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“Wind Turbines and Health

2015; Lippincott Williams & Wilkins; Volume: 57; Issue: 10 Linguagem: Inglês

10.1097/jom.0000000000000559

1536-5948

Robert J. McCunney, Kenneth A. Mundt, W D Colby, Robert A. Dobie, Kenneth Kaliski, Mark A. Blais,

Vehicle Noise and Vibration Control

WIND TURBINES AND HEALTH: AN INFORMED OPINION Response to May and McMurtry Letter We welcome the commentary to our critical review on whether living near wind turbines may adversely affect health.1 We note that May and McMurtry neither indicate that we misinterpreted any of the scientific literature we cited nor identify any peer-reviewed article of pertinence that we failed to identify in our critical review of the peer reviewed literature. In contrast, May and McMurtry use their response to our review as a forum to address issues of their personal concern to them about wind energy. Little, if any, commentary is directed to our methods, assessment, and recommendations. We have chosen not to engage in editorial debate on non-health-related aspects of wind energy, such as the repeated allusions May and McMurtry make to wind turbine "proponents" and "opponents," of which we are neither. As described in detail below, their "letter" would have been more appropriate as an editorial or opinion piece because little of their commentary is directed to our review and when the comments are directed to the review, are often incorrect. Responses to the letter follow. May and McMurtry state: "Modern IWT do produce ILFN. [Infrasound low frequency noise.] The counterclaims by the proponents of IWT and their paid experts lack credibility." It is unclear to whom May and McMurtry refer when they describe "proponents" and "paid experts." If directed toward our scientific review, they apparently missed or ignored our statements that wind turbines generate infrasound and low frequency sound (pages e110 and e111, for example) where we clearly note "low frequency sound near wind farms is typically audible." May and McMurtry state: "There appears to be considerable inertia and reluctance on the part of proponents to conduct independent epidemiological clinical studies of this kind, even after wind turbine noise has been recognized as a problem for communities." This comment again appears to be editorial in nature as opposed to directed toward any methodological or interpretive issues with our review. Further, we comment in considerable detail about recommended areas for further inquiry (ie, research), such as including enhanced noise characterization, analysis of predicted noise values contrasted with measured levels post installation, longitudinal assessments of health pre- and postinstallation, experimental studies in which subjects are "blinded" to the presence or absence of infrasound, and enhanced measurement techniques to evaluate annoyance," among many others. These are the building blocks of good epidemiological studies, of which indeed we are "proponents." To support their view that wind turbines cause infrasound/low frequency noise that adversely affects people's health May and McMurtry cite a 30-year-old report that evaluated noise from a downwind-design turbine (blades downwind of the tower—an obsolete design not used in modern turbines).2 Not cited by May and McMurtry, however, is a letter published by Kelley 2 years later in which a metric is proposed that limits infrasound and low-frequency noise to levels that are 7 dB above the threshold of perception for non-impulsive periodic random sources (ie, upwind-design wind turbines). ("A proposed metric for assessing the potential of community annoyance from wind turbine low-frequency noise emissions," November 1987, Proceedings of Windpower '87, San Francisco, CA). Thus, their argument appears to be imbalanced, perhaps due to selective reliance on outdated material. Referring to our article, May and McMurtry state: "Their review seems preoccupied with personality factors." Among over 20,000 words in the manuscript, 326 (less than 2%) addressed "Personality Factors and Wind Turbine Sound": hardly a "preoccupation." Clearly, as with many illnesses, individual factors are important to consider in understanding why some people report being annoyed in the presence of wind turbines. May and McMurtry claim "that the nocebo effect has been used by wind energy 'proponents' [again undefined] as a way of invalidating claims about adverse health effects." The nocebo response is widely recognized in medicine.3–7 The nocebo effect has also been shown to be operative in well-conducted studies that have addressed individual and blinded responses to infrasound.8,9 The nocebo effect is not a theoretical construct. It has been demonstrated in other areas of health care as well as in the context of blinded studies to infrasound.5,8–10 We note this important concept not to discount symptoms people may experience but to ensure thoroughness in any clinical assessment. Clearly, this phenomenon needs to part of any differential diagnosis as a possible explanation or contributor to symptoms, based on the results of experimental studies, in which subjects were blinded to the type of noise exposure.7,8 May and McMurtry devote two full paragraphs to a study led by an acoustician of 38 people in New Zealand to support their contention of a link between noise, annoyance, and adverse health effects.11 As noted in our review, noise may create annoyance, annoyance may lead to stress, and stress may lead to sleep disturbance and potential health effects. However, as Shepherd et al note, "While strong correlations exist between the sound level and the perceived loudness of a sound, there is no clear relationship between level and the psychological responses that individuals have to a sound." Thus, although noise may be associated with annoyance, many other factors other than noise, including attitudes toward wind turbines, the visual effect of turbines and whether people derive economic benefit from their use, can affect self-reporting of annoyance. Shepherd et al did not correlate turbine noise (or even distance from turbines—a poor surrogate of actual sound measurements) with