Summary

The Sergeant First Class Heath Robinson Honoring Our Promise to Address Comprehensive Toxics Act of 2022 (PACT Act; PL 117-168) recognizes the long-term cost of war by calling for studies to examine the relationships between specified exposures and health outcomes in military and veteran populations. Section 506 of the act required the Department of Veterans Affairs (VA) to contract with the National Academies of Sciences, Engineering, and Medicine (the National Academies) to examine health outcomes in active-duty military veterans who were potentially exposed to radiological and chemical hazards from their participation in the Manhattan Project at specified locations.

The Manhattan Project was a large-scale, secret program of the U.S. federal government to develop a nuclear weapon under direction of the Army Corps of Engineers; its official dates are January 12, 1942, to August 15, 1947. On August 6 and 9, 1945, the United States detonated these weapons above Hiroshima and Nagasaki, Japan, respectively, resulting in a catastrophic event with immediate casualties¹ on the order of hundreds of thousands and many additional latent adverse health outcomes among the survivors. The use of these weapons ushered in the nuclear age, and while the Manhattan Project resulted in landmark scientific accomplishments, it also generated a wide array of health, safety, and environmental concerns.

Although the primary sites of the Manhattan Project were Oak Ridge, Tennessee; Hanford, Washington; and Los Alamos, New Mexico, it involved

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¹ The range of estimated immediate casualties is ~110,000–210,000.

an estimated 200 sites around the country and included research and academic institutions, military and government institutions, private companies, and contractors. Its activities included large-scale production; research; uranium mining, milling, and refining; component fabrication; and waste management. The primary sites performed multiple roles and had the largest number of service members. The Manhattan Project involved numerous chemical and radiological hazards, and each step of the manufacturing process could result in exposure to multiple hazards.

The Manhattan Project employed 500,000–600,000 individuals, most of whom were civilians, but thousands of service members also participated. After World War II ended, many of the military and civilian personnel moved on with their lives, but the waste from the project remained at or near the sites. Responsibility for these sites has changed hands over time and involved multiple federal, state, and private entities. Records documenting the wartime work, including lists of individuals who worked at each site, were often destroyed or archived in various locations, thus fragmenting the historical record of the people and work conducted.

Although the Manhattan Projected ended nearly 80 years ago, health outcomes related to its activities remain relevant, as each site had its own activities and related exposures from which more can still be learned about the long-term effects on those who were immediately exposed, communities that continue to be exposed, and those who might be exposed to such hazards in the future. For example, the concerns of citizens in and around St. Louis, Missouri, about radioactive contamination from Manhattan Project activities in the area led in part to the passage of section 506.

STATEMENT OF TASK

Before the National Academies began its work, VA determined that a feasibility assessment was necessary to ascertain whether the epidemiologic study proposed in the legislation could be conducted given the specified period and uncertainties regarding what records or data exist for identifying individual veterans, their quantifiable project-related exposures, and where those records are located. The full statement of task is in Chapter 1, Box 1-1. VA specified 13 sites of interest (Oak Ridge, Tennessee; Hanford, Washington; Los Alamos, New Mexico; three sites in St. Louis County, Missouri (Coldwater Creek, St. Louis Airport Project Site, and West Lake Landfill); Alamogordo, New Mexico (until July 16, 1945); Lake Ontario Ordnance Works, New York; the University of Chicago, Illinois; Iowa State College, Ames, Iowa; Dayton, Ohio; Monticello, Utah; and Uravan, Colorado). Each had different roles in the project and thus different potential exposures, number of onsite personnel (military and civilian), and their connection with surrounding communities. As part of its feasibility

assessment, the committee would estimate the number of veterans involved in the Manhattan Project, identify and characterize available records (including contents and format) on them and their exposures (radiological, chemical, and mixtures) and health outcomes (specifically cancer and cause of death). It would also delineate a process or considerations for accessing those records and identify, if possible, the temporal, human, and financial resources required for an epidemiologic study. Based on the availability and characterization of the records and its expert judgment, the committee would offer conclusions on the feasibility of conducting the study specified in PL 117-168 section 506 or provide alternative methods to examine associations between exposures and adverse health outcomes in Manhattan Project veterans. No recommendations were to be made.

