Cause of Death Summary Table
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Description:
This analytic data file set consists of 18 files generated for a case-control study conducted by the U.S. DHHS, NIOSH, Centers for Disease Control and Prevention in 2001, of mortality patterns among 8,877 uranium enrichment workers (both sexes and all races) employed for at least one day at the Gaseous Diffusion Plant in Piketon, Ohio between September 1, 1954 and December 31, 1991.
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 deaths 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 the hematopoietic systems including leukemia, were evaluated in more detail. The study report and findings were reviewed by experts outside NIOSH.
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 to 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, lymphoreticulosarcoma, and all cancers combined. Worker deaths from cancers of the lympho-hematopoietic tissue, including leukemia, equalled 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 (cod, demogr, filmdhd, jobdhd, and workhist) contain cause of death, demographic, exposure, and work history data. The other 13 files contain exposure data for case-control analysis on leukemia, lung cancer, hematopoietic cancer, and stomach cancer for electromagnetic frequency (EMF) exposure, for chemical exposures of fluoride, nickel, and uranium, and for internal and external radiation at different lag times.
Number of data files: 18
Cohort Size: 8877
Notes: For clarification of variable names with a /365.25 portion, the following example is provided: Worker A spends 2 years in a work area where the mean measured daily work shift exposure to the magnetic field (measured in
shift is 3.2 mG. He also worked 1 year in an area with a work shift mG value of 1.1 mG. The worker worked 220 days (work shifts) the first year, 230 days (work shifts) the second year, and 215 days (work shifts) the third year. The wor
exposure over the three years working at the plant would be:
3.2 mG (exposure received in a day or work shift) x 220 days worked in year #1 (from work history) x 1 year/365.25 days = 1.93 mG-year
3.2 mG (exposure received in
shift) x 230 days worked in year #2 (from work history) x 1 year/365.25 days = 2.02 mG-year
1.1 mG (exposure received in a day or work shift) x 215 days worked in year #3 (from work history) x 1 year/365.25 days = 0.65 mG-year
mG-days cumulative exposure (or when divided by 365.25 days in a year) 4.6 mG-years cumulative exposure
Notes: In creating the Analysis files for submission to CEDR the original study files were modified to reflect the changes that were made by the LTAS and Case Control programs concerning dates and vital status. Modi any subject who died after the study end date of 12/31/1991 was recoded to an ALIVE vital status; all of their death information was removed from their records; any work history record that occurred after 12/31/1991 was deleted - when working past 12/31/1991, (i.e. there were still ACTIVE) an END date of 12/15/1991 was assigned and a new field was created to indicate the subject was still ACTIVE on the study end date.
Notes: This study was conducted by the Centers for Disease Control and Prevention (CDC); National Institute for Occupational Safety and Health (NIOSH); Division of Surveillance, Hazard Evaluations, and Field Studies; Energy Research Branch through a Memorandum of Understanding (MOU) established between the Department of Energy (DOE) and the Department of Health and Human Services. This MOU provides for the independent conduct of epidemiologic rese of current and former workers in the DOE nuclear weapons complex. More information about the NIOSH Occupational Energy Research Program may be found at http://www.cdc.gov/niosh/2001-133.html.
Contact Information:
Ahrenholz, Ph.D. Steven
Assistant Branch Chief
National Institute for Occupational Safety and Health
Robert A. Taft Laboratories /MS-R44
4676 Columbia Parkway
Cincinnati, OH 45226-9987
(423) 576-2866
Fax: 576-9557
Email: SAhrenholz@cdc.gov
Notes: This manual and PC LTAS are in the public domain and may be freely copied.