title: Exposure-response relations of alpha-amylase sensitisation in British bakeries and flour mills.
abstract: OBJECTIVE
  To describe the levels of exposure to fungal alpha-amylase in British bakeries and flour mills, and to describe the relation between exposure to alpha-amylase and sensitisation to fungal alpha-amylase.
  
  
  METHODS
  495 personal flour dust samples were taken in seven British bakeries and flour mills and analysed for alpha-amylase with an immunoassay. Workers at the sites were asked to fill out questionnaires on work related symptoms, smoking history, and work history, and they were skin prick tested with common allergens and fungal alpha-amylase to assess sensitisation.
  
  
  RESULTS
  Exposure to high concentrations of alpha-amylase occur in a few areas of British bakeries and flour mills, and there can be considerable differences in exposures to alpha-amylase between sites and between exposure groups, and even within similar exposure groups from different sites. Exposure to the highest concentrations of alpha-amylase was found in the dispensing and mixing areas of the bakeries (geometric mean (GM) 39.7 ng/m3). Exposure to alpha-amylase showed only a moderate correlation with concentrations of dust (r = 0.42) and flour aeroallergen (r = 0.46). The results also showed a relation between exposure to alpha-amylase and sensitisation to fungal alpha-amylase (prevalence ratio (PR) for medium exposure 3.9, 95% confidence interval (95% CI) 0.8 to 20.2, PR for high exposure 9.9, 95% CI 2.8 to 34.6) compared with the low exposure category). Atopic subjects had an increased risk of sensitisation, but this was not significant.
  
  
  CONCLUSIONS
  This study suggests that exposure to alpha-amylase is a considerable health risk in British bakeries and flour mills. A small proportion of workers are exposed to alpha-amylase at concentrations that result in high rates of sensitisation. A reduction in exposure to alpha-amylase is likely to reduce this risk.
authors.affiliation: T H Huxley School of Environment, Earth Sciences and Engineering, Centre for Environmental Technology, Imperial College of Science, Technology and Medicine, London, UK. m.nieuwenhuijsen@ic.ac.uk
authors.forename: M J
authors.initials: MJ
authors.lastname: Nieuwenhuijsen
authors.forename: D
authors.initials: D
authors.lastname: Heederik
authors.forename: G
authors.initials: G
authors.lastname: Doekes
authors.forename: K M
authors.initials: KM
authors.lastname: Venables
authors.forename: A J
authors.initials: AJ
authors.lastname: Newman Taylor
mesh_terms: D000328:Adult; D001236:Aspergillus oryzae / Q000201:enzymology; D004391:Dust / Q000009:adverse effects; D005260:Female; D005433:Flour / Q000032:analysis*; D005525:Food-Processing Industry; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D000516:alpha-Amylases / Q000009:adverse effects / Q000276:immunology
chemical_list: D004391:Dust; D000516:alpha-Amylases