ORIGINAL ARTICLE
InternatIonal Journal of radIatIon BIology
2025, Vol. 101, no. 2, 186–204
A mechanistic understanding of human magnetoreception validates the
phenomenon of electromagnetic hypersensitivity (EHS)
Denis L. Henshawa and Alasdair Philipsb
aatmospheric Chemistry group, School of Chemistry, university of Bristol, Bristol, uK; bIndependent Scientist, Brambling, Beeswing, dumfries,
Scotland, uK
ABSTRACT
Background: Human electromagnetic hypersensitivity (EHS) or electrosensitivity (ES) symptoms in
response to anthropogenic electromagnetic fields (EMFs) at levels below current international safety
standards are generally considered to be nocebo effects by conventional medical science. In the
wider field of magnetoreception in biology, our understanding of mechanisms and processes of
magnetic field (MF) interactions is more advanced.
Methods: We consulted a range of publication databases to identify the key advances in
understanding of magnetoreception across the wide animal kingdom of life.
Results: We examined primary MF/EMF sensing and subsequent coupling to the nervous system
and the brain. Magnetite particles in our brains and other tissues can transduce MFs/EMFs, including
at microwave frequencies. The radical pair mechanism (RPM) is accepted as the main basis of the
magnetic compass in birds and other species, acting via cryptochrome protein molecules in the eye.
In some cases, extraordinary sensitivity is observed, several thousand times below that of the
geomagnetic field. Bird compass disorientation by radio frequency (RF) EMFs is known.
Conclusions: Interdisciplinary research has established that all forms of life can respond to MFs.
Research shows that human cryptochromes exhibit magnetosensitivity. Most existing provocation
studies have failed to confirm EHS as an environmental illness. We attribute this to a fundamental
lack of understanding of the mechanisms and processes involved, which have resulted in the design
of inappropriate and inadequate tests. We conclude that future research into EHS needs a quantum
mechanistic approach on the basis of existing biological knowledge of the magnetosensitivity of
living organisms.
Abbreviations: CRY: cryptochrome protein molecules expressed by (italised) CRY or cry genes;
hCRY: human cryptochrome; DECT: Digital Enhanced Cordless Telecommunications (a wireless
Standard); EF(s): electric field(s); ES: electrosensitivity; EHS: electromagnetic hypersensitivity (EHS);
ELF: extremely low frequency magnetic fields, 3 Hz to 3 kHz; ELF-EMFs: extremely low frequency
electric and magnetic fields, 3 Hz to 3 kHz; EMF(s): electric and magnetic field(s) or electromagnetic
field(s) (EMFs can refer only to the magnetic component and used interchangeably with MFs,
reflecting their use in the literature); EMR: electromagnetic radiation; FAD: Flavin adenine dinucleotide;
FADH: Flavin radical (FADH•); GM-field or GMF: geomagnetic field; GM-storms: geomagnetic storms;
HPA: Hypothalamic-pituitary-adrenal axis; ICNIRP: International Commission on Non-Ionizing
Radiation; IEI-EMF: idiopathic environmental intolerance attributed to EMF; ISCA1 (MagR): protein
involved in assembly of iron-sulfur clusters; LAN: Light at night; MF(s): magnetic field(s); PEMF:
pulsed electromagnetic fields; RF EMF(s): radio frequency electromagnetic field(s); RPM: radical pair
mechanism; RP(s): radical pair(s); ROS: reactive oxygen species; rTMS: repetitive transcranial magnetic
stimulation; S-T: singlet – triplet (in RPM mechanism); Trp: Tryptophan; μT: microtesla; nT: nanotesla;
ULF-MFs: ultra-low frequency magnetic fields; VGIC: voltage gated ion channels; VLF: 3–30 kHz; WHO:
World Health Organization
1. Introduction
Human electromagnetic hypersensitivity (EHS) or simply elec-
trosensitivity (ES), known in the past as microwave syndrome,
is a general term describing adverse responses to exposure
to one or more of the features of electromagnetism
(Schliephake 1932). These include time-varying electric fields
(EFs), magnetic fields (MFs), extremely low-frequency electric
and magnetic fields (ELF-EMFs), such as those associated
with power lines, and radio frequency electromagnetic fields
(RF-EMFs) from modern wireless devices, such as mobile
phones, together with their electromagnetic radiation (EMR).
