Baker Brothers

Special Exposure Cohort 

Petition Evaluation Report

James W. Neton, PhD, CHP

Associate Director for Science

National Institute for Occupational Safety and Health

Division of Compensation Analysis and Support

December 2012

Knoxville, TN
EEOICPA Facility Listing 

 Baker Brothers 

 State: Ohio Location: Toledo 

 Atomic Weapons Employer (AWE) 1943-1944; Residual 

Radiation 1945-1994, 1996; Department of Energy (DOE) 

1995 (remediation) 

 Facility Description: Between June 1943 and July 1944, 

DuPont and the University of Chicago subcontracted the 

Baker Brothers company to machine roll metal rods into 

uranium slugs that were used for fuel in the world's first 

production reactors located in Oak Ridge, TN and 

Hanford, WA
 June 5, 2012: NIOSH received an 83.13 petition 

for period of 1943 through 1996

 July 24, 2012: Petition qualified for evaluation

 November 14, 2012: Evaluation Report 

approved

 SEC class recommended: 1943 - 1944

Petition Overview
Petition Overview—cont. 

Basis for Qualification

Radiation exposures and radiation doses 

potentially incurred by members of the proposed 

class were not monitored either through personal 

monitoring or through area monitoring
Petition Overview—cont. 

 Petitioner requested class: 

All employees who worked in any area of Baker 

Brothers, in Toledo, Ohio, from June 1, 1943 

through December 31, 1996

 NIOSH recommended class: 

All employees who worked in any area of Baker 

Brothers, in Toledo, Ohio, from June 1, 1943 

through December 31, 1944
Class Evaluated by NIOSH 

 All employees who worked in any area of Baker 

Brothers, in Toledo, Ohio, from June 1, 1943 

through December 31, 1996

 The start date of the evaluation period is 

consistent with the start of Manhattan Engineer 

District (MED) operations at Baker Brothers

 The end date of evaluation represents the last 

day of the calendar year that Baker Brothers is 

listed as covered on the EEOICPA facility list
Sources of Available Information

 Site Profile Battelle-TBD-6000, used to model 

external doses for the machining process, and to 

estimate contamination levels from operations

 ORAUT-OTIB-0070 methods used to model 

residual period doses

 NIOSH Site Research Database: 154 documents 

researched

 Normal data searches were also conducted
Previous Dose Reconstructions

NIOSH DCAS Claims Tracking System 

Information current as of November 28, 2012

 Baker Brothers claims submitted for dose reconstruction 4

 Claims with employment in the AWE contract period only 1

 Claims with employment in the residual period only 2

 Claims with employment in both AWE and residual periods 1

 Claims for which dosimetry records were obtained 0
 Baker Brothers was a DuPont subcontractor used 

for production level machining of uranium slugs

 The uranium slugs were used in the first 

production reactors at the Clinton Engineer 

Works and the Hanford Engineer Works

Baker Brothers AWE Operations
 Machining work started in June 1943

 Utilized four lathes for both rough and finish 

turning

 Machining work was completed in August 1944

 Shipping records indicate scrap metal and 

turnings remained on site through October 1944

Baker Brothers AWE Operations—cont. 
Baker Brothers Site

Uranium 

machined 

here
 First order was for Clinton Engineer Works

• 41,133 slugs produced from 2,107 rods

• Rods received were about 8 feet long; finished slug 

size varied from about 4” to 6” long and up to about 

1.3” diameter

• Initial order of slugs were shipped out by the end of 

October 1943

Slug Production
 Additional slug work by Baker Brothers:

• Milling grooves into previously machined Clinton 

slugs

• Development work for the Hanford slugs

• Reclaiming used experimental slugs

• Production of slugs for Hanford in 1944

Slug Production—cont. 
 Total number of slugs machined:

• 41,133 slugs produced for Clinton

• 12,435 slugs grooved and refaced

• 16,899 slugs produced for Hanford

• Approximately 90 tons of uranium metal received and 

shipped in 1943

• Precise tonnage of uranium metal handled in 1944 not 

available

Amount of Uranium Processed
 DOE (Formerly Utilized Sites Remedial Action Program -

FUSRAP) documents reported that the Baker Brothers facility 

was decontaminated to existing guidelines at the end the 

contract. 

 A Corps of Engineer letter from 1944 indicates that the Baker 

Brothers contract was to be closed out as soon as all scrap, 

turnings, and sweepings were shipped. 

 The Baker Brothers assets were eventually liquidated and 

the machinery and equipment were sold at auction. The 

property was subsequently used primarily for offices and 

motor brokerage and electrical services.

