title: Retrospective exposure assessment to airborne asbestos among power industry workers.
abstract: BACKGROUND
  A method of individually assessing former exposure to asbestos fibres is a precondition of risk-differentiated health surveillance. The main aims of our study were to assess former levels of airborne asbestos exposure in the power industry in Germany and to propose a basic strategy for health surveillance and the early detection of asbestos related diseases.
  
  
  METHODS
  Between March 2002 and the end of 2006, we conducted a retrospective questionnaire based survey of occupational tasks and exposures with airborne asbestos fibres in a cohort of 8632 formerly asbestos exposed power industry workers. The data on exposure and occupation were entered into a specially designed computer programme, based on ambient monitoring of airborne asbestos fibre concentrations. The cumulative asbestos exposure was expressed as the product of the eight-hour time weighted average and the total duration of exposure in fibre years (fibres/cubic centimetre-years).
  
  
  RESULTS
  Data of 7775 (90% of the total) participants working in installations for power generation, power distribution or gas supply could be evaluated. The power generation group (n = 5284) had a mean age of 56 years, were exposed for 20 years and had an average cumulative asbestos exposure of 42 fibre years. The occupational group of "metalworkers" (n = 1600) had the highest mean value of 79 fibre years. The corresponding results for the power distribution group (n = 2491) were a mean age of 45 years, a mean exposure duration of 12 years and an average cumulative asbestos exposure of only 2.5 fibre years. The gas supply workers (n = 512) had a mean age of 54 years and a mean duration of exposure of 15 years.
  
  
  CONCLUSIONS
  While the surveyed cohort as a whole was heavily exposed to asbestos dust, the power distribution group had a mean cumulative exposure of only 6% of that found in the power generation group. Based on the presented data, risk-differentiated disease surveillance focusing on metalworkers and electricians from the power generating industry seems justified. That combined with a sensitive examination technique would allow detecting asbestos related diseases early and efficiently.
authors.affiliation: Institute of Occupational and Social Medicine, Medical Faculty, RWTH Aachen University, Aachen, Germany. mfelten@ukaachen.de.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Felten
authors.forename: Lars
authors.initials: L
authors.lastname: Knoll
authors.forename: Christian
authors.initials: C
authors.lastname: Eisenhawer
authors.forename: Diana
authors.initials: D
authors.lastname: Ackermann
authors.forename: Khaled
authors.initials: K
authors.lastname: Khatab
authors.forename: Johannes
authors.initials: J
authors.lastname: Hüdepohl
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zschiesche
authors.forename: Thomas
authors.initials: T
authors.lastname: Kraus