The antennas contained in mobile phones, including smartphones, emit radiofrequency (RF) radiation (non-ionizing "radio waves" such as microwaves);
the parts of the head or body nearest to the antenna can absorb this
energy and convert it to heat. Since at least the 1990s, scientists have
researched whether the now-ubiquitous radiation associated with mobile
phone antennas or cell phone towers is affecting human health.
Mobile phone networks use various bands of RF frequency, some of which
overlap with the microwave range. Other digital wireless systems, such
as data communication networks, produce similar radiation.
In response to public concern, the World Health Organization established the International EMF Project
in 1996 to assess the scientific evidence of possible health effects of
EMF in the frequency range from 0 to 300 GHz. They have stated that
although extensive research has been conducted into possible health
effects of exposure to many parts of the frequency spectrum, all reviews
conducted so far have indicated that, as long as exposures are below
the limits recommended in the ICNIRP
(1998) EMF guidelines, which cover the full frequency range from
0–300 GHz, such exposures do not produce any known adverse health
effect.
The WHO states that "A large number of studies have been performed over
the last two decades to assess whether mobile phones pose a potential
health risk. To date, no adverse health effects have been established as
being caused by mobile phone use."
International guidelines on exposure levels to microwave
frequency EMFs such as ICNIRP limit the power levels of wireless
devices and it is uncommon for wireless devices to exceed the
guidelines. These guidelines only take into account thermal effects, as
non-thermal effects have not been conclusively demonstrated. The official stance of the British Health Protection Agency
(HPA) is that "[T]here is no consistent evidence to date that WiFi and
WLANs adversely affect the health of the general population", but also
that "... it is a sensible precautionary approach ... to keep the
situation under ongoing review ...". In a 2018 statement, the FDA
said that "the current safety limits are set to include a 50-fold
safety margin from observed effects of Radio-frequency energy exposure".
In 2011, International Agency for Research on Cancer (IARC), an agency of the World Health Organization, classified wireless radiation as Group 2B –
possibly carcinogenic. That means that there "could be some risk" of
carcinogenicity, so additional research into the long-term, heavy use of
wireless devices needs to be conducted.
Exposure
Mobile phones
A mobile phone connects to the telephone network by radio waves exchanged with a local antenna and automated transceiver called a cellular base station (cell site or cell tower). The service area served by each provider is divided into small geographical areas called cells, and all the phones in a cell communicate with that cell's antenna. Both the phone and the tower have radio transmitters
which communicate with each other. Since in a cellular network the
same radio channels are reused every few cells, cellular networks use
low power transmitters to avoid radio waves from one cell spilling over
and interfering with a nearby cell using the same frequencies.
Mobile phones are limited to an equivalent isotropic radiated power
(EIRP) output of 3 watts, and the network continuously adjusts the
phone transmitter to the lowest power consistent with good signal
quality, reducing it to as low as one milliwatt when near the cell
tower. Tower channel transmitters usually have an EIRP power output of
around 50 watts. Even when it is not being used, unless it is turned
off, a mobile phone
periodically emits radio signals on its control channel, to keep contact
with its cell tower and for functions like handing off the phone to
another tower if the user crosses into another cell. When the user is
making a call, the phone transmits a signal on a second channel which
carries the user's voice. Existing 2G, 3G, and 4G networks use frequencies in the UHF or low microwave bands, 600 MHz to 3.5 GHz. Many household wireless devices such as WiFi networks, garage door openers, and baby monitors use other frequencies in this same frequency range.
Radio waves decrease rapidly in intensity by the inverse square
of distance as they spread out from a transmitting antenna. So the
phone transmitter, which is held close to the user's face when talking,
is a much greater source of human exposure than the tower transmitter,
which is typically at least hundreds of metres away from the user. A
user can reduce their exposure by using a headset and keeping the phone itself further away from their body.
Next generation 5G cellular networks, which began deploying in 2019, use higher frequencies in or near the millimetre wave band, 24 to 52 GHz.
Millimetre waves are absorbed by atmospheric gases so 5G networks will
use smaller cells than previous cellular networks, about the size of a
city block. Instead of a cell tower, each cell will use an array of
multiple small antennas mounted on existing buildings and utility poles.
In general, millimeter waves penetrate less deeply into biological
tissue than microwaves, and are mainly absorbed within the first
centimeter of the body surface.
Cordless phones
The HPA also says that due to the mobile phone's adaptive power ability, a DECT
cordless phone's radiation could actually exceed the radiation of a
mobile phone. The HPA explains that while the DECT cordless phone's
radiation has an average output power of 10 mW, it is actually in the
form of 100 bursts per second of 250 mW, a strength comparable to some
mobile phones.
Wireless networking
Most wireless LAN
equipment is designed to work within predefined standards. Wireless
access points are also often close to people, but the drop off in power
over distance is fast, following the inverse-square law. However, wireless laptops are typically used close to people. WiFi had been anecdotally linked to electromagnetic hypersensitivity but research into electromagnetic hypersensitivity has found no systematic evidence supporting claims made by sufferers.