the reported annoyance or sleep effects. Moreover, the sample population around the recently opened wind farm of the Shepherd study was unusually predisposed to annoyance, with a reported "1000 noise complaints" in the first year of operation. Shepherd et al note that, "the conflict between the Makara community and the wind farm developers could also potentially reduce HRQOL or amplify annoyance reactions and sleep difficulties." Although the Shepherd study found a difference between the turbine and control group on sleep quality and self-reported energy levels, they found no difference between the turbine and control groups for self-rated general health or even neighborhood noise annoyance. In any case, such cross-sectional surveys cannot and do not demonstrate causation. Curiously, May and McMurtry failed to acknowledge a much larger study (over 1000 participants in contrast to Shepherd's 38) of health-related quality of life (HRQOL) in which the highest quality of life was noted among those people living closest to the turbines and later noted in a more recent article.12,13 Although we would not interpret these results as demonstrating a protective effect of wind turbine emissions (as could be done if interpreted at face value), we urge a more comprehensive and balanced evaluation before drawing such strong conclusions about HRQOL in the context of wind turbines. Regarding the paragraph starting, "Methodological issues have also been raised by a recent acoustic survey of Waterloo wind farm …" The paragraph is not a critique of our paper, but an observation that Hansen et al had different measurement results than the South Australian EPA, and the author recommends more research into the effects of low frequency sound. Hansen et al did not link low frequency sound or infrasound (the latter of which was below perception thresholds) to health effects. Our paper makes no mention of the South Australian EPA study or Hansen's unpublished critique. Again, May and McMurtry offer an editorial perspective as opposed to a comment relevant to our review. May and McMurtry refer to an unpublished conference presentation not available through the PubMed indexing system.14 "In contrast, we consider that a more sophisticated analysis of noise has been provided by Large and Stigwood suggesting that the focus on decibel levels and frequency parameters ignores crucial elements of noise character and noise context. Comparisons between wind turbine noise and a fridge for example are misleading, since the noise from a fridge is relatively constant with limited variation, whereas wind farm noise is often highly changeable and variable, without predictability or regularity. Logically transportation noise cannot reasonably be compared with wind farm noise, with the latter already having been shown to be more annoying." According to common standards used by regulatory agencies and by us in our review, we relied upon peer-reviewed published papers. Again, May and McMurtry are making comments not germane to our review. Nowhere in our review do we compare wind turbine sound to a refrigerator. In addition, our report specifically cites sources that show that wind turbine noise is more annoying than traffic noise. Another example of a random editorial comment not directed to our review is their claim that "Focusing on 'direct' causal links alone is unwarranted." Again and to the contrary, nowhere in our review is the term "direct health effects" used or even implied. Regarding, "In addition, McCunney et al suggest that the rate of complaints around wind farms is relatively low, and that generally only a small proportion of people report some degree of annoyance with wind turbines. The systematic review by Schimdt [sic] and Klokker points to a less comforting picture, with some studies even reporting a majority of households being annoyed. As a general statement, they report 10% to 45% of the population being annoyed if the sound exposure is above 40 dB (A), but less than 10% of the population annoyed if the sound exposure is less than 35 dB (A)." There are two confounding issues here. One is related to the low level of complaints around wind farms, which we assessed with reports. Then, there is the percentage of those who are annoyed, which is different and which has been assessed in cross-sectional studies. Schmidt does not address complaints—only annoyance. The studies that Schmidt cites with prevalence of annoyance associated with wind farms over 50% were all self-published surveys done around individual wind farms. None appear to have used scientifically sound methods and none addressed any dose–response relationship with either measured or modeled level of sound at the residence. None used controls. A Canadian report investigated noise-related complaints because of operating wind farms in Alberta, Canada, over its entire history of wind power. Some turbines had been in operation for 20 years.15 Among over 31,000 contacts (phone, e-mail, letter), 5 noise-oriented complaints at utility-scale wind farms were reported over this period, none of which were repeated after the complaints were addressed. Complaints were more common during construction of the wind farms; other power generation methods (gas, oil, etc) received more complaints than wind power. An Australian study also found a very low complaint rate (less than 1%) for residents living within 5 km of turbines greater than 1 MW. Complaints were concentrated among a few wind farms; many wind farms never received complaints.16 This is another example where May and McMurtry's selective citation does not reflect a representative or balanced interpretation of the literature, and may be misleading to readers. In summary, rather than being a response to our review of the peer reviewed scientific and medical literature, the May and McMurtry letter appears to be a forum for the authors to promulgate their personal views about potential health implications of living near wind turbines. An editorial would have been a more appropriate format for them to express their concerns. Very little of their commentary, some assertions of which are completely incorrect, is directed to our review.