title: Trends in asbestos and non-asbestos fibre concentrations in the lung tissues of Japanese patients with mesothelioma.
abstract: OBJECTIVE
  We aimed to elucidate changes in asbestos and non-asbestos fibre concentrations in the lung tissues of Japanese patients with mesothelioma over time.
  
  
  METHODS
  Lung tissues were obtained from 46 patients with mesothelioma who died or underwent surgery between 1971 and 2005. All of the patients had a history of occupational asbestos exposure. We classified patients into four groups according to the period during which their lung tissue was obtained. Asbestos and non-asbestos fibre concentrations were determined by transmission electron microscopy with energy-dispersive X-ray analysis using a low-temperature ashing procedure.
  
  
  RESULTS
  From the 1970s to the 2000s, we observed a decrease in the geometric mean of total asbestos concentration (67.4-1.05 million fibres per gram dry lung), chrysotile concentration (25.0-0.66 million fibres per gram dry lung), amphibole asbestos concentration (21.3-0.76 million fibres per gram dry lung), and non-asbestos fibre concentration (326-19.3 million fibres per gram dry lung). The mean duration of asbestos exposure decreased from 33.7 to 17.6 years, and the mean duration since the last exposure increased from 0.3 to 21.5 years. The percentage of longer fibres to total fibres tended to increase over time, whereas the mean fibre length did not differ significantly.
  
  
  CONCLUSIONS
  The present study suggested that asbestos and non-asbestos fibre concentrations in the lung tissues of Japanese patients with mesothelioma who have occupational histories of asbestos exposure may have decreased from the 1970s to the 2000s.
authors.affiliation: Nagoya City Public Health Research Institute, 1-11 Hagiyama-cho, Mizuho-ku, Nagoya, Aichi 467-8615, Japan;
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Sakai
authors.forename: Naomi
authors.initials: N
authors.lastname: Hisanaga
authors.forename: Eiji
authors.initials: E
authors.lastname: Shibata
authors.forename: Michihiro
authors.initials: M
authors.lastname: Kamijima
authors.forename: Gaku
authors.initials: G
authors.lastname: Ichihara
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: Tamie
authors.initials: T
authors.lastname: Nakajima
mesh_terms: D000368:Aged; D001194:Asbestos / Q000032:analysis*; D002273:Carcinogens / Q000032:analysis*; D005260:Female; D006801:Humans; D007564:Japan; D008175:Lung Neoplasms / Q000473:pathology*; D008297:Male; D008654:Mesothelioma / Q000473:pathology*; D008875:Middle Aged; D019016:Mineral Fibers / Q000009:adverse effects / Q000032:analysis*; D009784:Occupational Diseases / Q000209:etiology* / Q000473:pathology; D016273:Occupational Exposure / Q000009:adverse effects*
chemical_list: D002273:Carcinogens; D019016:Mineral Fibers; D001194:Asbestos
keywords: asbestos; lung; mesothelioma; non-asbestos fibre; trend