Electrosensitivity

A blogger writes,

The reason I am writing to you has to do with a recent paper (which has received a lot of press coverage) on ‘electrosensitivity’ – in simple English, whether mobile phone signals can be detected by humans, and whether exposure causes harm. (the full title of the paper is ‘Does Short-Term Exposure to Mobile Phone Base Station Signals Increase Symptoms in Individuals who Report Sensitivity to Electromagnetic Fields? A Double-Blind Randomised Provocation Study’, and you can find it here – free access.)

I find the authors’ conclusions against electrosensitivity being detectable/harmful as unwarranted given the data, and their analysis in many cases is questionable. Read this for example:

58 self-reported sensitive and 121 control individuals came in for testing. Of these, 56 sensitive and 120 controls completed the open provocation test, while 44 sensitive and 115 controls (114 excluding one observation that was left out due to a ‘technical error’) also completed the double-blind tests.

Participants made on/off judgements during both the 5 minute and 50 minute double-blind exposures. Only 2 sensitive and 5 control participants were able to correctly identify all 6 on/off judgements.

If I did the maths correctly, the probability of 2 or more individuals out of 44 getting 6 binary choices right by chance is 26%, while for 5 or more out of 114 to be right this probability is a mere 3.4%.

And there’s also this:

For the three quick double-blind tests (in session 1) and the three 50-minute double-blind tests (sessions 2 to 4) participants judged whether the base station was on or off and indicated how confident they were of this judgement using a scale from 0 ‘not at all sure’ to 100 ‘completely sure’. The ROC curve method was chosen to analyze the responses as this takes into account not only accurate (hits) and inaccurate responses (false alarms), but also how confident participants are of their judgments.

Sensitive participants had an accuracy rate of 55.2% during the 5 minute tests (d ́=-0.08, sensitivity=66.4%, specificity=32.7%) and 59.8% during the 50 minute tests (d ́=0.20, sensitivity=69.3%, specificity=40.9% ). The control group had an accuracy rate of 51·4% during the 5 minute tests (d ́=0.10, sensitivity=51.7%, specificity=50.8%) and 50.1% during the 50 minute tests (d ́=0.06, sensitivity=48.0%, specificity=54.3%). For each group the 95% confidence interval on the ROC curves include the diagonal axis, implying that participant performance for each group did not differ from chance.

Personally, I never thought there was anything to ‘electrosensitivity’ – but contrary to the authors’ interpretations of the data I believe their findings actually constitute cause for worry (or at least more research). At the risk of coming across as too harsh, the whole paper strikes me as being unbalanced to say the least; and while I am not familiar with some of the statistical techniques employed, the analysis seems to be somewhat sloppy.

I don’t really have anything to say here–my only experience studying electromagnetic fields is in Section 21.8 of our new book. It was pretty unpleasant to try to read the linked paper–I’m glad I didn’t have to review it!

5 thoughts on “Electrosensitivity

  1. Bob O'H, I think you missed the point of the post: the blogger says that the authors of the study characterized it as not finding any deleterious effects, but I think he (the blogger) is saying that if you look at the data it looks like they're wrong and something bad is happening (or at least might be).

    As for me, I know I (like Jim) am quite sensitive to EM radiation in the range of 400 to 700 nanometers, especially when my eyes are open.

  2. Anonymous – that was indeed the point I was making, although I specifically mentioned the authors' interpretation of the results regarding ability to detect the signal (not harm). There are three main points:

    1. With regards to harm – finding a large effect that is not statistically significant at the 2.5% level (are the authors seriously implying that radiation is actually good for some people?) does not mean that the effect is not there – especially when your sample is small, and there was (likely highly non-random) attrition.

    2. Asking the subjects of the study to quantify 'how certain they are their prediction is right', and then using these estimates (after transforming them!) to assess whether they can detect the signals seems to me to be a silly thing to do, on so many levels.

    3. When you observe something, the probability of that something happening by chance is 3.4%, and your conclusion is that the results are consistent with a random outcome because the probability is 'just' 96.6% that it isn't – well, that should get a reader thinking.

    As Andrew said, the paper makes for a very unpleasant read, and it's actually fairly difficult at times to exactly understand what the authors did – I will keep struggling with it for a bit more, and will be posting my thoughts in full on my blog soon.

  3. I believe the above study has problems in how the research was conducted. To recognize when the EMS begins or ends might be inaccurate. My experience with EMS is as follows: I don't always feel the effects of the EMS immediately, but the longer I sit at the computer the worse it gets and the longer it takes for the symptoms to subside, up to a few days. My problem with EMS is severe skin irritation. There is no visible sign on my skin but it prickles as though I have spent the day installing fiberglass insulation. The microwave and CFL's also affect me the same way. So for me to be exposed to EMS for 5 minutes may not be recognized until later.
    Gary

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