title: Dermal uptake and excretion of 4,4'-methylenedianiline during rotor blade production in helicopter industry--an intervention study.
abstract: OBJECTIVE
  Workers using composite materials by fibre reinforced laminate technology are exposed to 4,4'-methylenedianiline (MDA), a liver toxicant and suspected human carcinogen, during the production of rotor blades in helicopter industry. The aim of the study presented here was to assess the internal dose of MDA and the suitability of various personal protection measures at the workplace.
  
  
  METHODS
  Ambient monitoring and biological monitoring was carried out by analysing MDA in air and urine samples in seven workers of a highly specialized workplace (rotor blade production). Three different concepts of personal protection measures were applied to study the route of uptake and to evaluate strategies in decreasing workplace exposure. In addition, elimination kinetics of MDA was studied in three workers who were exposed to MDA on three consecutive working days.
  
  
  RESULTS
  Ambient monitoring consistently provided air levels at or below the limit of quantification of 0.1 μg m(-3). Nevertheless, MDA was detected in 89% of all post-shift urine samples and median concentration was 4.2 μg l(-1). MDA in urine were >20 times higher than expected on data from ambient monitoring alone. A significant decrease in exposure could be achieved when workers have worn MDA-protective overalls in combination with MDA-protective gloves and a splash protection shield (from 9.8 μg l(-1) down to 3.7 μg l(-1)). The results show that MDA is taken up primarily via the skin at the workplaces under study. The excretion of MDA in urine was observed to be delayed after dermal exposure.
  
  
  CONCLUSIONS
  Exposure assessment of MDA should be carried out by biological monitoring rather than ambient monitoring. For this purpose, urine samples midweek or at the end of the week should be used based on the observed delay in the excretion of MDA after dermal absorption. Uptake of MDA via the skin could not be completely avoided even if state-of-the-art personal protection measures were applied.
authors.affiliation: Institute and Outpatient Clinic of Occupational, Social, and Environmental Medicine, Friedrich-Alexander University Erlangen-Nürnberg (IPASUM), Schillerstr. 25/29, 91054 Erlangen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Weiss
authors.forename: Hubert
authors.initials: H
authors.lastname: Schuster
authors.forename: Johannes
authors.initials: J
authors.lastname: Müller
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Schaller
authors.forename: Hans
authors.initials: H
authors.lastname: Drexler
authors.forename: Jürgen
authors.initials: J
authors.lastname: Angerer
authors.forename: Heiko U
authors.initials: HU
authors.lastname: Käfferlein
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis; D000401:Aircraft / Q000295:instrumentation*; D000814:Aniline Compounds / Q000032:analysis* / Q000493:pharmacokinetics; D015415:Biomarkers / Q000652:urine; D002273:Carcinogens / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D006801:Humans; D016273:Occupational Exposure / Q000032:analysis* / Q000517:prevention & control*; D011481:Protective Clothing / Q000592:standards*; D012869:Skin Absorption; D001559:Benzhydryl Compounds
chemical_list: D000395:Air Pollutants, Occupational; D000814:Aniline Compounds; D015415:Biomarkers; D002273:Carcinogens; C009505:4,4'-diaminodiphenylmethane; D001559:Benzhydryl Compounds