Clarifications on the Design and Interpretation of Conclusions from Health Canada’s Study on Wind Turbine Noise and Health

Abstract

It has been extensively communicated that Health Canada's Community Noise and Health Study (CNHS) did not find positive associations between wind turbine noise (WTN) levels and any of the evaluated health outcomes, beyond an increase in the prevalence of high annoyance toward several wind turbine features. The authors emphasize that this general conclusion remains bound by the study strengths and limitations. Following the publication of the CNHS findings, there has been interest among some individuals to present alternative interpretations of the results originally reported by Michaud et al. (J Acoust Soc Am 139(3):1443-1454, 2016. https://doi.org/10.1121/1.4942391). While recognizing the importance of independent scientific re-evaluation and/or reinterpretation, this commentary serves to clarify and, where necessary, correct some of the information put forward by others. One factor that has been re-evaluated by external stakeholders is the subsample of participants that comprise the lowest WTN category. In their reanalysis, they have eliminated this category, or introduced alternative comparative data. This paper identifies substantial issues associated with the re-evaluation put forth. To thoroughly address these issues and to avoid further confusion or misinterpretation, the authors of the CNHS provide a comparison between the CNHS health condition prevalence data and nationally representative health-based surveys conducted in Canada during the same calendar year. In addition, this paper responds to comments received to date on the CNHS, including the study's age range, the generalization of findings, the provision of raw data, and conclusions on the association between WTN level and health.

Response to Noise Emitted by Wind Farms in People Living in Nearby Areas

“…However, this study results support an association between the increasing wind turbine noise level and an increase in the prevalence of annoyance in relation to various wind turbine features, including noise, perceived indoor vibration during turbines’ operation, visual impacts, shadow flicker, and the aircraft warning lights on top of the turbines [11,12,13,14]. …”

Health Canada’s Wind Turbine Noise and Health Study—A Review Exploring Research Challenges, Methods, Limitations and Uncertainties of Some of the Findings

“…… one must avoid potential "apples to oranges" comparisons as the sample population in the CNHS is not generalizable. This has been identified by the CNHS authors as one of the limitations (i.e., caution on extrapolation beyond the study sample because the communities in the study may have important differences when compared to others in Canada, or elsewhere) [33].…”

“…Michaud et al 2018 [33] observe that "higher perceived stress scores were related to higher hair cortisol concentrations". The study by Michaud et al [29], Table I states that hair cortisol values ranged from 18 to 7139 ng/g (pg/mg) with Table 3 indicating many samples were over 200 ng/g.…”

“…During 2013, in collaboration with Statistics Canada [25], Health Canada conducted its cross-sectional study and published results during 2014, 2015 and 2016 [24]- [32]. Subsequently in response to comments expressed by some, Health Canada clarified the Health Canada Study design and interpretation of conclusions [33].…”

“…While the Federal Court case relates to clinical trial data, it appears in principle there is a potential to apply its ruling to the Health Canada Study raw data file. Michaud et al encourage "constructive criticism of scientific research" and acknowledges this "often stimulates improvements in future studies" [33]. In addition, it appears a revised data file is publically available through the Statis- [34].…”