title: Overlap in prevalence between various types of environmental intolerance.
abstract: Environmental intolerance (EI) is characterized by attribution of several, multisystem symptoms to specific environmental exposures, such as exposure to odorous/pungent chemicals, certain buildings, electromagnetic fields (EMFs) and everyday sounds. The symptoms are medically unexplained, non-specific and the symptoms overlap between different types of EI. To approach the issue of underlying mechanisms the matter of overlap in prevalence between intolerances can provide valuable information. The aim of the study was to examine if the overlap between intolerance to odorous/pungent chemicals, certain buildings, EMFs and sounds is larger than the expected overlap if no association would exist between them. The study was using cross-sectional data from the Västerbotten Environmental Health Study in Sweden; a large questionnaire-based survey. 8520 adults (18-79 years) were randomly selected after stratification for age and sex, of whom 3406 (40%) participated. Individuals with the four types of intolerance were identified either through self-report, or by having been physician-diagnosed with a specific EI. The overlaps between the four EIs were greater than predictions based on coincidence for both self-reported and diagnosed cases (except for the overlap between diagnosed intolerance to sounds and EMFs). The results raise the question whether different types of EI share similar underlying mechanisms, or at least that the sufferers of EI share some predisposition to acquire the conditions.
authors.affiliation: Department of Psychology, Umeå University, SE-901 87 Umeå, Sweden. Electronic address: eva.palmquist@psy.umu.se.
authors.forename: Eva
authors.initials: E
authors.lastname: Palmquist
authors.affiliation: Department of Psychology, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Anna-Sara
authors.initials: AS
authors.lastname: Claeson
authors.affiliation: Department of Psychology, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Gregory
authors.initials: G
authors.lastname: Neely
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå University, Sweden.
authors.forename: Berndt
authors.initials: B
authors.lastname: Stenberg
authors.affiliation: Department of Psychology, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Steven
authors.initials: S
authors.lastname: Nordin
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018777:Multiple Chemical Sensitivity / Q000453:epidemiology*; D009622:Noise / Q000009:adverse effects; D015995:Prevalence; D018877:Sick Building Syndrome / Q000453:epidemiology; D013548:Sweden / Q000453:epidemiology
keywords: Environmental intolerance; Multiple chemical sensitivity; Noise sensitivity; Overlap; Prevalence; Sick building syndrome