Despite the focus of popular cinematic and scholarly histories of the Manhattan Project on the Trinity test (the first detonation of a nuclear weapon, near Alamogordo, New Mexico), the scope of this report did not include veterans who participated in atmospheric nuclear weapons testing, including the Trinity test. Environmental contamination from Manhattan Project wastes was also out of scope, as were project activities that took place outside the continental United States (e.g., the Marshall Islands). People other than military personnel who worked or lived at or near the sites, including civilian scientists or contractors, military families, and surrounding communities of so-called downwinders, were also excluded from this report.

APPROACH TO INFORMATION GATHERING

The National Academies committee comprised 10 members with expertise in radiation and environmental epidemiology, cancer epidemiology, occupational health, health physics, dose reconstruction from radiation and chemical exposures, radiation exposure and risk assessment, radiobiology, military and veterans’ health, the history of the Manhattan Project, and historical research of archives. The committee held eight information-gathering sessions, four of these near specified locations to hear from site-specific experts to identify, understand, and characterize records and information available at these locations.

Based on each site’s history, literature searches, and information-gathering sessions, the committee determined that of the 13 specified sites, only the following 6 had a military presence during the Manhattan Project era: Oak Ridge, Hanford, Los Alamos, Uravan, Dayton, and Alamogordo. The three St. Louis sites had no evidence of a military presence during 1942–1947, and the contamination from waste that occurred at those sites falls outside the time frame for this feasibility assessment. Many other Manhattan Project sites in the continental United States also had a military presence, but these were not part of the statement of task.

The committee’s approach to information gathering was shaped by the secret and compartmentalized history of the Manhattan Project, its fragmented historical records, and the changing landscape of the sites’ administration. Because no single source or database contains all the necessary information (records for individual military personnel, their locations, exposures, and health information) to address the statement of task, the committee focused on information discovery and characterization for those veterans who served between January 12, 1942, and August 15, 1947, at the six specified locations.

The committee attempted to systematically identify and characterize (i.e., describe the contents, condition, and format) exposure and health outcomes records and data using a variety of information-gathering activities. This included 24 invited speakers and 20 information requests to federal agencies (including VA, Department of Energy (DOE), and National Archives and Records Administration (NARA)), researchers, advocacy organizations (e.g., Atomic Heritage Foundation), site-specific historians, museum curators, and hospital records departments for clinics that existed during the Manhattan Project; requests for public comment; and literature searches, including government and government-contractor reports, historical documents, and databases on locations and exposures. The committee only requested examples of records from subject-matter experts, as it was not permitted to collect records. Because some nuclear research and technology continues to be classified, this assessment was limited to identifying and characterizing unclassified or declassified publicly available information. Details and summaries of presentations, responses to information requests, and examples of applicable records are discussed in Chapters 4, 5, and 6. Although the committee encountered several difficulties obtaining information from some agencies, that lack did not impede its ability to respond completely to its statement of task or form the conclusions it made.

IDENTIFYING THE VETERAN POPULATION

To estimate the number of veterans exposed to toxic substances during the Manhattan Project (subtask 1), the entire veteran population for the dates and locations needs to be identified before their exposures can be ascertained. The committee quickly discovered that a comprehensive roster of all service members who participated in the Manhattan Project does not exist, overall or by site. Only after identifying individual veterans can their demographic and military characteristics be determined (subtask 2).

Most Manhattan Project military personnel served in the Army, and all were assigned to the Manhattan Engineer District (MED). The committee was able to determine that MED personnel were assigned to one of three units: 9812th Technical Service Unit, 1467th Service Command

Unit, and 4817th Service Command Unit. On February 1, 1945, the entire military portion of MED was assigned to the 9812th. MED headquarters staff, along with the majority of technical personnel in the Special Engineer Detachment (SED), were assigned to the 9812th. Nontechnical military personnel also supported MED and were in two units within the Eighth Service Command: Provisional Engineer Detachment (PED), military police, and Women’s Army Corps (WACs; not assigned to Oak Ridge) were assigned to the 4817th. WACs assigned to Oak Ridge were assigned to the 1467th. Although PED personnel only appear to have served at Los Alamos and Alamogordo, military police and WACs served at numerous MED locations, including the three primary sites.

