, but this seems unlikely). Note that the Th-230 was 

also called "ionium" and was referred to that way in Mallinckrodt records. 

6.0 Summary of Available Monitoring Data 

The following table summarizes the types and amounts of monitoring data currently available to 

NIOSH to support dose reconstructions relevant to the petitioning class. It should be noted that the 

“number of employees” column refers to the number of available records for white, male employees at 

Mallinckrodt. It should also be noted that white, male workers accounted for nearly the entire work 

force in the production areas. According to Mason (1977), no women ever worked in the production 

areas and very few black employees were employed during the 1946-1957 time frame. All other 

monitoring record and monitored employee counts shown on the table represent all records contained 

within the database, regardless of sex or gender. 

16
 
Summary of Available Monitoring Data for Mallinckrodt Workers (1946-1

Year 

Total 

Number of 

Employeesb 

1946 522 1947 587 1948 599 1949 676 1950 784 1951 887 1952 883 1953 920 1954 943 1955 1020 1956 1037 1957 1227 

Breath Radon 

# of 

Records 

# of 

Employees 

Monitored 

d d d d 

118 54 187 119 175 123 469 174 390 164 388 212 402 238 240 221 

1 1 5 5 

Urinalysis 

# of 

Records 

# of 

Employees 

Monitored 

0 0 0 0 

384 319 835 373 

1092 500 1284 531 1922 679 2423 715 1947 741 1905 833 

803 661 

1040 815 

Area 

Radon 

# of 

Records 

d d 

386 507 380 721 708 613 714 621 215 210 

U Dust Exposure 

Recordsa 

# of 

Records 

# of 

Employees 

150 

93 

146 

71 

165 58 

1268 397 

564 196 

2097 689 1700 728 

829 311 880 323 

1521 856 

0 0 0 0 

a Based on breathing zone dust sampling measurements, results were used to calculate time weighted daily average exposu

regularly assigned employee job categories. “Number of Employees” data column refers to the number of employees whdust concentration exposure values based on known job duties. 

b Total number of employees data currently reflects database records of the white, male population of the Mallinckrodt wor

External monitoring record numbers represented are annual exposures, hence the one-to-one correspondence with the num

monitored. 

d Additional hard copy records have been identified but not yet input into the ORAU database nor counted. 

17

c 
It is understood that monitoring was never provided for all Uranium Division workers, but that the 

initial (and later) site dosimetry and radiological sampling was provided for those areas and 

individuals with the highest potential for exposure. This conclusion is supported by the review of the 

data from 1943-1947, as compared to the sample data from 1948-1955. This is also supported by a 

number of reports from these early years and studies conducted in later years (AEC 1948c, MED 

1944j, Rochester 1948a, AEC 1950a, MED 1945e, MCW 1946g, MCW 1950t, MCW 1955d, Mason 

1958a, ORAU 1977, ORAU 1980b, and the Mallinckrodt TBD). 

The monitoring data that are available include: external dosimetry beginning in late 1945 (with a pilot 

program commencing in mid-1945 and complete employee monitoring after March 1948), urinalysis 

beginning in the summer of 1947 with a comprehensive program in 1948, breath radon results that 

began in 1945, area radon sampling from 1946-1957, and dust monitoring data beginning in 1943 with 

a formal dust monitoring program including breathing zone measurements starting in 1948. Radiation 

measurements and evaluations of dust exposure during the earlier years of operation (1943-1947) 

were performed on an area-wide, episodic basis to determine whether the facility was in compliance 

with “tolerance” area dose rates. ORAU (1983b) stated that the equipment used to do the air dust 

surveys during this period (1943-1947) was not very good. HASL had confidence in readings greater 

than or equal to 25 ug/m3

, but has less confidence in readings in the range of 10 ug/m3 . 

The formal air dust monitoring program resulted in a series of AEC and Mallinckrodt dust study 

reports (e.g., AEC 1954b, MCW 1949d). The air sampling and report production were at times 

performed by AEC NYOO, Mallinckrodt, or were joint efforts between the two (ORAU 1983a). 

Based predominantly on breathing zone dust sampling measurements, time-weighted, daily average 

exposure averages were calculated for all regularly assigned employee job categories. The data from 

these studies have been captured in a CER database and are summarized in the following table under 

“Uranium Dust Exposure Records.” 

The AEC's HASL staff was committed to the time-weighted average as being most representative of 

total exposure. As Glauberman and Harris (1958) stated, "HASL has found from experience that the 

multiple-sample time-weighted average exposure procedure is the most accurate....The GA [general 

area] sample normally will tend to underestimate an operator's exposure and the BZ [breathing zone] 

sample to overestimate it, but by time-weighting the average concentrations for both types of samples 

an operator's exposure may be closely evaluated... [this method] yields reasonably reproducible 

results.” 

Review of the individual dust study reports indicates that the sampling procedures and subsequent 

calculations were consistent. Typical of language found in many of the dust study reports, the 

following is an excerpt from a report for a Plant 6 study conducted during October and November of 

1948: 

“Dust samples were taken in the breathing zone of the operators, either while working on some 

specific operation or in the general area. A few samples were taken at points other than the 

breathing zone in order to locate specific dust sources.” 

An additional excerpt from the same 1948 report (consistent with other reports) describes the overall 

sampling process: 

18
 
 

 

 

 

 

 

 

“Dust samples were collected on 1-1/8 inch diameter Whatman #41 filter paper discs, using a 

modified Fischer pump. The rate of flow was maintained at 0.50 cubic feet per minute, with the 

collecting period varying from 45 seconds to 30 minutes depending upon sampling conditions 

and job time. 

The samples were counted in a parallel plate alpha counter for sufficient length of time so 

that the statistical variations would be no more than +/- 10 % at the 0.9 confidence level. A 

few samples of low strength may have errors as high as +/- 20 %. The data presented in 

“Lectures on Radiochemistry, Lecture #9” November 12, 1946 by Alan A. Jarrett, Clinton 

Laboratories, were used in the error calculations. 

The dust concentration in alpha disintegrations per minute per cubic meter (alpha d/m/m3) is 

determined from the counting rate of the sample as follows: 

c/m = c/m of sample – (c/m background + c/m control) 

 d/m/m3 = c/m_________

 (G) (1-A) (Q) (t) 

 d/m/m3 = _ c/m______________

 (0.52) (1-0.30) (0.01415) (t) 

= _c/m x 194_

 t 

Where c/m = alpha counts per minute, corrected for counter background and controls 

G = counter geometry (52 %) 

A = filter paper alpha absorption (30%) 

Q = rate of sampling (0.50 cfm = 0.01415 cubic meters per minute) 

T = sampling time in minutes 

d/m/m3 = alpha disintegrations per minute per cubic meter of air 

In order to establish the weighted average dust exposure on a given operation, an approximate 

time study was made in order to determine the appropriate weight factor to assign a given dust 

concentration.” 

Section 7.0 of this report describes the practical relevance of data availability and limitations with 

respect to the feasibility of dose reconstructions. 

19
 
 

7.0 Evaluation of Feasibility of Dose Reconstruction 

The feasibility determination for the class of employees covered by this evaluation report is governed 

by text within 42 C.F.R. § 83.13(c)(1). Under this regulation, NIOSH must establish whether or not it 

has access to sufficient information to either estimate the maximum radiation dose that could have 

been incurred under plausible circumstances by any member of the class or that the information is 

sufficient to estimate the radiation doses of members of the class more precisely than using a 

maximum dose exposure scenario for the proposed time period. If NIOSH were to have access to the 

information sufficient for either of the above cases, then dose reconstruction would be feasible. If 

NIOSH does not and will not have sufficient information on a timely basis for members of the 

proposed worker class to reconstruct dose, it is infeasible to conduct dose. 

In making determinations of feasibility, NIOSH begins by evaluating whether current or completed 

NIOSH dose reconstructions demonstrate the feasibility of estimating with sufficient accuracy the 

potential radiation exposures of the class (identified in section 6.0 of this report). If the evaluation of 

completed dose reconstructions does not provide necessary information to show feasibility, NIOSH 

systematically evaluates the sufficiency of different types of available monitoring, process, and source 

or source term data, which together or individually might assure NIOSH that it can estimate either the 

maximum doses members of the class might have incurred or more precise quantities that reflect the 

variability of exposures experienced by groups or individual members of the class. This approach is 

specified in the SEC Petition Evaluation Internal Procedures (OCAS-PR-004) available at 

www.cdc.gov/niosh/ocas. 

The table below indicates that as of January 25, 2005, there were a total of 246 claims submitted to 

NIOSH for individuals that worked at the MCW Destrehan Street facility, with dose reconstructions 

being completed for 51 (or approximately 17%). The table further indicates that 49 of the 51 

completed claims have been recommended for compensation. 

DOE Covered Site Information 

Site Name: Mallinckrodt Chemical Co., Destrehan St. Plant 

Number of Cases: 

Active 

246 

Pulled 

4 

Complete Total 

304 GT50% LT50% Total 

49 5 51 

A more detailed review of the 49 claims recommended for compensation indicates that 31 (70%) had 

a lung cancer as a primary cancer; with leukemia, colon, brain, esophageal, bone, skin, and bladder 

making up the remaining cancers. It is understood that many of these claimants with lung cancers 

were involved in the handling or storage of uranium ore at the site. An additional Evaluation Report 

for the MCW site is being submitted concurrently with this report, for individuals that worked during 

the 1942-1945 period at Mallinckrodt. This proposed worker class for 1942-1945 is known to have 

conducted much experimental work manually with very limited radiological control mechanisms in 

place. As a result of this, personal or area monitoring data or information to develop source terms was 

20
 
not available for these early operations and the tasks were much different than those beginning in 

1946, it was not feasible to conduct dose reconstructions for that time frame. 

Section 6.0 of this Report includes a summary table of the data currently available to NIOSH to 

support dose reconstructions relevant to this evaluation. A considerable amount of the radiological 

dosimetry information for the site was obtained in the past to support previous epidemiological studies 

of the MCW worker population. As discussed in section 6.0, it is understood from the Mallinckrodt 

TBD and other supporting site records that monitoring was never provided for all Uranium Division 

workers, but that the initial (and later) limited site dosimetry and radiological sampling was provided 

for those individuals with the highest potential for exposure. The monitoring data that are available 

include: external dosimetry beginning in late 1945 (with a pilot program commencing in mid-1945), 

urinalysis for uranium beginning in the summer of 1948, breath radon results that began in 1945, and 

air dust monitoring data beginning in 1944 with a formal air dust monitoring program beginning in 

1948 (AEC 1950a). Note that though a formal program was not initiated until 1948, air sampling was 

used in 1943 as a means of indicating process problems. The currently available records could be 

used to either 1) provide best estimate exposures to individuals or 2) used as surrogate (or co-worker) 

data to estimate maximum (or plausible) exposure conditions for those claimants who may not have 

been adequately sampled or monitored at the site. 

Note the summary table indicates the trend of available exposure records (external dosimetry and 

urinalysis data) significantly increases from 1946 through 1957. 

