Over the past 50 years, as a result of producing tens of thousands of nuclear weapons, DOE’s facilities have also produced radioactive and other toxic substances that pose potential health threats to DOE’s workers and the communities located nearby. These substances include the radionuclides uranium, plutonium, and cesium; toxic metals; organic solvents; and chlorinated hydrocarbons. Epidemiological research—research on the incidence, distribution, and control of disease in a population—provides a scientific evaluation of the health effects of exposing workers and the public to such potentially harmful materials. Such research uses health, exposure, environmental monitoring, and personnel records to analyze health effects and evaluate methods to protect people and prevent harm. As such, epidemiological research is essential to a comprehensive occupational and environmental health program. DOE and its predecessor agencies have a long history in epidemiological research, starting with studies of the survivors of the atom bomb. In the past, much of this research was conducted by DOE or its contractors in secret and concentrated on the correlation between the rates of cancer-related deaths of workers at DOE’s nuclear weapons complex and their exposure to ionizing radiation. A number of separate mortality studies—studies of death rates—have been conducted on approximately 420,000 workers over the past 30 years. However, because the records that researchers needed to study the health effects of working in DOE’s facilities were maintained differently at each facility and were difficult to locate, the types and quality of epidemiological research that could be conducted were limited. To alleviate these problems and facilitate epidemiological research on the health effects of exposure to radiation and other hazards, the Secretarial Panel recommended that DOE continue developing CEDR as a comprehensive repository of data on its workers. In addition, to break down what was perceived as “a wall of secrecy” and to help establish the credibility of and maintain independence in the conduct of DOE’s epidemiological research, the Secretarial Panel recommended opening this research and its supporting data to external investigation and scrutiny. Among other things, the Secretarial Panel recommended that DOE execute a memorandum of understanding with the Department of Health and Human Services (HHS), making HHS responsible for long-range, analytic epidemiological studies, while DOE remained responsible for descriptive epidemiology. As a result, much of the epidemiological research on DOE’s facilities is now managed by HHS. Within HHS’ Centers for Disease Control and Prevention, which implemented this memorandum of understanding, the National Institute for Occupational Safety and Health was made responsible for occupational health research (i.e., research on workers employed by DOE and its contractors), while the National Center for Environmental Health was made responsible for research involving the environment, including communities near DOE’s facilities. The Secretarial Panel also called for greater outside scrutiny by recommending that the National Academy of Sciences (NAS) play a key role in overseeing and monitoring the development of CEDR. In response to the Secretarial Panel, as well as a concurrent request from DOE to provide general scientific advice on the status and direction of DOE’s epidemiological programs, NAS established a Committee on DOE Radiation Epidemiological Research Programs. In 1990, this committee issued a report making a number of recommendations about access to data for researchers outside DOE, the types of data to be included in CEDR, and its future development. The report also noted that use of CEDR will depend on ease of access to the information it contains and researchers’ perception of its value. Beginning in 1990, a DOE contractor facility, the Lawrence Berkeley Laboratory, in Berkeley, California, constructed a prototype, known as preCEDR, to serve as the basis of CEDR. In 1992, DOE made data available through this system. In August 1993, DOE published a catalog of data available in CEDR to assist current and potential users in identifying data sets for potential use and to provide instructions on how to obtain access to these data. Through fiscal year 1994, DOE had received $14.35 million in appropriations for CEDR, of which it had spent $9.45 million for CEDR and related expenses and redirected the remaining $4.9 million to other activities. CEDR is budgeted at $1 million for fiscal year 1995, of which $500,000 was funded as of February 1995. DOE does not have available the uniform demographic, exposure, medical, and environmental data that would make CEDR a comprehensive and valuable epidemiological resource for independent researchers. The Secretarial Panel recommended in 1990 that DOE define a minimum set of data necessary for epidemiological research and routinely maintain and collect these data at all DOE facilities. As part of this effort, in May 1992 DOE requested that each of its facilities, within 3 years, complete an inventory of 123 specific types of records that the Department believed were important for conducting epidemiological studies. We reported on this and