title: [The hygiene hypothesis is invalid].
abstract: The hygiene hypothesis offers an interesting explanation for the recent increase in allergy. However, all the studies that support this hypothesis are observational and cohort studies, which implies that no causal relationships can be assessed with sufficient validity. Exposure to environmental allergens and infections may very well not be determined by chance but by the behaviour of the parents. Therefore, the hygiene hypothesis should not be accepted without critical reflection of the facts presented.
authors.affiliation: Universiteit Maastricht, Onderzoeksinstituut Caphri, capaciteitsgroep Huisartsgeneeskunde, Postbus 616, 6200 MD Maastricht.
authors.forename: C P
authors.initials: CP
authors.lastname: van Schayck
mesh_terms: D000485:Allergens / Q000276:immunology*; D004777:Environment; D004781:Environmental Exposure; D019317:Evidence-Based Medicine; D006801:Humans; D006920:Hygiene; D006967:Hypersensitivity / Q000209:etiology* / Q000276:immunology; D007107:Immune System / Q000502:physiology*
chemical_list: D000485:Allergens