The majority of uranium operations were shutdown at the Mallinckrodt Destrehan Street facility in 

1957 and were transferred to the Weldon Spring facility (Some Plant 7 activities continued at the 

Destrehan Street facility until July 1958. Additionally, other post processing and shutdown-related 

activities may have continued into 1958. These site activities would have been on a smaller scale as 

compared to production operations.). 

The evaluation that follows examines separately the availability of information necessary for 

reconstructing internal and external radiation doses of members of the proposed worker class. 

7.1 Internal Radiation Doses 

The principal source of internal radiation exposure for members of the proposed class was exposure to 

radioactive dust particles via direct and indirect handling/processing of ores and other solid 

compounds or from the drying of liquid radioactive materials and subsequent resuspension of the 

dried radioactive material into the breathing zone through traffic, housekeeping, and other means of 

disturbance. The resulting airborne contamination could be inhaled, directly exposing tissues of the 

respiratory tract and other internal organs. 

Exposure to radon and its progeny was another significant internal exposure hazard predominantly in 

ore handling/storage/processing areas or in areas where individuals worked with waste raffinate 

materials containing high concentrations of radium. It is known that during times when pitchblende 

ores (ores that possessed both high uranium and radium concentrations) and their wastes were 

processed, there was more radium available to parent the radon progeny (and discussed later, to cause 

elevated external exposure). Radon (and resulting progeny) then became more highly concentrated in 

the air in those areas. It was noted that even in areas with increased ventilation, concentrations in 

some cases remained elevated. 

21
 
Internal exposure to individuals via the ingestion pathway, is accounted for in section 5.3 of the 

Mallinckrodt TBD, whereas the absorption of radioactive materials into the body through the skin is 

accounted for by dose reconstructors on a claim specific basis. 

Monitoring records are available for all time periods, except for urinalyses and air dust measurements, 

to conduct dose reconstructions. Operations in Plant 1 and 2 were shutting down and being moved to 

Plant 6 in the 1945/1946 time frame. Operations in the 1946-1957 time frame were taking place in 

Plants 4 and 6. Engineering controls were being incorporated within the plants to provide increased 

ventilation, shielding, and a decrease in direct contact with the radioactive materials (Plant 6 was 

designed and built in an attempt to reduce personal exposures at the site mainly by using continuous, 

rather than batch, flow of materials). In 1949 it had become clear to AEC that process improvements 

to Plants 4 and 6 were not enough to bring about satisfactory control of dust and other hazards (AEC 

1949b; AEC 1951b). As Mallinckrodt reminded AEC, Plant 6 had been built as an ordinary 

processing plant with no special provisions for health hazards because it was not expected to be used 

more than eight months (AEC 1951b; MCW 1950t). AEC authorized funding for dust control and 

mechanization improvements, which were installed between 1949-1950. Plant 6 was shut down for a 

time in late 1949-1950 for this purpose. Due to the following criteria: 

•	 Similar radioisotopes and plant operations during the time frames of 1946 through 1948, 

•	 Quantities of material increased, 

•	 Similar engineering and radiological controls during the time frame, 

•	 Air sample data for 1946 and 1947, 

•	 Personal and Area Monitoring data is present and adequate for 1948 to be used for the years, 

and 1946 and 1947; 

exposures can be “back extrapolated” from time periods where adequate data is available back to time 

frames that may have gaps in data. This back extrapolation from data available in 1948 can be used to 

evaluate and reconstruct individual exposures to radiation/radioactive materials at the Mallinckrodt 

site in 1946 and 1947. Based upon this information, either individual monitoring or surrogate data 

can be used to reconstruct radiological exposures during the entire 1946 -1957 time frame. 

The subsections below summarize the type of data that is available for use in reconstructing doses at 

Mallinckrodt. 

7.1.1 Urinalysis Information and Available Data 

Mallinckrodt uranium processing workers were given pre-employment physicals that included an 

initial urinalysis and a blood count (MED 1942) and they were also provided with annual physicals 

that included a urinalysis and a blood count. These annual physicals were identified as “follow-up” 

examinations (MED 1942; MCW 1955d; Mason 1958a). Neither of these early urinalyses appears to 

have included the determination of the presence of radionuclides in the body. Urinalysis results for 

uranium are available from a routine sampling program that began in the summer of 1948 and from 

testing performed retrospectively in 1949 to evaluate acute exposures of concern or potential for 

injury due to chronic exposure to radioactive materials during early site operations. 

From about the summer of 1948 (MCW 1950c) through the end of site operations, the annual physical 

included a measurement of uranium in the urine for all process workers. In addition, up to March 

1954 process workers provided urine samples for analysis every 4-6 months depending on their 

22
 
worker class (MCW 1955d; Mason 1958a). After this time period, the sampling frequency was no 

more than semiannual (MCW 1955d). The earliest site urinalyses appear to have been performed as a 

means of retroactively checking for acute exposures or for the onset of damage due to chronic 

exposure rather than for dose measurement purposes. 

An increasing number of urine samples were collected from 1948 until the number peaked in 1953. A 

report (MCW 1955d) noted that NYOO was analyzing a substantial number of urine samples (about 

2500 a year) and that the samples were split, with half going to AEC-NYOO for radiological analysis 

and the other half sent to Barnes Hospital for medical analysis. 

Historical site information is provided in Sections 3.0 and 4.0 of the Mallinckrodt TBD. These 

Sections of the TBD describe the history of site use and operations. The ability to use a surrogate data 

set to “back extrapolate” exposures to periods where there may be data gaps or where data may not be 

available is dependant on having the criteria given in Section 7.1 of this Evaluation Report (e.g., 

similar exposure conditions). Plants 4 and 6 were the primary production facilities operating in 1946 

through 1950 (Plant 7 coming online in late 1950) and they had similar exposure conditions until 1949 

when upgrades to the dust control and mechanization processes were made to Plant 6. Urinalysis data 

available for 1948 and 1949 can be used with other internal exposure information to back extrapolate 

internal dose for 1946 and 1947 where data is not available. 

Other facts related to Mallinckrodt Urine Data 

In addition, much work was conducted on site to determine the solubility classes and effective particle 

sizes of the materials that individuals were exposed to in an attempt to understand the metabolic 

properties of the contaminant inside the body. The uranium refining operations at Mallinckrodt 

produced what was at the time believed to be insoluble uranium compounds, e.g., UO2, UF4, and 

uranium metal (Lippmann 1958) and no soluble forms, such as UF6, appear to have been produced at 

the site. Uranium tetrafluoride (UF4) is now considered as being moderately soluble in the body. 

Further, Eisenbud (1958) reported that, “It has been shown that in these [uranium processing] plants 

the mass median diameter was about 2 μm.” But he also noted that while the peak for alveolar 

retention is 1-2 μm for dust of unit density (i.e., 1 g/cm3), uranium oxide dust has a density of 9 or 10 

g/cc, so that a 1-2 μ particle would behave as though it were a 3-6 μm particle of unit density. This 

information indicates that the internal dosimetry models given in ICRP Publication 66 (ICRP 1995a) 

are applicable (e.g., 5 μm sized particle and a solubility class of M for UF4) for conducting internal 

dose assessments for claimants at Mallinckrodt. 

In 1949, AEC compared the Mallinckrodt urinalyses against those for other sites handling similar 

material and concluded that the results were consistently, inexplicably high (MCW 1950e). 

Subsequent data analysis showed a gradual precipitation of uranium in the Barnes Hospital (local to 

St. Louis) standards, which meant that the daily standard curves showed a gradual loss of slope over 

time, up to 30%. After 1949, only samples taken within one hour of the start of the weekly shift were 

accepted (ORAU 1983b) for analyses. Because of the questions regarding the validity of the samples, 

the apparent variations in sample analysis methods, and even who was doing the analyses, the 

Mallinckrodt urinalysis data should be used with caution, at least when the data was taken by Barnes 

prior to about 1951. However, the errors, if any, are in the conservative (high) direction and thus are 

claimant-favorable. 

With the processing of waste raffinates (AM-7 residues) in 1955-1957 came an increased level of 

thorium containing material that was potentially made available for intake by process workers. It does 

23
 
not appear that urine samples were differentiated during urinalysis between uranium (and its 

daughters) and thorium. Hence in dose reconstruction, urinalysis data from early 1955 on for workers 

who processed thorium wastes should be examined on a case-by-case basis to see if any special 

evaluation for thorium was done. If not, then dose estimates from air sampling data may have to be 

made. Section 6.1 of the TBD indicates a technique to use by dose reconstructors to account for and 

assess this internal exposure to the isotopes Th-230, Ac-227, and Pa-231. Either uranium urinalysis or 

air sample results can be used to assess this exposure. These internal assessments can be conducted 

based upon estimated (claimant favorable) isotopic distributions. For simplification of the dose 

reconstruction process, the low-contributing isotopes may be conservatively ignored or their 

contributions may be folded into those of other isotopes when appropriate for the organ type and 

intake mode. 

7.1.2 Information and Available Data Regarding Other Types of Bioassay 

A program of breath radon measurement began June 1945 (MED 1945e and MCW 1946g) for 

workers who worked in areas where there was a potential for radium intake. Individuals were 

categorized into various sampling groups. MCW (MCW 1950i) gives a list of worker sampling 

groups or occupational areas, along with a rating of the need for workers of each type or in each area 

to have their exhaled breath sampled for radon content (the radon content in breath was used to 

determine the amount of radium that was deposited in the body). These sampling groups included: 

most of the Manufacturing (process), Stores (warehouse), and Maintenance (craft) workers were in the 

“Definite” category, while most of the Power Plant, Occupancy, Plant Protection (guard), Research, 

Laboratory, and Laundry workers were in the “Possible” category and most of the Health & Safety, 

Office & Administration, and Plant 4 workers had most of their people in the “Improbable” category. 

(Plant 4 was known as the “Metal Plant” and converted UO3 to UF4 and then to metal. Radium 

bearing materials, and radon, would have been insignificant in the building.) The first breath radon 

measurements were thought to be worthless by MED because the MED expert concluded that the 

samples were contaminated at the time they were taken (MED 1945e). 

It should be noted here that the measured sample results were biased high (indicating internal radium 

exposures greater than what was actually present). These samples were considered biased high 

because individuals left samples after breathing radon contaminated air in their work environment. 

The workers would subsequently provide samples with radon activity not from radium content in their 

body, but from the radon in the environment. 

As a result, MED directed Mallinckrodt to have breath radon samples taken only in a room away from 

the plant and only when the employee had not worked for at least 48 hours and while he was still 

wearing his street clothes (MED 1945e). This would allow the employees to purge their lungs of 

environmental radon, remove other sources of contaminating the sample and then when samples were 

pulled the results were indicative to radium content in the body. 

