Epidemiological Evidence for a Health Risk from Mobile Phone Base Stations

Abstract

Human populations are increasingly exposed to microwave/radiofrequency (RF) emissions from wireless communication technology, including mobile phones and their base stations. By searching PubMed, we identified a total of 10 epidemiological studies that assessed for putative health effects of mobile phone base stations. Seven of these studies explored the association between base station proximity and neurobehavioral effects and three investigated cancer. We found that eight of the 10 studies reported increased prevalence of adverse neurobehavioral symptoms or cancer in populations living at distances < 500 meters from base stations. None of the studies reported exposure above accepted international guidelines, suggesting that current guidelines may be inadequate in protecting the health of human populations. We believe that comprehensive epidemiological studies of long-term mobile phone base station exposure are urgently required to more definitively understand its health impact.

Full text

Human populations are increasingly exposed to
microwave/radiofrequency (RF) emissions from wire-
less communication technology, including mobile
phones and their base stations. By searching PubMed,
we identified a total of 10 epidemiological studies that
assessed for putative health effects of mobile phone
base stations. Seven of these studies explored the asso-
ciation between base station proximity and neurobe-
havioral effects and three investigated cancer. We
found that eight of the 10 studies reported increased
prevalence of adverse neurobehavioral symptoms or
cancer in populations living at distances < 500 meters
from base stations. None of the studies reported expo-
sure above accepted international guidelines, suggest-
ing that current guidelines may be inadequate in pro-
tecting the health of human populations. We believe
that comprehensive epidemiological studies of long-
term mobile phone base station exposure are urgently
required to more definitively understand its health
impact. Key words: base stations; electromagnetic field
(EMF); epidemiology; health effects; mobile phone;
radiofrequency (RF); electromagnetic radiation.
INT J OCCUP ENVIRON HEALTH 2010;16:263–267
INTRODUCTION
Mobile phone base stations are now found ubiquitously
in communities worldwide. They are frequently found
near or on shops, homes, schools, daycare centers, and
hospitals (Figure 1). The radiofrequency (RF) electro-
magnetic radiation from these base stations is regarded
as being low power; however, their output is continu-
ous.1This raises the question as to whether the health
of people residing or working in close proximity to base
stations is at any risk.
METHODS
By searching PubMed and using keywords such as base
station, mast, electromagnetic field (EMF), radiofre-
quency (RF), epidemiology, health effects, mobile
phone, and cell phone, and by searching the refer-
ences of primary sources, we were able to find only 10
human population studies from seven countries that
examined the health effects of mobile phone base sta-
tions. Seven of the studies explored the association
between base station proximity and neurobehavioral
symptoms via population-based questionnaires; the
other three retrospectively explored the association
between base station proximity and cancer via medical
records. A meta-analysis based on this literature is not
possible due to differences in study design, statistical
measures/risk estimates, exposure categories, and end-
points/outcomes. The 10 studies are therefore summa-
rized in chronological order (Table 1).
RESULTS AND DISCUSSION
We found epidemiological studies pertaining to the
health effects of mobile phone base station RF emis-
sions to be quite consistent in pointing to a possible
adverse health impact. Eight of the 10 studies reported
increased prevalence of adverse neurobehavioral symp-
toms or cancer in populations living at distances < 500
meters from base stations. The studies by Navarro et
al.,2Santini et al.,3Gadzicka et al.,4and Hutter et al.5
reported differences in the distance-dependent preva-
lence of symptoms such as headache, impaired con-
centration, and irritability, while Abdel-Rassoul et al.6
also found lower cognitive performance in individuals
living ≤10 meters from base stations compared with the
more distant control group. The studies by Eger et al.7
and Wolf and Wolf8reported increased incidence of
cancer in persons living for several years < 400 meters
from base stations. By contrast, the large retrospective
study by Meyer et al.9found no increased incidence of
cancer near base stations in Bavaria. Blettner et al.10
reported in Phase 1 of their study that more health
problems were found closer to base stations, but in
Phase 211 concluded that measured EMF emissions
were not related to adverse health effects (Table 1).
Each of the 10 studies reviewed by us had various
strengths and limitations as summarized in Table 1. Per-
263
Epidemiological Evidence for a Health Risk
from Mobile Phone Base Stations
VINI G. KHURANA, LENNART HARDELL, JORIS EVERAERT, ALICJA BORTKIEWICZ,
MICHAEL CARLBERG, MIKKO AHONEN
Received from: Department of Neurosurgery, The Canberra Hos-
pital, The Australian National University Medical School, Garran,
Australia (VGK); Department of Oncology, University Hospital,
Orebro, Sweden (LH, MC); Research Institute for Nature and Forest
[INBO], Brussels, Belgium (JE); Department of Work Physiology
and Ergonomics, Nofer Institute of Occupational Medicine, Lodz,
Poland (AB); Department of Computer Science, University Hospital,
Orebro, Sweden (MA). Send correspondence to: Dr. Vini G. Khu-
rana, Department of Neurosurgery, The Canberra Hospital, PO Box
103, Woden ACT 2606, Australia; email: <vgkhurana@gmail.com>.
Disclosures: The authors declare no conflicts of interest.

