Occupational exposure to trichloroethylene and cancer risk for workers at the Paducah Gaseous Diffusion Plant.

OBJECTIVE: The Paducah Gaseous Diffusion Plant (PGDP) became operational in 1952; it is located in the western part of Kentucky. We conducted a mortality study for adverse health effects that workers may have suffered while working at the plant, including exposures to chemicals. MATERIALS AND METHODS: We studied a cohort of 6820 workers at the PGDP for the period 1953 to 2003; there were a total of 1672 deaths to cohort members. Trichloroethylene (TCE) is a specific concern for this workforce; exposure to TCE occurred primarily in departments that clean the process equipment. The Life Table Analysis System (LTAS) program developed by NIOSH was used to calculate the standardized mortality ratios for the worker cohort and standardized rate ratio relative to exposure to TCE (the U.S. population is the referent for ageadjustment). LTAS calculated a significantly low overall SMR for these workers of 0.76 (95% CI: 0.72-0.79). A further review of three major cancers of interest to Kentucky produced significantly low SMR for trachea, bronchus, lung cancer (0.75, 95% CI: 0.72-0.79) and high SMR for Non-Hodgkin's lymphoma (NHL) (1.49, 95% CI: 1.02-2.10). RESULTS: No significant SMR was observed for leukemia and no significant SRRs were observed for any disease. Both the leukemia and lung cancer results were examined and determined to reflect regional mortality patterns. However, the Non-Hodgkin's Lymphoma finding suggests a curious amplification when living cases are included with the mortality experience. CONCLUSIONS: Further examination is recommended of this recurrent finding from all three U.S. Gaseous Diffusion plants.

Cohort follow-up: the 21st century procedures.

The basic logic of designing an occupational cohort study has changed little since William R. Gaffey outlined the issues of follow-up, measurement of exposure, and analysis of data. However, many new avenues of tracking workers for epidemiological studies have been developed since Gaffey wrote his paper in 1973. Many disease registries also perform follow-up of subjects for vital status determination, so the procedures used with this process are common to the two applications. This article speaks to cohort construction for this occupational research as well as describes the 2007 methods for vital status follow-up. Rises in concern about work-related disease risks and the scientific resources for performing these studies coincided with the computer revolution. Government and private sources of data on vital status have changed in several ways over the 35 years since Gaffey's seminal paper. Some systems make the process of follow-up more rapid and productive, and some barriers have been imposed as societal concerns for privacy have risen. We describe the process of linking 5 sources of data to compile a roster of 6,820 workers employed at the Paducah Gaseous Diffusion Plant from 1953 to 2003. The record linkage processes achieved a final death cohort of 1672 deaths--the ascertainment of these deaths (by time period) was 1379 (1979-2003) and 293 (1953-1978); follow-up then was 100% for this cohort.