Breath radon samples were collected by obtaining one-liter samples of exhaled breath after two days 

of non-exposure, usually on a Monday morning (AEC 1949g; AEC 1950a; MCW 1950g). The 

samples were measured at the National Bureau of Standards (AEC 1949g) or at NYOO (AEC 1950a, 

MCW 1955d) by an “automatically recording pulse-counting device” (AEC 1950a). If a sample was 

over the “tolerance level” of 1 x 10-10 Ci/L, then a recheck (repeat sample) was made, immediately 

(AEC 1949g). The lower limit (of detection) was 0.1 pCi/L and there was confidence in readings of 

greater than or equal to 0.5 pCi/L (ORAU 1983b). In 1946, it was reported that of 40 workers tested, 

24
 
the maximum level was the tolerance level of 1 x 10-11 Ci/L (MCW 1946g). For 1945, few radon 

breath analyses of employees are available, but began increasing in 1946. 

Whole body and lung counts appear to have been performed rarely, if at all, because Mallinckrodt had 

no invivo examination capability, and workers had to be sent to sites outside Missouri for this to be 

done or a mobile counter would have had to be brought to St. Louis. Individual whole body and lung 

count data are not available for the period covered by this evaluation. Air sampling and urinalyses 

were the predominant internal exposure indicators used at Mallinckrodt. 

7.1.3 Airborne Dust Levels 

Towards the end of 1945, major processes being conducted in Plants 1 and 2 were being transferred to 

Plants 4 and 6 and later to other site facilities. It is important to indicate that while very little is 

known regarding the research and laboratory type operations that took place in Plants 1 and 2, 

handling methods, or even source terms that were present; considerably more information is known 

about operations in Plants 4, 6, and the subsequent facilities that were used after the 1945 time period. 

As discussed in section 5.1, Plant 6 was constructed to increase production and safety in the 

production process. Safety concerns had been recognized by MED and Mallinckrodt as early as 1944 

and 1945. Subsequently, Plant 6 was designed for continuous operations with less manual operations 

as compared to the earlier batch processing. It was felt with this new design exposures would be 

significantly reduced. However with the increased production rate and the increased use of the 

pitchblende ore, workers were exposed to significant dust , radon, and external doses. These safety 

concerns were identified by MED and Mallinckrodt in 1948 and further engineering controls were 

implemented in 1949. This is supported by the sample data available for 1946-1948, prior to the 

engineering controls instituted in 1949. 

As mentioned in earlier sections, by 1949 MCW processes had been improved to reduce exposures 

and formal monitoring programs were being utilized. Regular dust monitoring utilizing extensive 

breathing zone samples in the calculation of time weighted average dust exposures were initiated in 

1948. Details regarding the sampling techniques and calculations used are given in section 6.0. The 

dust monitoring records available from 1949-1957 are quite extensive and support the feasibility of 

internal dose reconstruction for that time period. 

The ability to assess the affects of contaminated dust on MCW workers from 1946-1948 prior to 

process improvements and a regular dust sampling program is based on the following available 

information: 

1.	 Complete dust study time weighted average study reports for Plants 4 and 6 are 

available (MCW1949c, MCW1949d). These studies were performed in 1948 

prior to the major improvements started in 1949, 

2.	 The studies were performed using the same techniques as used in the formal 

program, 

3.	 Plants 4 and 6 were essentially the only two plants actively engaged in 

processing operations during the 1946-1948 time frame, and 

4.	 Processes at Plants 4 and 6 remained predominantly unchanged during the 

1946–1948 time frame. 

25
 
 

The exposure information obtained via the 1948 Plant 4 and 6 dust studies (MCW 1949c, MCW 

1949d) therefore support the feasibility of internal dose reconstruction for employees present during 

the 1946-1948 time period. 

7.1.4 Radon and Thoron 

Radon levels could be substantially elevated in enclosed areas in Plants 1 and 4 where material 

containing uranium daughter products were stored. It is likely that workers were exposed to short, 

high level exposures when opening 55 gallon drums of ore, opening storage rooms, and other 

enclosed equipment containing ore and residues (ORAU 1989a). 

Some early radon measurements occurred in 1945 in Plants 1 and 4 using methods developed at the 

facility. However, routine air sampling for radon did not begin until 1946, when samples were taken 

once a week in known, high-radon areas (MCW 1950d). Another reference indicated that beginning 

perhaps in the mid-1940s, radon samples were taken once a week in high-radon areas (MCW 1950e). 

This included the outdoor yard areas from which measurements indicated that some outdoor area was 

always downwind and that the Plant 6 outdoor background (based on “ordinary” emissions to the 

outdoor plant atmosphere) was on the order of 1 x 10-11 Ci/l (MCW 1949n). The principal locations 

which were found in 1946 to be difficult to keep radon concentrations below tolerance levels were the 

rail cars during unloading of ore drums and in the ore and residue storage area (MED 1946c). In 

locations affected by the digestion vent exhaust and the residue, the radon levels were likely to have 

varied depending on the stage and timing of processing. A percentage of the radon produced during 

decay, which would have varied depending on particulars of the ore and processing conditions, would 

be adsorbed on the surface of the ore particles. When the ore was digested in acid, the adsorbed radon 

was released and the gamma activity of the ore slurry would drop. When the radium was 

subsequently precipitated from the acid solution as a sludge, the precipitate would adsorb some of the 

radon, resulting in an increase in gamma activity as the precipitate “aged” (AEC 1947e). The high 

radium content of the sludge also would significantly contribute to elevated radon emanation. 

Enclosed spaces in MED/AEC refineries produced radon concentration levels of up to 10-7 to 10-8 

Ci/L from 1944-1949 (Eisenbud 1975). Improvements in ventilation reduced these exposures, but did 

not generally control them to within the preferred level of 10-10 Ci/L until 1949. 

With the commencement of radon sampling preceding by some years the processing of high-radium 

and thus high-radon pitchblende ores and the apparent competence of the Mallinckrodt health and 

safety and instrument people at developing and using radon-measuring instruments, the radon 

measurements taken can be regarded as reasonably representative of the conditions. 

ORAU (1989a) estimated the radon exposures of approximately 184 Mallinckrodt Plant 6 workers as 

part of a larger study. They calculated the working level (WL) for each job title using the mean radon 

concentration value from all available surveys in 1946-1957 for each job title's assigned work area; 

exposure estimates were then calculated in units of working level months (WLMs) for each job title. 

It was assumed that an equilibrium factor of 0.25 applied for radium and its daughters was based on 

plant and memoranda, other documents, and findings from uranium mine and residential radon 

studies. Their approach of assigning a WLM value for each job title for a single grouped period of 

years (rather than breaking it down by years) was due to the lack of survey data for many of the years. 

The “roving operator” and the production/processing/manufacturing operators were assigned the 

average area radon levels for the entire Plant 6 area and the highest daily work time breakdowns of all 

26
 
 

the production processes. Weekly rotation as practiced at Mallinckrodt was handled by assigning an 

average radon level of all available survey data from those work areas in the rotation plan for that job 

title. Pertinent results are shown in the table below for information. These results are for the years of 

pitchblende processing and so would presumably be conservative for the pre-pitchblende years. This 

information is available for the purposes of reconstructing dose to claimants in this proposed class. 

Exposure rates of 184 Mallinckrodt workers, based on surveys done in 1946-1957 (ORAU 1989a) 

Job title 

No. of 

workers 

WLM per month 

worked Job title 

No. of 

workers 

WLM per month 

worked 

Manufacturing operator 3 .138 Recovery operator 13 .052 

Operator, process develop 1 .138 Guard 3 .047 

Production operator 2 .138 Porter, Lab 1 .044 

Roving operator 3 .138 Digest operator 2 .042 

Cleanup operator 8 .127 Pilot Plant operator 4 .041 

Maintenance (general) 1 .111 Clerk, Manufacturing Office 1 .040 

K-65/GLC sampler 1 .102 Clerk, Production Office 8 .040 

Pot Room operator 14 .097 Feed operator 2 .038 

K-65/AJ-4 sampler 4 .096 Filter press operator 3 .038 

Raffinate operator 9 .092 Plant monitor 1 .030 

Barium operator 6 .091 Health office 2 .020 

C-3 (Centrifuge) operator 18 .084 Engineer, senior mechanical 1 .018 

Feinc operator 12 .084 Furnace operator 12 .010 

Director, technical 1 .077 Industrial relations (office) 1 .010 

Mail boy (office) 2 .057 Ether House operator 17 .008 

Porter, Production 6 .056 Machinist (instrument) 2 .008 

Ore Room operator 16 .055 Chemist 4 .003 

During a relatively short contract period between July 1955 and March 1957, the pitchblende raffinate 

materials were brought back onsite and processed to concentrate Th-230 for the Mound facility. 

Though not a major contributor to exposure, thoron gas (Rn-220) and its daughters were released 

during the process and caused additional internal exposure; small in comparison to the radon (Rn-222) 

progeny that was released (a factor of approximately 200 less). The thoron half-life is 55 seconds, 

meaning that it is not available in the air long before it decays to a particulate, radioactive daughter. 

Due to the relatively short half-life, individuals would have to be physically close to the source to 

incur much exposure. The TBD provides a technique to determine internal exposure due to the 

inhalation of thoron gas. 

7.2 External Radiation Doses 

As discussed in Section 5.2.1, the pitchblende ores and resulting waste contained high levels of Ra226. Ra-226 (in equilibrium with its progeny) constitutes a significant gamma radiation source and 

thus produced most of the external penetrating, whole-body dose received by the workers, while Th234 and Pa-234m (immediate daughters in the uranium series), both beta emitters, would have 

produced most of the skin and extremity dose. 

The subsections below summarize the extent of information available for reconstructing the external 

doses of members of the class. Most of the information summarized below is provided in greater 

detail in the TBD. 

27
 
 

 

 

It is important to note that limited, external dosimetry commenced at the site in mid-June 1945, with 

subsequent implementation of individual dosimetry later in the year. Though calendar year 1946 was 

not included, the following tables are provided to indicate the extent of monitoring and magnitude of 

measured exposure within the external dosimetry program at MCW. It must be noted here that the 

reference for these tables was written in 1980 and that number of “workers monitored” does not match 

with the numbers in the Table given in Section 6.0 of this report. It should also be noted that the era 

of pitchblende use (early 1945 on) was mostly covered by film badge monitoring, so that the doses 

characteristic of this work are known. 

