Analgetic effects of non-thermal GSM-1900 radiofrequency electromagnetic fields in the land snail Helix pomatia.

Abstract

To investigate whether mobile phone radiation might affect snail nociception, employing radiofrequency (RF) electromagnetic fields (EMF) which, to our knowledge, have hitherto not been studied in a snail model. Exposure to extremely low frequency (ELF) magnetic fields has however been shown to significantly affect nociceptive responses.
In the present study, we exposed 29 land snails of the strain Helix pomatia to global system for mobile communications (GSM) EMF at 1900 MHz at the non-thermal level 48 mW/kg for 1 hour each and 29 snails were sham controls. The experiments took place during the onset of summer, with all snails being well out of hibernation. Before and after GSM or sham exposure, the snails were subjected to thermal pain by being placed on a hot plate. The reaction time for retraction from the hot plate was measured by two blinded observers.
Comparing the reaction pattern of each snail before and after exposure, the GSM-exposed snails were less sensitive to thermal pain as compared to the sham controls, indicating that RF exposure induces a significant analgesia (Mann-Whitney p < 0.001).
This study might support earlier findings, describing beneficial effects of EMF exposure upon nociception.

Full text

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International Journal of Radiation Biology, March 2012; 88(3): 245–252
© 2012 Informa UK, Ltd.
ISSN 0955-3002 print / ISSN 1362-3095 online
DOI: 10.3109/09553002.2012.644257
Analgetic eff ects of non-thermal GSM-1900 radiofrequency
electromagnetic fi elds in the land snail Helix pomatia
Henrietta Nittby 1 , Mehri Kaviani Moghadam 1 , Wenjun Sun 1,4 , Lars Malmgren 3 , Jacob Eberhardt 2 ,
Bertil R. Persson 2 & Leif G. Salford 1
Departments of 1 Neurosurgery , 2 Medical Radiation Physics , and 3 the MAX Lab , The Rausing Laboratory , Lund University ,
Lund , Sweden , and 4 Bioelectromagnetics Lab , Zhejiang University School of Medicine , Hangzhou , China
Correspondence: Dr Henrietta Nittby, Institute of Clinical Sciences, Department of Neurosurgery, Lund University Hospital, SUS, SE-22185 Lund, Sweden.
E-mail: Henrietta.Nittby@med.lu.se
(Received 15 June 2011 ; revised 2 November 2011 ; accepted 17 November 2011 )
Introduction
During recent years, an increasing number of scientifi c
reports have shown signifi cant, but often weak eff ects of
electromagnetic fi elds (EMF) on cells in vitro, experimental
animals and humans (for reference, see Hyland 2000 and
Salford et al. 2008).
Since 1988 our group has studied the eff ects of non-
thermal radiofrequency (RF) EMF upon the rat mamma-
lian blood-brain barrier (BBB) (Salford et al. 1992, 1993,
1994, 2001, Persson et al. 1997, Eberhardt et al. 2008, Nittby
et al. 2009). Th ese have been shown to cause signifi cantly
increased leakage of the rat blood albumin past the BBB of
exposed rats, at specifi c absorbed power levels of 0.0001 – 1
W/kg, in a total series of about 2,000 animals. One remark-
able observation is that the lowest specifi c absorbed power
levels, with whole-body average specifi c absorbed power
below 0.01 W/kg, give rise to the most pronounced albumin
leakage (Persson et al. 1997, Salford et al. 2007).
EMF have been shown to have a variety of biological
eff ects (Giuliani and Soff ritti 2010). Extremely low fre-
quency (ELF) exposure has been shown to induce many
diff erent types of cellular changes, prompting the question
whether it might induce carcinogenesis. Other studies, on
the other hand, have not shown any signifi cant variations
in the cellular parameters, including micronucleus forma-
tions, lipid peroxidation, antioxidant enzyme changes and
protein transcription (for review, see Santini et al. 2009).
