ABSTRACT
BACKGROUND: White asbestos (chrysotile) has been used in dentistry since 1930 when it was introduced as a lining material for casting rings. METHODS: All three patients presented with pleural plaques on chest X-rays as well as on CT-scans. They were working as dentists for 35-45 years. Under the instructions of the first dentist we represented precisely the whole process of manipulating a kind of paper that contained asbestos. In order to measure asbestos fibers concentration we used the membrane filter method and phase contrast optical microscopy. Dry asbestos sheets were scanned with x-ray diffraction and electron microscope. RESULTS: Analysis of the filter demonstrated 0.008 fibers/cm(3) during the sampling period. X-ray diffraction analysis revealed that the material consisted of chrysotile exclusively. Electron microscope pictures confirmed the presence of chrysotile. CONCLUSION: Everyday occupational exposure for many years even to low asbestos levels, under poor ventilation conditions in a closed space, could cause pleural lesions.
Subject(s)
Asbestos, Serpentine/toxicity , Asbestosis/diagnostic imaging , Dentists , Occupational Diseases/diagnostic imaging , Occupational Exposure/adverse effects , Pleura/diagnostic imaging , Aged , Aged, 80 and over , Calcinosis/diagnostic imaging , Carcinoma, Squamous Cell/diagnostic imaging , Dental Casting Technique , Humans , Lung Neoplasms/diagnostic imaging , Male , Microscopy, Electron, Scanning , Microscopy, Phase-Contrast , Pulmonary Disease, Chronic Obstructive/diagnostic imaging , Tomography, X-Ray Computed , X-Ray DiffractionABSTRACT
BACKGROUND: Asbestos exposure is related to serious adverse health effects. However, there is disagreement about the relationship between chrysotile exposure and mesothelioma or lung cancer. OBJECTIVES: Our aim was to investigate the mortality rate among workers exposed to relatively pure chrysotile in an asbestos cement factory. PATIENTS AND METHODS: In an asbestos cement plant opened in 1968, we prospectively studied all 317 workers. A quantity of 2,000 tons of chrysotile, with minimal amphibole contamination, was used annually until 1 January 2005. Asbestos fiber concentration was measured regularly. Date and cause of death were recorded among active and retired workers. RESULTS: Asbestos fiber concentration was always below permissible levels. Fifty-two workers died during the study. The cause was cancer in 28 subjects; lung cancer was diagnosed in 16 of them. No case of mesothelioma was reported. Death was attributed to cardiovascular diseases in 23 subjects and to liver cirrhosis in 1. Overall mortality rate was significantly lower than that of the Greek general population, standardized mortality ratio (SMR) was 0.71 (95% CI 0.53-0.93). Mortality due to cancer was increased (SMR 1.15, 95% CI 0.77-1.67), mainly due to lung cancer mortality (SMR 1.71, 95% CI 0.98-2.78), but not significantly. CONCLUSIONS: Occupational exposure to relatively pure chrysotile within permissible levels was not associated with a significant increase in lung cancer or with mesothelioma. Decreased overall mortality of workers indicates a healthy worker effect, which--together with the relatively small cohort size--could have prevented small risks to be detected.