Annual gamma exposures, 1947 – June 1957 (ORAU 1980b) 

Year 

Workers 

Monitored 

Annual Gamma Exposure, R 

0 - 1 1 - 5 5 - 10 10 - 15 >/= 15 

1947 253 70 131 27 18 7 

1948 366 120 171 47 19 9 

1949 554 370 141 41 2 0 

1950 615 475 133 7 0 0 

1951 694 512 171 11 0 0 

1952 757 659 88 10 0 0 

1953 763 619 142 2 0 0 

1954 756 566 188 2 0 0 

1955 871 766 105 0 0 0 

1956 958 944 14 0 0 0 

Highest gamma doses to workers, 1947-June 1957 (ORAU 1980b) 

Year 

Annual Dose, R Weekly Dose, R/week 

Min Avg Max Min Avg Max 

1947 14.4 16.1 23.5 0.28 0.31 0.45 

1948 14.9 17.0 20.3 0.25 0.33 0.39 

1949 7.7 9.0 13.3 0.15 0.17 0.26 

1950 4.5 5.4 7.1 0.09 0.11 0.14 

1951 5.0 5.9 7.1 0.10 0.11 0.14 

1952 5.1 5.9 6.6 0.10 0.12 0.13 

1953 4.0 4.6 5.7 0.08 0.09 0.11 

1954 3.9 4.4 5.1 0.08 0.09 0.10 

1955 3.9 4.4 5.1 0.08 0.09 0.10 

1956 1.1 1.4 1.9 0.04 0.06 0.07 

7.2.1 Film Badge Monitoring 

Workers were not individually monitored for external dose prior to December 1945, except for a 

limited pilot program starting around June of 1945. Currently available film badge records indicate 

monitoring for the weeks ending July 29, August 5, August 12, and August 26 of that year and then 

there is a gap until the week ending December 9, 1945. Total (accumulated) doses for the period from 

December 9, 1945 to March 25, 1946 were reported, by individual, in a memorandum from the 

University of Rochester School of Medicine and Dentistry (Rochester 1950). The same film badge 

was in use throughout Mallinckrodt uranium operations for AEC (MCW 1961a), i.e., from 1945 

28
 
through the end of operations. This was a two-element type of dosimeter. The film was a DuPont 

Type 552 film packet containing two dental-size films wrapped together. 

ORAU (1980b) stated that after the start of the film badge monitoring program all Mallinckrodt 

employees who were cleared to have access to production areas wore film badges at all times, with the 

purpose being to provide maximum assurance that all exposures were registered. Contemporary 

references indicate that film badges were issued as a combination security-exposure badge to all 

employees, except for “office females” who presumably never entered process areas (MCW 1955d, 

MCW 1955c, MCW 1956i). In addition, workers were directed to wear their badges when they went 

to the SLAPS or “the Range” (MCW 1949q). The Range appeared to be a firing range (near or at the 

storage area) where the guards would practice shooting and where some materials were stored (e.g., 

AEC 1949E reports that some UO2 was drawn from this storage area for use in production). Plant 6 

workers were also told to wear their Plant 6 badges when they visited Plant 4, and vice versa for Plant 

4 workers, and not to wear a visitors’ badge (MCW 1948d). 

From April 22, 1946 through the end of MED/AEC work at MCW in 1957 or 1958, film badges were 

processed on a weekly basis as part of a routine dose monitoring program. Badges for Plant 4 began 

to be changed only every two weeks in early September 1954 (MCW 1954d); all badges began to be 

changed every two weeks as of January 30, 1955, because of a shortage of health personnel to read the 

badges and the comparatively low doses then being recorded on the badges (MCW 1955b, MCW 

1956i). 

This information indicates that film badging was provided at Mallinckrodt from 1946 through the end 

of operations and that it is available for use directly, or if needed for surrogate data, to conduct dose 

reconstructions. 

7.2.2 Gamma, Beta, and Nonspecific Beta-Gamma Exposures 

After high-grade pitchblende ores began to be used, refinery workers were exposed to photons from 

radionuclides in equilibrium with U-238 and U-235. Ra-226, through its Pb-214 and Bi-214 

daughters, contributed gammas to workplaces where ore was stored or processed. Upon removal of 

the uranium daughters, processed material became radiologically innocuous until the passage of time 

resulted in the ingrowth of Th-234 and Pa-234m and the consequent domination of the dose profile by 

electrons. Mallinckrodt worker dose records demonstrate this difference, with significant doses for 

mixed photons and electrons in the refinery operations and high electron doses with little photon dose 

in the metal plants. 

In 1946 the principal source of significant gamma radiation was said to be the drums of ore as they 

were stacked in the receiving warehouse (MED 1946c). The gamma dose rate could be as high as 50 

mR/hr near stacks of drums of pitchblende ore at 25% concentration and with a radium content of 

about 100 mg/ton (Eisenbud 1975). A 1958 AEC report documents dose rates of 0.8-8.0 mR/hr, with 

an average of 3.0 mR/hr, as the gamma dose rate at three feet from bulk ore concentrates (AEC 1958, 

Table XI), these exposure rates are likely to have been associated with domestic ores. The maximum 

external gamma radiation doses associated with exposure to ores could be estimated for the class, if 

necessary, by assuming constant exposure to the ore barrel storage locations. Dose rate survey 

information is available for this area and dose rates could be modeled assuming maximum 

29
 
concentrations of Ra-226. More detail addressing how these radiation doses could be estimated is 

provided in the TBD in section 7.4. 

In some cases, gamma dose rates from wastes could have been substantially higher than those for the 

ore. Dose rates at points adjacent to stacks of drums of radium-bearing residues (precipitates) were as 

high as 100 mR/hr (~ 300 mg Ra/ton) (Eisenbud 1975) and up to 275 mR/hr for direct contact with the 

drums (MCW 1949g). AEC (1948c) gave the gamma contact dose rate with the radium-containing 

Feinc filtrate residue under conditions of secular equilibrium (conditions resulting in maximum 

exposures) as over 300 mR/hr. The highest dose rates would have been associated with operations 

involving manual transfer and manipulation of the waste materials. These included: 1.) the various 

dumping, scooping, and scraping operations in which feed, UO2, UO3, UF4, and dust were handled or 

crucibles and furnaces were cleaned; 2.) the “plowing” (scraping) of the centrifuges; and 3.) the 

scraping of cake off the Feinc filter cloths (this was the pitchblende cake during the pitchblende 

years). Maximum external gamma radiation doses associated with exposure to residues could be 

estimated for the class, if necessary, by assuming a maximum dose rate associated with operations 

involving the Feinc (rotary vacuum filter) in Plant 6. NIOSH has adequate monitoring data for such 

operations, which would have produced higher gamma dose rates than those occurring in Plants 1, 2, 

and 4, because of the higher concentration of radium-bearing materials. More detail addressing how 

these radiation doses could be estimated is provided in the TBD in section 7.4. 

The Th-234/Pa-234m combination (from U-238 and U-234) produced about 1500 alpha dpm/mg U 

and 1500 beta dpm/mg U when the daughters were in equilibrium, producing 240 mrad/hr at the 

surface of U metal, 208 mrad/hr at the surface of UO3, and 183 mrem/hr at the surface of UF4. 

Further, during UO3 prep much of the beta-active material was removed, but built back up to 50-100% 

by the time it got to the UF6 production facilities (Baker 1958). This suggests that significant buildup 

could occur before the UO3 left the Mallinckrodt facilities because the storage time might be weeks 

and the transport time was likely less than a few days. Eisenbud (1975) pointed out that 90% of 

equilibrium beta activity was restored by 90 days after vacuum casting. Eisenbud (1975) reported 

high dose rates, up to 1 rad/week to the body and even more to the hands, from loading of UF4 into 

UF6 reaction vessels. This too implies that if enough time had elapsed, UF4 loaded at Mallinckrodt 

into the bombs could also produce relatively high beta dose rates. Metallic uranium in equilibrium 

with Th-234/Pa-234m could produce up to 235 mrad/hr to the basal epithelium when the metal was in 

contact with bare skin; heavy gloves would significantly reduce this (Eisenbud 1975). 

In addition to the beta dose rate from the uranium as natural uranium, uranium oxide, etc., there were 

two waste concentrates that produced high beta dose rates. First, when ether was used to extract the 

uranium from uranyl nitrate, Th-234 and Pa-234m were left in the aqueous phase (also called the 

aqueous uranium tails) (Eisenbud 1975). This aqueous solution was filtered, resulting in a residue 

(cake) containing the beta emitters. MED (1942) stated that 1942 measurements indicated that the 

intensity was low and that no precautions needed to be taken for disposal; however, MED/AEC 

appears to have been more concerned about this later on. Another source of the tails was the UO2­

derived shotgun sample, which could have the Th-234 and Pa-234 concentrated to 30-300 times their 

activity in normal uranium metal in equilibrium, depending on how long the UO2 had stood between 

production and sampling (MED 1944m). The fourth and final ether extraction performed in 

processing a shotgun sample produced liquor so concentrated in these beta emitters that it was said 

that the tolerance dose of beta radiation could be reached by keeping the hands above the liquor for 10 

minutes per day. Besides that, the chemist handled the sample for 5-10 minutes from removal from 

the furnace to bottling, wearing no gloves and directly touching the containers. MED (1944m) 

30
 
advised changing from rubber gloves to leather gloves (to increase the dose rate reduction from a 

factor of 2 to a factor of 3) and using crucible tongs (to increase the distance to about 10”) for 

conveying the evaporation dish to the heating areas. 

Second, in the vacuum recasting of the uranium metal, impurities in the metal volatilized and 

condensed on the cooler portions of the furnace, creating spot deposits (AEC 1949b; Eisenbud 1975). 

The impurities contained Th-234 and Pa-234m, which were concentrated to a significant degree in the 

deposits (AEC 1949b; Eisenbud 1975). This deposit residue could have "up to 1000 times the beta 

activity of natural uranium" (AEC 1949b). Manual contact with these deposits during charging, 

discharging, cleaning, and repair of the furnaces provided "opportunity for hand irradiation of a 

greater magnitude than whole body" (AEC 1949b), possibly as much as 2-3 rads/week to exposed skin 

and perhaps to the eyes when the original ore was pitchblende at 25% average enrichment (Eisenbud 

1975). Mallinckrodt (MCW 1949a) observed that 25% of Plant 4 workers received over 500 

mrep/week beta and 3-6 workers per week received 2000 mrep or more; AEC (1949g) also observed 

that the beta values (on film badges) from Plant 4 consistently ranged up to 2.7 rep/week. 

Because of the high hand doses, the processing of the uranium derbies and billets was studied in 1948 

by Mallinckrodt (MCW 1948b). The results of the study were used to reduce skin and extremity 

doses in the new Plant 6E. This was done by minimizing individual exposure to large bare surfaces of 

uranium and minimizing the accumulation of scale and powdered residues in which the Th-234 and 

Pa-234m concentrated, especially in the recasting or metal remelt step. 

Maximum external beta doses for the class can be determined from film badge data (section 6.0), dose 

rate surveys, and data from similar operations at other DOE sites. More detail addressing how these 

radiation doses could be estimated is provided in the TBD in section 7.4. 

7.2.3 Neutrons 

No neutron exposure measurements are available for the Mallinckrodt site. Neutron exposure could 

have occurred from the radium-beryllium (Ra-Be) source or neutrons produced by the alpha-neutron 

reaction in the mixtures of uranium/thorium and fluorine, which occurred after 1954. Maximum 

neutron doses associated with exposure during this period could be estimated by multiplying the 

measured or reconstructed gamma exposures at the Mallinckrodt facility by the known ratio of 

neutron to gamma dose for alpha-neutron reactions in fluorine matrices. 

Section 5.4.2 of the MCW TBD discusses the techniques used to estimate neutron exposures to site 

personnel based on knowledge of the source terms and handling of the alpha-neutron source that was 

in use at the site. 