From a meta-analysis of data from in vitro and short-term
animal studies of ELF eff ects upon carcinogenesis, it was
concluded that the majority of the studies showed positive
correlation between ELF exposure and biological eff ects
(Juutilainen et al. 2006). However, most studies used mag-
netic fi elds of 100 μ T or higher. Also, various eff ects of ELF
have been described in nerve cells and immune cells, still
leaving the fi eld open as to whether the ELF would present
a risk factor for higher organisms such as humans (Santini
et al. 2009). Regarding RF eff ects, there are studies show-
ing signs of increased carcinogenesis, as well as no eff ects
(Vijayalaxmi and Prihoda 2009). In a meta-analysis includ-
ing 63 publications, from 1990 – 2005, on genotoxic eff ects on
cells in vitro or in vivo, it was concluded that the diff erence
between RF-radiation-exposed and sham-/unexposed con-
trols was small with very few exceptions (Vijayalaxmi and
Prihoda 2009).
Given the many eff ects of ELF upon biology, some of
these have also been utilized for medical and therapeutic
purposes. For example, medical applications of ELF mag-
netic fi elds are used to integrate osteochondral autografts
(Benazzo et al. 2008), healing of bone-fractures and treatment
245
Abstract
Purpose : To investigate whether mobile phone radiation
might aff ect snail nociception, employing radiofrequency (RF)
electromagnetic fi elds (EMF) which, to our knowledge, have
hitherto not been studied in a snail model. Exposure to extremely
low frequency (ELF) magnetic fi elds has however been shown to
signifi cantly aff ect nociceptive responses.
Materials and methods : In the present study, we exposed 29 land
snails of the strain Helix pomatia to global system for mobile
communications (GSM) EMF at 1900 MHz at the non-thermal
level 48 mW/kg for 1 hour each and 29 snails were sham controls.
The experiments took place during the onset of summer, with
all snails being well out of hibernation. Before and after GSM
or sham exposure, the snails were subjected to thermal pain by
being placed on a hot plate. The reaction time for retraction from
the hot plate was measured by two blinded observers.
Results : Comparing the reaction pattern of each snail before
and after exposure, the GSM-exposed snails were less sensitive
to thermal pain as compared to the sham controls, indicating
that RF exposure induces a signifi cant analgesia (Mann-Whitney
p ? ? 0.001).
Conclusion : This study might support earlier fi ndings, describing
benefi cial eff ects of EMF exposure upon nociception.
Keywords: GSM , Helix pomatia , nociception
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246 H. Nittby et al .
of bone-related diseases such as osteoporosis (for review see
Funk and Monsees 2006). Time-varying ELF magnetic fi elds
in the range of 1 – 100 Hz at the fracture site are supposed to
be among the most eff ective in medical measures used today
(Pilla 2002, Funk and Monsees 2006) and interestingly, physi-
ological eff ects have been suggested to be induced at certain
parametric windows, such as ELF fi elds of 8 – 60 Hz and low
amplitudes (Gartzke and Lange 2002). Recent studies have
shown that specially designed pulsed ELF magnetic fi elds
(PEMF) induce analgesia in humans after acute exposure
(Robertson et al. 2010) but also in chronic-pain conditions
after 2 ? 40-min exposures repeated daily for 7 days (Th omas
et al. 2007).
In earlier studies in London, Ontario, Canada, on the
nociception of rodents, the animals were placed on a
metal surface at a standard temperature (50 ° C for mice)
and the time taken to respond to the heat stimulus with
a stereotypic adverse withdrawal was recorded. The mag-
netic resonance imaging (MRI) machine used a static
magnetic field of 0.15 T and an RF field of 6.37 MHz
(approximated SAR-value would be 0.05 W/kg for the full
22 slice sequence given a radius of the exposed subject of
0.02 m). The exposure to a pulsed time-varying magnetic
field of the type used during an MRI procedure resulted
in an enhanced basal nocturnal sensitivity and reduced
levels of morphine induced analgesia in mice (Prato et al.
1987). Furthermore, mice exposed to the RF part of the
MRI signal demonstrated an enhanced basal nocturnal
sensitivity, whereas the morphine induced analgesia was
still intact as compared to saline-injected controls.
Further studies with the land snail Cepaea nemoralis
showed that continuous ELF fi elds (at 60 Hz, 100 μ T) expo-
sure induced hyperalgesia in a duration-dependent manner
(at exposure times ranging from 0.5 – 120 hours) (Kavaliers
et al. 1990). However, by changing the characteristics of the
ELF to a 15-min PEMF exposure, instead a state of analge-
sia was increased in C. nemoralis , both in untreated snails
and after enkephaline inhibitor induced opioid analgesia
(Th omas et al. 1997).
Taken together, there is a solid evidence for eff ects of ELF
magnetic fi elds upon nociception (Del Seppia et al. 2007).
