title: Is there a threshold concentration of cat allergen exposure on respiratory symptoms in adults?
abstract: OBJECTIVE
  Cat allergen concentrations higher than 8 μg/g in settled house dust, have been suggested to provoke exacerbation of allergic respiratory symptoms. However, whether the 8 μg/g of indoor cat allergen concentration is indeed the minimal exposure required for triggering the asthma related respiratory symptoms or the development of sensitization has not yet been confirmed. We studied the associations between domestic cat allergen concentrations and allergic symptoms in the European Community Respiratory Health Survey II, with the aim of confirming this suggested threshold.
  
  
  METHODS
  Cat allergen concentrations were measured in the mattress dust of 3003 participants from 22 study centres. Levels of specific immunoglobulin E to cat allergens were measured in serum samples using an immunoassay. Information on allergic symptoms, medication use, home environment and smoking was obtained from a face-to-face interview.
  
  
  RESULTS
  Domestic cat allergen concentrations were not associated with allergic/ asthmatic symptoms in the entire study population, nor in the subset sensitized to cat allergen. We also found no association among individuals exposed to concentrations higher than 8 μg/g. However, exposure to medium cat allergen concentrations (0.24-0.63 μg/g) was positively associated with reported asthmatic respiratory symptoms in subjects who have experienced allergic symptoms when near animals.
  
  
  CONCLUSIONS
  The proposed 8 μg/g threshold of cat allergen concentrations for the exacerbation of allergic/ respiratory symptoms was not confirmed in a general European adult population. Potential biases attributable to avoidance behaviours and an imprecise exposure assessment cannot be excluded.
authors.affiliation: Paediatric Epidemiology, Institute of Social Medicine, Epidemiology and Health Economics, Charité University Medical Centre Berlin, Berlin, Germany; Helmholtz Zentrum München, German Research Centre for Environmental Health, Institute of Epidemiology, Neuherberg, Germany.
authors.forename: Chih-Mei
authors.initials: CM
authors.lastname: Chen
authors.affiliation: Helmholtz Zentrum München, German Research Centre for Environmental Health, Institute of Epidemiology, Neuherberg, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Thiering
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain; Netherlands Institute for Health Services Research (NIVEL), Utrecht, The Netherlands.
authors.forename: Jan-Paul
authors.initials: JP
authors.lastname: Zock
authors.affiliation: Department of Health Sciences, University of Pavia, Pavia, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Villani
authors.affiliation: Unit of Occupational Medicine, University Hospital of Verona, Verona, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Olivieri
authors.affiliation: Occupational and Environmental Medicine, Umeå University, Umeå, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Modig
authors.affiliation: Respiratory Epidemiology and Public Health Group, Imperial College London, London, United Kingdom.
authors.forename: Deborah
authors.initials: D
authors.lastname: Jarvis
authors.affiliation: Department of Medical Science, Occupational and Environmental Medicine, Uppsala University, Uppsala, Sweden.
authors.forename: Dan
authors.initials: D
authors.lastname: Norbäck
authors.affiliation: Unit of Epidemiology and Medical Statistics, University of Verona, Verona, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Verlato
authors.affiliation: Helmholtz Zentrum München, German Research Centre for Environmental Health, Institute of Epidemiology, Neuherberg, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Heinrich
mesh_terms: D000328:Adult; D016902:Air Pollution, Indoor / Q000009:adverse effects; D000485:Allergens / Q000032:analysis* / Q000276:immunology / Q000633:toxicity; D000818:Animals; D001249:Asthma / Q000276:immunology*; D002415:Cats; D004391:Dust / Q000276:immunology; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology* / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D008875:Middle Aged
chemical_list: D000485:Allergens; D004391:Dust; D007073:Immunoglobulin E