The committee examined numerous documents and heard from several historians regarding Manhattan Project military personnel, who ranged from a low of 30–40 SED members at the Dayton Project to several thousand at Los Alamos and peaked at 5,600 in 1945. Without collecting the records necessary to create a complete list of individuals, an exact quantification of veterans could not be made. While exact numbers are not available, using the available historical authorized unit strengths by year and other information on the military presence at each site, including the estimated peak of 5,600 in 1945, the committee found that of the estimated 600,000 workers engaged in the Manhattan Project 1942–1947, approximately 10,000 were military personnel. These numbers do not provide information about identity, demographics, tasks, and years of service that would be needed for a roster.

However, the committee identified sources of military records and a process that could be used to create such a roster. The best source is the National Archives at St. Louis, which manages all military files for veterans with a rolling separation date of 62 (or more) years; these files are accessioned to NARA by the Department of Defense and given permanent status. The first step would be to request the relevant unit records from January 1942 through August 1947. Those for January 1942 would be the basis of the roster (names and service numbers), and each monthly unit report thereafter would build the roster. The National Archives at St. Louis indicated that the unit records for all three units for 1944–1946 (the height of Manhattan Project activities) were destroyed in 1975, so that the information from this source is incomplete.

The next step to address missing information from unit records would be using the unit’s morning reports (daily reports documenting status changes for individual service members). Each report lists the name, rank, service number, unit designation, geographical location, and map coordinates for each veteran. These only include individuals with changes and so are not a roster themselves. They are stored on microfilm, commonly degraded, may be difficult to read, contain abbreviations that need to be

decoded, and were handwritten until 1943—which may affect readability and the time to extract relevant information. The National Archives at St. Louis indicated that the available morning reports do not appear to correspond to the same months and years as the available unit records and are not available for the three units for 1946 or 1947, although they are available for the 9812th for 1945, 4817th for August–December 1943 and 1944, and 1467th for 1944.

The incomplete roster developed from unit and morning reports could be used to request from the National Archives at St. Louis the official military personnel record for each individual that could provide information on service dates, locations, jobs, etc. However, a fire in the archives in 1973 destroyed approximately 80% of these files for World War II and post–World War II Army personnel discharged through 1959. A complete list of lost records does not exist, and therefore, how many records were lost for service members who worked on the Manhattan Project is unknown.

The lack of a roster directly impacts the fourth subtask—to determine other non-Manhattan Project military missions of these veterans that may have exposed them to toxic substances and contributed to their overall health risks. Ideally, an official military personnel file could be used to determine a record of all duty stations and assignments, but how many of these files were destroyed is unknown. Technical personnel most likely only served in the military during the Manhattan Project. Once the individual left military service, determining their job history becomes more difficult unless they remained within the energy worker complex, in which job history may be requested through records management or, if they developed certain diseases, energy employee compensation programs. Without job type and history, it would be impossible to determine even general classes of potential exposures.

The committee found numerous barriers that limit compiling a full or even partial roster. Comprehensive research involving substantial human and financial resources would be required to identify individuals assigned to MED units. Such research is compromised by the 1973 archives fire and the scheduled destruction of morning reports for 1944–1946 that constrain using the standard methodologies for constructing rosters. The committee further found that creating a partial roster based on existing information for the few years where unit records or morning reports are available would be lengthy, time consuming, and costly (financially and in human resources); would require interagency support and cooperation for records access; and would ultimately be incomplete.

Due to the incomplete unit records and morning reports available at the National Archives at St. Louis, the committee finds that secondary sources, such as the Atomic Heritage Foundation, DOE site-specific records for personnel who had careers in DOE after the Manhattan Project, and

obituaries may be used to verify or supplement information missing from official military personnel records at the national archives. Although some supplementary records could augment existing information, accessing them might be extremely time and resource intensive.

Conclusion 4-1: The committee concludes that the approximate quantification of Manhattan Project military veterans is possible. However, given the missing unit records and morning reports for several years, especially the lack of unit rosters for 1944–1946—the years of highest Manhattan Project activity—the committee further concludes that the creation of a near-complete roster of individuals with identifying information based only on military records available through the National Archives is unlikely to be possible.