ELF magnetic fi elds have also been shown to have a thera-
peutic benefi t by increasing pain thresholds not only in ani-
mals, but also in humans (Shupak et al. 2003).
Th e EMF in mobile phone radiation are quite diff er-
ent from the ELF fi elds described above. For global system
for mobile communications (GSM) mobile phones, the
frequency is higher (915 MHz or 1800/1900MHz) and the
modulation is diff erent (pulse modulated fi elds at 217 Hz).
To our knowledge, hitherto no study has investigated the
eff ect of mobile phone radiation upon the pain perception in
snails in vivo. Th us we performed the present study, inves-
tigating whether GSM-1900 (global system for mobile com-
munications at 1900 MHz) EMF might aff ect the nociceptive
response in the land snail H. pomatia , using this specifi c snail
model since it reacted in a very specifi c pattern to thermal
pain and since this snail is freely available in the outskirts of
Lund, Sweden, meaning that we could use fresh and active
snails for the study.
Materials and methods
GSM exposure
An anechoic chamber was used for GSM exposure of the
snails (Malmgren 1998) (see Figure 1). Th e shielded enclo-
sure of the anechoic chamber was made of six demount-
able plywood board panels laminated with copper foil and
covered with absorbing material on the inside. Th e internal
dimensions of the enclosure were depth 1,000 mm, width
1,100 mm, and height 2,050 mm.
Th e EMF were generated by means of a directional antenna
placed in the top part of the anechoic chamber. Th e GSM sig-
nal was generated by a test mobile phone that was specially
designed for test purposes and generated GSM-1900 signals.
Th is generated a GSM modulated test signal with a peak
power output of 33 dBm. Th e signal from the mobile phone
was fed into a power amplifi er before feeding the antenna.
By using calibrated attenuators it was possible to have full
control over the power fed to the antenna (Malmgren 1998).
Th e performance of the anechoic chamber had been deter-
mined previously (Malmgren 1998) by measuring the fi eld in
a number of points in the far fi eld region with a directional
antenna and compared to measurements in free space. Th e
fi eld was measured with a radiation meter (EMR, Wandel &
Goltermann, San Diego, CA, USA) at 9 points on a 0.4 ? 0.4
meter test surface at 1.5 GHz 0.94 m from the antenna both
in free space and in the chamber. A fi eld variation by ? 0.5 dB
over the test surface was found.
Th e snails were placed in the anechoic chamber at an elec-
tric fi eld strength of 16 V/m, which corresponded to a radia-
tion power density of 0.68 W/m 2 . One at a time, snails were
Figure 1. Exposure set-up. Anechoic chamber for GSM and sham
exposure and Styrofoam box for placement of the snails (representative
picture of the Styrofoam box and snail). Magnifi cation of Styrofoam box
1:5, magnifi cation of anechoic chamber 1:12.
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Eff ects of GSM radiation upon snail nociception 247
placed in a small box specially designed for the RF exposure
(dimensions: outer 10 ? 10 ? 8 cm and inner 7 ? 6 ? 3.5 cm)
made of Styrofoam material and with a net covering). Th e
antenna was placed 0.45 m from the Styrofoam box.
Th e whole-body specifi c absorption rate (SAR) depended
on the orientation of the snail with regard to the electric
and magnetic fi eld components of the applied 1,900 MHz
radiation. Numerical computations were performed for two
diff erent orientations with the freely available Finite Diff er-
ence Time Domain (FDTD) computer code (FDTD99) from
Brooks Airforce Base (LeBlanc et al. 2000).
For FDTD calculations, the snail was approximated as a
sphere with diameter 21 mm (snail in shell), since there is
no snail model for the FDTD program. Th e sphere was fi lled
with a physiological salt solution. Th e two extreme polariza-
tions for the radiation that could occur were E-polarization
or H-polarization, when the snail was irradiated from above
(Table I). Th e program assumed a power fl ux density of
1 mW/cm 2 and far fi eld irradiation. Th e Styrofoam box in
which the animals were irradiated was aligned along the
E-fi eld.
Hot plate
In order to test the sensitivity of snails to heat, they were
placed on a hot plate (EPECON AB, Helsingborg, Sweden)
pre- and post-GSM/sham exposure. Th e hotplate consisted
of a ceramic surface, being connected to a water bath,
whereby hot water was circulated to heat the surface (for
set-up see Figure 2). Th e power from water bath was 800 W.
