The 'Essex study' (Eltiti S, Wallace D, Ridgewell A, Zougkou K, Russo R, Sepulveda F, et al. Does short-term exposure to mobile phone base station signals increase symptoms in individuals who report sensitivity to electromagnetic fields? A double-blind randomized provocation study. Environ Health Perspect. 2007a;115:679–683), funded by Mobile Telecommunications and Health Research (MTHR), UK in 2007 has created huge controversy in the ES world since its publiciation.

The aim of the study (according to the author) was 'to investigate whether short-term exposure to GSM and UMTS base station signals affects attention, memory and physiological components in 44 electrosensitive and 44 control participants.
The participants performed four testing sessions (at least one week apart from each other): a) baseline measurement before exposure, b) exposure to GSM, c) exposure to UMTS and d) sham exposure.
Cognitive functioning was measured using a digit symbol substitution test (given a table displaying the correspondence between pairs of digits [from 1 to 9] and symbols, subjects have to fill in blank squares with the symbol that is paired with the digit displayed above the square; subjects have to fill in as many squares as possible in 90 sec), a digit span test and mental arithmetic tasks (5 sec to complete addition and subtraction equations; 187 trials).......'
Main outcome of study (according to author) was that...
'... the groups did not differ significantly in their cognitive performance on the baseline measurements. Cognitive functioning was not affected by short-term exposure to either GSM or UMTS signals in control participants and electrosensitive participants.
Electrosensitive participants had a significantly higher level of skin conductance than control participants while performing the cognitive tasks (independent of exposure condition). Blood volume pulse and heart rate did not differ between the two groups nor were they affected by the type of exposure.'

However, the methods used in the study have been widely criticised.

Dr Andrew Goldsworthy, one of the study's critics, has now raised a further question:

I would like to query the definition of electrosensitivity as used in the Essex study by Eltiti et al. According to one of the participants, who asked to see the raw data (which he was perfectly entitled to under the Freedom of Information Act) the volunteers were only classified as electrosensitive if they could tell correctly when the signal was both turned on and turned off. Apparently, about 70% of them could tell when it was switched on but their ability to tell when it was switched off was no better than chance.

This is what I would expect for a traumatic experience. For example, if you hit your thumb with a hammer, the pain persists for a while, so that, although you know instantly when you hit it, you cannot say precisely when it stops hurting. If this is correct, this 70% should have been classified as electrosensitive and not as non-sensitive.

If this is what happened it completely alters the outcome of the whole study and the paper may need to be retracted. Their argument is so illogical as to be unbelievable, since exactly the same logic could be used to argue that hitting your thumb with a hammer cannot possibly hurt.

ES-UK would like to follow up on Dr Goldsworthy's suggestion but needs to contact as many as possible of the Essex participants in order to do so.

If you took part in the trial, even if you did not complete it, or know anyone who did, please contact ES-UK on 0845 643 9748 or by email at contact ES-UK.

More articles on mobile phones and masts

First Published in 2007 update Sepember 2009

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