Facility Status Post Production
Potential Radiation Exposures 

During the Evaluated Period

 Sources of internal dose

• Inhalation and ingestion of uranium from machining 

operations

• Inhalation and ingestion of uranium from residual 

contamination

 Sources of external dose

• Photon and beta exposure from uranium metal

• Photon and beta exposure from residual contamination
Radiological Monitoring Data

 AWE Contract Period, 1943-1944

• Workers had periodic medical monitoring, but no 

personal monitoring data is available or known to exist

• Limited air sample data:

1943 (3 samples); 1944 (4 samples);

Samples were collected during visits by doctors from 

the Metallurgical Laboratory
Radiological Monitoring Data—cont. 

 Residual and Remediation Periods, 1945-1996

• Bioassay data available for the remediation period in 

1995

• Air sampling conducted in 1989 and in 1995

• No personal external dosimetry data

• Radiation and contamination surveys performed in 

1981, 1989, 1990, 1995 and 1996
Dose Reconstruction, AWE Period

 Internal Dose 1943-1944

• Six air sample results from three days in 1943-1944 are 

insufficient to characterize episodic exposures from 

operations and fires

• Data in Battelle-TBD-6000 from other sites in later years 

not necessarily representative of exposure from 

machining in 1943-1944

• Internal dose cannot be reconstructed with sufficient 

accuracy
Dose Reconstruction, AWE Period—cont. 

 External Dose 1943-1944

• No radiation measurements from Baker Brothers are 

available for the AWE contract period

• External dose data in Battelle-TBD-6000 is 

representative of external dose rates from uranium 

metal in 1943-1944

• External dose from exposures in 1943-1944 can be 

reconstructed with sufficient accuracy
Dose Reconstruction, 

Residual Period

 Internal Dose 1945-1996

• Calculation of airborne radioactivity in 1945 made from 

estimates of bounding contamination levels at the 

beginning of the residual period

• Detection limit of air samples taken in 1989 was used 

with the 1945 airborne radioactivity estimate to 

determine a source term depletion rate of 0.164/yr

• Annual inhalation and ingestion intakes for each year 

were calculated through 1994
Dose Reconstruction, 

Residual Period—cont. 

 Internal Dose 1945-1996, cont.

• For the remediation period in 1995, bioassay data are 

available for remediation workers

• General area airborne radioactivity data is available for 

other workers in 1995

• 1995 dose bounds dose from work in 1996, which 

consisted of confirmation surveys and decontamination 

of a couple spots identified during the surveys
 External Dose 1945-1996

• Characterization data indicated relatively low radiation 

levels, not significantly higher than background for 

whole body exposures in most areas

• Highest dose rates and soil contamination levels were 

found in the outdoor courtyard where the uranium 

metal had been staged in 1943-1944

• Bounding external dose of 0.037 mrem per work year 

was calculated based on continuous exposure in the 

courtyard from 1945 to 1996

Dose Reconstruction, 

Residual Period—cont. 
 AWE Contract Period, 1943-1944

• NIOSH found that the available air monitoring records 

are insufficient to estimate intakes

• Baker Brothers was one of the first companies to 

machine uranium on a production scale

• Methods of applying coolant, controlling fires, and 

controlling exposures were developed concurrent with 

operations at Baker Brothers

• Intakes cannot be estimated with sufficient accuracy

Feasibility of Dose Reconstruction
Feasibility of Dose Reconstruction—cont. 

 AWE Contract Period, 1943-1944

• NIOSH found that external dose from exposure to 

uranium metal can be estimated using available 

uranium metal dose rate measurement data

• External dose during the AWE Contract Period can be 

reconstructed with sufficient accuracy
 Residual and Remediation Periods, 1945-1996

• NIOSH found that internal doses can be estimated with 

sufficient accuracy based on estimates of bounding 

contamination levels at the start of the residual period 

and air sampling results from the later residual period

• Internal dose during remediation can be estimated 

using available worker and area monitoring data

• External dose during the residual and remediation 

periods be estimated based on measured dose rates

Feasibility of Dose Reconstruction—cont. 
Summary

Feasibility Findings for Baker Brothers Petition 

June 1943 – December 1944

Source of Exposure Reconstruction 

Feasible

Reconstruction 

NOT Feasible

Internal

- Uranium X

External

- Uranium beta-gamma X

 - Neutron N/A

 - Medical X-ray N/A
Summary

Feasibility Findings for Baker Brothers Petition 

January 1945 – December 1996

Source of Exposure Reconstruction 

Feasible

Reconstruction 

NOT Feasible

Internal

- Uranium X

External

- Uranium beta-gamma X

 - Neutron N/A

 - Medical X-ray N/A
All Atomic Weapons Employees who worked at the 

Baker Brothers site in Toledo, Ohio, during the 

period from June 1, 1943 through December 31, 

1944, for a number of work days aggregating at 

least 250 work days, occurring either solely under 

this employment, or in combination with work days 

within the parameters established for one or more 

other classes of employees included in the Special 

Exposure Cohort

Recommended Class