title: Does heredity modify the association between farming and allergy in children?
abstract: OBJECTIVE
  It has been suggested that living on a farm decreases the risk of childhood allergy, especially if farming involves livestock. The aim of this study was to examine the association between farming and allergy in children, and the influence of atopic heredity in this association.
  
  
  METHODS
  The cross-sectional data of the 7981 children aged 13-14 y who participated in the Finnish ISAAC study between the years 1994 and 1995 were used to evaluate the association between farming and allergy.
  
  
  RESULTS
  Living on a farm was associated with a decreased risk of current symptoms of allergic rhinoconjunctivitis among all children (aOR 0.79; 95% CI 0.63, 0.99), and with a decreased risk of hay fever, especially among those children with a parental history of hayfever (aOR 0.60; 95% CI 0.40-0.89, p = 0.072 for interaction). The children of farmers with a history of hay fever also had a decreased risk of current wheeze (aOR 0.38; 95% CI 0.12-1.24, p = 0.040 for interaction). No significant association was found between farming and either asthma or eczema. Children living on a farm with livestock had the lowest risk of allergic rhinoconjunctivitis (aOR 0.69), followed by those living on a farm without livestock (aOR 0.89) compared with the non-farming children (p-value for trend 0.024).
  
  
  CONCLUSIONS
  Our results support the recent findings on a decreased risk of allergy among the children living on farms. A possible differential effect of parental history of hay fever on the relation of farming environment and the risk of allergic symptoms warrant further investigation.
authors.affiliation: Department of Pediatrics, Kuopio University Hospital, Kuopio, Finland. Sami.Remes@ktl.fi
authors.forename: S T
authors.initials: ST
authors.lastname: Remes
authors.forename: J
authors.initials: J
authors.lastname: Pekkanen
authors.forename: L
authors.initials: L
authors.lastname: Soininen
authors.forename: M
authors.initials: M
authors.lastname: Kajosaari
authors.forename: T
authors.initials: T
authors.lastname: Husman
authors.forename: A
authors.initials: A
authors.lastname: Koivikko
mesh_terms: D000293:Adolescent; D000383:Agriculture; D001249:Asthma / Q000453:epidemiology* / Q000235:genetics; D003430:Cross-Sectional Studies; D004485:Eczema / Q000453:epidemiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology* / Q000235:genetics; D008297:Male; D016017:Odds Ratio; D015995:Prevalence; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology / Q000235:genetics; D012907:Smoking