7.2.4 Occupational X-ray Examinations 

MED (1944d) stated that the medical program recommended by MED was being followed by 

Mallinckrodt. This included a routine chest x-ray prior for employment and annually thereafter and a 

pelvic x-ray for those employees handling fluorides for the time periods of 1942-1944. MED (1944d) 

thought that the pelvic x-ray could be dispensed with and apparently this was subsequently done. 

Later documents also indicate that Mallinckrodt uranium processing workers were given a preemployment physical that included a chest x-ray (MCW 1955d and Mason 1958a). They were also 

31
 
given an annual physical that included a chest x-ray (MCW 1955d and Mason 1958a). That these xrays were actually given is indicated in the series of Mallinckrodt Health Office and other reports 

(e.g., MCW 1951b, MCW 1954e, MCW 1955d). Section 7.4 of the TBD indicates the assumptions 

and techniques available to reconstruct Mallinckrodt workers’ exposure to occupational medical X-ray 

examinations. Both Posterior–Anterior (PA) and Lateral Chest X-ray examinations are assumed to 

have been conducted for employees at Mallinckrodt on an annual basis for the time period covered by 

this Petition Evaluation Report (Pelvic examinations were not given to site workers during the timeperiod covered in this Evaluations Report, they are not discussed in this document). 

7.3 Petition Basis Evaluation 

An evaluation was conducted by the reviewing health physicist early in the process to determine 

whether the submitted petition and supporting documentation qualified the proposed worker class for 

formal evaluation. A total of 23 referenced documents (or statements that were provided separately) 

were received and reviewed during the SEC petition qualification step. Eleven of the 23 documents 

provided information that qualified the petition for evaluation. [The other twelve (12) documents 

provided by the petitioner either did not indicate: 1) unmonitored, unrecorded, or inadequately 

monitored or recorded exposure incidents or 2) exposures were not monitored; were lost, falsified, or 

destroyed; or information regarding monitoring, source, source term, or processes were unavailable 

for the site.] Since the release of Rev.0 of the site TBD, new information and data have been retrieved 

that provides additional site information to support dose reconstruction. The TBD is under revision to 

include this information. This evaluation report is the result of the formal review of the petition 

supplied for the Mallinckrodt Destrehan Street site. 

The following text presents evaluation summaries of the statements and documents submitted by the 

petitioners that qualified SEC Petition 00012 for evaluation. (All supporting information that was 

submitted in the petition was carefully reviewed to determine the extent to which it supported the 

petition basis and for its usefulness in determining feasibility/infeasibility of performing dose 

reconstruction.) Only those documents and statements that, to at least some extent, qualified the 

petition for evaluation have been included in this report. An evaluation of all submittals is available 

in a "Professional Judgment Document" which is part of the project record. Note that there currently 

are two evaluation reports for the Mallinckrodt Destrehan Street site (SEC-00012-1 and SEC-00012­

2) that take the initially petitioned time frame at the site (1942 – 1957) and split it so that early (1942 

– 1945) and later (1946 – 1957) activities are covered separately. 

1. By virtue of the site profile, conducted by NIOSH/ORAU, there is limited to no individual 

data from 1942 until 1948 (see Doc A1, A2, and A3). 

For the time frame included in this evaluation report (1946 – 1957), external dosimetry and air sample 

records are available for the entire period. As discussed in section 6.0, the initial (and later) site 

dosimetry and radiological sampling was provided for those areas and individuals with the highest 

potential for exposure. Therefore, using the air monitoring data from 1946 and 1947 and comparing it 

to the air sample data and urine data from later years, an exposure matrix for 1946 and 1947 could be 

established. Urine sample results are available for the majority of the time frame, beginning in the 

summer of 1948. Therefore, though the documents supported qualifying the petition for evaluation, 

currently available data or techniques given in the TBD indicate that dose reconstructions could be 

conducted for the 1946-1957 time frame at Mallinckrodt, except for the issues raised in response to #4 

below. 

32
 
 

2. In reference to Breath Radon (see Doc A6 and A7, site profile p. 25 and 41) – please see 

(Doc A4). Very few BR samples were taken and tested in 1946, none before. It didn’t get 

going until 1948 and ended in 1957. Again, the use of 0.000 is misleading. 

For the time frame included in this evaluation report (1946-1957), limited breath radon samples were 

obtained. Many area radon samples were taken to evaluate internal exposure conditions. The TBD 

provides a technique to assess internal exposure to individuals to radon. As discussed in the 

resolution to the initial comment above, urinalysis results were collected at Mallinckrodt and used 

(with surrogate data) to assess internal exposure to site workers. The TBD also indicates a technique 

to assess internal exposures to other radioisotopes based upon uranium urinalysis results. Site breath 

radon results indicated as “.000” will not effect the ability to reconstruct dose to site individuals 

because surrogate information is available for use. Therefore, though the documents supported 

qualifying the petition for evaluation, currently available data or techniques given in the TBD indicate 

that dose reconstructions could be conducted for the 1946-1957 time-frame at Mallinckrodt, with 

respect to radon exposures. 

3. Possible lost medical records (see Doc A8). Page 3, not one complete set of medical 

records/files from Weldon Spring. Possible destruction of key records V2161 (see A8, page 4). 

Cover letter states these were the best records in the world in regard to uranium exposed 

workers. 

NIOSH searched epidemiology records available at ORAU and extensive research conducted to match 

employee medical records to employment record lists did not indicate a loss of medical records. 

Documentation is available in the ORAU Records Storage Vault documenting this research. 

Therefore, though the document supported qualifying the petition for evaluation, a destruction of 

medical records was not confirmed and would not limit dose reconstructions from being conducted for 

the 1946 – 1957 time frame at Mallinckrodt. 

4. Altered illegally/conscious cover-up (see Doc A9). Referencing to a 1949 dust evaluation, 

records and formal report was never prepared on this study; this was on the advice of MCW 

attorneys to avoid subpoena. There was a fake benchmark and correspondence on whether 

one might even consider making this study (by lying) more favorable or even not recording it 

at all. 

The letter from M. G. Mason, a former health and safety representative at Mallinckrodt, to Thomas F. 

Mancuso, MD, an AEC research study director at the University of Pittsburgh, contains the statement: 

“Perhaps they [estimates of worker internal exposures based upon a dust sample result evaluation] 

could be presented in a more favorable way or not even made a part of your records.” This statement 

could be interpreted as a recommendation by a site safety representative to cover-up a study. 

Although NIOSH believes that the air sample data from that study were maintained and are available 

to NIOSH, the fact that personnel responsible for worker protection are documented to have discussed 

hiding the results of an analysis on worker exposures is profoundly troubling. It raises the question as 

to whether safety personnel might have taken other, undocumented actions, to obfuscate or change the 

existing air sample data. If such actions were taken, NIOSH would not be able to detect misleading 

air monitoring data during the 1946-1948 period because the quality of the urinalysis monitoring data 

at Mallinckrodt prior to 1949, which provides the best means to validate the air monitoring data, and 

vice versa, was brought into question in a review by the AEC’s Health and Safety Laboratory. 

33
 
 

Further, the routine urinalysis program was not fully functional until 1949. Under certain 

circumstances, NIOSH can substitute radiological source term and process information for both 

personal and area monitoring data, but the Mallinckrodt operations involved a diversity of source 

terms and processes, as are briefly summarized in Section 5.0 of this report. This combination of 

source terms and processes result in too many different plausible exposure scenarios to model with 

reasonable certainty of identifying and characterizing the highest plausible radiation exposures, as 

would be needed to estimate maximum radiation doses to members of the class. 

The specter of doubt raised by the Mason document also poses added difficulties for dose 

reconstruction for employees who worked after 1948 because, despite the scientific and technical 

ability of NIOSH to validate doses from multiple sources of information, such procedures are difficult 

or impossible for most claimants to comprehend. This may pose a special credibility problem for the 

NIOSH dose reconstruction program among Mallinckrodt claimants. 

Based on the documentation of concern, the limitations of data prior to 1949, and the complexity of 

plausible exposure scenarios, NIOSH would not have sufficient information to reasonably estimate 

radiation doses for Mallinckrodt employees prior to 1949. This situation differs substantially from 

1949-1957, given the availability of data from a fully operational urinalysis program as well as the 

added oversight of the radiation monitoring by the Atomic Energy Commission’s Health and Safety 

Laboratory (HASL), which possessed recognized expertise in monitoring radiation exposure in the 

workplace. The overall extent of monitoring and consistency of radiological practices after 1949 

provides a relatively high level of confidence, from a scientific and technical standpoint, concerning 

the ability to estimate radiation doses with sufficient accuracy for compensation purposes. As 

discussed above, however, this confidence would be unlikely to be held by Mallinckrodt claimants, 

given the high level of skepticism among some of their members and advocates, which can only be 

abetted by the documentation discussed above. 

5. Letter to Dr. Tom Mancuso, MD stating that the quality of records is much more spotty than 

those in Hanford and Oak Ridge. Also states that records were incomplete and in many cases, 

not found at all (see Doc A11). 

The majority of this document is illegible, but two sentences identified by the petitioner indicate “My 

inspection of the records indicated that many of them were spotty, ... much more spotty than those 

that we have in Hanford or Oak Ridge.” As indicated in the response to #3 above, when ORAU 

obtained the Mallinckrodt records, significant research was conducted to verify the existence of 

records and assign them to individuals when possible. It has been acknowledged that there are gaps in 

the data, but the use of air sample data, urinalysis results, and surrogate data will allow internal dose 

estimates to be conducted. Therefore, though the document supported qualifying the petition for 

evaluation, currently available data or techniques given in the TBD indicate that dose reconstructions 

could be conducted for the 1946-1957 time-frame at Mallinckrodt, except for the issues raised under 

the response to #4 above. 

6. In addition, the first two statements that were received in a later fax 

(20040930\{09516D4D-780C-4113-B16A-91788B35B26D), indicate that 1) neither actinium, 

protactinium, nor ionium were monitored and 2) urine sample results were inadequate to 

assess for actinium or protactinium. 

34
 
Both statements that were provided indicated the air or urine samples were not analyzed for Ac-227, 

protactinium, or ionium. The TBD provides techniques to estimate internal exposures to each of these 

isotopes based upon the general air or uranium specific urine sample results and estimated (claimant 

favorable) isotopic distributions. The use of air sample data, urinalysis results, and surrogate data 

would allow internal dose estimates to be conducted. Therefore, though the document supported 

qualifying the petition for evaluation, currently available data or techniques given in the TBD indicate 

that dose reconstructions could be conducted for the 1946 – 1957 time-frame at Mallinckrodt, except 

for the issues raised under the response to #4 above. 

7.4 Summary of Feasibility Findings 

The information in the previous subsections describes techniques that were used at Mallinckrodt to 

monitor both internal and external exposures to radioactive materials and direct radiation sources. It 

appears from historical documentation that individuals were monitored based upon exposure potential. 

During the early years of operations, the most highly exposed individuals were monitored. Both the 

number of persons monitored and available monitoring records increased from the commencement of 

site radiological handling operations (the initial determination was that site activities would not take 

place for an extended period of time and that the processing of uranium would present an extreme 

exposure hazard.). An evaluation of whether dose reconstructions could be conducted for claims for 

the site operational period of 1942 – 1945 time period was addressed in another document (SEC 

00012-1). 