Increasing numbers of people (in the region of 3%) claim
they are sensitive to such man-made time-varying EMFs,
© 2024 the author(s). Published with license by taylor & francis group, llC.
CONTACT denis l. Henshaw d.l.henshaw@bris.ac.uk atmospheric Chemistry group, School of Chemistry, university of Bristol, Bristol, uK
https://doi.org/10.1080/09553002.2024.2435329
this is an open access article distributed under the terms of the Creative Commons attribution license (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited. the terms on which this article has been published allow the posting of the accepted
Manuscript in a repository by the author(s) or with their consent.
ARTICLE HISTORY
received 26 September 2024
revised 8 november 2024
accepted 22 november 2024
KEYWORDS
Magnetic fields; eMf;
electromagnetic hypersensitivity;
eHS; magnetoreception;
cryptochromes
InternatIonal Journal of radIatIon BIology
2025, Vol. 101, no. 2, 186–204
A mechanistic understanding of human magnetoreception validates the
phenomenon of electromagnetic hypersensitivity (EHS)
Denis L. Henshawa and Alasdair Philipsb
aatmospheric Chemistry group, School of Chemistry, university of Bristol, Bristol, uK; bIndependent Scientist, Brambling, Beeswing, dumfries,
Scotland, uK
ABSTRACT
Background: Human electromagnetic hypersensitivity (EHS) or electrosensitivity (ES) symptoms in
response to anthropogenic electromagnetic fields (EMFs) at levels below current international safety
standards are generally considered to be nocebo effects by conventional medical science. In the
wider field of magnetoreception in biology, our understanding of mechanisms and processes of
magnetic field (MF) interactions is more advanced.
Methods: We consulted a range of publication databases to identify the key advances in
understanding of magnetoreception across the wide animal kingdom of life.
Results: We examined primary MF/EMF sensing and subsequent coupling to the nervous system
and the brain. Magnetite particles in our brains and other tissues can transduce MFs/EMFs, including
at microwave frequencies. The radical pair mechanism (RPM) is accepted as the main basis of the
magnetic compass in birds and other species, acting via cryptochrome protein molecules in the eye.
In some cases, extraordinary sensitivity is observed, several thousand times below that of the
geomagnetic field. Bird compass disorientation by radio frequency (RF) EMFs is known.
Conclusions: Interdisciplinary research has established that all forms of life can respond to MFs.
Research shows that human cryptochromes exhibit magnetosensitivity. Most existing provocation
studies have failed to confirm EHS as an environmental illness. We attribute this to a fundamental
lack of understanding of the mechanisms and processes involved, which have resulted in the design
of inappropriate and inadequate tests. We conclude that future research into EHS needs a quantum
mechanistic approach on the basis of existing biological knowledge of the magnetosensitivity of
living organisms.