taining to those base station studies in which EMF meas-
urements were not carried out,3,4,7,9 it should be noted
that distance is not the most suitable classifier for expo-
sure to RF-EMF. Antennae numbers and configurations,
as well as the absorption and reflection of their fields by
houses, trees, or other geographic hindrances may
influence the exposure level. Further, self-estimation of
distance to nearest base station is not the best predictor
of exposure since the location of the closest base station
is not always known. Such exposure misclassification
inevitably biases any association towards null. Multiple
testing might also produce spurious results if not
adjusted for,3,5 as might failure to adjust for participant
age and gender.7Latency is also an important consider-
ation in the context of cancer incidence following or
during a putative environmental exposure. In this
regard, the study by Meyer et al.9found no association
between mobile phone base station exposure and
cancer incidence, but had a relatively limited observa-
tion period of only two years. On the other hand, the
studies by Eger et al.7and Wolf and Wolf8found a sig-
nificant association between mobile phone base station
exposure and increased cancer incidence, although the
approximate five-year latency between base station
exposure and cancer diagnosis appears to be unexpect-
edly short in both of these studies.
Other problems in several population-based ques-
tionnaires are the potential for bias, especially selection8
and participation2,3,5,6,11 biases, and self-reporting of
outcomes in combination with the exposure assessment
methods used. For example, regarding limitations in
exposure assessment, in a large two-phase base station
study from Germany,12,13of the Phase 1 participants (n =
30,047), only 1326 (4.4%) participated with a single
“spot” EMF measurement recorded in the bedroom for
Phase 2. Further, health effect contributions from all
relevant EMF sources and other non-EMF environmen-
tal sources need to be taken into account.12 We acknowl-
edge that participant concern instead of exposure
could be the triggering factor of adverse health effects,
however this “nocebo effect” does not appear to fully
explain the findings.4,5 Further, the biological relevance
of the overall adverse findings (Table 1) is supported by
the fact that some of the symptoms in these base-station
studies have also been reported among mobile phone
users, such as headaches, concentration difficulties, and
sleep disorders.13,14 Finally, none of the studies that
found adverse health effects of base stations reported
RF exposures above accepted international guidelines,
the implication being that if such findings continue to
be reproduced, current exposure standards are inade-
quate in protecting human populations.15
264 • Khurana et al. www.ijoeh.com • INT J OCCUP ENVIRON HEALTH
Figure 1—Mobile phone base stations ("antennae" or "masts") in Australia. Upper left: Community shop roof showing
plethora of flat panel antennae. Upper right: Hospital roof with flat panel antennae painted to blend in. Lower left:
Top of a street light pole. Lower center: Mast erected next to a daycare center. Lower right: Antennae mounted on
an office block top floor.

