One of my fears when I wrote my previous post about Wi-Fi was that I was opening a Pandora’s Box on the whole field of electromagnetic fields and health. As I expected, shortly after I posted that blog a number of people tweeted to me explaining how wrong I was about Wi-Fi, with many describing stories of Electromagnetic Hypersensitivity (EHS). Well as my dad used to say: in for a penny, in for a pound. I may as well cover that topic as well. In this post, therefore, I will look into the topic of EHS and in doing so will re-visit the concept of the Nocebo effect.
The World Health Organization defines EHS as:
a variety of non-specific symptoms, which afflicted individuals attribute to exposure to EMF [electromagnetic fields]. The symptoms most commonly experienced include dermatological symptoms (redness, tingling, and burning sensations) as well as neurasthenic and vegetative symptoms (fatigue, tiredness, concentration difficulties, dizziness, nausea, heart palpitation, and digestive disturbances). The collection of symptoms is not part of any recognized syndrome.
Before I can go into a discussion of EHS, however; I will need to introduce a couple topics I have not yet covered in my blog: the double-blind study and the concept of a systematic review or meta-analysis.
In my previous post Risk Assessment Epilogue: Have a bad case of Anecdotes? Better call an Epidemiologist I describe the field of epidemiology which the World Health Organization defines as the study of the distribution and determinants of health-related states or events (including disease), and the application of this study to the control of diseases and other health problems. In the field of epidemiology the most reputable testing is carried out through clinical trials. A clinical trial is a prospective study in which humans are exposed to “something” at the discretion of the investigator and followed for an outcome. The biggest problem with clinical trials is that they are conducted on humans and by humans. This is a problem because humans are not machines; we are a very social species who give off any number of non-verbal cues every time we interact. This is a problem in epidemiology because in order to confirm that an outcome of a study is due to the “something” in the study, we have to ensure that those very things that make us human do not influence the outcome. As a consequence, in the field of epidemiology randomized double blind placebo control (RDBPC) studies are considered the “gold standard” of studies.
In an RDBPC study both the subjects participating in the study and the researchers carrying out the study are unaware of when the experimental medication or procedure has been given. In drug tests this means splitting the participants into groups where some of the participants get the active ingredient (or medicine) and the other half are given a placebo (historically a sugar pill made to look like the medicine being tested) and ensuring that the treating physicians are not aware of which of the subjects got the real pill and which got the sugar pill. In the testing of EHS this means that neither the scientist doing the experiment, nor the subject of the test actually know when the subject of the test is being exposed to an EM field. As I will describe later, a lot of testing has been done on EHS using either double-blind or single-blind (the person getting the test does not know) methodologies and as I will discuss the results have been entirely consistent.
As I have mentioned previously at this blog, the statistics we use in science are very sensitive to population size (number of subjects tested). The more subjects tested, the more likely you will be able to identify a small signal or weak effect in a large population. The problem with clinical trials is that each individual study is limited by its budget, its geography and the number of subjects it can test. In a field like EHS there are hundreds of people all over the globe who claim to be particularly sensitive to EM fields. They can’t all be tested at the same time or in the same study so instead the literature is full of small studies of a handful of individuals. In order to take advantage of the strength of population statistics, scientists have developed the tools of the meta-analysis. A meta-analysisor alternatively, a review article, represents an attempt by one or more authors to summarize the current state of the research on a particular topic. In a meta-analysis the authors will often combine the findings from independent studies in order to enlarge the sample size in the hopes of identifying an effect that might have been missed in the individual studies included in the analysis.
This long introduction is intended to save me a lot of time because, like the study of RF in humans, there is a broad literature on EHS and numerous reviews and meta-analyses have been carried out. This is fortunate for me because that means someone else has done all the work for me. So let’s see what the literature says?
In 2005, Rubin, Munshi and Wessley conducted a Systematic Review of Provocation Studies on Electromagnetic Hypersensitivity. Their conclusion:
The symptoms described by “electromagnetic hypersensitivity” sufferers can be severe and are sometimes disabling. However, it has proved difficult to show under blind conditions that exposure to EMF can trigger these symptoms. This suggests that “electromagnetic hypersensitivity” is unrelated to the presence of EMF, although more research into this phenomenon is required.
