title: Follow-up study of workers in a nylon carpet yarn plant after remedial actions taken against a contaminated humidification system.
abstract: OBJECTIVE
  To investigate the effectiveness of remedial actions taken against a contaminated humidification system, after an outbreak of humidifier disease in a nylon carpet yarn plant.
  
  
  METHODS
  Two and 6 years after modification, a follow-up investigation of a stratified (age, smoking habits) sample of exposed (n = 75) and non-exposed (n = 56) workers was carried out. Outcome-parameters were: respiratory symptoms, spirometry, skin tests and serology with various humidifier fungi. In addition, the yearly incidence of work-disability because of chronic respiratory disease during the 2 years before, and 11 years after the modification was compared.
  
  
  RESULTS
  At follow-up, exposed workers, who remained at the same workplace no longer had significantly more frequent chronic respiratory symptoms. The prevalence of positive serology was still higher (P < 0.05) in exposed workers after 2 years, but at the 6 year follow-up investigation, the difference was no longer significant. Prevalence of positive skin tests after 2 years no longer differed from that of the non-exposed workers. Slopes (ml/years) of the graphs of forced vital capacity (FVC) and one-second forced expiratory volume (FEV1) during the 6 year follow-up after the first investigation did not differ between exposed and non-exposed workers, both before and after adjustment for age, smoking habits and results of skin tests and serology before modification. Before modification, exposed workers with a positive late skin test had a lower FVC than non-exposed workers. After 6 years of follow-up their FVC was still lower, but the difference was no longer significant. There were no indications of selective loss to follow-up. After remedial actions no new cases of humidifier disease occurred. Moreover, the yearly incidence of work-disability in this plant because of chronic respiratory disease, decreased from 1.30% to 0.27% compared with a decrease from 0.30% to 0. 12% in other synthetic fibre plants.
  
  
  CONCLUSIONS
  Follow-up investigation of exposure-effects demonstrated the effectiveness of remedial actions taken against a contaminated humidification system.
authors.affiliation: University Groningen Department of Social Medicine, The Netherlands. h.s.molanus-van.veen@med.rug.nl
authors.forename: T M
authors.initials: TM
authors.lastname: Pal
authors.forename: J W
authors.initials: JW
authors.lastname: Groothoff
authors.forename: D
authors.initials: D
authors.lastname: Post
authors.forename: J G
authors.initials: JG
authors.lastname: de Monchy
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005430:Floors and Floorcoverings; D005500:Follow-Up Studies; D006801:Humans; D007221:Industry; D019570:Inhalation Exposure / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009757:Nylons / Q000009:adverse effects* / Q000032:analysis; D009784:Occupational Diseases / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D016273:Occupational Exposure / Q000517:prevention & control*; D012129:Respiratory Function Tests; D012140:Respiratory Tract Diseases / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*
chemical_list: D009757:Nylons