EXPOSURES AND ASSOCIATED RECORDS

The committee was asked to determine the types of radiological, chemical, and combined exposures that the veterans may have encountered during Manhattan Project activities at the specified sites, including the industrial and scientific processes and those that created waste (subtask 3). The committee was also asked to characterize records on those exposures, including their quality and completeness, and determine what types of exposure assessment might be possible for an epidemiologic study or whether a different type of analysis is needed.

The quality and quantity of exposure data determine the type of study that can be conducted. The committee created a three-tiered approach to exposure assessment, with each tier representing a different level of data availability and completeness to help frame what designs may be feasible. Given the wide variety of heterogenous exposures and availability of records for those exposures across Manhattan Project sites, exposure assessments would need to be conducted site by site and might require different tiers. Tiers 1, 2, and 3 are individual-level, group-level, and risk assessments, respectively.

Many processes were being performed for the first time under strict time constraints, and standards and practices for monitoring and recording worker exposures were being refined and developed in tandem. During the Manhattan Project, chemical exposures were not well documented and usually only reported for a high exposure, whereas radiological exposures were documented more frequently. Implementation of MED’s radiation dosimetry guidance varied by site, as did dosimeter availability, type, and accuracy, particularly in the early years of the project. Some external radiation exposure monitoring is available starting in 1944, but the dosimeters continued to be refined, so not all dosimetry records from the project period are comparable

and may need to be converted to current measures. Early dosimetry records may be available only for personnel working in technical jobs; are owned by different sites, agencies, and offices; and may be difficult to read. Internal radiation monitoring was not implemented until 1945 or later and limited to infrequent bioassay measurements. Many individuals would only have bioassay measurements if they continued working for DOE after 1945–1946. The quality and content of the radiological exposure records varied by site but generally became more complete and standardized with time.

Records managers and health physicists from Oak Ridge, Hanford, and Los Alamos who presented to the committee stated that the exposure records seldom contained an indicator of military status, and the examples provided for 1942–1947 confirm that observation. The committee was able to assess the type and availability of data across the examples provided, technical documents, past studies, and existing databases to determine which tier of exposure assessment may be possible for Manhattan Project veterans.

The committee found that some records exist for radiological exposures for 1942–1947, but record gaps, inconsistent record maintenance, differences across sites, limitations in the dosimetry programs, and changing contemporary technology would all affect the time and effort needed to extract usable information.

For chemical exposures during the entire Manhattan Project and external radiological exposures pre-1944, the committee determined that area monitoring measurements or documents detailing the processes performed are the best sources of site and individual exposure information. Individual-level assessment (tier 1) would not be possible given the limited records pre-1944. However, individual estimates based on group-level exposure may be possible (tier 2). This may be accomplished either through the use of job exposure matrices, if individual job histories are known, or through estimates based on duration of exposure as a surrogate.

When only group-level exposure data are available and no individual exposures were recorded or can be reconstructed, a risk assessment (tier 3) may be considered; exposure information is combined with published dose–response data to estimate potential health risks associated with the measured exposures. This approach might be used for internal radiation exposures or if job histories cannot be determined for chemical and external radiological exposures that occurred during the Manhattan Project.

Conclusion 5-1: Given limitations of exposure records and lack of indication of military status, the committee concludes that individual exposure estimates (tier 1) would not be possible for the Manhattan Project. Group-based exposure assessments (tier 2) could cover all chemical, radiological, and combined exposures. A risk assessment (tier 3) may be used if veterans’ job histories cannot be determined.

SOURCES OF HEALTH OUTCOME INFORMATION

The committee was asked to assess health outcome records (subtask 5), including cancer occurrence and cause of death for Manhattan Project veterans, and characterize their quality and completeness. Connecting a diagnosable medical condition to a specific environmental or occupational exposure is difficult in general and more so when the exposure and outcome occurred decades earlier and the availability and completeness of health records are unknown. Several health outcomes associated with exposure to ionizing radiation, chemicals, and metals used during the Manhattan Project have been well documented. As military personnel at each site had different jobs, this would lead to heterogenous exposures, with a resulting difference in the risks of adverse health outcomes. The committee did not comprehensively assess or conduct a weight-of-the-evidence analysis of any associations between project exposures and possible health outcomes.

