20

Until recently, I have only heard about studies proving electrosensitivity being entirely a nocebo effect.

Now I just found out about a study:

Electromagnetic Field Sensitivity, William J. Real et al., 1991.

I have not myself read the study, but it claims it was a double blind test containing 16 subjects. 100% of the ones that were allergic responded to the electricity.

Are there any attempts to repeat the same study? Does it have any known critisism?  

26

Where you have a number of studies with conflicting results, it is time for a meta-analysis, which carefully combines a number of studies, to get a more statistically powerful sample.

This study was cited by a meta-analysis:

G. James Rubin, Jayati Das Munshi and Simon Wessely, Electromagnetic Hypersensitivity: A Systematic Review of Provocation Studies Psychosomatic Medicine 67:224-232 (2005), doi: 10.1097/​01.psy.0000155664.13300.64

Their abstract covers the territory very well:

Objectives: The objectives of this study were to assess whether people who report hypersensitivity to weak electromagnetic fields (EMFs) are better at detecting EMF under blind or double-blind conditions than nonhypersensitive individuals, and to test whether they respond to the presence of EMF with increased symptom reporting.

Perfect - that seems to be directly aimed at your question.

Results: Thirty-one experiments testing 725 "electromagnetically hypersensitive" participants were identified. Twenty-four of these found no evidence to support the existence of a biophysical hypersensitivity, whereas 7 reported some supporting evidence. For 2 of these 7, the same research groups subsequently tried and failed to replicate their findings. In 3 more, the positive results appear to be statistical artefacts. The final 2 studies gave mutually incompatible results. Our metaanalyses found no evidence of an improved ability to detect EMF in "hypersensitive" participants.

I'm not sure where the Real et al study fit in here, but if it gave a positive result, it was in the minority. (Although, it should also be considered by its sample size and methodological strength, which aren't covered by the numbers here.)

Conclusions: 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.

So, nocebo appears to be a plausible explanation.

-1

I found a recent study (2011): Electromagnetic Hypersensitivity: Evidence for a Novel Neurological Syndrome (McCarty, Carrubba, Chesson, Frilot, Gonzalez-Toledo & Marino).

To my untrained eyes, it looks very serious (double-blind, no conflict of interests, controlling for somatization, etc.). It also mentions the meta-analysis from 2005.

Some conclusions:

The subject developed symptoms in association with the presentation of a pulsed electric field significantly (p < .05) more often than could reasonably be explained on the basis of chance

And:

Our aim here was to concentrate on the previously unaddressed question whether acute exposure to weak EMF could produce real but not precisely predictable somatic effects mediated by nonpsychological processes. Within the limitations of the study, we concluded that we demonstrated the neurological syndrome in the subject we studied.

So, at this point, it seems there's a possibility that some people (3-5% of the population, maybe) are actually hypersensitive to electromagnetic fields and that cell towers, mobile phones, wireless access points, etc. might be a real problem (although more research is still needed).

  • 3
    While it would make sense for this study to be included in any future meta-analyses, the results of this study are rather weak. One person was tested. The p-values were never stated, and were only marginally significant (e.g. p<0.05), and then only in SOME of the tests. NOTE: I tried repeating the analysis of Experiment 3, using a two-tailed Chi Squared test (Fisher's Exact, and Chi-Squared with and without Yates correction). It does NOT appear to be significant. I'd appreciate it if someone more experienced at this would give it a go. – Oddthinking Oct 7 '12 at 10:11
  • "One person was tested." But with the proper methodology, one person would be enough to prove that electromagnetic hypersensitivity might be a real thing, right? Of course, that still wouldn't mean most people complaining about cell towers, etc. are not suffering from a nocebo effect. – Olivier Bruchez Oct 7 '12 at 19:53
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    Yes. Having only one person tested doesn't provide support for the "3-5% of the population" claim. It also increases the risk of conspiracy - i.e. that a hoax is being perpetrated against scientists unable to detect magic tricks. – Oddthinking Oct 8 '12 at 0:52
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    According to the paper itself "there was no requirement that the same symptom must reoccur when the EMF provocation was repeated" which sounds like an experiment designed to allow random effects to be counted. That and the fact there was only a single subject is damning for the experimental quality of the paper. – matt_black Oct 6 '13 at 13:39
  • I forgot to mention: I raised this over at Stats.SE and they seemed to agree the results are very weak. – Oddthinking May 2 '14 at 6:52

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