Th e hot plate was placed 75 cm away from the water bath. At
this distance, the magnetic fi eld was 0.2 μ T, which is accept-
able for the exposure on the hot plate. Th e temperature was
determined with a digital thermometer (Testo 735, Testo AG,
Lenzkirch, Germany).
Th e nociceptive threshold was determined by measuring
the latency of the avoidance or withdrawal behaviour of the
snails in response to thermal stimulus, which in this case was
achieved by placing the snails on the hot plate. Th e measure-
ment of the latency started when the snail was placed on the
hot plate with an extended foot and ended as soon as the
animal lifted the head-foot complex to a minimum of 1 cm
and then returned to its original position without retraction
of any body part.
As described by Achaval et al. (2005), a biphasic avoid-
ance behaviour was expected:
Time-point 1 ( T1 ): An immediate reaction when the
snail was placed on the hot plate with retraction of the
foot as well as oral tentacles. Th us, the body was par-
tially retracted into the shell (see Achaval et al. 2005 for
further description).
Time-point 2 ( T2 ): After the T1 reaction the retracted
tentacles began to protract and the snail displayed
searching movements. Subsequently, the head-and-
foot complex was lifted 1 cm or more from the hot
plate, defi ning the T2 (see Achaval et al. 2005 for further
description) (Figure 3).
Time-point 3 ( T3 ): After this reaction, the animals
returned to the original position without retraction of
body parts (Figure 4).
In the study by Achaval et al. (2005), the average latency of
the avoidance behaviour response (defi ned as T2, see below)
was 33 s, when the snail Megalobulimus abbreviatus (nearly
double the size of H. pomatia ) was used. In our model, at
temperatures between 20 ° C and 35 ° C, no avoidance reaction
was seen. However, when the temperature reached up to
48 – 49 ° C, the reaction time would approach 30 s on average.
Th erefore, a temperature between 49 ° C and 50 ° C was chosen
and the temperature of the hot plate was controlled before
the initiation of each experiment. A thermal stimulus of 50 ° C
had been defi ned as a stressful thermal condition (Achaval
et al. 2005).
We only included snails which reacted as described above
during the pre-GSM/sham testing on the hot plate. Snails
with aberrant nociceptive reaction, e.g., immediate retrac-
tion of the whole body into the shell and no further reaction,
were thus excluded from GSM or sham exposure and thus
not used for the experiment (3 snails in the GSM and 5 snails
in the sham group had to be replaced, due to lack of normal
heat reaction in the pre-exposure test, that is 87.5% of 64
snails could be used in the study).
Animals
Helix pomatia snails were collected at a known habitat for
these snails in the fringe of the woods in the outskirts of
Lund. Th is type of land snail was larger than the C. nemoralis
and weighed about than 10 times more (Figures 5 and 6).
Table I. FDTD calculations the snail approximated as a sphere resulting
in whole-body SAR of about 0.7 W/kg for an input of 10 W/m 2 .
Model
Sphere
Sphere
Polarization
E-polarization
H-polarization
Whole body (W/kg)
0.68
0.68
Figure 2. Hot plate set-up. A water bath (left) circulating hot water to the heat plate (right) upon which the snails were placed for thermal avoidance
test. Magnifi cation for the hot plate 1:9.
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248 H. Nittby et al .
invertebrates). All eff orts were made to ameliorate suff ering
of the animals, only keeping them on the hotplate as short as
possible, until the avoidance response had been registered,
and removing them if no heat reaction could be detected.
Fifty-eight snails, collected on 7 June 2010, were used in this
experiment, which was performed from 15 June until 23 July
2010. Th is means that we used highly active animals, out of
hibernation since about one month and a half. Th ey were
kept in constant room temperature and with moisturized cli-
mate, which excluded the risk for aestivation. Twenty-nine
snails were GSM exposed for 1 h, and 29 snails were sham
controls.
Immediately before and after the 1-h session of GSM/
sham exposure, each animal was hydrated with a water spray
until it came completely out of its shell (all snails did not
need exactly the same amount of water spray to come out of
their shell) and then placed upon the heated plate in order to
detect the reaction to thermal stimulus. All experiments and
all behavioural reactions of the snails on the hot plate were
video-recorded.
