title: Wind turbines and idiopathic symptoms: The confounding effect of concurrent environmental exposures.
abstract: Whether or not wind turbines pose a risk to human health is a matter of heated debate. Personal reactions to other environmental exposures occurring in the same settings as wind turbines may be responsible of the reported symptoms. However, these have not been accounted for in previous studies. We investigated whether there is an association between residential proximity to wind turbines and idiopathic symptoms, after controlling for personal reactions to other environmental co-exposures. We assessed wind turbine exposures in 454 residences as the distance to the closest wind turbine (Dw) and number of wind turbines <1000m (Nw1000). Information on symptoms, demographics and personal reactions to exposures was obtained by a blind questionnaire. We identified confounders using confounders' selection criteria and used adjusted logistic regression models to estimate associations. When controlling only for socio-demographic characteristics, log10Dw was associated with "unnatural fatigue" (ORadj=0.38, 95%CI=0.15-1.00) and "difficulty concentrating" (ORadj=0.26, 95%CI=0.08-0.83) and Nw1000 was associated with "unnatural fatigue" (ORadj=1.35, 95%CI=1.07-1.70) and "headache" (ORadj=1.26, 95%CI=1.00-1.58). After controlling for personal reactions to noise from sources different from wind turbines and agricultural odor exposure, we did not observe a significant relationship between residential proximity to wind turbines and symptoms and the parameter estimates were attenuated toward zero. Wind turbines-health associations can be confounded by personal reactions to other environmental co-exposures. Isolated associations reported in the literature may be due to confounding bias.
authors.affiliation: The Mærsk Mc-Kinney Møller Institute, Faculty of Engineering, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark. Electronic address: vbv@mmmi.sdu.dk.
authors.forename: Victoria
authors.initials: V
authors.lastname: Blanes-Vidal
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Harvard University, Boston, MA 02115, United States.
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
mesh_terms: D000328:Adult; D000368:Aged; D001288:Attention; D004244:Dizziness / Q000209:etiology; D004781:Environmental Exposure; D005221:Fatigue / Q000209:etiology; D005260:Female; D006261:Headache / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009325:Nausea / Q000209:etiology; D009622:Noise / Q000009:adverse effects; D059205:Renewable Energy / Q000009:adverse effects*; D011795:Surveys and Questionnaires; D013577:Syndrome; D014919:Wind
keywords: Confounding; Health; Noise; Odor; Traffic; Wind turbines