The ZIA Company was the principal subcontractor to Los Alamos National Laboratory (LANL) from 1946 to June of 1986. ZIA performed construction and maintenance functions at LANL. The group at ZIA responsible for construction was called LACI and data for LACI workers are also included in this file. The one analytic file contains demographic and exposure data for 5,424 employees of the ZIA company hired before 1/1/1979 and monitored either for external radiation or plutonium as of 12/31/1984.
There are data for 365 females; 11 are Native Americans the rest are white (unknown race assumed white). There are 94 Native American males, 10 black males, 1 oriental male, and 4954 white males. Demographic data were abstracted from four primary record sources provided by the ZIA Company and supplemented with data from LANL records. Vital status was ascertained for 97% of the 5,424 workers through December 31, 1984, the end of study date.
There were 1,197 deaths identified in this cohort as of end of study. An additional 51 workers were identified as dead with no certificate, giving a 96% recovery rate for death certificates. Vital status was determined from information provided by the Social Security Administration (SSA) valid through December 31, 1984. Some deaths after end of study are recorded.
The sources of occupational radiation exposures for the ZIA Company were external radiation, primarily gamma, and internal deposition of plutonium- 238 and plutonium-239. Pocket chambers or film dosimeters were used for personnel monitoring from 1944 through 1980, when they were replaced with thermoluminescent dosimeters. Formal bioassay programs to monitor for internal exposures were begun in 1944. External exposure data consist of dates (in decimalized notation) at which the worker was first monitored, first received a positive exposure, first accumulated 1 rem whole body dose, first accumulated 5 rems whole body dose, and first received 10 rems whole body dose. Whole body dose was defined as the sum of all tritium, neutron and penetrating gamma readings.
Annual penetrating external dose from 1944 to 1984 is also present on the file. External data were available through 1984. Data pertaining to internal plutonium exposure include isotope, dates (in decimalized notation) of first and last samples, and estimated body burdens (in units of both nCi and nCi- years) of plutonium-239 and 238 combined. Dates the worker received a dose of 2, 5, and 10 nCi are also present as separate readings for plutonium-238 and plutonium-239.
Body burdens were estimated as of 12/31/1984 or death date and as of last sample date. The computer code PUQFUA was used to generate body burden data. Dosimetry data were provided by the health physics group at LANL which is responsible for monitoring of all ZIA (and other subcontractor) personnel in addition to LANL employees. These radiation data can include readings while employed at ZIA, LANL or another subcontractor of LANL; Therefore, sample dates may not fall within the period worked at ZIA for all workers in this file. Work was funded by The United States Department of Energy (DOE).