A 30-year mortality and respiratory morbidity study of refractory ceramic fiber workers

Abstract

Aim: Report mortality (n = 1119), cancer incidence (n = 1207) and radiographic (n = 1451) findings from a 30-year investigation of current and former refractory ceramic fiber (RCF) workers.

Methods: Cause of death, health and work histories, radiographs and spirometry were collected. Mortality and cancer incidence were analyzed. Logistic regression analysis investigated the associations of latency and cumulative fiber exposure (CFE) on radiographic changes.

Results: The mortality study showed no increase in standardized mortality rates (SMR) for lung cancer, but urinary cancers were significantly elevated in the higher exposed group (SMR = 3.62, 95% CI: 1.33–7.88) and leukemia in the total cohort (SMR = 2.51, 95% CI: 1.08–4.94). One death attributed to mesothelioma was identified (SMR = 2.86, 95% CI: 0.07–15.93) in a worker reporting some asbestos exposure. The overall rate of pleural changes was 6.1%, attaining 21.4% in the highest CFE category for all subjects (adjusted odds ratio (aOR) = 6.9, 95% CI: 3.6–13.4), and 13.0% for those with no reported asbestos exposure (OR= 9.1, 95% CI: 2.5–33.6). Prevalence for recent hires (≥1985) was similar to the background. Interstitial changes were not elevated. Localized pleural thickening was associated with small decreases in spirometry results.

Conclusion: Increases in leukemia and urinary cancer but not lung cancer mortality were found. One death attributed to mesothelioma was observed in a worker with self-reported asbestos exposure and a work history where occupational asbestos exposure may have occurred, rendering uncertainties in assigning causation. Radiographic analyses indicated RCF exposure alone is associated with increased pleural but not interstitial changes. Reductions in RCF exposure should continue. The mortality study is ongoing.

Keywords:

• Synthetic vitreous fibers
• cancer
• pleural plaques
• chest radiographs
• mesothelioma

Acknowledgements

We thank the men and women who participated in this study. The authors are grateful for the assistance of Dr. James Yiin with the LTAS, Connie Thrasher for administrative support, and the many staff and students who have been involved over 30 years.

Disclosure statement

Drs. LeMasters, Lockey, Levin and Mr. Hilbert and Mr. Burkle report funding from the High Temperature Insulation Wool Coalition through the University of Cincinnati for conducting this research. The contracts between the sponsor and the University of Cincinnati allowed the researchers to independently design the study, collect, analyze and interpret the data and publish the findings without interference. Drs. Shipley, Perme and Meyer report payment for B-readings from the University of Cincinnati. Dr. Shipley reports B-reading for various government, corporate and legal entities. Dr. Meyer reports B-reading for the Center for Asbestos Related Disease, Libby, Montana.