| This analytic data file set consists of one file generated for a cohort study published as a NIOSH report in 2005 of workers at the Idaho National Laboratory (INL) (formerly Idaho National Engineering and Environmental Laboratory) in Idaho Falls, Idaho. |
| The Idaho National Laboratory is a large DOE facility near Idaho Falls, Idaho. Since its construction in 1949, INL has conducted a wide variety of activities, including engineering and basic scientific research, nuclear reactor design and testing, nuclear material chemical processing, and the construction, servicing and demolition of large-scale facilities. In addition, the U.S. Navy maintains its Naval Reactors Facility (NRF) at INL, where research and testing of Navy ship reactors occurs, as well as training of military and civilian personnel involved in the naval nuclear surface ship and submarine program. An epidemiologic cohort mortality study was initiated by researchers at the National Institute for Occupational Safety and Health to evaluate hazards associated with ionizing radiation and other exposures among workers at the INL facility. This report refers to the Idaho National Engineering and Environmental Laboratory (INEEL). On February 1, 2005 the Idaho National Engineering and Environmental Laboratory and Argonne National Laboratory-West became the Idaho National Laboratory. |
| This cohort study included 63,561 civilian workers ever employed by the DOE, its contractors, or the Naval Reactors Facility (NRF) at INL at any time between 1949 and 1991. Vital status and causes of death if deceased were ascertained for each worker through 1999. Exposures were estimated to external ionizing radiation using site records available through 1998. Potential exposure to internal radiation was also categorized. The INL cohort was predominantly white (96%) and male (81%). The median year of birth was 1942. The median length of follow-up for the cohort was 21 years, and the median year of hire for white males (WM) was 1973. |
| The mortality of workers who were badged for ionizing radiation exposure was compared to that of unbadged workers. Workers receiving higher external radiation doses were compared to those receiving lower doses. The cohort was also divided into subcohorts for the evaluation of non-radiological hazards and other factors at INL. Subcohorts that could be identified include construction and maintenance/service workers, asbestos workers, painters, reactor workers, chemists and chemical operators, security workers, and drivers. Mortality patterns were also evaluated for cohort members by the type of employer they worked for (prime contractors, subcontractors, or multiple types of contractors). |
| The statistical analysis consisted of SMRs, standardized rate ratios (SRRs), and Poisson regression analysis. SMRs were calculated for the cohort by comparing mortality with both the U.S. population and to a regional population consisting of the states of Idaho, Montana, and Wyoming, while standardizing on sex, race (white or non-white), age in five-year intervals, and calendar year in 5-year intervals. SRRs were calculated based on a comparison of the baseline categories to the regional population and on internal comparisons, for exposed subcohorts. Poisson regression was used to evaluate associations between external radiation and cancers, by estimating the risk of death per unit of dose for several groups of interest, as described in the report. |
| Although no smoking information was available for the cohort, two surrogates for smoking behavior were evaluated: socioeconomic status (SES), as defined by the worker's first job title at INL, and state of origin as Utah, Idaho, Montana, or Wyoming, which was used as an indicator of possible membership in the Latter Day Saints religion (which is associated with lower rates of smoking and alcohol consumption). Smoking-related cancers were also analyzed separately as part of the Poisson regression analysis to determine whether they were related differently to radiation than non-smoking-related cancers. |
| The median duration of employment was just over 3 years. About 57% of the cohort was ever monitored for exposure to external radiation. The average cumulative external dose among the monitored workers was about 13 mSv. The highest average doses for workers, as well as collective doses across the site, occurred during the 1960s. About 47% of the cohort was classified as ever having been a construction or maintenance service worker. Smaller groups were identified as asbestos workers, painters, reactor workers, chemical workers, security workers, or drivers. About half the cohort came from the states of Utah, Idaho, Montana, and Wyoming. The cohort consisted of many professional (16%) and administrative/technical (15%) workers but also had a large percentage who were skilled manual or non-manual (33%) and partly skilled or unskilled (15%) workers. About 21% were of unknown SES. |
| When compared to the regional population, INL workers exhibited slightly lower mortality rates (overall SMR: 0.96, 95% confidence interval [CI] 0.94-0.97, 10,788 deaths), but cancer rates were elevated (all-cancer SMR: 1.07, 95% CI: 1.03-1.11, 2,873 deaths). Workers monitored internally and externally for ionizing radiation exposures showed lower mortality than non-monitored workers for most causes of death. |
| Mortality rates for certain cancers were elevated among the INL cohort, or among individual subcohorts. Non-Hodgkin lymphoma (NHL) was elevated in the overall cohort, particularly among painters and female construction workers. Brain tumor mortality rates were elevated among male chemical workers and security workers. Construction and maintenance service workers showed elevated mortality rates from asbestosis and cancers likely to be mesotheliomas. Mortality rates for these causes were particularly high among those identified as asbestos workers. Bus and truck drivers showed elevated rates of death from transportation accidents, and security workers exhibited higher mortality rates from accidental falls and other non-transportation accidents compared to other workers. |
| An inverse external radiation dose-response relation was observed for emphysema, heart disease, and smoking-related cancers, suggesting negative confounding by smoking (that is, those receiving higher doses may have smoked with lower frequency or at a lower rate than those receiving lower doses). The excess relative risk (ERR) per 10 mSv (1 rem) of cumulative exposure was -0.0023, with an upper 95% confidence limit (CL) of 0.0459. Positive, but non-significant, associations were detected for brain tumors, leukemia, and lymphatic cancers, particularly when off-site dose was included in the model. At a 20-year dose lag, the ERR per 10 mSv for all brain tumors combined was 0.087 (95% CI: -0.0037 to 0.338). At a 7-year lag, the ERR per 10 mSv for non-CLL leukemia was 0.054 (95% CI: -0.011 to 0.24). The ERR per 10 mSv for CLL was negative, even when a longer lag period was used. For NHL, the ERR per 10 mSv was 0.020 (upper 95% CL: 0.10) and for multiple myeloma was 0.064 (95% CI: -0.015 to 0.35). |
| The INELCMA1_d1 (INEL2CEDR) file contains the following variables, where available: sex, race (white/non-white), date of birth (DOB), date of death (DOD), date last observed, vital status (VS), underlying cause of death, first hire date, last termination date, first monitoring date, date of first positive dose, annual cumulative onsite dose (1950 to 1998), annual cumulative onsite + offsite dose (1950 to 1998), SES, and indicator variables for migrant, construction, asbestos, painter, reactor, chemical, security, and driver worker status. |
