Time-period mortality patterns in a Gaseous Diffusion Plant workforce

Background: We sub-divided a cohort of 6820 workers at the Paducah (KY) Gaseous Diffusion Plant (PGDP) which was traced from 1953 to 2003. The subdivisions were made to assess the mortality risks in a sub-group of workers employed solely during the plant's refit period, a time of suspected higher exposure to metal dusts (nickel, arsenic, chromium and uranium) and trichloroethylene. Methods: This article describes a comparison of exposures and causes of death for 754 workers employed exclusively during the period of 1975-1979, with 1554 workers who worked in this period as well as other years. This interval was when the gaseous diffusion cascade facilities were re-fit. The workers employed ‘only’ during this period have a variety of deterministic factors (age-at-hire, duration of employment) that distinguish this sub-group of employees from the ‘long-term’ workforce. Results: The ‘only 1975-1979’ workers had a larger fraction of minorities and female workers. This ‘only’ sub-group was disproportionately employed in unskilled labor positions. The ‘only’ workers were younger than the referent group, and a 14-year earlier mean age at death. The all-cause mortality standardized rate ratio [SRR] was 1.58 [95% Cl: 0.97-2.42]. The ‘only’ group was significantly different from the ‘ever’ workers with respect to suicides, SRR = 3.74 [95% Cl: 1.86-6.69], and for homicides, SRR = 11.71 [95% Cl: 3.20-30.03]. Conclusions: These elevated mortality risks do not seem to be due to PGDP employment exposures to metal dusts or trichloroethylene. Socio-economic factors may be a determinant for the patterns of suicides and murders described for this sub-group of employees. These findings provide guidance for communities with a dominant local employer. Persons who experience short-term hiring may warrant public health services to mitigate their risk of tragic deaths. A case-control study of these deaths is recommended to clarify individual risk behaviors.