VOL 16/NO 3, JUL/SEP 2010 • www.ijoeh.com Health Risks from Mobile Phone Base Stations • 265
TABLE 1 Summary of Epidemiological Studies of Mobile Phone Base Station Health Effects
Base
Publication Clinical Study Station EMF
(Year; Country) Assessment Design Details Participants Measured Key Findings Strengths Limitations
Navarro2Neuro- Survey- GSM-DCS 101 Yes More symptoms with Detailed questionnaire, Low participation, self-
(2003; Spain) behavioral questionnaire 1800 MHz closer proximity to base EMF measured, distan- estimated distances,
station (< 150 m) ces studiedasubjects awareb
Santini2Neuro- Survey- n/s 530 No More symptoms with Detailed questionnaire, As above, plus no EMF
(2003; France) behavioral questionnaire closer proximity to base distances & other EMF measurements, no base
station (< 300 m) exposures assessed station details
Eger7Cancer Retrospective GSM 967 No 3 x risk of cancer after Maximum beam Other environmental risk
(2004; incidence case review 935 MHz 5 yrs of exposure intensity calculated, factors not assessed;
Germany) (< 400 m); early age reliable cancer data analysis not adjusted for
of cancer diagnosis collection age and sex.
Wolf & Wolf8Cancer Retrospective TDMA 1844 Yes > 4 x risk of cancer Reliable cancer & dem- Not all environmental risk
(2004; Israel) incidence case review 850 MHz after 3–7 yrs exposure ographic data, no other factors assessed; possible
(< 350 m); early age major environmental selection bias; no age,
of cancer diagnosis pollutant identified sex adjustment.
Gadzicka4Neuro- Survey- n/s 500 No More headache with Detailed questionnaire, Subjects aware, no base
(2006; Poland) behavioral questionnaire proximity < 150 m; distances & EMF studied, station details
nocebo unlikelycnocebo studied
Hutter5Neuro- Cross- 900 MHz 336 Yes Headaches & impaired Detailed questionnaire Subjects aware, low
(2006; Austria) behavioral sectional concentration at higher and testing, EMF mea- participation rate
power density; nocebo sured, distances studied;
unlikely nocebo effect studied
Meyer9Cancer Retrospective n/s 177,428 No No increased cancer Wide population Observation period only 2
(2006; incidence case review incidence in municipal- assessed (Bavaria) years, vague definitions of
Germany) ities with or without exposure, exposure onset
base stations unknown, distance to base
station unknown
Abdel-Rassoul6Neuro- Cross- n/s 165 Yes More symptoms & lower Detailed questionnaire Exact base station details
(2007; Egypt) behavioral sectional cognitive performance and testing, EMF mea- n/s, low number of
if living under or < 10 m sured, distances studied, participants
from base station subjects unaware
Blettner10 Neuro- Cross- n/s 30,047 No More health complaints Wide population EMF measurements not car-
(2009; behavioral sectional closer to base station assessed, detailed survey, ried out (see phase II in Berg-
Germany) (< 500 m) nocebo effect assessed Beckhoff et al., 2009; below)
Berg-Beckhoff11 Neuro- Cross- GSM 900 MHz 1326 Yes Health effects probably Measured EMF emissions, Low participation, no
(2009; behavioral sectional GSM 1800 MHz caused by stress and not standardized detailed list of symptoms
Germany) UMTS 1920–1980 by RF-EMF questionnaires published, single “spot” mea-
MHz surement in one place in
dwelling, no occupational
exposure assessed, time lag
from assessment of symptoms
and EMF measurement
n / s = not specified.
a“Distance” refers to distance between base station and subjects’ households.
b“Subjects aware” refers to study participants being aware of the nature of the study.
c“Nocebo” effect unlikely because the majority of subjects in the study reported little or no concern for base station proximity.

CONCLUSIONS
Despite variations in the design, size and quality of
these studies as summarized in Table 1, it is the con-
sistency of the base-station epidemiological litera-
ture from several countries that we find striking. In
particular, the increased prevalence of adverse neu-
robehavioral symptoms or cancer in populations
living at distances < 500 meters from base stations
found in 80% of the available studies. It should be
pointed out that the overall findings of health prob-
lems associated with base stations might be based on
methodological weaknesses, especially since expo-
sure to RF electromagnetic radiation was not always
measured.
There are some proposed mechanisms via which
low-intensity EMF might affect animal and human
health,16,17 but full comprehensive mechanisms still
remain to be determined.18,19 Despite this, the accu-
mulating epidemiological literature pertaining to the
health effects of mobile phones13,20 and their base sta-
tions (Table 1) suggests that previous exposure stan-
dards based on the thermal effects of EMF should no
longer be regarded as tenable. In August 2007, an
international working group of scientists, researchers,
and public health policy professionals (the BioInitia-
tive Working Group) released its report on EMF and
health.21 It raised evidence-based concerns about the
safety of existing public limits that regulate how much
EMF is allowable from power lines, cellular phones,
base stations, and many other sources of EMF expo-
sure in daily life. The BioInitiative Report21 provided
detailed scientific information on health impacts
when people were exposed to electromagnetic radia-
tion hundreds or even thousands of times below limits
currently established by the FCC and International
Commission for Non-Ionizing Radiation Protection in
Europe (ICNIRP). The authors reviewed more than
2000 scientific studies and reviews, and have con-
cluded that: (1) the existing public safety limits are
inadequate to protect public health; and (2) from a
public health policy standpoint, new public safety
limits and limits on further deployment of risky tech-
nologies are warranted based on the total weight of
evidence.21 A precautionary limit of 1 mW/m2 (0.1
microW/cm2or 0.614 V/m) was suggested in Section
17 of the BioInitiative Report to be adopted for out-
door, cumulative RF exposure.21 This limit is a cau-
tious approximation based on the results of several
human RF-EMF studies in which no substantial
adverse effects on well being were found at low expo-
sures akin to power densities of less than 0.5 – 1
mW/m2.2,5,22–26 RF-EMF exposure at distances > 500 m
from the types of mobile phone base stations reviewed
herein should fall below the precautionary limit of
0.614 V/m.
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