The four major exposure monitoring techniques in place at Mallinckrodt included: external 

dosimetry, urinalysis, air dust sampling/analysis, and radon analysis. External exposure records (see 

section 7.2.1 of this report) indicate weekly and biweekly film badge exchange frequencies beginning 

April 22, 1946 and extending through the end of site operations. Uranium urinalysis results (see 

section 7.1.1) are available beginning in the summer of 1948, also extending through the end of site 

operations. Air dust sampling (see section 7.1.3) began onsite in 1943 to aid in evaluating locations of 

potential internal exposure and of the need for changes in processes and equipment. It was expanded 

into a comprehensive program beginning in 1949. Finally, radon analyses (see section 7.1.4) began in 

1945 in Plants 1 and 4, using methods developed at the facility. Routine air sampling for radon did 

not begin until 1946, when samples were taken once a week in known, high-radon areas (a limited 

number of breath radon samples were also conducted for site workers, but the results can only be used 

as a qualitative indicator of exposure). 

As discussed under item #4 of Section 7.3 of this report, the petitioners have provided documentation 

that raises concern about the integrity and hence the validity of Mallinckrodt air dust monitoring data 

in particular. Assuming that the dust monitoring data were not valid, particularly that it might not 

include the highest measured exposures, NIOSH would not have sufficient information to reliably 

reconstruct internal doses from radiological dusts for employees who worked prior to 1949. Other 

exposures could be reconstructed from a scientific and technical standpoint, as indicated in the two 

tables below: 

35
 
The table below summarizes the results of the feasibility findings for each exposure source for 

the period from 1946-1948 

Source of Exposure Maximum or Accurate 

Exposure can be determined 

Maximum or Accurate 

Exposure cannot be determined. 

Internal X 

- Airborne Dust X 

- Radon X 

External X 

- Gamma X 

- Beta X 

- Neutron X 

- Occupational X rays X 

The table below summarizes the results of the technical feasibility assessment for each exposure 

source for the period from 1949-1957 

Source of Exposure Maximum or Accurate 

Exposure can be determined 

Maximum or Accurate 

Exposure cannot be determined. 

Internal X 

- Airborne Dust X 

- Radon X 

External X 

- Gamma X 

- Beta X 

- Neutron X 

- Occupational X rays X 

This evaluation has attempted to address in reasonable detail the scientific and technical matters 

concerning the feasibility of completing dose reconstructions. NIOSH has also come to a 

determination concerning the extent to which the documentation concerning data integrity casts 

excessive doubt on the validity of data available for dose reconstruction. NIOSH has determined that 

it cannot provide reasonable assurance of validity for dose reconstructions involving internal 

exposures of radiological dusts during the 1946-1948 period, which would include all employees 

working during this time period, because all employees had potential exposure to such dust. 

NIOSH has not resolved how to weigh the scientific and technical evidence, which support the 

feasibility of reconstructing internal as well as external radiation doses incurred during the 1949-1957 

period, against the evidence that raises questions about the integrity of monitoring data. In this 

weight-of-the-evidence test, NIOSH questions whether the data integrity issue outweighs the scientific 

and technical evidence. NIOSH questions whether its scientific and technical evidence is viable in 

this particular case, for the purposes of the EEOICPA compensation program because it does not 

provide a transparent basis by which NIOSH could assure Mallinckrodt claimants that they would 

receive reasonable estimates of their radiation doses. This is an important issue that NIOSH is likely 

to encounter in evaluating other SEC petitions in the future. Hence, NIOSH will seek the advice of 

36
 
 

the Board on the consideration of such issues generally, as well as on this specific weight-of-theevidence determination with respect to the 1949-1957 period at Mallinckrodt. 

In summary, NIOSH has determined that it is not feasible to estimate radiation doses with sufficient 

accuracy for employees of the Uranium Division at the Mallinckrodt Destrehan Street facility (and 

associated facilities) during the operating years of 1946-1948. A determination of feasibility 

concerning a second class employed from 1949-1957 will be made after obtaining the advice of the 

Board. 

8.0 Evaluation of Health Endangerment 

The health endangerment determination for the classes of employees covered by this evaluation report 

is governed by EEOICPA and 42 C.F.R. § 83.13(c)(3). Under these requirements, if it is not feasible 

to estimate with sufficient accuracy radiation doses for members of the class, NIOSH must also 

determine that there is a reasonable likelihood that such radiation doses may have endangered the 

health of members of the class. The regulation requires NIOSH to assume that any duration of 

unprotected exposure may have endangered the health of members of a class when it has been 

established that that the class may have been exposed to radiation during a discrete incident likely to 

have involved levels of exposure similarly high to those occurring during nuclear criticality incidents. 

If the occurrence of such an exceptionally high level exposure has not been established, then NIOSH 

is required to specify that health was endangered for those workers who were employed for a number 

of work days aggregating at least 250 work days within the parameters established for the class or in 

combination with work days within the parameters established for one or more other classes of 

employees in the SEC. 

As discussed in section 5.1 of this report and as documented in the dust monitoring results available to 

NIOSH, Mallinckrodt employees had significant exposures to radiological dusts. On this basis, 

NIOSH has determined that it is reasonably likely that such exposures to alpha-emitting dust may 

have endangered the health of the Mallinckrodt workers covered by the two class definitions provided 

in section 9.0 of this evaluation. 

The NIOSH evaluation did not identify any evidence from the petitioners or from other resources that 

would establish that the classes were exposed to radiation during a discrete incident or similar 

conditions resulting from the failure of radiation exposure controls and likely to have produced levels 

of exposure similarly high to those occurring during nuclear criticality incidents. NIOSH is not aware 

of any report of such an occurrence at the facility. The evidence reviewed in this evaluation indicates 

that some workers in the classes may have accumulated substantial chronic exposures through 

repeated, episodic inhalations of radionuclides. Consequently, NIOSH is specifying that health was 

endangered for those workers covered by this evaluation who were employed for a number of work 

days aggregating at least 250 work days within the parameters established for these classes or in 

combination with work days within the parameters established for one or more other classes of 

employees in the SEC. 

9.0 Proposed Class Definition 

This evaluation defines one class of employees for which NIOSH has established that it cannot 

estimate radiation doses with sufficient accuracy and whose health may have been endangered by such 

radiation doses. This class includes employees of DOE or DOE contractors or subcontractors 

37
 
employed by the Uranium Division of Mallinckrodt during the period from 1946 through 1948 and 

whom were employed for a number of work days aggregating at least 250 work days, occurring either 

solely under this employment, or in combination with work days of employment occurring within the 

parameters (excluding aggregate work day requirements) established for other classes of employees 

included in the SEC. 

The evaluation defines a second class of employees which includes employees of DOE or DOE 

contractors or subcontractors employed by the Uranium Division of Mallinckrodt during the period 

from 1949 through 1957 and whom were employed for a number of work days aggregating at least 

250 work days, occurring either solely under this employment, or in combination with work days of 

employment occurring within the parameters (excluding aggregate work day requirements) 

established for other classes of employees included in the SEC. For this class, the advice of the 

Board concerning the matter of data reliability, as discussed above, as well as the advice of the Board 

as generally provided for under 42 C.F.R. pt. 83.15 will be obtained. 

This evaluation, in conjunction with SEC Evaluation Report Petition SEC-00012-1 (1942-1945), 

completes the NIOSH evaluation of SEC Petition No. 12, which covered all workers within the 

Uranium Division of the Mallinckrodt Destrehan Street facility in St. Louis, Missouri, over the entire 

period of operation from 1942 through 1957. 

In consultation with the Division of Energy Employees Occupational Illness Compensation, 

Department of Labor, NIOSH has determined that Plants 1, 2, 4, 6, and 7 are functionally equivalent 

to that portion of the Mallinckrodt Destrehan Street facility known as the Uranium Division, and has 

therefore proposed class definitions that utilize that designation. 

38
 
10.0 References 

Note: The reference document identifier matches the references from the Mallinckrodt TBD. 

AEC 1947e 

Atomic Energy Commission (AEC).Visit to Mallinckrodt, St. Louis, Missouri. Memorandum to G. W. 

Beeler from R. V. Randall, 17 February 1947. 

AEC 1948c 

Atomic Energy Commission (AEC). Mallinckrodt Chemical Works Proposal for Improvement in the 

Method of Feinc Filtrate Clarification. Memorandum to W. E. Kelley from B. S. Wolf; 24 September 

1948. 

AEC 1949b 

Atomic Energy Commission (AEC). Health Hazards in NYOO Facilities Producing and Processing 

Uranium. Report by the New York Operations Office Medical Division.18 April 1949. 

AEC 1949e 

Atomic Energy Commission (AEC). Monthly Status and Progress Report for February 1949, NYOO. 

Report by W. E. Kelley. 7 April 1949. 

AEC 1949g 

Atomic Energy Commission (AEC). Visit to Mallinckrodt Chemical Works, St. Louis, Missouri. 

Memorandum to Files from H. Blatz. 1 March 1949. 

AEC 1950a 

Atomic Energy Commission (AEC). An Estimate of Cumulative Multiple Exposures to Radioactive 

Materials, Mallinckrodt Chemical Works, Plants 4 and 6. Report covering July 1942 to October 1949. 

Mallinckrodt-5; 20 November 1950. 

AEC 1951b 

Atomic Energy Commission (AEC). The Production of Uranium Feed Materials. Report to the 

Commission by the AEC Director of Production, with note by Secretary R. B. Snapp. 22 May 1951. 

AEC 1954b 

Atomic Energy Commission (AEC). Mallinckrodt Chemical Works Plant 6 Occupational Exposure to 

Airborne Contamination. [HASL-]MCW-15; January 1954. 

AEC 1955b 

Atomic Energy Commission (AEC). Design Criteria for SLPC Expansion. Memorandum to M. 

Eisenbud from W. B. Harris. 18 January 1955. 

AEC 1955c 

Atomic Energy Commission (AEC). Discussion of Ionium Toxicology at Rochester, July 14, and 

Mallinckrodt, July 15. Memorandum to C. L. Dunham from R. E. Albert. 19 July 1955. 

39
 
AEC 1955e 

Atomic Energy Commission (AEC). Mallinckrodt Chemical Works Plants 6E & 7E Occupational 

Exposure to Airborne Contamination. HASL-MCW-24; 22 June 1955. 

AEC 1958 

Atomic Energy Commission (AEC). Environmental Hazards Associated with the Milling of Uranium 

Ore. HASL-40; Revised, 14 November 1958. 

AEC 1959 

Atomic Energy Commission (AEC)?. St. Louis Airport Site, Summary. Report regarding types and 

inventories of wastes stored [MO.1-2]; 11 April 1959. 

AEC 1967 

Atomic Energy Commission (AEC). Historical Review of the Mallinckrodt Airport Cake. Report 

(transmitted with cover letter from J. R. Katz, legislative assistant to Missouri Congressman Robert A. 

