Literature Review Conducted By Danish ENT Academics Finds Dose Response Relationship
A recently published Systematic Literature Review conducted by two Danish Ear Nose and Throat Academics working at two different Danish University Hospital ENT departments has found there is evidence in the literature of a dose response relationship between wind turbine noise and sleep disturbance and noise annoyance symptoms.
A dose response relationship is one indicator of a direct causal relationship.
The authors have joined the chorus of health professionals calling for multidisciplinary research.
At present it seems reasonable to conclude that noise from wind turbines increases the risk of annoyance and disturbed sleep in exposed subjects in a dose-response relationship. There seems to be a tolerable limit of around LAeq of 35 dB. Logically, accepting higher limits in legislations may lead to increased numbers of annoyed subjects. It therefore seems reasonable to conclude that a cautious approach is needed when planning future wind farms. Furthermore, there is an indication that noise annoyance and sleep disturbance are related and that disturbed sleep potentially can lead to adverse health effects. These conclusions are, however, affected by a potential risk for selection and information bias even in the larger cross-sectional studies providing the current best evidence. The evidence for adverse health effects other than sleep disturbance is primarily supported by case-series reports which certainly may be affected by various sources of bias. Larger cross-sectional surveys have so far been unable to document a relationship between various symptoms such as tinnitus, hearing loss, vertigo, headache and exposure to wind turbine noise. One limitation causing this could be that most studies so far have only measured LAeq or Lden. An additional focus on the measurement of low-frequency sound exposure as well as a more thorough characterisation of the amplitude modulated sound and the relationship between objective and subjective health parameters could lead to different conclusions in the future. Finally, in regards to the objective measurement of health-related disorders in relation to wind turbine noise, it would be valuable to demonstrate if such health-related outcomes fluctuate depending on exposure to wind turbine noise.
Jesper Hvass Schmidt
Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
Department of Audiology and Department of ENT Head and Neck Surgery, Odense University Hospital, Odense, Denmark
Department of ENT Head and Neck Surgery & Audiology, Copenhagen University Hospital, Copenhagen, Denmark
Faculty of Health and Medical Sciences, Copenhagen University, Copenhagen, Denmark
PLoS ONE 9(12): e114183. doi:10.1371/journal.pone.0114183