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Types of Studies


Types of CEDR Data Video

The CEDR program provides a repository of data that have been generated for epidemiologic or environmental health studies funded by DOE. Most of these studies have been published in peer-reviewed journals; however, there are also data that have been used in student dissertations, presentations, and technical reports.

A large portion of the data file sets offered in CEDR relate to specific individuals. This is because epidemiologic studies often require the collection of detailed information for each individual in the study. Therefore, the data files developed by the original researchers who performed DOE's worker and mortality studies usually contained personal identifiers as well as many other variables that, when used in combination, might uniquely identify an individual. As a public agency, DOE has responsibilities to promote openness by sharing its health data and also to maintain rights of privacy of its current and former workers. To meet these needs, it was necessary to establish a data release policy for CEDR. Personal identifiers, such as name and social security number, are replaced with a unique identification number before the individual data are loaded into CEDR. Personal dates, including the starting and ending dates of employment, date of birth, and date of death, are truncated, leaving either year only or year and month. In addition, users of these data are required to complete access request and confidentiality forms stating that the data are to be used only for research purposes.

There are other data file sets and reports in CEDR that are not linked to particular individuals. Since there are no individual privacy concerns with these data, they are presented in their entirety, and no confidentiality statements are required to use the data. This type of CEDR holding includes general descriptions and documentation for the DOE worker health and mortality studies.

DOE Worker Health and Mortality Studies

Mortality Studies Video

DOE's worker health and mortality studies began in the early 1960s when the feasibility of using existing employee and facility records for conducting long-term follow-up studies was explored. Based on the promising findings from the feasibility study, a 5-year pilot study was initiated in 1964. The primary DOE sites selected for this pilot study were the Hanford Site in the State of Washington and the Oak Ridge Site, which consisted of three major facilities in the State of Tennessee. Other facilities operating at several smaller sites were also included. To obtain the information needed for a retrospective cohort study, considerable effort was expended on locating, copying, and abstracting data from various plant records located onsite and offsite. When it was determined that further processing and validation of these data would be necessary to ensure their proper use in epidemiologic studies, the Hanford cohort became the primary focus of the health and mortality studies.

In the 1970s, the study was expanded, and the responsibility for collecting and updating data for subsequent long-term worker studies was assigned to three epidemiologic research groups: Oak Ridge Associated Universities (ORAU), Los Alamos National Laboratory (LANL), and the Hanford Site, where staff from the Pacific Northwest Laboratory (PNL) and Hanford Environmental Health Foundation (HEHF) formed a team.

ORAU assumed responsibility for studies of worker populations at the Oak Ridge Site, which included the K-25 Facility (also known as the Gaseous Diffusion Plant), the Y-12 Facility, and the X-10 Facility (also known as the Oak Ridge National Laboratory or ORNL). In addition, ORAU was assigned the studies of workers at two gaseous diffusion plants in Paducah, Kentucky, and Portsmouth, Ohio; the Feed Materials Production Center in Fernald, Ohio; two uranium processing plants located at the Mallinckrodt Chemical Works in St. Louis and Weldon Springs, Missouri; and the nuclear fuel production plant, called the Savannah River Site (SRS), in South Carolina.

ORAU prepared a master roster of all contractor employees at each of these facilities and retrieved many of the death certificates used by the three epidemiologic research groups. Each research group then extracted and coded the cause-of-death information from the death certificates for use in their respective studies. Each worker was assigned a unique identifier number, which allowed information pertaining to that worker to be linked together, regardless of the research center that collected the data or the file in which it appeared.

The epidemiologic research group at LANL assumed responsibility for studies of all workers monitored for exposure to plutonium by contractors conducting operations at the following sites: the LANL/Zia Company in New Mexico; the Rocky Flats Plant in Colorado; the Mound Laboratory in Ohio; and the Pantex Plant in Texas. The LANL study population also included ORNL and SRS workers having potential exposures to plutonium. LANL also performed an additional, long-term clinical follow-up study of a small group of workers exposed to plutonium at Los Alamos during the early days of the Manhattan Project.

The epidemiologic research team in Richland, Washington, with staff at HEHF and PNL, took primary responsibility for studying the operations workers who were employed by the major contractors at the Hanford Site in Washington. This research team also performed several related studies. One of the larger studies was a combined mortality study that included workers at ORNL, Rocky Flats, and Hanford. The HEHF/PNL team, along with several researchers from the other centers, also participated in an international, combined mortality study, which was performed by the International Agency for Research on Cancer and included workers from these three sites. Smaller studies conducted by the Hanford team included congenital malformations that occurred in offspring of individuals who lived in communities near the Hanford Site and lung cancers among monitored Hanford workers.

During the performance of the various studies, efforts were made to determine the vital status of each worker included in cohort mortality studies at the selected sites. Mortality was ascertained from employee rosters through searches conducted by the Social Security Administration, the National Death Index, and other sources, as appropriate. Death certificates, requested from State vital records offices, provided cause-of-death information, which was coded according to the International Classification of Diseases. Personal radiation-monitoring information available at the sites was examined or collected for most studies.

Data were regularly collected by the three epidemiologic research centers. Each center used slightly different procedures and methodologies to merge, document, validate, and analyze the data. The work performed by the three epidemiologic research centers, as well as by a number of other researchers, during two decades resulted in the collection of valuable information on a large number of workers at DOE sites and in the publication of numerous scientific papers and articles.

The electronic data files generated in the course of worker studies are located in CEDR either as working data file sets or analytic data file sets.

Other CEDR Data

Complex Chemical Feasibility Study

Some workers in the DOE nuclear weapons facilities were exposed to complex mixtures of chemicals and radioactive materials, such as plutonium. It is known that exposures to such mixtures of possible carcinogens may produce adverse health effects, but it is usually difficult to measure each individual's exposure to these agents. The purpose of this study was to examine the feasibility of using existing records and information to estimate a worker's exposure to such complex mixtures of chemicals so that the estimates would be useful for epidemiologic studies. A methodology was developed that used data found in records about chemical purchases, work areas, and plant operations, and it was applied to a small pilot population of Rocky Flats workers. Data collected included information about worker locations, operations performed, and results of samples indicating workplace exposures to various chemicals. The study was expanded to include populations from Y-12, K25, ORNL, and Savannah River.

Salmon Site Descriptive Study

Between 1964 and 1970, two nuclear and two non-nuclear bombs were detonated in a large underground salt dome in Lamar County, Mississippi, for the purpose of measuring the seismographic activity that these explosions generated in salt domes. The site was deactivated and decommissioned in June 1972 upon completion of the testing program. Because of concerns that effluents from the tests might have increased cancer deaths among nearby residents, a mortality study of residents of Lamar County was conducted. The purpose of the study was to determine if there was an association between living near the salt dome and death due to cancer.

Radium Dial Painter Data

The opportunity to study a group exposed to a potentially toxic material is rare, and it is even more rare to collect sufficient data on the group to determine the potency and effects of the material. However, such an opportunity emerged in the 1920s when skeletal lesions became associated with workers called luminizers or dial painters, who painted luminous dials on timepieces with paint containing radioactive radium as the energy source for luminosity.

Under the Internal Emitter Program conducted at DOE’s Argonne National Laboratory, researchers identified about 6,000 people with significant radium exposures, including about 500 individuals, mostly women, who were dial painters. Many were located and followed until death; in these cases, the cause of death and body content of radium were determined. The files available in CEDR contain much of the data, such as demographics, measurements of radium body content, calculated doses, radium exposure history, and clinical examination results that were generated during this research.

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