To: The Editors of PLOS ONE February 19, 2016
cc: ICNIRP, Dr. Eric van Rongen
WHO, Dr. Emilie van Deventer

Dear Editors,

Black et al. (PLOS ONE, January 13, 2016) reported that radio-frequency electromagnetic fields (RF EMFs) at intensities below existing RF exposure limits can elicit neuropathic pain in a rat tibial neuroma transposition model. They conclude that patient reports of RF EMF pain would thus be substantiated in the case of peripheral nerve injury. Unfortunately, the article is fundamentally flawed; inadequate methodology and many inconsistencies undermine the main conclusions of the paper. As this paper generates confusion and spreads misinformation concerning the established physiological effects of non-ionising radiation at the existing exposure limits, we feel obliged to comment on the validity of the study.

Below, we will list some of the major errors and inconsistencies in the paper.

1) Proper dosimetry of the system is completely missing.
2) In in-vivo studies, the numerical exposure assessment is a fundamental requirement, which is missing.
3) Dose range information for the moving animals has to be reported.
4) Properly controlled and documented environmental conditions are reported.
5) The RF power density is reported to be 756 mW/m2 in Introduction (page 2) and in Section “RF EMF stimulation”, while in the “Results” section (page 3), in the caption of Fig. 1 and in the supporting information, it is reported to be a million times larger, i.e., 756 mW/mm2. The latter value, 756 kW/m2, is about 500 times stronger than sunlight.
6) The reported SAR value (specific absorption rate) is 0.36 W/kg. An easy calculation shows that a 10-minute exposure at this SAR would result at a temperature rise of only about 70 mK (0.07 °C). This contradicts the measured temperature increase of 2.1 °C in the animal. Even if there were no temperature regulation in the rat (blood flow, thermal conduction and infrared radiation), the SAR required for this temperature increase would need to be 30-fold higher than the reported value.

The paper by Black et al. does not meet the requirements of good scientific practice. Therefore, we strongly suggest that the paper be withdrawn from PLOS ONE.

Tapio Ala-Nissilä, Professor of Physics
Risto Ilmoniemi, Professor of Biomedical Engineering
Jafar Keshvari, Adjunct Professor of Bio-electromagnetics

Aalto University, Espoo, Finland