The committee considered several sources of health information, categorized as those pertaining to the general U.S. population (i.e., not limited to military personnel) and those with military-specific information. The former included the National Death Index (NDI), state-based death records, Social Security Administration data, state and national cancer registries, and commercial sources, such as Ancestry.com and obituaries. Military-specific health information sources included the official military personnel files held by the National Archives at St. Louis, VA administrative and clinical records, and the VA cancer registry. Military sources are fewer and more difficult to access, while the broader non-military sources have been used successfully to obtain health outcomes for numerous epidemiologic investigations.

Medical records are not centralized or standardized because of differential access to medical care, relatively few disease diagnoses require reporting, and most of the sources the committee examined were established decades after the end of the Manhattan Project, so there is no comprehensive coverage for the veterans of interest. DOE site-specific records would only be available for veterans who had careers with DOE and are not comprehensive. Not all veterans used VA health or benefits, and VA administrative databases are not searchable by service era; records must be searched by name or identifier number, which would depend on creating a roster. It is unknown how many of the personnel files at the National Archives at St. Louis would be available or complete, given the millions of records destroyed by the 1973 fire, making this source limited for use in an epidemiologic study.

Given that no comprehensive, centralized, and longitudinally collected health data for all Manhattan Project veterans is available and that less than 1% of World War II veterans were alive in 2024, the committee found that death certificates are generally systematically available (obtained individually either through NDI or the individual states) for these veterans.

The committee determined that a mortality study is a feasible approach, although connecting cause of death directly to Manhattan Project exposures is unlikely.

Conclusion 6-1: Given the lack of health records available for individual veterans covered by the statement of task and the lack of nationwide, comprehensive cancer incidence data, the committee concludes that cancer incidence is not a feasible health outcome for an epidemiologic study of Manhattan Project veterans. However, mortality is a feasible outcome for such a study given the systematic surveillance of death in the United States.

FEASIBILITY ASSESSMENT

For its feasibility assessment, the committee summarized the many factors, including expertise, time, and budget estimates, necessary for conducting an observational epidemiologic study of health outcomes in veterans who had radiological and chemical exposures during the Manhattan Project. The committee used five key elements required for such a study to assess the availability and content of the exposure and health records, which correspond to the five subtasks of the statement of task and have been used by other National Academies committees for epidemiologic assessments of veteran populations:

• Identification of a population of interest from which a representative sample can be drawn,
• Individual-level exposure assessment of adequate quality,
• Individual-level health outcome assessment of adequate quality,
• Identification of an appropriate comparison group and ability to control for contributing factors, and
• Sufficient sample size for precise estimation.

Table S-1 summarizes the availability of information for each subtask by the 13 specified Manhattan Project sites, only 6 of which had a documented military presence, and therefore, have relevant information. For elements other than military presence, the committee denotes whether the information is possible, limited, or unknown. Possible indicates evidence that records exist, but the amount of time and effort required for individual assessment for the element is unclear. Limited indicates evidence of records, but these were incomplete and would not cover all military personnel or the full period. Unknown indicates records with this type of information were not identified, and it remains unclear whether these exist or can be located. Much of the information is limited or unknown, as it was not systematically

recorded. Some demographic and military characteristics would be known from unit records and morning reports used to generate a roster of individuals for the years that these records are available.

In sum, the committee found that key information that would be needed to conduct an observational epidemiologic study on health outcomes in veterans resulting from radiological and chemical exposures during Manhattan Project activities is not available at the individual level or at a level of detail necessary for epidemiologic analyses.

FINAL OBSERVATIONS AND CONCLUSIONS

Committee efforts to learn about records of Manhattan Project activities and their postwar stewardship yielded a variety of responses, ranging from bureaucratic silence to detailed overviews supported by organization leaders and shared by staff archivists, historians, and technical experts. Access to these records is challenging in large part because exposure and health information are incomplete, including gaps in years of coverage, and scattered across multiple agencies, and offices within a given agency. The committee heard from records managers at several federal agencies about the effort and time that goes into maintaining, organizing, and reconstructing records. The fragmentation of records and other sources of information among sites and over time, and changes in site stewardship and records management, create additional barriers to access and use these records for research. Additionally, records are difficult to read and extract information from.

