Epidemiologic assessment of the risk for adverse pulmonary effects from persistent occupational exposure to Mount St. Helens' volcanic ash (tephra).
Bernstein-RS; McCawley-MA; Attfield-MD; Green-F; Dollberg-DD; Baxter-PJ; Merchant-JA
Mount St. Helens: one year later. Keller SAC ed. Cheny, WA: Eastern Washington University Press, 1982 Jan; :207-213
Risks arising from occupational exposure to volcanic ash dispersed by the explosion of a volcano were investigated. Samples of volcanic ash were chemical and toxicologically evaluated. Loggers were recruited by a random selection from five exposed and two nonexposed logging camps. Job categories were stratified in descending order of probable exposure intensity to volcanic ash. Worker respiratory symptoms and lung function were assessed and chest roentgenograms were taken. Industrial hygiene surveys were performed over separate 2 week periods in June and September 1980. In the respirable fraction of the ash, the free silica (7631869) content was 3 to 7 percent. No zeolites or other carcinogenic asbestiform fibrous silicates were seen. Tests for mutagenicity were negative and heavy metals were not found in toxic concentrations. Exposed and control logger populations showed no significant differences in demographic, physiologic, and chest roentgenographic parameters examined. Cough, phlegm, eye irritation, and headache were significantly more prevalent among exposed workers in June, but only eye irritation and headache remained significantly elevated by September. There was no evidence of pneumoconiosis among these timber workers, many of whom had been exposed to old volcanic dusts for many years. Only for exposed cutters in June did the geometric mean airborne dust concentrations exceed 0.8 milligrams/cubic meter. Pulmonary function tests showed no exposure related shifts between the two testing periods. The authors conclude that there were no detectable short term effects of volcanic ash exposure among these occupationally exposed loggers. However, research on long term in-vitro and in-vivo fibrogenesis in experimental animal lungs following silicate and free silica dust instillation suggest the necessity for continued respiratory protection, industrial hygiene monitoring, medical surveillance of high risk groups, and toxicological evaluation of future ash falls.
Humans; Medical-surveys; Occupational-respiratory-disease; Employee-exposure; Airborne-particles; Biological-effects; Physiological-measurements; Respiratory-irritants; Air-quality-measurement; Dust-analysis; Medical-research
Mount St. Helens: one year later