title: A longitudinal study on Raynaud's phenomenon in workers using an impact wrench.
abstract: OBJECTIVE
  The purpose of this study was to clarify the occurrence of Raynaud's phenomenon among workers using an impact wrench for a long time.
  
  
  METHODS
  The subjects were 704 workers regularly using an impact wrench and taking special medical examinations for vibration syndrome from 1981 to 2008. Raynaud's phenomenon was observed in 39 subjects during the observation period.
  
  
  RESULTS
  The mean operating years at the occurrence of Raynaud's phenomenon was 25.5 ± 8.3 (standard deviation) yr. The mean total operating time (geometric average) at the occurrence of Raynaud's phenomenon was 11,689 h. By the person-year method, the incidence rate of Raynaud's phenomenon was 6.27 persons per 1,000 person-years. The estimated risk of developing Raynaud's phenomenon did not increase until 12 years after starting to operate an impact wrench but increased exponentially after that. The vibration level of an impact wrench (from 4.9 m/s(2) to 22.6 m/s(2)) exceeded the occupational exposure limit value (4.9 m/s(2)). Various countermeasures, such as introducing automatically apparatus and keeping the working environment warm to protect from cold exposure, were taken at the factory.
  
  
  CONCLUSIONS
  These findings showed that the rate of occurrence of Raynaud's phenomenon was not high, although the vibration level of the impact wrench was high. This may result from various countermeasures to prevent the occurrence of Raynaud's phenomenon. A long period of exposure to vibration had the potential to lead to the occurrence of Raynaud's phenomenon even under various countermeasures.
authors.affiliation: Occupational Health Research and Development Center, Japan Industrial Safety and Health Association, Tokyo, Japan. y-aiba@jisha.or.jp
authors.forename: Yoko
authors.initials: Y
authors.lastname: Aiba
authors.forename: Kenya
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ohshiba
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ikeda
authors.forename: Ikuharu
authors.initials: I
authors.lastname: Morioka
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Miyashita
authors.forename: Hidesuke
authors.initials: H
authors.lastname: Shimizu
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology* / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects*; D016272:Occupational Health / Q000706:statistics & numerical data*; D016016:Proportional Hazards Models; D011928:Raynaud Disease / Q000453:epidemiology* / Q000209:etiology; D012307:Risk Factors; D013577:Syndrome; D013997:Time Factors; D014732:Vibration / Q000009:adverse effects*; D017132:Workplace / Q000523:psychology; D055815:Young Adult