title: Asthma and allergic symptoms in relation to house dust endotoxin: Phase Two of the International Study on Asthma and Allergies in Childhood (ISAAC II).
abstract: BACKGROUND
  Several studies have consistently reported inverse associations between exposure to endotoxin in house dust and atopy. With regard to the association between house dust endotoxin and asthma, the results are inconsistent.
  
  
  OBJECTIVE
  To study the association between house dust endotoxin levels and respiratory symptoms and atopy in populations from largely different countries.
  
  
  METHODS
  Data were collected within the International Study on Asthma and Allergies in Childhood Phase Two, a multi-centre cross-sectional study of 840 children aged 9-12 years from six centres in the five countries of Albania, Italy, New Zealand, Sweden and the United Kingdom. Living room floor dust was collected and analysed for endotoxin. Health end-points and demographics were assessed by standardized questionnaires. Atopy was assessed by measurements of allergen-specific IgE against a panel of inhalant allergens. Associations between house dust endotoxin and health outcomes were analysed by logistic regression. Odds ratios (ORs) were presented for an overall interquartile range increase in exposure.
  
  
  RESULTS
  Many associations between house dust endotoxin in living room floor dust and health outcomes varied between countries. Combined across countries, endotoxin levels were inversely associated with asthma ever [adjusted OR (95% confidence interval (CI)) 0.53 (0.29-0.96) for endotoxin levels per m(2) of living room floor] and current wheeze [adjusted OR (95% CI) 0.77 (0.64-0.93) for endotoxin levels per gram of living room floor dust]. There were inverse associations between endotoxin concentrations and atopy, which were statistically significant in unadjusted analyses, but not after adjustment for gender, parental allergies, cat and house dust mite allergens. No associations were found with dust quantity and between endotoxin exposure and hayfever.
  
  
  CONCLUSIONS
  These findings suggest an inverse association between endotoxin levels in living room floor dust and asthma in children.
authors.affiliation: Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands. u.gehring@uu.nl
authors.forename: U
authors.initials: U
authors.lastname: Gehring
authors.forename: M
authors.initials: M
authors.lastname: Strikwold
authors.forename: D
authors.initials: D
authors.lastname: Schram-Bijkerk
authors.forename: G
authors.initials: G
authors.lastname: Weinmayr
authors.forename: J
authors.initials: J
authors.lastname: Genuneit
authors.forename: G
authors.initials: G
authors.lastname: Nagel
authors.forename: K
authors.initials: K
authors.lastname: Wickens
authors.forename: R
authors.initials: R
authors.lastname: Siebers
authors.forename: J
authors.initials: J
authors.lastname: Crane
authors.forename: G
authors.initials: G
authors.lastname: Doekes
authors.forename: R
authors.initials: R
authors.lastname: Di Domenicantonio
authors.forename: L
authors.initials: L
authors.lastname: Nilsson
authors.forename: A
authors.initials: A
authors.lastname: Priftanji
authors.forename: A
authors.initials: A
authors.lastname: Sandin
authors.forename: N
authors.initials: N
authors.lastname: El-Sharif
authors.forename: D
authors.initials: D
authors.lastname: Strachan
authors.forename: M
authors.initials: M
authors.lastname: van Hage
authors.forename: E
authors.initials: E
authors.lastname: von Mutius
authors.forename: B
authors.initials: B
authors.lastname: Brunekreef
mesh_terms: D000415:Albania / Q000453:epidemiology; D000485:Allergens / Q000032:analysis / Q000276:immunology*; D000918:Antibody Specificity; D001249:Asthma / Q000453:epidemiology* / Q000276:immunology; D002648:Child; D003430:Cross-Sectional Studies; D004391:Dust / Q000032:analysis / Q000276:immunology*; D004731:Endotoxins / Q000032:analysis / Q000276:immunology*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D007558:Italy / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D012135:Respiratory Sounds / Q000276:immunology; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D000485:Allergens; D004391:Dust; D004731:Endotoxins; D007073:Immunoglobulin E