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expert reaction to study looking at weak radiofrequency electromagnetic fields and the circadian clock of the German cockroach

A study, published in the Journal of the Royal Society Interface, reports that electromagnetic fields have an impact on the internal clocks of German cockroaches.


Dr John O’Neill, Research Group Leader, MRC Laboratory of Molecular Biology, said:

“I’m quite surprised this paper made it through peer review.  The central claim is that “We observed that static magnetic fields slow down the cockroach clock rhythm under dim UV light”.  Looking at their analysis results however, the authors in fact observe that constant UV and green light slow down cockroach circadian rhythms, whereas magnetic fields appear to essentially have no effect on them.

“Some of the different conditions achieve statistical significance, but the effect size is small and the data very noisy because they do not appear to be using a very robust assay, i.e., many (up to 50%) of cockroaches have been excluded from analysis due to not showing any circadian rhythms in the first place.  The quality of the cockroach circadian rhythms is not something the reader can assess for themselves however, as no examples of cockroach circadian rhythms under the various experimental conditions are shown.

“Due to poor experimental design (insufficient controls) and inappropriate statistical tests (they needed to perform 2-way analysis of variance for light intensity vs magnetic field intensity, then post-test), it is difficult to be absolutely confident that magnetic fields have no effect on the cockroach clock, especially since no raw or even processed data is shown.  On the basis of this paper however, I think that German cockroaches can feel quite relaxed that there is no compelling evidence that magnetic fields affect their circadian rhythms.  Humans should be even less worried about magnetic fields affecting their circadian rhythms, since we are never subject to constant UV light that was used in these experiments, and particularly since our circadian clock is adjusted each day, by the times we see light and when we eat, so that it runs with a period of exactly 24 hours.”


Dr Richard Findlay, Chair of the EMF & Optical Radiation Committee, Society for Radiological Protection, said:

“In short, it’s not great research.  They state that radiofrequency fields have been shown to have effects on animal ‘compass orientation’, i.e. navigation.  This is not correct.  Field effects have been shown to affect navigation in birds for exposure to static and low frequency fields, but not at radiofrequencies (e.g. Wi-Fi, TV, radio).

“They claim their research showed that radiofrequency fields slowed down the circadian clock of a cockroach.  Firstly, they are barely into the radiofrequency spectrum (they researched up to 10 MHz).  Also, their claim is contrary to a number of previous studies that have shown no significant effects of fields on circadian rhythms (including the excellent work by Contalbrigo et al 2009 on rats1).

“They propose that weak, potentially flawed, evidence of RF effects on cockroaches opens the possibility of radiofrequency fields affecting ‘many clock-dependent events in living systems.’  This is speculative at best.  For example, returning to the subject of navigation, magnetite crystals in a bird’s beak provide positional information – hence there is a potential mechanism for bird navigation.  However, just because magnetite has been found in humans as well gives no evidence for a human ‘lost navigational sense’.

“I don’t think that members of the public should be overly concerned by this research.”

1 Contalbrigo L, Stelletta C, Falcioni L, Casella S, Piccione G, Soffritti M, Morgante M. Effects of different electromagnetic fields on circadian rhythms of some haematochemical parameters in rats. Biomed Environ Sci. 2009 Aug;22(4):348-53


‘Weak radiofrequency fields affect the insect circadian clock’ by Premysl Bartos et al. was published in the Journal of the Royal Society Interface at 00:01 UK time on Wednesday 18 September 2019. 

DOI: 10.1098/rsif.2019.0285


Declared interests

Dr John O’Neill: “None.”

Dr Richard Findlay: “I am currently the chair of the Society for Radiological Protection’s EMF & Optical Radiation Committee, as well as director of the consultancy EMFcomp Limited.  I don’t believe I have a conflict of interest, I have no investments in any telecoms companies.  I have previously carried out work for commercial organisations, but have also carried out work for universities, public bodies such as PHE and people considered ‘activists’.  I believe I’m independent, coming from a scientific point of view.  The Society for Radiological Protection is a registered charity and pretty independent, so I don’t think we have any conflict of interest.”

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