We chose to register only the T2 reaction in line
with earlier experience (Achaval et al. 2005). The reac-
tion time of each snail was measured from the films by
Th e animals were kept in a terrarium-like wooden box
(with background electromagnetic fi eld levels from electric-
ity transmission and distribution facilities being 0.03 μ T),
with food (natural vegetation) and water ad libitum . Th e air
was moisturized repeatedly every day. Th e animals were sub-
jected to normal light and dark variations with 12-h cycles of
on-off (on 08:00 – 20:00 h). Th e snails weighed 23.8 ? 4 g.
Each snail was used only once, in order to avoid possible
eff ects of habituation upon the thermal reaction behaviour.
Due to diurnal variations of the reactions of snails to noci-
ceptive stimulus, e.g., a longer latency during the mid-dark
period than during the mid-light period for C. nemoralis (Yu
and Kavaliers 1991), all experiments were carried out dur-
ing the same light-period of the day, around noon (approx.
10:00 – 14:00 h).
Before each GSM/sham exposure the snails were weighed
and hydrated by sprinkling. Th e animals were un-anaesthetized
during the exposure. Each animal was sham exposed for
1 h or exposed to RF for 1 h at 1,900 MHz at the level of
0.68 W/m 2 resulting in a SAR-value of about 48mW/kg as
estimated from the FDTD program.
Th e use of H. pomatia in the present studies did not
require any ethical approval in Sweden (studies including
Figure 3. Th e T2 reaction. Th e head-and-foot complex was lifted 1 cm
or more from the hot plate, defi ning the T2 reaction time. Figure from
the video recordings. Magnifi cation 1:1.5.
Figure 4. Th e T3 reaction. Th e animal in original position without
any retracted body parts. Figure from the video recordings.
Magnifi cation 1:1.5.
Figure 5. Helix pomatia . In the terrarium-like wooden box.
Magnifi cation 1:4. Figure 6. Helix pomatia . In nature. Magnifi cation 1:1.5.
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Eff ects of GSM radiation upon snail nociception 249
two observers independent of each other and blind to the
exposure condition.
Statistics
Th e T2 reaction was compared pre- and post-sham/GSM
exposure. Th e median measurement of the two independent
and blinded observers was used for statistical evaluations.
For each of the observers, the distribution of reaction time
T2 pre- and post-GSM and sham exposure was examined, as
well as the distribution of the diff erence of the reaction time
T2 post minus pre GSM and sham exposure. Since skewness
and kurtosis showed values signifi cantly diff erent from those
of a normal distribution, we only used non-parametric tests
for statistical analyses. For comparison of diff erence in T2
reaction post minus pre GSM or sham exposure, the two-
sided Mann-Whitney test was used (SPSS software).
Using Spearman ’ s correlation value, there was a signifi cant
correlation between the two observers at a level of 0.754 (cor-
relation signifi cant at the 0.01 level with a two-tailed test).
Results
Th e two blinded observers ’ measurements of the T2 reaction
time did not diff er signifi cantly from each other (Wilcoxon
NS). Th e Spearman correlation coeffi cient between day of
exposure and the reaction time T2 was: For T2 pre-exposure:
0.17; for T2 post-exposure 0.06; for the diff erence post- –
pre-T2 ? 0.09. Th us, it could be concluded that there was no
signifi cant correlation between day of exposure and result.
Out of 29 GSM exposed snails, 26 snails showed an
increased T2 reaction time after the GSM exposure as
compared to before exposure, and three snails showed a
decreased reaction time after GSM exposure. Regarding
the 29 sham snails, 15 showed an increased reaction time
whereas 14 snails on the other hand showed a decreased
reaction time.
Th e median reaction time before GSM exposure was
23.5 s and before sham 26.5 s. After GSM exposure, the
median reaction time was 28.0 s and after sham 26.0 s.
When we compared the diff erence in reaction time post-
GSM exposure minus pre-GSM exposure for each indi-
vidual snail, we found that the median reaction time was
increased with a median value of 9.0 s (1st and 3rd quartiles
1.75 – 18.5 s). Regarding the sham group, the median value
of the diff erence post sham minus pre sham was 0.0 s (1st
and 3rd quartiles ? 5.0 – 4.3 s).
Th e mean reaction time pre-GSM exposure was 23.5 s
(standard deviation [SD] 6.9 s) and pre-sham 27.7 s (SD 6.9 s).
