Findings

Scientific literature

Biological and physiological effects

Experimental research on the biological effects of RF and microwave fields is very broad and includes
studies of volunteers, animals and in vitro, cell-based techniques . The studies cover the effects
of RF and microwave radiation between 100 MHz and 60 GHz and focus both on the functional
changes in the brain (influence of exposure to RF and microwave fields on the head) and on
carcinogenic processes, reproduction and development, the cardiovascular system and longevity (as a
result of whole body exposure to RF and microwave fields).
The biological effects observed on the cardiovascular, endocrine and immune systems and on the
behaviour of animals studied seem to be thermal effects of acute exposure to RF and microwave
radiation, with increases of at least 1 °C or 2 °C in temperature needed to produce these effects. As to
the increased risk of developing cancer after exposure to RF or microwave fields, the evidence for
such an association is extremely weak. Since the radiation from mobile phones and signal stations
does not have enough energy to break chemical or molecular bonds directly, there is no basis in theory
to suggest that they can damage DNA. Moreover, a biological mechanism that explains any possible
carcinogenic effect from RF or microwave fields has yet to be identified. Because of the difficulties in
interpreting findings from laboratory studies, the hypothesis that RF or microwave radiation is harmful
and could have effects on health that have not yet been recognized cannot be rejected.

Indirect experimental results are difficult to extrapolate. In vitro experiments that show abnormal cell
proliferation, changes in cell membranes, and movement of ions and substances across membranes are
difficult to extrapolate to people. It is also difficult to extrapolate to people the observed effects on
cerebral functions that relate to the behaviour of rodents since, among other reasons, the whole brain
of these small animals is exposed to radiation whereas the brains of people who use mobile phones,
although being exposed, receive the highest exposure in the part closest to the handset. Moreover, the
thermal effects of radiation are unlikely to be seen in people, as the increase in the local temperature of
the brain induced by the microwaves generated by mobile phones is negligible (it has been estimated
to be up to 0.1 °C) (7). Finally, there is no evidence of non-thermal effects on human health.
It is important to distinguish between biological (or physiological) effects and psychological and
health effects. The demonstration of an RF or microwave radiation effect in experimental research
does not necessarily mean that such exposure will lead to harmful effects on human health. Human
bodies, with the aid of their immune, nervous or endocrine systems, can effectively resist some
external pressures, adapt to them and maintain the stability (homeostasis) disrupted by those changes.

Clinical effects

Within human population studies, epidemiological studies provide the most direct information on the
long-term effects on health of any potential harmful agent. To assess the adverse effects on health that
may result from the use of mobile phones, research with a specific focus on cancer has been carried
out. By the end of the 1990s, the number of studies was small and the works presented major
methodological limitations, the most outstanding one being the lack of enough people with an
exposure time long enough to accurately assess the potential adverse late effects on health of mobile
phone use.
The majority of those studies suggested the need for additional, high-quality research. As a result of
these recommendations, a series of multinational case-control studies, coordinated by the International
Agency for Research on Cancer (IARC), were set up after a detailed feasibility study was carried out
in 1998 and 1999.

Overall, these studies are named the INTERPHONE Study (8), and their primary objective is to assess
whether exposure to RF or microwave radiation from mobile phones is associated with a risk of
cancer. Priority is given to epidemiological studies of the relationship between the use of mobile
phones and the incidence of:
• brain tumours;
• salivary gland tumours, acoustic neuromas and other head and neck tumours; and
• leukaemia and lymphomas.
If the risk of developing a brain tumour exists at all, the wider use of mobile phones and the expected
number of people who will develop a brain tumour will be sufficient to detect a potential 1.5-fold
increase in risk 5–10 years from the start of use.
Participant countries, with the longest and highest use of mobile phones, are Australia, Canada,
Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden and the
United Kingdom. Initially, the study expected to find about 6000 cases of glioma and meningoma
(both benign and malignant), 1000 cases of acoustic neuroma, 600 cases of parotid gland tumour and
their respective controls. The first results of the INTERPHONE Study were available in 2004 (9, 10)
and, since then, four additional papers have been published (11–14). It should also be noted that these
studies evaluated the impact on health of exposure to RF and microwave radiation emitted by mobile
phones, and not by antennas and base stations.

