| This analytic data file set consists of 18 files, PGDPSA01_d1 through PGDPSA01_d18, generated for a case-control study of mortality patterns among 8,877 uranium enrichment workers (both sexes and all races) employed for at least 1 day at PORTS between September 1, 1954, and December 31, 1991, conducted by the U.S. Department of Health and Human Services (DHHS), NIOSH, Centers for Disease Control and Prevention (CDC) in 2001. |
| Data from these files were used in the life table analysis, as well as in the case control selections for lung cancer, stomach cancer, hematopoietic cancers, and leukemia. |
| How This Study Was Done: This epidemiologic study examined the causes of death among all PORTS workers employed by the facility between September 1, 1954, and December 31, 1991. Deaths among the workers were compared with rates for the general U.S. population. Possible relationships were evaluated for deaths from several types of cancer and exposures to ionizing radiation and certain chemicals (fluoride, uranium metal, and nickel). Based upon previous health studies of nuclear facility workers, including an earlier NIOSH investigation at PORTS, deaths from cancers of the stomach, lung, and the lymphatic and hematopoietic systems including leukemia, were evaluated in more detail. |
| Study Findings: Approximately 88% of the cohort was still alive through the end of 1991. Overall cohort mortality was significantly less than expected, when compared with the United States population, as was mortality from all cancers. A total of 1,088 deaths from all causes occurred in this cohort through 1991. A total of 1,518 deaths could be expected based upon rates in the general U.S. population. The lower mortality among these workers is consistent with the healthy worker effect, which is found in most occupational epidemiologic studies. No statistically significant excesses in mortality from any specific cause were identified. Analyses of possible relationships between causes of death and the identified exposures failed to reveal any dose-response trends. For leukemia, no effect of cumulative exposure to either external or internal radiation was identified. Additionally, no dose-response relationships were observed for cancers of the stomach, lung, Hodgkin’s disease, lymph reticulosarcoma, and all cancers combined. Worker deaths from cancers of the lymphohematopoietic tissue, including leukemia, equaled U.S. rates. Stomach cancer deaths were greater than expected (12.7 deaths expected, 15 deaths found), but this difference was not statistically significant. Deaths from these cancers had been found to be slightly elevated in a previous NIOSH study of PORTS. |
| Study Limitations: The young average age of this cohort with 88% still living in 1991 made it difficult to fully assess patterns of death associated with work exposures. Estimated radiation and chemical exposures developed for this study are subject to error since monitoring results for chemicals and various forms of radiation were incomplete. Potentially important factors that may have an effect on the observed outcome, such as lifestyle factors (e.g., smoking), radiation due to medical procedures, and other workplace exposures could not be evaluated. |
| Study Advantages: A comprehensive exposure assessment was conducted, making use of nearly all health physics and industrial hygiene data from 1954 through 1991. The patterns of exposures used in this study were evaluated by experienced workers at the site. Analysis with these estimates increased the ability to detect associations between exposures and death. |
| This study design was a good tool for evaluating the causes of death in workers with chronic low-level radiation exposures. |
| The first four files and the 18th file (PGDPSA01_d1, PGDPSA01_d2, PGDPSA01_d3, PGDPSA01_d4, and PGDPSA01_d18) contain cause of death, demographic, exposure, and work history data. Contributing causes of death were coded, as well as the nature of injury. Both were coded with various ICD versions. An indicator variable for the ICD version was included. Demographic fields included sex, race, date of birth, and date
of death. Gamma radiation exposures in PGDPSA01_d3 are reported in Radiation Absorbed Dose (RAD). The work history in PGDPSA01_d4 includes employment dates and a job category field. The job category field was created by NIOSH as a way to group people with similar exposures based on departments. The department and area codes for the work history are found in PGDPSA01_d18. The other 13 files contain exposure data for case-control analyses on leukemia, lung cancer, hematopoietic cancer, and stomach cancer for electromagnetic frequency (EMF) exposure (milligauss), for chemical exposures of fluoride (exposure score), nickel (µg/m3), and uranium (exposure score), and for internal (DPM) and external radiation (millirad) at different lag times. |
