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Use of mobile phones and risk of brain tumours: update of Danish cohort study

BMJ 2011; 343 doi: (Published 20 October 2011) Cite this as: BMJ 2011;343:d6387

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Mobile phone radiation could be detected by the human brain.

Re: Use of mobile phones and risk of brain tumours: update of Danish
cohort study. Frei, et al. 343:doi:10.1136/bmj.d6387

In their introduction, Frei et al. [1] state: "So far, the mechanism
of potential non-thermal interaction between radio frequency
electromagnetic fields (EMFs) and living systems is unknown." This
statement does not concur with scientific knowledge.

Mobile phones typically have three types of EMF emissions associated
with them: in the GSM system a 900 MHz radio frequency, a 217 Hz pulsing
signal and an extremely low frequency magnetic field (ELF MF) associated
with the battery [2]. The ELF component has so far been ignored in all
epidemiological studies of mobile phone exposure and cancer. During phone
use, this ELF component exposures the whole brain to MFs ranging from a
few to tens of micro-tesla, above the intensity of power frequency ELF-MFs
that have been repeatedly associated with increased risk of brain tumours
in adults [3,4].

Animals across a wide range of species detect small changes in the
Earth's magnetic field, which is exploited for navigation. Homing pigeons
and newts are estimated to have a limiting magnetic detection sensitivity
of 0.01 micro-tesla and magnetic compass sensitivity below 0.2 degrees
[5]. Two types of magneto-receptor are widely discussed [6, 7], one based
on structures of magnetite particles, the other on a chemical compass
exploiting the radical pair mechanism, RPM in which low intensity MFs
alter the quantum spin state of the unpaired electrons in a free radical
pair. Both mechanisms are relevant to the interaction of mobile phone EMFs
in humans.

Thus, the human brain contains magnetite particles [8], some up to
600 nm in size, capable at body temperature of transducing both low
intensity ELF MFs and microwave EMFs [9, 10].

The RPM forms part of basic spin chemistry [11] in which low
intensity MFs can increase the lifetime of free radical pairs by singlet-
to-triplet, S-T, interconversion of their quantum spin states. The
increased lifetime of free radicals allows increased availability to cause
biological damage, for example to DNA. The energy levels involved are some
ten million times below thermal energy, the action being of the nature of
a quantum mechanical switch.

There is compelling evidence that the avian magnetic compass utilises
the RPM acting in the eye on cryptochromes protein molecules [12], best
known for their function in controlling circadian rhythms. The magnetic
compass can be disrupted by radio frequency fields. In the American
cockroach disruption was seen by 1.2 MHz fields at 0.018 micro-telsa [13],
well below current ICNIRP public exposure guidelines [14]. There is
evidence that human cryptochromes are magneto-sensitive [15] and that ELF
MFs disrupt circadian rhythms in man [16].

IARC has recently classifieds radio frequency EMFs as a 2B possible
carcinogen, based on the main body of case-control epidemiology and
accumulated exposure to mobile phone radiation and increased risk of brain
tumours in heavy users [17]. Research into the possible health effects of
mobile phones should now concentrate on designing epidemiological studies
with more relevant exposure metrics and at investigating further the
mechanistic pathways by which exposure may increase the risk of brain
tumours and other adverse health outcomes. Meanwhile, precaution against
undue exposure is warranted and should be encouraged.


1. Frei P, Poulsen AH, Olsen JH, Schuz J. 2011 Use of mobile phones
and risk of brain tumours:update of Danish cohort study. BMJ
2011;343:d6387 doi: 10.1136/bmj.d6387

2. Tuor M, Ebert S, Schuderer J, Kuster N. Assessment of ELF Exposure
from GSM Handsets and Development of an Optimized RF/ELF Exposure Setup
for Studies of Human Volunteers. Foundation for Research on Information
Technologies in Society, Report: BAG Reg. No. 2.23.02.-18/02.001778,
Zurich, January 2005.

3. O'Carroll MJ, Henshaw DL. 2008. Aggregating epidemiological
evidence: comparing two seminal EMF reviews. Risk Anal 28:225-234.

4. Kheifets L, Monroe J, Vergara X, Mezei G, Afifi AA. 2008.
Occupational electromagnetic fields and leukaemia and brain cancer: An
update to two meta-analyses. JOEM 50:677-688.

5. Gould JL. 2010 Animal Navigation: Longitude at Last. Curr Biol
21;R226 DOI: 10.1016/j.cub.2011.01.063

6. Lohmann KJ. 2010. Magnetic-field perception. Nature 464:1140-1142.

7. Phillips JB, Muheim R, Jorge PE. 2110. A behavioral perspective on
the biophysics of the light-dependent magnetic compass: a link between
directional and spatial perception? J Exp Biol 213, 3247-3255.

8. Kirschvink JL, Kobayashi-Kirschvink A, Woodford BJ. 1992.
Magnetite biomineralization in the human brain. PNAS USA 89:7683-7687.

9. Vanderstraeten J, Gillis P. 2010. Theoretical Evaluation of
Magnetoreception of Power-Frequency Fields. Bioelectromagnetics 31:371-

10. Kirschvink JL. 1996. Microwave Absorption by Magnetite: A
Possible Mechanism for Coupling Nonthermal Levels of Radiation to
Biological Systems. Bioelectromagnetics 17:187-194.

11. Brocklehurst R, McLauchlan KA 1996. Free radical mechanism for
the effects of environmental electromagnetic fields on biological systems.
Int J Radiat Biol. 69:3-34.

12. Ritz T, Wiltschko R, Hore PJ, Rodgers CT, Stapput K, Thalau P,
Timmel CR, Wiltschko W. 2009. Magnetic compass of birds is based on a
molecule with optimal directional sensitivity. Biophys J. 96, 3451-3457.
(doi:10. 1016/j.bpj.2008.11.072)

13. V?cha M, P??ov? T,and Mark?ta Kv??alov? M. 2009. Radio frequency
magnetic fields disrupt magnetoreception in American cockroach. J Exp
Biol. 212;3473-3477.

14. ICNIRP Guidelines 1998: International Commission on Non-Ionizing
Radiation Protection: Guidelines for limiting exposure to time-varying
electric, magnetic and electromagnetic field (up to 300 GHz). Health Phys

15. Foley LE, Gegear1 RJ, Reppert SM. 2011. Human cryptochrome
exhibits light-dependent magnetosensitivity. Nature Comm. DOI:

16. Henshaw DL, Reiter RJ. 2005. Do magnetic fields cause increased
risk of childhood leukaemia via melatonin disruption? Bioelectromagnetics
Suppl 7:S86-S97.

17. WHO IARC Monograph Working Group, Carcinogenicity of
radiofrequency electromagnetic fields. Lancet Oncol. 2011 Jul;12(7):624-6.

Competing interests: No competing interests

23 October 2011
Denis L Henshaw
Emeritus Professor of Human Radiation Effects
School of Chemistry University of Bristol Cantocks Close, Bristol, BS8 1TS