With regard to brain tumours, most of the studies yielded negative results, although a few of them
suggested an increased risk for mobile phone users. Because of these results, it is not possible to
establish an association between the use of mobile phones and an increased risk of brain tumours.
With regard to acoustic neuroma – a rare, benign tumour on the auditory nerve – the studies available
reported inconsistent results, except for the most recent ones, which found an association between an
increase in the risk of this type of tumour and 10 years or more of mobile phone use; moreover, the
increased risk is confined to the side of the head where the phone was usually held. No indications of
an increased risk for less than 10 years of mobile phone use were found. Before definite conclusions
can be drawn, the results of these studies have to be confirmed by additional research.
This type of research, however, faces several problems. One is that long-time users first used analogue
phones, and then digital phones. No risk has been found for digital phone use only, but then the
follow-up time is shorter. Other methodological problems, such as recall bias, have been identified:
people, especially patients, might have a selective memory on the side of the head where the telephone
was used .
A number of clinical complaints related to the use of mobile phones are reported in the scientific
literature. They include headache, fatigue, sleep disorders, loss of memory, dizziness, feelings of heat
or tingling in the auricular (or auditory) area or in the head, vertigo, deafness and blurred vision. Very
few studies are available, and their results provide no evidence of an association between these
symptoms and the use of mobile phones. It should be noted, however, that these are general,
nonspecific symptoms that may be induced by a wide range of causes. Since they represent a problem
for those suffering, the cause should be elucidated.
In summary, the evidence available does not support the hypothesis that mobile phone use is
associated with an increased risk of malignant brain tumours, but an increase in the risk of acoustic
neuroma after 10 years or more of mobile phone use has been found. Therefore, it seems that neither
acoustic neuroma nor brain tumours are related to mobile phone use of less than 10 years.
Nevertheless, those studies were conducted with data from the time when only analogue mobile
phones had been in use for more than 10 years, and they cannot determine if the results would be similar after long-term use of digital mobile phones. Likewise, a carcinogenic effect after a very long
period of exposure would remain undetected.
The most important and clearly defined effect of mobile phones on health, and the only clearly
established risk from an epidemiological perspective, is motor vehicle accidents, which obviously are
not related to exposure to RF or microwave radiation. The results of some studies show that the use of
a mobile phone up to 10 minutes before a crash is associated with a fourfold increase in the risk of
having a collision that results in injury. The risk increases irrespective of whether or not a hands-free
phone is used .
Table 2 describes the characteristics of the design of epidemiological studies and the outcomes of
these studies.

Reports (grey literature)

Since the year 2000, a significant number of reports and reviews on the connection between mobile
phone use and health have been issued by committees, institutions, expert groups and agencies of
worldwide prestige, to appraise relevant literature, draw up guidelines and make recommendations to
limit exposure to RF and microwave radiation.
The National Radiological Protection Board summarized  the information from several sources,
from the publication of the Stewart Report, in May 2000, to the end of 2004. The Board, an
independent body that is now part of the Health Protection Agency, has responsibility for advising
government departments and others in the United Kingdom on standards of protection for exposure to
ionizing and non-ionizing radiation, which includes electric and magnetic fields.
The Stewart Report (5) is a widely quoted review on mobile phones and health. The Government of
the United Kingdom commissioned the Independent Expert Group on Mobile Phones, which was
chaired by Sir William Stewart, to prepare the Report. The Report concluded that the balance of
evidence did not suggest that exposure below international guidelines could cause adverse effects on
health. However, it recommended that a precautionary approach – that is, limiting exposure to RF and
microwave radiation, planning the location and setting of base stations and encouraging a selective use
of mobile phones – be adopted until more detailed and scientifically robust information on any adverse
effects on health becomes available. Besides health issues, the Report offered advice on exposure
standards and planning to government, industry and others and on public information and consumer
choices. It also proposed setting up a research programme.
According to the National Radiological Protection Board summary report , most of the 26 reports
examined reached similar conclusions and made comparable recommendations. Overall, the reports
acknowledge that exposure to low-level RF and microwave fields may cause a variety of slight
biological effects on cells, animals or people, particularly on brain activity during sleep, but the
possibility of exposure causing adverse effects on health remains unproven. The reports also present
guidance on public policy to decision-makers and legislators, and some of them favour any form of
precautionary or prudent approach to reducing personal exposure to the fields produced by mobile
phones.

Specifically, most reports recommend limiting the use of mobile phones by children. This has been
recommended in the absence of explicit scientific data. However, ethical and practical concerns limit
or prevent experimental studies on children. Because of a much higher cumulative exposure than
today's adults when they were at the same age, children might be more vulnerable to any effects of RF
and microwave radiation. As long as adverse effects on health cannot be ruled out with some degree of
certainty, it appears to be appropriate to instruct children and their parents about a prudent use of
mobile phones. Moreover, in the absence of new scientific evidence, WHO is focusing attention on the
potential effects of exposure to electromagnetic fields on children . Finally, many reports agree
that the distraction caused by mobile phone use while driving represents a serious threat to health.

Table 3 contains a selection of national and international reports on mobile phone use and its effects
on health, along with the links to the corresponding web pages.