Wind turbines and adverse health effects: Applying Bradford Hill’s criteria for causation

ABSTRACT

The weight of evidence indicates occurrences of adverse health effects (AHEs) from living and working near industrial wind turbines (IWTs). Descriptions of the AHEs being reported by those living or working near the turbines are similar. While these occurrences have been associated with exposure to audible and inaudible noise annoyance, the causation of reported wind turbine‑associated health effects remains controversial. 

Establishing an argument of causation of adverse health outcomes has important clinical, scientific, and societal implications. Bradford Hill (BH) criteria have been widely used to establish causality between an environmental agent and risk of disease or disability, but have not previously been used to evaluate the relationship between IWTs and AHEs. The objective was to apply the BH criteria to evaluate the relationship between IWTs and AHEs. The nine criteria include the strength of the association, consistency, specificity, temporal sequence, biological gradient, plausibility, coherence, experimental evidence, and analogous evidence. These nine criteria have been applied to IWT exposure and reported AHEs using peer‑reviewed and other published literature that describes clinical, animal, and laboratory studies, testimony and reported experiences, and internet sources. Applying the BH criteria to the IWT‑related clinical, biological, and experimental data demonstrates that the exposure to IWTs is associated with an increased risk of AHEs. 

This analysis concludes that living or working near IWTs can result in AHEs in both people and animals. Our findings provide compelling evidence that the risk of AHEs should be considered before the approval of wind energy projects and during the assessment of setback distances of proposed and operational projects.

CONCLUSION

Incontrovertible proof of causation has tended to be an elusive goal. The debate of determining causality associated with placing IWTs near family homes is similar to past controversies around the debate of causality from the use of tobacco products and from worker exposures to asbestos and coal. The “best available evidence” is the current standard, and it is our contention that the Bradford Hill criteria are that standard.

Based on our analysis of clinical, biological, and experimental evidence and its concordance with the nine BH criteria, we conclude that there is a high probability that emissions from IWTs, including infrasound and LFN, result in serious harm to health in susceptible individuals living and/or working in their proximity. These effects can be attributed to IWT‑related events such as recurring sleep disturbance, anxiety and stress, and likely others. 

With the growing weight of evidence  indicating this causation and the rapid proliferation of IWT installations globally, preventative actions should be taken, and policies implemented that are more cautiously protective of public health, safety, and welfare rather than wait for absolute certainty. More stringent regulation is needed to recognize, monitor, analyze, and document effects on the health of local residents and animals. Of concern is the lack of determination of the safe exposure cumulative dose of noise, including LFN and infrasound, for adults, the elderly, and particularly for fetuses and young children. There are no evidence‑based guidelines for setbacks of IWT; rather regulations have a wide variance across jurisdictions. The concern is compounded by the lack of centralized vigilance monitoring for those who have constant, long‑term exposure while living in their homes. Our findings provide compelling evidence that there is a pressing need for risk assessment before deployment of IWT into rural community settings that consider more effective and precautionary setback distances. A margin of safety sufficient to prevent pathogenic LFN from being detected by the human vestibular system is paramount before proceeding with political or economic policies. 

As written by Hill: “All scientific work is incomplete— whether it be observations or experimental. All scientific work is liable to be upset or modified by advancing knowledge. That does not confer upon us a freedom to ignore the knowledge we already have, or to postpone the action that it appears to demand at a given time.”[2]