title: Screening of miners and millers at decreasing levels of asbestos exposure: comparison of chest radiography and thin-section computed tomography.
abstract: BACKGROUND
  Chest radiography (CXR) is inferior to Thin-section computed tomography in the detection of asbestos related interstitial and pleural abnormalities. It remains unclear, however, whether these limitations are large enough to impair CXR´s ability in detecting the expected reduction in the frequency of these asbestos-related abnormalities (ARA) as exposure decreases.
  
  
  METHODS
  Clinical evaluation, CXR, Thin-section CT and spirometry were obtained in 1418 miners and millers who were exposed to progressively lower airborne concentrations of asbestos. They were separated into four groups according to the type, period and measurements of exposure and/or procedures for controlling exposure: Group I (1940-1966/tremolite and chrysotile, without measurements of exposure and procedures for controlling exposure); Group II (1967-1976/chrysotile only, without measurements of exposure and procedures for controlling exposure); Group III (1977-1980/chrysotile only, initiated measurements of exposure and procedures for controlling exposure) and Group IV (after 1981/chrysotile only, implemented measurements of exposure and a comprehensive procedures for controlling exposure).
  
  
  RESULTS
  In all groups, CXR suggested more frequently interstitial abnormalities and less frequently pleural plaques than observed on Thin-section CT (p<0.050). The odds for asbestosis in groups of decreasing exposure diminished to greater extent at Thin-section CT than on CXR. Lung function was reduced in subjects who had pleural plaques evident only on Thin-section CT (p<0.050). In a longitudinal evaluation of 301 subjects without interstitial and pleural abnormalities on CXR and Thin-section CT in a previous evaluation, only Thin-section CT indicated that these ARA reduced as exposure decreased.
  
  
  CONCLUSIONS
  CXR compared to Thin-section CT was associated with false-positives for interstitial abnormalities and false-negatives for pleural plaques, regardless of the intensity of asbestos exposure. Also, CXR led to a substantial misinformation of the effects of the progressively lower asbestos concentrations in the occurrence of asbestos-related diseases in miners and millers.
authors: Pulmonary Division, Heart Institute, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors: Mario
authors: M
authors: Terra-Filho
authors: Occupational Health Area, Department of Social and Preventive Medicine, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil; Department of Clinical Medicine, Faculdade de Medicina de Jundiaí, Jundiaí, São Paulo, Brazil.
authors: Ericson
authors: E
authors: Bagatin
authors: Respiratory Division, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors: Luiz Eduardo
authors: LE
authors: Nery
authors: Respiratory Division, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors: Lara Maris
authors: LM
authors: Nápolis
authors: Respiratory Division, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors: José Alberto
authors: JA
authors: Neder
authors: Radiology Division, Department of Radiology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Radiology Division, Fleury Group, São Paulo, Brazil.
authors: Gustavo de Souza Portes
authors: GS
authors: Meirelles
authors: Department of Radiology, Delfin Clinic and Portuguese Hospital, Salvador, Bahia, Brazil.
authors: C Isabela
authors: CI
authors: Silva
authors: Department of Radiology, University of British Columbia, Vancouver, B.C., Canada.
authors: Nestor L
authors: NL
authors: Muller
mesh_terms: D017636:Asbestos, Amphibole / Q000009:adverse effects*; D017632:Asbestos, Serpentine / Q000009:adverse effects*; D001938:Brazil; D003430:Cross-Sectional Studies; D005189:False Positive Reactions; D006801:Humans; D008137:Longitudinal Studies; D008403:Mass Screening; D008867:Microtomy; D008906:Mining / Q000706:statistics & numerical data*; D016273:Occupational Exposure / Q000706:statistics & numerical data*; D013902:Radiography, Thoracic / Q000379:methods* / Q000706:statistics & numerical data; D013147:Spirometry; D014057:Tomography, X-Ray Computed
chemical_list: D017636:Asbestos, Amphibole; D017632:Asbestos, Serpentine; C005846:tremolite