title: Farming environment and prevalence of atopy at age 31: prospective birth cohort study in Finland.
abstract: BACKGROUND
  Cross-sectional studies have shown an association between the farming environment and a decreased risk of atopic sensitization, mainly related to contact with farm animals in the childhood.
  
  
  OBJECTIVE
  Investigate the association of a farming environment, especially farm animal contact, during infancy, with atopic sensitization and allergic diseases at the age of 31.
  
  
  METHODS
  In a prospective birth cohort study, 5509 subjects born in northern Finland in 1966 were followed up at the age of 31. Prenatal exposure to the farming environment was documented before or at birth. At age 31, information on health status and childhood exposure to pets was collected by a questionnaire and skin prick tests were performed.
  
  
  RESULTS
  Being born to a family having farm animals decreased the risk of atopic sensitization [odds ratio (OR) 0.67; 95% confidence interval (CI) 0.56-0.80], atopic eczema ever (OR 0.77; 95% CI 0.66-0.91), doctor-diagnosed asthma ever (OR 0.74; 95% CI 0.55-1.00), allergic rhinitis at age 31 (OR 0.87; 95% CI 0.73-1.03) and allergic conjunctivitis (OR 0.86; 95% CI 0.72-1.02) at age 31. There was a suggestion that the reduced risk of allergic sensitization was particularly evident among the subjects whose mothers worked with farm animals during pregnancy, and that the reduced risk of the above diseases by farm animal exposure was largely explained by the reduced risk of atopy. Having cats and dogs in childhood revealed similar associations as farm animals with atopic sensitization.
  
  
  CONCLUSIONS
  Contact with farm animals in early childhood reduces the risk of atopic sensitization, doctor-diagnosed asthma and allergic diseases at age 31.
authors.affiliation: Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland. jussi.lampi@thl.fi
authors.forename: J
authors.initials: J
authors.lastname: Lampi
authors.forename: D
authors.initials: D
authors.lastname: Canoy
authors.forename: D
authors.initials: D
authors.lastname: Jarvis
authors.forename: A-L
authors.initials: AL
authors.lastname: Hartikainen
authors.forename: L
authors.initials: L
authors.lastname: Keski-Nisula
authors.forename: M-R
authors.initials: MR
authors.lastname: Järvelin
authors.forename: J
authors.initials: J
authors.lastname: Pekkanen
mesh_terms: D000328:Adult; D000383:Agriculture; D000485:Allergens / Q000276:immunology; D000818:Animals; D000829:Animals, Domestic / Q000276:immunology*; D001249:Asthma / Q000453:epidemiology*; D002415:Cats; D015331:Cohort Studies; D003233:Conjunctivitis, Allergic / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004285:Dogs; D005387:Finland / Q000453:epidemiology; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology; D006969:Hypersensitivity, Immediate / Q000453:epidemiology*; D015995:Prevalence; D011446:Prospective Studies; D012220:Rhinitis / Q000453:epidemiology; D012882:Skin Tests
chemical_list: D000485:Allergens