title: Pulmonary fibrosis in workers exposed to non-asbestiform tremolite asbestos minerals.
abstract: BACKGROUND
  Studies of the health effects of non-asbestiform asbestos minerals remain inconclusive. Nephrite is a type of non-asbestiform tremolite mineral. We assessed the risk for pulmonary fibrosis in workers who process nephrite.
  
  
  METHODS
  A cross-sectional study that included 344 stone workers and their families was undertaken in Taiwan in 2010. The diagnostic criteria for pulmonary fibrosis included (1) radiographic fibrosis profusion of 1/1 or greater and (2) audible lung crackles confirmed by physician. The nephrite samples were analyzed using polarized light and transmission electron microscopy combined with selected-area electron diffraction and energy-dispersive x-ray spectroscopy.
  
  
  RESULTS
  After excluding 16 subjects with histories of tuberculosis or previous employment in metal casting and welding, as well as 23 family members who had not worked in the stone industry, we analyzed 305 subjects. Processing nephrite increased the risk for pulmonary fibrosis (odds ratio = 2.8 [95% confidence interval = 1.0-9.9] and unchanged after adjustment for age and smoking). Bulk sample analyses showed that the nephrite is a tremolite mineral composed of both asbestiform and non-asbestiform components. The cat's-eye nephrite had the highest asbestiform fibrous content, and the average length and aspect ratio of elongated mineral particles were the highest of all the nephrite types. Compared with workers processing other types of nephrite, workers processing cat's-eye nephrite had the highest risk for pulmonary fibrosis.
  
  
  CONCLUSIONS
  Processing non-asbestiform tremolite mineral may increase the risk for pulmonary fibrosis. Medical monitoring is warranted for workers with such exposure.
authors.affiliation: Department of Occupational Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan.
authors.forename: Hsiao-Yu
authors.initials: HY
authors.lastname: Yang
authors.forename: Ruei-Hao
authors.initials: RH
authors.lastname: Shie
authors.forename: Pau-Chung
authors.initials: PC
authors.lastname: Chen
mesh_terms: D000328:Adult; D000395:Air Pollutants, Occupational / Q000032:analysis / Q000633:toxicity*; D017636:Asbestos, Amphibole / Q000032:analysis / Q000633:toxicity*; D001195:Asbestosis / Q000175:diagnosis / Q000209:etiology*; D003430:Cross-Sectional Studies; D019652:Extraction and Processing Industry; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D019016:Mineral Fibers / Q000032:analysis / Q000633:toxicity; D008903:Minerals / Q000032:analysis / Q000633:toxicity*; D015999:Multivariate Analysis; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D016016:Proportional Hazards Models; D012307:Risk Factors; D013052:Spectrometry, X-Ray Emission; D011795:Surveys and Questionnaires; D013624:Taiwan
chemical_list: D000395:Air Pollutants, Occupational; D017636:Asbestos, Amphibole; D019016:Mineral Fibers; D008903:Minerals; C005846:tremolite