Also in 2005, Seitz et. al. prepared a paper titled: Electromagnetic hypersensitivity (EHS) and subjective health complaints associated with electromagnetic fields of mobile phone communication—a literature review published between 2000 and 2004. Their conclusion:
based on the limited studies available, there is no valid evidence for an association between impaired well-being and exposure to mobile phone radiation presently. However, the limited quantity and quality of research in this area do not allow to exclude long-term health effects definitely.
In 2007, Oftedal et. al. conducted an RDBPC on mobile phones titled: Mobile phone headache: a double blind, sham-controlled provocation study. The results of that study:
The study gave no evidence that RF fields from mobile phones may cause head pain or discomfort or influence physiological variables. The most likely reason for the symptoms is a nocebo effect.
In 2008, Roosli conducted a systematic review on radiofrequency electromagnetic field exposure and non-specific symptoms of ill health. His conclusion:
This review showed that the large majority of individuals who claims to be able to detect low level RF-EMF are not able to do so under double-blind conditions. If such individuals exist, they represent a small minority and have not been identified yet. The available observational studies do not allow differentiating between biophysical from EMF and nocebo effects.
Between 2005 and 2010 there was a lot of hype on the topic of EHS and as a consequence a lot more research was carried out on the topic. As a consequence, in 2010 Rubin, Nieto-Hernandez and Wessley carried out an updated systematic review of provocation studies on Idiopathic Environmental Intolerance Attributed to Electromagnetic Fields (Formerly ‘Electromagnetic Hypersensitivity’). Their conclusion:
No robust evidence could be found to support this theory. However, the studies included in the review did support the role of the nocebo effect in triggering acute symptoms in IEI-EMF sufferers. Despite the conviction of IEI-EMF sufferers that their symptoms are triggered by exposure to electromagnetic fields, repeated experiments have been unable to replicate this phenomenon under controlled conditions.
Most recently, in 2012 Kwon et.al. did another review titled: EHS subjects do not perceive RF EMF emitted from smart phones better than non-EHS subjects. Their conclusion was like all the rest of the studies:
In conclusion, there was no indication that EHS subjects perceive RF-EMFs better than non-EHS subjects.
As you can see, the academic literature is essentially unanimous. Every case where a supposedly EHS sensitive individual was put under a double-blind procedure the result has been the same: the supposedly sensitive individual was unable to perceive an EM field at a rate higher than would be contributed purely by chance. Don’t even try to ask me about Dr. Havas and her study in the European Journal of Oncology. As described quite clearly at Skeptic North that was not a blind study and was clearly a case of someone not reading the warnings pamphlet that came with her heart rate monitor.
You will notice above that most of the reviews attribute the symptoms of EHS to the “nocebo effect”. I have written about the nocebo effect before at this blog but to summarize. The “nocebo effect” is the opposite of the placebo effect. While the placebo effect has the ability to help you feel better in the absence of any active ingredients, the nocebo effect has the ability to make a person feel poorly in the absence of any active stimuli. As described in this review paper the nocebo effect is not as well studied as the placebo effect but it has been demonstrated to be real.
It is important to recognize a couple things about the nocebo effect. First and foremost, people who “feel bad” or claim to be “sick” via the nocebo effect are neither lying nor are they fakers, rather they are doing one of two things. They are either associating actual symptoms from other causes to the “nocebo” or they are having phantom symptoms based on their minds playing tricks on them. There are any number of celebrated cases where people have be shown that their “illnesses” were all in their minds. By far the most entertaining one is described in this article from Daily Tech. In that case a community complained about EHS symptoms even though the radio towers supposedly causing the symptoms had been turned off during the time the community members claimed they were being made ill by the towers.
So to summarize, as I described in my previous blog posting, untold thousands of studies have been conducted on Wi-Fi and the results are clear, RF is not a serious human health risk. Rather, it is almost a perfect example, a de minimis risk (which I discuss in another blog post). As I discuss, a de minimis risk is a risk that, while it may exist, is too small to be of societal concern. EHS, meanwhile is a real problem but not one related to the presence or absence of RF fields. Instead it is related to the real concerns about Wi-Fi that have been spread by individuals who ignore the mountains of peer-reviewed research, meta-analyses and systematic reviews that demonstrate that Wi-Fi is not a risk to human health. EHS has, quite literally, become the textbook example of the nocebo effect. When a whole community can claim to be made sick by a transmission tower, that has been turned off, you have a classic case of individuals quite literally scaring themselves and their children sick.