title: Environmental factors as a cause for the increase in allergic disease.
abstract: OBJECTIVE
  To be able to understand the interaction among genetic factors, environmental exposure to allergens, and nonspecific adjuvant factors contributing to the increase in atopic diseases in developed countries.
  
  
  METHODS
  Peer-reviewed literature identified by searching medical databases.
  
  
  METHODS
  Careful review of epidemiologic cross-sectional, sequential, and longitudinal population studies and, when appropriate, intervention studies. The criteria used to accept a study reporting environmental factors influencing the prevalence of allergic diseases were adopted from the report published by the US Department of Health and Education in 1964 (Hill AB, Principles of Medical Statistics, 9th Ed. New York: Oxford University Press, 1971, p. 323)
  
  
  RESULTS
  There is ample evidence that specific environmental factors may cause sensitization and development of allergic symptoms and disease in susceptible individuals. It is unclear when and how long a sufficient exposure will result in clinical symptoms related to the immunoglobulin E-sensitizing agents.
  
  
  CONCLUSIONS
  Environmental factors play an important role for the development and manifestation of allergic conditions in genetically predisposed subjects. It is well documented that increased exposure to indoor allergens and selected outdoor allergens (eg, grass pollen and molds) and smoking are important risk factors for development of asthma and allergic sensitization. The importance of other environmental factors is less clear and which environmental factors that cause the increase in prevalence of allergic disease is still unknown.
authors.affiliation: Department of Internal Medicine, Bispebjerg University Hospital of Copenhagen, Denmark. hendriknolte@compuserve.com
authors.forename: H
authors.initials: H
authors.lastname: Nolte
authors.forename: V
authors.initials: V
authors.lastname: Backer
authors.forename: C
authors.initials: C
authors.lastname: Porsbjerg
mesh_terms: D000485:Allergens / Q000276:immunology*; D000818:Animals; D002415:Cats; D004781:Environmental Exposure; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology* / Q000209:etiology* / Q000235:genetics; D008019:Life Style; D012307:Risk Factors
chemical_list: D000485:Allergens