Abbreviations: CRY: cryptochrome protein molecules expressed by (italised) CRY or cry genes;
hCRY: human cryptochrome; DECT: Digital Enhanced Cordless Telecommunications (a wireless
Standard); EF(s): electric field(s); ES: electrosensitivity; EHS: electromagnetic hypersensitivity (EHS);
ELF: extremely low frequency magnetic fields, 3 Hz to 3 kHz; ELF-EMFs: extremely low frequency
electric and magnetic fields, 3 Hz to 3 kHz; EMF(s): electric and magnetic field(s) or electromagnetic
field(s) (EMFs can refer only to the magnetic component and used interchangeably with MFs,
reflecting their use in the literature); EMR: electromagnetic radiation; FAD: Flavin adenine dinucleotide;
FADH: Flavin radical (FADH•); GM-field or GMF: geomagnetic field; GM-storms: geomagnetic storms;
HPA: Hypothalamic-pituitary-adrenal axis; ICNIRP: International Commission on Non-Ionizing
Radiation; IEI-EMF: idiopathic environmental intolerance attributed to EMF; ISCA1 (MagR): protein
involved in assembly of iron-sulfur clusters; LAN: Light at night; MF(s): magnetic field(s); PEMF:
pulsed electromagnetic fields; RF EMF(s): radio frequency electromagnetic field(s); RPM: radical pair
mechanism; RP(s): radical pair(s); ROS: reactive oxygen species; rTMS: repetitive transcranial magnetic
stimulation; S-T: singlet – triplet (in RPM mechanism); Trp: Tryptophan; μT: microtesla; nT: nanotesla;
ULF-MFs: ultra-low frequency magnetic fields; VGIC: voltage gated ion channels; VLF: 3–30 kHz; WHO:
World Health Organization
1. Introduction
Human electromagnetic hypersensitivity (EHS) or simply elec-
trosensitivity (ES), known in the past as microwave syndrome,
is a general term describing adverse responses to exposure
to one or more of the features of electromagnetism
(Schliephake 1932). These include time-varying electric fields
(EFs), magnetic fields (MFs), extremely low-frequency electric
and magnetic fields (ELF-EMFs), such as those associated
with power lines, and radio frequency electromagnetic fields
(RF-EMFs) from modern wireless devices, such as mobile
phones, together with their electromagnetic radiation (EMR).
Increasing numbers of people (in the region of 3%) claim
they are sensitive to such man-made time-varying EMFs,
© 2024 the author(s). Published with license by taylor & francis group, llC.
CONTACT denis l. Henshaw d.l.henshaw@bris.ac.uk atmospheric Chemistry group, School of Chemistry, university of Bristol, Bristol, uK
https://doi.org/10.1080/09553002.2024.2435329
this is an open access article distributed under the terms of the Creative Commons attribution license (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited. the terms on which this article has been published allow the posting of the accepted
Manuscript in a repository by the author(s) or with their consent.
ARTICLE HISTORY
received 26 September 2024
revised 8 november 2024
accepted 22 november 2024
KEYWORDS
Magnetic fields; eMf;
electromagnetic hypersensitivity;
eHS; magnetoreception;
cryptochromes
INTERNATIONAL JOURNAL OF RADIATION BIOLOGY 187
particularly those at radio frequencies. The reported EHS symp-
toms are wide ranging and include headaches, tinnitus, fatigue,
and skin symptoms, such as prickling, burning sensations, and
rashes. These reactions occur at exposure levels well below the
natural MF strength of the Earth and many orders of magnitude
below current international guidelines for EMF exposure
(Figures 1 and 2, Appendix A) (ICNIRP 2010, 2020; IEEE 2019).
Conventional medical science usually attributes EHS symp-
toms as being psychologically driven by ‘electrophobia’ or the
‘nocebo’ response. The World Health Organization (WHO) cur-
rently states that ‘EHS has no clear diagnostic criteria and that
there is no scientific basis to link EHS symptoms to EMF expo-
sure’. The WHO uses the term idiopathic environmental intoler-
ance attributed to EMF (IEI-EMF) (WHO 2005).
Most subjective provocation studies fail to confirm EHS
as an environmental illness. However, a fundamental lack of
understanding of the mechanisms and processes involved
has resulted in the design of completely inappropriate prov-
ocation tests (Leszczynski 2022) and in unsustainable inter-
pretation of their findings (Bosch-Capblanch et al. 2024).
Interdisciplinary research has established in numerous
species that all forms of life respond to MFs, in some cases
with extraordinary sensitivity. Many species also respond to
EFs, although the body of available research is limited in
comparison to that concerning magnetoreception.