Young, to Dr. W. E. Mott, Director, Division of Environmental Control Technology, Department of 

Energy, 26 July 1978). 1967. 

Baker 1958 

Baker RC. Beta Exposure During Uranium Processing. In: Symposium on Occupational Health 

Experience and Practices in the Uranium Industry. Proceedings of a United States Atomic Energy 

Commission conference. New York City: United States Atomic Energy Commission; HASL-58; 

1958: 189-194 

Eisenbud 1958 

Eisenbud M. Discussion of Apparent Anomalies in Lung Retention of Uranium. In: Symposium on 

Occupational Health Experience and Practices in the Uranium Industry. Proceedings of a United 

States Atomic Energy Commission conference. New York City: United States Atomic Energy 

Commission; HASL-58; 1958: 212-213. 

Eisenbud 1975 

Eisenbud M. Early Occupational Exposure Experience with Uranium Processing. In: Occupational 

Health Experience with Uranium. Proceedings of a United States Atomic Energy Commission 

conference. Arlington, Virginia: ERDA-93; 1975: 9-24. 

FUSRAP undated 

Formerly Utilized Sites Remedial Action Program (FUSRAP), Army Corps of Engineers. History of 

Material Storage at the St. Louis Airport. Undated. 

FUSRAP 1996 

Formerly Utilized Sites Remedial Action Program (FUSRAP), US Department of Energy. 

Management Action Process Document for the St. Louis, Missouri, FUSRAP Sites. Draft; March 

1996. 

FUSRAP 2003b 

Formerly Utilized Sites Remedial Action Program (FUSRAP), Army Corps of Engineers. Personal 

Communication; J. Mattingly of FUSRAP to J. L. Westbrook of MJW Corporation, based on Drawing 

No. 3517-2; 2003. 

40
 
Glauberman and Harris 1958 

Glauberman H, Harris WB. Air Sampling Procedures in Evaluating Exposures. In: Symposium on 

Occupational Health Experience and Practices in the Uranium Industry. Proceedings of a United 

States Atomic Energy Commission conference. New York City: United States Atomic Energy 

Commission; HASL-58; 1958: 208-211. 

ICRP 1995a 

International Commission on Radiological Protection (ICRP). Age-Dependent Doses to Members of 

the Public from Intake of Radionuclides: Part 4 Inhalation Dose Coefficients. ICRP Publication 71; 

1995. 

Lippmann 1958 

Lippmann M. Correlation of Urine Data and Medical Findings with Environmental Exposure to 

Uranium Compounds. In: Symposium on Occupational Health Experience and Practices in the 

Uranium Industry. Proceedings of a United States Atomic Energy Commission conference. New York 

City: United States Atomic Energy Commission; HASL-58; 1958: 103-114. 

MCW 1946g 

Mallinckrodt Chemical Works (MCW). No subject. Letter to W. D. Fleming of the Manhattan 

Engineer District from S. H. Anonsen of Mallinckrodt. 9 November 1946. 

MCW 1948b 

Mallinckrodt Chemical Works (MCW). Beta Radiation Problem at Plant Four. Letter to [J. F.] 

Hubbell of Singmaster & Breyer from K. J. Caplan of MCW. 2 August 1948. 

MCW 1948d 

Mallinckrodt Chemical Works (MCW). Change of Film Badge on Week Ends. Memorandum to 

(Guard) Chief Gerk from K. J. Caplan. 1 November 1948. 

MCW 1949a 

Mallinckrodt Chemical Works (MCW). Beta Radiation -- Metal Plant. Letter to B. S. Wolf of AEC 

from H. E. Thayer of Mallinckrodt Chemical Works. 9 February 1949. 

MCW 1949c 

Mallinckrodt Chemical Works (MCW). Dust Study at MCW Plant 4, 26 January 1949. Report 

transmitted by memorandum, Dust Study at MCW Plant 4, to H. H. Thayer from K. J. Kaplan. 2 

February 1949. 

MCW 1949d 

Mallinckrodt Chemical Works (MCW). Dust Study of Plant Six, October-November 1948. Memo and 

report to H. E. Thayer from K. J. Kaplan; 21 April 1949. 

MCW 1949g 

Mallinckrodt Chemical Works (MCW). No subject. Letter to M. Eisenbud of AEC from K. J. Caplan 

of Mallinckrodt Chemical Works. 6 May 1949. 

41
 
MCW 1949n 

Mallinckrodt Chemical Works (MCW). Radon in General Yard Area of Plant Six. Memorandum to H. 

E. Thayer from K. J. Caplan. 11 August 1949. 

MCW 1949q 

Mallinckrodt Chemical Works (MCW). Use of Film Badge During Off-Plant Work. Memorandum to 

Mr. Anonsen et al. from K. J. Caplan. 21 April 1949. 

MCW 1950c 

Mallinckrodt Chemical Works (MCW). Evaluation of Past Dust Exposures at Plant 4 and Plant 6. 

Letter to M. Eisenbud of AEC from K. J. Caplan of Mallinckrodt. 16 January 1950. 

MCW 1950d 

Mallinckrodt Chemical Works (MCW). Health Physics Program for Plant Six and Plant Four. Letter 

to J. J. Koenig of the Atomic Energy Commission from K. J. Caplan of MCW. 14 April 1950. 

MCW 1950e 

Mallinckrodt Chemical Works (MCW). Health Physics Program for Plant Six and Plant Four. Letter 

to J. J. Koenig of the Atomic Energy Commission from K. J. Caplan of MCW. 14 April 1950. 

MCW 1950g 

Mallinckrodt Chemical Works (MCW). No subject. Letter to H. I. Blatz of AEC from M. G. Mason of 

Mallinckrodt. 20 April 1950. 

MCW 1950i 

Mallinckrodt Chemical Works (MCW). No subject. Letter to H. I. Blatz of AEC from K. J> Caplan of 

MCW. 18 January 1950. 

MCW 1950t 

Mallinckrodt Chemical Works (MCW). Radiation Exposure of MCW Plant Six Employees. Letter to 

C. L. Karl of the Atomic Energy Commission from H. E. Thayer of MCW. 5 May 1950. 

MCW 1954a 

Mallinckrodt Chemical Works (MCW). K-65 Sampling Lab. Report by (apparently) E. Roddy. Circa 

5 January 1954. 

MCW 1954d 

Mallinckrodt Chemical Works (MCW). Plant Four Film Badges. Memorandum to M. G. Mason et al. 

from G. R. Messerli. 10 September 1954. 

MCW 1955b 

Mallinckrodt Chemical Works (MCW). Film Badge Program. Memorandum to C. D. Harrington et al. 

from M. G. Mason. 31 January 1955. 

MCW 1955c 

Mallinckrodt Chemical Works (MCW). Film Badge Reports, Mallinckrodt Chemical Works Uranium 

Division. Letter to H. J. McAlduff, Jr. of AEC from M. G. Mason of MCW. 5 April 1955. 

42
 
MCW 1955d 

Mallinckrodt Chemical Works (MCW). Mallinckrodt Chemical Works Health Program: Policies, 

Status, and Summary. Report by M. G. Mason of Mallinckrodt. 21 February 1955. 

MCW 1956i 

Mallinckrodt Chemical Works (MCW). Summary of the Mallinckrodt Chemical Works Film Badge 

Program. Memorandum to J. W. Miller from K E. Brandner. May 1956. 

MCW 1961a 

Mallinckrodt Chemical Works (MCW). Activity Levels, Final Radioactivity Survey, Destrehan Street 

Facilities. Report by the Health and Safety Department; 30 November 1961. 

MED 1942 

Manhattan Engineer District (MED). Supplemental Report To Complete Preliminary Survey of Plants 

Engaged in Production of Materials. Report by H. L. Friedell of the Corps of Engineers (MED). 23 

December 1942. 

MED 1944d 

Manhattan Engineer District (MED). No subject. Letter to H. E. Thayer of Mallinckrodt Chemical 

Works from J. L. Ferry of the Corps of Engineers. 11 May 1944. 

MED 1944j 

Manhattan Engineer District (MED). Progress Report of the Special Materials Division of the Medical 

Section. Memorandum to S. L. Warren from J. L. Ferry. 3 January 1944. 

MED 1944m 

Manhattan Engineer District (MED). Visit to Mallinckrodt Chemical Company -- 20 September 1944. 

Memorandum to The Madison Square Area Engineer from R. A. Tybout. 22 September 1944. 

MED 1945e 

Manhattan Engineer District (MED). No subject. Letter to S. H. Anonsen of Mallinckrodt Chemical 

Works from B. J. Mears of MED. 9 July 1945. 

MED 1946c 

Manhattan Engineer District (MED). No subject. Letter to H. E. Thayer of Mallinckrodt Chemical 

Works from W. F. Bale of MED. 18 November 1946. 

Mason 1958a 

Mason MG. A Summary of Fifteen Years of Experience with Dust Problems in the Refining and 

Fabrication of Uranium. In: Symposium on Occupational Health Experience and Practices in the 

Uranium Industry. Proceedings of a United States Atomic Energy Commission conference. New York 

City: United States Atomic Energy Commission; HASL-58; 1958: 3-9. 

Mason 1977 

Mason, M. G. [Title page lost]. Report of MED/AEC operations and processes at Mallinckrodt 

Chemical Works, 1942-1957; apparently provided to Oak Ridge Associated Universities for use in 

their study of Mallinckrodt workers. 19 August 1977. 

43
 
ORAU 1977 

Oak Ridge Associated Universities. The MCW 10-01-49 Dust Exposure Evaluation: Facts and 

Recommendations about a Prime Record. Report, no author or data listed. Circa 1977. 

ORAU 1980b 

Oak Ridge Associated Universities. Radiation Exposure Data, Mallinckrodt Uranium Division 

Operations, January 1947 through June 1956. Report, no author or data listed. Circa 1980. 

ORAU 1983a 

Oak Ridge Associated Universities (ORAU). Call from Mont Mason. Memorandum of telephone 

conversation between Mont G. Mason of Mallinckrodt and an unnamed employee of Oak Ridge 

Associated Universities(?). 2 December 1983. 

ORAU 1983b 

Oak Ridge Associated Universities (ORAU). Interview with John Harley from NYOO's HASL 

Concerning Radiation Monitoring Done at HASL. Memorandum to D. Cragle, D. Robie, and W. 

Tankersley from E. Dupree. 25 March 1983. 

ORAU 1989a 

Oak Ridge Associated Universities (ORAU). Mallinckrodt Chemical Works: Radon Dose 

Assessment. Memorandum to MCW File from J. 

ORAU 1991 

Oak Ridge Associated Universities (ORAU). Mallinckrodt Chemical Works: Four-Plant Study 

Classifications of Radium, Radon, and Thorium Exposure. Memorandum from J. N. Ingle to Files. 16 

September 1991. 

ORAUT 2004 

Oak Ridge Associated Universities Team (ORAUT), for NIOSH. TBD for Atomic Energy Operations 

at the Iowa Army Ammunition Plant (IAAP). ORAUT-TKBS-0018. Rev. 0; 16 April 2004. 