The committee made one overarching observation: no central repository or single information source exists at any location, geographic area, agency, or organization, or in any report or other documentation that contains even minimal information about the individual service members who participated in Manhattan Project activities 1942–1947 and their potential exposures or possible health outcomes. As illustrated by efforts to search, identify, access, and synthesize hundreds of thousands of documents and records for the Los Alamos Historical Document Retrieval and Assessment Project, the many complex bureaucratic, historical, and present-day factors highlight how any study of Manhattan Project veterans would require an estimated budget of millions of dollars to support a years-long effort. It would involve extensive professionals, approval for their access to and use of physical and digital records, and extensive data analysis and synthesis.

The many factors considered in the committee’s assessment and its findings and conclusions on identifying veterans, the type and availability of exposure records, and the type and availability of health records, particularly for death, led to its overall conclusion regarding the feasibility of using the identified information and records to conduct an epidemiologic study as requested in PL 117-168, section 506.

TABLE S-1 Availability of Each Statement of Task Element by Specified Site

^a Demographic information is likely available from a community cohort study conducted of all residents of Uravan, Colorado 1936–1984; some of them are likely veterans.

^b Internal dosimetry monitoring did not start until 1945 for most sites and was restricted to only individuals who were likely to have been exposed. More internal monitoring data is available 1947 onward.

^c Data for 1942–1943 are largely missing; measurements for 1944–1947 were more systematically captured.

^d Cause of death is feasible to obtain via linkage to the National Death Index for deaths after 1979 or by obtaining individual death certificates for deaths prior to 1979, assuming the availability of individual identifiers such as name, Social Security number, and date of birth.

^e Alamogordo, New Mexico, until July 15, 1945 only.

Overarching Conclusion 1: The committee considered several aspects of feasibility for conducting an epidemiologic study and concluded that such a study on the relationships between radiological and chemical exposures from Manhattan Project activities and health outcomes in veterans who worked on the project is not feasible. This conclusion is based on the following:

• the incomplete availability of unit records and official military personnel files to create a full roster of individual veterans who served at the Manhattan Project sites of interest;
• the lack of systematically collected exposure information that can be linked to individual veterans; what information is available is limited to only some radiological exposures and no chemical exposures (except for accident reports which are high dose);
• the only systematically available health outcome is cause of death; and
• finally, other key elements, such as individual-level demographics and confounders, that would be needed to conduct an observational epidemiologic study are not available or severely limited.

The committee’s conclusion that an epidemiologic study on Manhattan Project veterans is not feasible led it to consider other study design options and found that the use of risk assessment to estimate adverse health outcomes would be the best alternative after considering issues of feasibility and efficiency of resources. Risk assessments can range in rigor—depending on the study objective, available data, models, and resources—from conservative screening analysis to progressively more refined, realistic, and comprehensive site- and population-specific assessments; they are often possible even with limited information and resources, although the level of confidence and scientific robustness of the result may vary. Dosimetry and chemical records could be used to inform dose reconstruction and, combined with modern risk models for radiological and chemical exposure, be used to estimate veterans’ health risk.

Overarching Conclusion 2: With careful consideration of the strengths and weaknesses of the exposure and health data, the committee concludes that a risk assessment could be conducted to estimate the potential health risks for Manhattan Project military veterans.

While this feasibility assessment focuses on veterans (who made up an estimated 1% of the Manhattan Project personnel), the committee acknowledges the varied and long-term potential health impacts of it on civilian populations and communities. The committee’s determination that an epidemiologic study of health outcomes among veterans with Manhattan

Project–related exposures is not feasible should not be taken as an indicator that the project did not have long-term adverse impacts on its many workers and surrounding communities or that long-term studies of such exposures on communities are impossible. Expanding the knowledge base for community impacts is one avenue for innovative research to understand the Manhattan Project’s widespread and long-lasting health outcomes, but this may require approaches that differ greatly from those of classical epidemiology. The sources for health and exposure records described in this report, and information about their custodial organizations and general procedures to access them, may be of use to other scientific and historical endeavors. The committee’s experience with information gathering and substantial difficulties it encountered in contacting the appropriate offices or personnel for this information—even with a congressional mandate—led it to find that obtaining records and extracting information would require substantial resources and interagency cooperation.

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