This study investigates whether EHS in people is a syn-
drome that adversely affects human well-being caused by
environmental exposures and if so, by what mechanism(s) it
occurs. We ask the following key questions:
i. How are some living organisms, including humans,
sensitive to EMFs from natural and anthropogenic
sources at levels well below the essentially static geo-
magnetic (GM) field of between 23 and 65 microtesla
(μT) and many orders of magnitude below current
human exposure guidance levels?
ii. What are the biophysical processes by which EMF sig-
nals may be sensed?
iii. Which biological processes account for responses to exposures?
iv. Which of these factors may be related to human elec-
tromagnetic hypersensitivity (EHS)?
By examining in detail the latest systematic reviews of human
epidemiological and experimental research (Röösli et al. 2024;
Figure 1. a contextual guide to dC–10 kHz environmental magnetic fields and their interactions. Illustrative natural and anthropogenic magnetic flux levels are
shown along with the ICnIrP and euroPaeM maximum exposure guidance levels (ICnIrP 2010; Belyaev et al. 2016). Common daily exposures at 50/60 Hz are in
the range of 0.1–10 microteslas. the threshold detection range for other species is discussed in detail in the main article text. Background levels are derived from
a number of sources (Itu-r P.372-16 2022; naSa report Cr-166661 1981; naSa report SP-8017 1969).
particularly those at radio frequencies. The reported EHS symp-
toms are wide ranging and include headaches, tinnitus, fatigue,
and skin symptoms, such as prickling, burning sensations, and
rashes. These reactions occur at exposure levels well below the
natural MF strength of the Earth and many orders of magnitude
below current international guidelines for EMF exposure
(Figures 1 and 2, Appendix A) (ICNIRP 2010, 2020; IEEE 2019).
Conventional medical science usually attributes EHS symp-
toms as being psychologically driven by ‘electrophobia’ or the
‘nocebo’ response. The World Health Organization (WHO) cur-
rently states that ‘EHS has no clear diagnostic criteria and that
there is no scientific basis to link EHS symptoms to EMF expo-
sure’. The WHO uses the term idiopathic environmental intoler-
ance attributed to EMF (IEI-EMF) (WHO 2005).
Most subjective provocation studies fail to confirm EHS
as an environmental illness. However, a fundamental lack of
understanding of the mechanisms and processes involved
has resulted in the design of completely inappropriate prov-
ocation tests (Leszczynski 2022) and in unsustainable inter-
pretation of their findings (Bosch-Capblanch et al. 2024).
Interdisciplinary research has established in numerous
species that all forms of life respond to MFs, in some cases
with extraordinary sensitivity. Many species also respond to
EFs, although the body of available research is limited in
comparison to that concerning magnetoreception.
This study investigates whether EHS in people is a syn-
drome that adversely affects human well-being caused by
environmental exposures and if so, by what mechanism(s) it
occurs. We ask the following key questions:
i. How are some living organisms, including humans,
sensitive to EMFs from natural and anthropogenic
sources at levels well below the essentially static geo-
magnetic (GM) field of between 23 and 65 microtesla
(μT) and many orders of magnitude below current
human exposure guidance levels?
ii. What are the biophysical processes by which EMF sig-
nals may be sensed?
iii. Which biological processes account for responses to exposures?
iv. Which of these factors may be related to human elec-
tromagnetic hypersensitivity (EHS)?
By examining in detail the latest systematic reviews of human
epidemiological and experimental research (Röösli et al. 2024;
Figure 1. a contextual guide to dC–10 kHz environmental magnetic fields and their interactions. Illustrative natural and anthropogenic magnetic flux levels are
shown along with the ICnIrP and euroPaeM maximum exposure guidance levels (ICnIrP 2010; Belyaev et al. 2016). Common daily exposures at 50/60 Hz are in
the range of 0.1–10 microteslas. the threshold detection range for other species is discussed in detail in the main article text. Background levels are derived from
a number of sources (Itu-r P.372-16 2022; naSa report Cr-166661 1981; naSa report SP-8017 1969).