Post-GSM exposure, the mean reaction time was 34.2 s (SD
16.2 s) and post-sham 27.3 s (SD 6.6 s). When we compared
the diff erence in reaction time post-GSM exposure minus
pre-GSM exposure for each individual snail, we found that
the mean reaction time was increased with a mean value of
10.69 s (SD 12.7 s). Regarding the sham group, the median
value of the difference post sham minus pre sham was
? 0.74 s (SD 7.1 s).
Th e Mann-Whitney U-test (two-sided) was used to test
the null hypothesis that the distribution of the diff erence in
the mean values of T2 after minus before exposure was the
same across the two categories of exposure (sham versus
GSM). Th e null hypothesis was rejected, at a signifi cance
level of 0.05 ( p -value ? 0.001), showing that the diff erence in
the T2 reaction time was signifi cantly diff erent in the GSM-
exposed group as compared to the sham group (two-sided
Mann-Whitney p ? 0.001) (Figure 7) and that there was a
signifi cant increase in the reaction time post-GSM exposure
minus pre-GSM exposure as compared to post-sham minus
pre-sham exposure.
Discussion
In the present study we showed that 1-h exposure to GSM-
1900 induced analgesia in the non-hibernating land snail
H. pomatia . In this context, it is important to point out that
we only used active snails for the present study. It has been
shown that 5 HT is involved in the enkephalin-induced
Figure 7. GSM as compared to sham regarding T2. Th e diff erence of T2 (mean value of the two observers) post GSM exposure minus pre GSM
exposure, compared to the diff erence post-sham minus pre-sham, is shown above. Th e Mann-Whitney non-parametric test showed a signifi cant
increase of this diff erence post- minus pre-exposure in the GSM group as compared to the sham group ( p ? 0.001, two-sided test) (measurements
of the two blinded observers were considered).
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250 H. Nittby et al .
described benefi cial eff ects of pulsed ELF fi elds (Shupak
et al. 2006, Th omas et al. 2007, Robertson et al. 2010). We have
previously searched for the mechanisms behind the ELF and
RF eff ects, which might be explained by alterations of Ca 2 ?
transport as has been found for ELF fi elds (Baur é us Koch et al.
2003) or possibly by the soliton theory (Salford et al. 2008).
Ca 2 ? has many important roles in all living organisms. Apart
from its structural role in bone matrix, plant cell walls and in
stabilizing membranes, it plays an essential role in cellular
homeostastasis, most notably as an intracellular messenger.
In order to explore the mechanism for possible biological
eff ects of the ELF radiation environment, we investigated
how the transport of Ca 2 ? over the membrane of spinach
plasma vesicles varies with frequency and amplitude of ELF
magnetic fi eld exposure. Baur é us Koch et al. (2003) found a
bio-resonance phenomenon, where appropriate combina-
tions of frequency and amplitude had the potency to aff ect
bio-membranes and their Ca 2 ? transport systems at various
degrees and directions. Our experimental results of the inter-
action of ELF magnetic fi elds with Ca 2 ? bound to proteins
in the cell membrane fi tted extremely well with quantum
mechanical interaction models (Lednev 1993, Blanchard and
Blackman 1994). Regarding the soliton model, the eff ects of
solitons in biological membranes have been discussed by
Heimburg and Jackson (2005). Th ey wrote:
Th e lipids of biological membranes and intact biomem-
branes display chain melting transitions close to tem-
peratures of physiological interest. During this transition
the heat capacity, volume and area compressibilities,
and relaxation times all reach maxima. Compressibili-
ties are thus nonlinear functions of temperature and
pressure in the vicinity of the melting transition, and we
show that this feature leads to the possibility of soliton
propagation in such membranes. In particular, if the
membrane state is above the melting transition, solitons
will involve changes in lipid state.
Th e authors discuss solitons in the context of several proper-
ties of nerve membranes under the infl uence of the action
potential, including mechanical dislocations and tempera-
ture changes. Our suggestion is that the EMF might be the
inducers of the solitary waves, thereby explaining eff ects
upon, for example, analgesia induced by EMF exposure
(Salford et al. 2008).
Th e vast knowledge about the physiology of the snail, its
neurotransmission systems and it simplicity as compared
the mammals may provide a tool for successful continued
search for the mechanisms behind the eff ects of the GSM
EMF upon biology. Defi nition and understanding of the
mechanisms will give scientists an opportunity to develop
and control the positive eff ects as well as the potentially
harmful eff ects of the interaction between the electromag-
netic fi elds and biology.