ORNL 1981 

Oak Ridge National Laboratory (ORNL). Radiological Survey of the Mallinckrodt Chemical Works, 

St. Louis, Missouri. DOE/EV-0005/27; ORNL-5715; December 1981. 

Rochester 1948a 

Rochester, University of (Rochester), School of Medicine and Dentistry. No subject. Letter from R. 

Hayes of Rochester to B. S. Wolfe of the Atomic Energy Commission. 29 January 1948. 

Rochester 1950 

Rochester, University of (Rochester), School of Medicine and Dentistry, Atomic Energy Project. No 

subject. Letter from R. Hayes of Rochester to J. Cherry of the Atomic Energy Commission, New York 

Operations Office. 12 January 1950. 

44
 
Attachment 1 

Mallinckrodt Documents and Reports 

From Site Research Database 

Mallinckrodt Notes 

Mallinckrodt Radon Sampling Procedures 

Mallinckrodt Uranium Processing Workers Mortality Report 1998 

Mallinckrodt Proposal for Radon Dose Assessment 1998 

Estimate of Cumulative Multiple Exposures MCW 1942-1949 

MCW - Contract Mods with UO2 Production Rates (w-7405-Eng-19) - 1946 

2.0 Site Description and History Close Out Report for FUSRAP 

Mallinckrodt Workplace Data Contamination Survey 1959 

MCW - Activity Levels, Final Radioactive Survey at Destrehan 1961 

MCW AEC - NRL Plant Inspections 1958-1996 

MCW - Ionization Chamber Calibration Curve 1948 

MCW - Codes for Radioactive Material Identification 1953-1955 

MCW - Columbium - Tantalum Plant Characterization on Plant 1994 

MCW - Contaminated Material Incineration 1959 

MCW - Control of Radiological Hazards during Uranium Processing 1948 

MCW - C-T Plant Environmental Information Document 1985 

MCW - C - T Preliminary Radiological Investigation (PRI) Final Report - 1993 

MCW - Dust Collector Filter Selection Decision Basis 1948-1950 

MCW - Environmental Analysis Report 1985 

MCW - Event Chronology for Rill Cotter Incident - 1978 

MCW - External Radiation Monitoring Program 1998 

MCW - Facility Radiological Inspections and Investigations 1993-1994, 1976 

MCW - Final Results of East Pile and HISS Spoil Piles 

MCW - General Information 

MCW - Health and Safety Program Developments 1948 

MCW - Health Correction Johns at the Work Site 1948 

Health Hazards in NYOO Facilities Producing & Processing Uranium 

MCW - Internal and External Radiological Monitoring Data 1958-1961 

MCW - Latty Ave. Site Report on Results of Radiological Survey 1977 

Information on FUSRAP and Surplus Facility Sites in Missouri 

MCW - Mallinckrodt Chemical Company Destrehan St. Plant 

MCW - Mallinckrodt Chemical Works MZ Report 

MCW - Medical Data Reinstated to Radiological Exposures 1950 

MCW - Monthly Report of Field Activities Sept 1950 

MCW - New York OPS Office Monthly Report of Field Activities 

MCW - NRC Inspections 1996, 1985-1986, 1978, 1979 

MCW - Occupational Exposure to Airborne Containments 1953 

MCW - Plant 4 Dust Control Letter - 1949 

MCW - Plant Changes to Adjust to Request for Increased Slang Grinding Capacity 

MCW - Plant Expansion to Increase Metal Plant Capacity 1952-1954 

MCW - Plant Operations & Controls for Radioactive Materials 

MCW - Rad. Contamination January 1959 

MCW - Radiation Exposure Conference Notes & Comments 1950 

45
 
MCW - Radiological Characterization on Data Set Volume 3 1998 

MCW - Radiological Characterization on Data Set Volume 4 1998 

MCW - Radiological Characterization on Data Set Volume 5 1998 

MCW - Radiological Characterization Data Set Volume 1 1998 

MCW - Radiological Characterization on Data Set Volume 2 1998 

MCW - Radiological Hazards & Controls for Uranium Operations 

MCW - Radon Progeny Measurements for 4088 4Q87, 2Q89,3Q90, & 4Q90 

MCW - Source Material Licensing - 1960-1961 

MCW - Source Material Licensing - 1961 & Environmental Assessment 

MCW - TLD Reports, Radon Reports Partial License Reports Radiological Surveys 

MCW - Urinalysis and Radon Analysis Program Basis 1949 - 1950 Surveys 

MCW - Whole Body Exposures for Selected Personnel - 1981 - 1985 

MCW - and Weldon Springs Possible Use of Quarry for Contaminated Debris Disposal 

United Nuclear Corporation - Mallinckrodt 

MCW - Plant Drawings and Maps - 1946 - 1955 

Documents Associated With Employees Exposure at MCW 

Dust Study of the New K-65 Ledoux Laboratory Installation 

Film Badge Data February Wage 1966 

Film Badge Program 

Employee Job History Sheet 

Information on X-ray Film & Procedure 

Monitoring Results for Donald L. Harrison 

Autopsy Report on OWEN KERSNER 

Radiation Exposure of Plant 6 Employees 

Radiological Limits for Plant 6 and Other Locations 

General Information about Product 

This document is a duplicate of another document - Refer to 010002059 for entire document 

Mallinckrodt - Fuel for the Atomic Age - Report on St. Louis - Area Uranium Processing Operations, 

1942 - 1967 

Historical Review of the Mallinckrodt Airport Cake 

External Radiation Exposure and Mortality in a Cohort of Uranium Processing Workers 

Radiological Survey of the Mallinckrodt Chemical Works, St. Louis 

Observation of the Electrolysis of UO2 at Mallinckrodt Chemical Works, Weldon Spring, Missouri 

from June 1, 1966, to October 7, 1966 

Disposal of Destrehan Street Facilities and Restoration of Site 

Lowman Mill and Disposal Site, Boise County, Idaho 

SLDS Fact Sheet 

Sales of Residues at the Airport Site 

Radon Breath Analysis (1945 - 1947) 

Breathe Samples at MCW (1945, 1946, and 1947) 

Utter Principle Potential Radioactive Hazards at Mallinckrodt 

X-Ray Examination Frequency Change (1946) 

Plant 6 Air Samples (1946) 

Mallinckrodt Film Badge Results (1945, 1946, 1947) 

Radon Breath Samples (1946 & 1947) 

Film Badges Results (1946 & 1947) 

Air Sampling Data - Feb - June 1944 

Film Badge Data and Radiation Measurements at Mallinckrodt (1944) 

46
 
 

Film Badge Reports (1945) 

Uranium Dust in Air 

Dust Samples 

Dust Samples 

Dust Samples 

Various Reports on Mallinckrodt Radiation Hazards (1944) 

Progress Report of the Special Materials Division of Medical 

Medical Programs in Report at the Mallinckrodt Project 

Film Badge Results (1945) 

Air Samples at Mallinckrodt 1945 

Uranium Refining Process 

Toxicology of Thorium 

Film Badge Results Aug 18 - Aug 25, 1947 

Film Badge Results Aug 4 - Aug 11, 1947 

Film Badge Date July 28 to August 4, 1947 

Film Badge Date June 2 to July 1947 

Film Badge Date Dec 30, 1946 to June 9, 1947 

Radiation Injuries from Uranium 

Extractions of Uranium Ore from Domestic Uranium Ore Concentrations 

Radon Breath Samples 

Film Badge Analysis May 27, 1946 - Sept 2, 1946 

Mallinckrodt Film Badge Results May 20-27, 1946 

Mallinckrodt Film Badge Results April 22- May 18, 1946 

Mallinckrodt Film Badge Results Feb 18 - March 16, 1946 

Mallinckrodt Film Badge Results March 18 - 25 1649 

Mallinckrodt Breath Sample Reports Various Dates 1945 - 1949 

NNES - Vol. 112B Listing of Papers on Processing Uranium Products 

Letter on Beta Effects to Skin 

Tabulation of Film Results from Badges Worn Aug 18 - 25 1947 

Tabulation of Film Results from Badges Worn May 19 - 26 1947 

Tabulation of Film Results from Badges Worn May 26 - June 2, 1947 

Tabulation of Film Results from Badges Worn June 2-9, 1947 

Tabulation of Film Results from Badges Worn June 9-16, 1947 

Tabulation of Film Results from Badges Worn June 16 - 23, 1947 

Tabulation of Film Results from Badges Worn June 23 - 30, 1947 

Tabulation of Film Results from Badges Worn June 30 - July 7, 1947 

Tabulation of Film Results from Badges Worn July 7 - 14, 1947 

Tabulation of Film Results from Badges Worn July 14 - 21, 1947 

Tabulation of Film Results from Badges Worn July 21 - 28, 1948 

Tabulation of Film Results from Badges Worn July 28 - Aug 4, 1947 

Tabulation of Film Results from Badges Worn Aug. 4 - 11, 1947 

MCW Dosimetry results 8/25/47 - 10/13/47 

Weekly dose results for MCW 4/1946 to 4/1947 

Weekly dose results for MCW 10-13-47 to 12-29-47 

Dust Study for Shotgun Lab 

Code used for Materials at MCW 

Radon & Dust Studies 1948 to 1953 

Work Permits for warehouse operations 

47
 
Dust Study at Plant 6 

Housekeeping Memo 

Dust Study Report Plant 6 

Comments on Plant 4 Operations 1951 

K-65 sapling lab conditions report 

Report -Pollution of Plant 6 Yard 

Memo on shipping empty drums 

Radon Dose Assessment 

The relationship between breath radon measurements & skeletal radium burdens 

Information from Mont Mason & other site specific information 

Interim Report on Film Badge Exposures in Shotgun Laboratory 

Film Badge Results 

Various Process Dust Studies 1961 

Radioactive Airborne Dust Study of Sampling of Feed Materials for Oil Analysis 

Radioactive Dust Concentrations U-Con Grinding in the Shotgun Laboratory 

Dust Study Information 

Documentation on Reconciling MCW Film Badge Data 

Hand Loading of Raw Ore into Secondary Elevator 

Radon in Ore Room 

Health Inspection of Plant 6, 10/17/55 

Scalehouse Sample Room Study 

Crucible Burn-Out Hood Stack at Plant 4 

Correction of Beta Radiation at Plant 4 Recasting Operations, August 1949 

Report-Dust Concentrations in Kinney Pump Discharge, August 1949 

Proper Use of Dust Collecting System on Vacuum Furnace 

Use of Old Crucibles in the Recast Furnace 

Procedure: Repair of Plant 4 Recast Furnace, September 1953 

Radiation Study of Plant 4 Recast Operations, November 1953 

Report of Radiation Exposure of FEWC Cloth Operators 

Air Studies 1948-50 and 1952 

Air Studies on Guards 

MCW Dust Exposure Evaluation Report 

MCW Plant 6 Air Sample Dust Results Sheet 

Individual Urinalysis Records 

Plant 6 Cloth Storage Room Radon Concentration 

Film Badge Results November 1948 - August 1950 

Four Plant Study 

Radiation Exposure Data, January 1947 - June 1956 

Exposure Monitoring Data 

48