other DOE efforts to manage records in a May 1992 report. DOE officials told us that when completed, this records inventory would be included in CEDR and would more easily identify for researchers where these specific types of records are located. Meanwhile, DOE is waiting for its facilities to complete their records inventories, which may take until 1996, before it takes steps to routinely collect and maintain the types of records it has already identified as important. In addition, the NAS committee stated that CEDR should be capable of supporting many kinds of epidemiological studies, including long- and short-term health surveillance, monitoring studies, screening programs, and long-term mortality studies. However, as we reported in December 1993, DOE probably will not establish a comprehensive health surveillance program until at least 1998. Such a program would standardize the documentation of workers’ occupational exposures to radiation and other industrial hazards—such as chemicals, gases, metals, and noise—and could identify trends in workers’ illnesses and injuries that might be related to these exposures. Until such a program is in place, the comprehensive data on health effects and exposure needed for important epidemiological research will not be available for placement in CEDR. Moreover, DOE’s Assistant Secretary for Environment, Safety, and Health told us in October 1994 that standardization of data at DOE’s facilities was a problem that would take several years to resolve. Without the important data necessary to support many types of epidemiological research, CEDR today mainly contains the limited data from DOE-sponsored mortality studies of workers at DOE’s facilities at Oak Ridge, Tennessee; Rocky Flats, Colorado; Hanford, Washington; and elsewhere. Of the 37 data sets in CEDR, 36 contain the retrospective information—data on past incidents—used to conduct these studies. (See app. I.) Some new data will be included when certain ongoing studies are completed. These studies include mortality studies of DOE’s workers at the Idaho National Engineering Laboratory and the Portsmouth Gaseous Diffusion Plant in Ohio; a study of cancer incidence among workers at Rocky Flats by the National Institute for Occupational Safety and Health; and studies from the National Center for Environmental Health, including estimates of the effect of the radiation from Hanford on the air and water in the surrounding area. While adding the results of these studies will make some of the data in CEDR more current, the system will still lack the comprehensive data discussed above that would make it the valuable resource that the Secretarial Panel and NAS recommended. According to many NAS committee members and CEDR users we spoke with, the current lack of comprehensive epidemiological data limits CEDR’s value for research. The Secretarial Panel cautioned DOE that retrospective data would have limited value for future research. Also, members of the NAS committee told us that the data on mortality that CEDR currently contains limit the types of studies that can be done and have minimal value for future research on health effects. NAS noted in its 1994 report that the scope of the data currently in CEDR limits the type of research that can be conducted. The data restrict researchers by defining the groups that can be studied, the variables that can be examined, and the analytic methods that can be applied. Officials at the National Institute for Occupational Safety and Health and the National Center for Environmental Health also stated that CEDR would be of greater value if it contained data on chemical exposures and health effects. These data will not be available until DOE’s health surveillance program is completed. Since CEDR contains only limited retrospective data, researchers who need more information must still locate records at DOE’s facilities, where the records are not consistently maintained. However, despite CEDR’s limited value for health effects research, several NAS experts, current users, and DOE officials believe that it has significant value as a teaching tool for students of epidemiology. DOE has made data from its mortality studies easy for outside researchers to access through CEDR, and thousands of people have accessed the system to see what basic data are available. However, few researchers have used the data for original studies on health effects. In addition, some members of the NAS Committee on Epidemiological Research and some researchers we interviewed noted problems that impair the usability of the data. Difficulties include a lack of data that have not been previously modified by other researchers to meet their specific research needs, data that are hard to work with because they have been edited to protect the privacy of the workers, and data that are not current. In addition, some researchers have encountered problems with the quality of the data, including missing and inconsistent data and inadequate documentation of the studies included. For these reasons, some CEDR users need to review original records at DOE’s facilities but find the records difficult to obtain. For the first time in its history, DOE has made the data used to support its epidemiological research accessible.