Acknowledgements
We are grateful to Professor Rolf Elofsson, at the Depart-
ment of Cell and Organism Biology, Institute of Zoology,
response to thermal pain in C. Nemoralis (Dyakonova et al.
1995), and that there is a seasonal variation in the 5 HT level
of the central nervous system of H. Pomatia , with increased
5 HT levels in the brain during the hibernation (Hirpi and
Salanki 1973). Th erefore, it is important that all the snails
included in the study were in the same state and that none of
the snails was hibernating.
Th e snail model has for long been used in research on pain
perception. Th e thermal withdrawal behaviour of the land
snail is stereotyped and reproducible (Achaval et al. 2005).
Endogenous opioid peptides are involved in the control of
this behaviour and administration of morphine increases
the reaction time as compared to controls, whereas naloxone
treatment decreases the reaction time (Kavaliers 1987, Acha-
val et al. 2005).
Many experiments have focused on the eff ect of ELF
magnetic fi elds and their interaction with pain in snails. Th e
main conclusion of this has been that the pain threshold is
decreased when snails have been exposed to ELF magnetic
fi elds. Also, the analgesic eff ect of μ and κ agonists such as
morphine was reduced (exposure for 15 – 30 min to 0.5 Hz
weak rotating magnetic fi elds of 1.5 – 8.0 G) in the land snail
C. Nemoralis (Kavaliers and Ossenkopp 1988). Also in fur-
ther studies, it has been described that exposure to magnetic
fi elds at 60 Hz signifi cantly attenuated morphine-induced
analgesia and sensitized the basal nociceptive responses of
C. nemoralis (Tysdale et al. 1991). Th e eff ects were related to
the duration of the exposure, with a signifi cantly decreased
time for thermal withdrawal after 2 h of magnetic fi eld expo-
sure as compared to control animals. Th e 2-h 60 Hz exposure
(100 μ T) aff ected the sensitivity to thermal nociception in a
manner comparable to that observed after treatment with
naloxone.
However, during certain conditions, instead a state of anti-
nociception can be reached. Th is is the case for specifi c pulsed
ELF fi elds of less than 3 kHz (PEMF), where eff ects has been
seen in chronic pain conditions such as rheumatoid arthritis
and fi bromyalgia (Shupak et al. 2006). Also, PEMF have been
used for conditions such as bone-fractures, pseudoarthroses
and failed joint fusions (Shupak et al. 2003).
Kavaliers et al. (1990) reported a duration-dependent
eff ect of ELF exposure upon nociception of C. nemoralis , with
reduction of the reaction time as the exposure time increased
(ranging from 0.5 – 120 h). On the other hand, a 15-min expo-
sure session to a PEMF was enough to induce analgesia in
C. nemoralis (Th omas et al. 1997), even though 30 min of
exposure would induce a signifi cantly higher level of analge-
sia as compared to the 15-min exposure (Th omas et al. 1998).
In order to be able to detect both relatively immediate eff ects
and at the same time take advantage of supposedly increased
eff ects after longer exposure time, we chose a 1-h exposure
session in the present study.
Interestingly, in our study the sham-exposed snails had
the same reaction time before and after sham exposure. Th is
might indicate a very limited habituation eff ect in this case.
Many of our observations in rodents in the past have dealt
with possibly harmful eff ects of GSM EMF. It is notable that
here we have an observation which might support the earlier
fi ndings others, like the London, Ontario group, which have
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Eff ects of GSM radiation upon snail nociception 251
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at Lund University, for excellent advice regarding the
biological functions of the snails. We also thank Profes-
sor Sven-Axel Bengtson, Head of the Museum of Zoology,
Lund University, and Professor Bengt Widegren at Rausing
Laboratory, Lund University, for further valuable advice
regarding snails. We are also deeply grateful to Mr Jimmie
Stjernstr ö m and EPECON AB, Helsingborg, Sweden, for
donating the hot plate to our laboratory, and to the staff of
Lund University Hospital ’ s Dept for Medical Technology,
who supplied the circulating water bath equipment. Th is
work was supported by the Hans and M ä rit Rausing Chari-
table Foundation.
Declaration of interest
Th e authors report no confl icts of interest. Th e authors alone
are responsible for the content and writing of the paper.
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