Users of wireless networking devices are typically exposed for
much longer periods than for mobile phones and the strength of wireless
devices is not significantly less. Whereas a Universal Mobile Telecommunications System (UMTS) phone can range from 21 dBm (125 mW) for Power Class 4 to 33 dBm (2W) for Power class 1, a wireless router can range from a typical 15 dBm (30 mW) strength to 27 dBm (500 mW) on the high end.
However, wireless routers are typically located significantly
farther away from users' heads than a phone the user is handling,
resulting in far less exposure overall. The Health Protection Agency
(HPA) says that if a person spends one year in a location with a WiFi
hot spot, they will receive the same dose of radio waves as if they had
made a 20-minute call on a mobile phone.
The HPA's position is that "... radio frequency (RF) exposures
from WiFi are likely to be lower than those from mobile phones." It also
saw "... no reason why schools and others should not use WiFi
equipment."
In October 2007, the HPA launched a new "systematic" study into the
effects of WiFi networks on behalf of the UK government, in order to
calm fears that had appeared in the media in a recent period up to that
time". Michael Clark of the HPA says published research on mobile phones and masts does not add up to an indictment of WiFi.
Effects studied
Blood–brain barrier
A
2010 review stated that "The balance of experimental evidence does not
support an effect of 'non-thermal' radio frequency fields" on the
permeability of the blood-brain barrier, but noted that research on low frequency effects and effects in humans was sparse.
A 2012 study of low-frequency radiation on humans found "no evidence
for acute effects of short-term mobile phone radiation on cerebral blood
flow".
Cancer
There is no strong or consistent evidence that mobile phone use
increases the risk of getting brain cancer or other head tumors. The
United States National Cancer Institute points out that "Radiofrequency
energy, unlike ionizing radiation,
does not cause DNA damage that can lead to cancer. Its only
consistently observed biological effect in humans is tissue heating. In
animal studies, it has not been found to cause cancer or to enhance the
cancer-causing effects of known chemical carcinogens." The majority of
human studies have failed to find a link between mobile phone use and
cancer. In 2011 the IARC, a World Health Organization working group, classified mobile phone use as "possibly carcinogenic to humans".
The IARC summed up their conclusion with: "The human epidemiological
evidence was mixed. Several small early case–control studies were
considered to be largely uninformative. A large cohort study showed no
increase in risk of relevant tumours, but it lacked information on level
of mobile-phone use and there were several potential sources of
misclassification of exposure. The bulk of evidence came from reports of
the INTERPHONE study, a very large international, multicentre
case–control study and a separate large case–control study from Sweden
on gliomas and meningiomas of the brain and acoustic neuromas. While
affected by selection bias and information bias to varying degrees,
these studies showed an association between glioma and acoustic neuroma
and mobile-phone use; specifically in people with highest cumulative use
of mobile phones, in people who had used mobile phones on the same side
of the head as that on which their tumour developed, and in people
whose tumour was in the temporal lobe of the brain (the area of the
brain that is most exposed to RF radiation when a wireless phone is used
at the ear)" The CDC states that no scientific evidence definitively answers whether mobile phone use causes cancer.
In a 2018 statement, the US Food and Drug Administration
said that "the current safety limits are set to include a 50-fold
safety margin from observed effects of radiofrequency energy exposure".
On 1 November 2018, the US National Toxicology Program published the final version (after peer review
that was performed through March 2018) of its "eagerly anticipated"
study using rats and mice, conducted over some ten years. This report
concludes after the review with an updated statement that "there is
clear evidence that male rats exposed to high levels of radio frequency
radiation (RFR) like that used in 2G and 3G cell phones developed
cancerous heart tumors.... There was also some evidence of tumors in the
brain and adrenal gland of exposed male rats. For female rats, and male
and female mice, the evidence was equivocal as to whether cancers
observed were associated with exposure to RFR".
An early analysis of preliminary results issued by the National
Toxicology Program had indicated that due to such issues as the
inconsistent appearances of "signals for harm" within and across species
and the increased chances of false positives due to the multiplicity of
tests, the positive results seen are more likely due to random chance.
The full results of the study were released for peer review in February
2018.
Male fertility
A decline in male sperm quality has been observed over several decades. Studies on the impact of mobile radiation on male fertility are conflicting, and the effects of the radio frequency electromagnetic radiation (RF-EMR) emitted by these devices on the reproductive systems are currently under active debate. A 2012 review concluded that "together, the results of these studies have shown that RF-EMR decreases sperm count and motility and increases oxidative stress".
A 2017 study of 153 men that attended an academic fertility clinic in
Boston, Massachusetts found that self-reported mobile phone use was not
related to semen quality, and that carrying a mobile phone in the pants
pocket was not related to semen quality.
Electromagnetic hypersensitivity
Some users of mobile phones and similar devices have reported feeling various non-specific symptoms
during and after use. Studies have failed to link any of these symptoms
to electromagnetic exposure. In addition, EHS is not a recognized
medical diagnosis.
Glucose metabolism
According to the National Cancer Institute,
two small studies exploring whether and how mobile phone radiation
affects brain glucose metabolism showed inconsistent results.
Effects on children
A report from the Australian Government's Radiation Protection and Nuclear Safety Agency (ARPANSA) in June 2017 noted that:
The 2010 WHO Research Agenda identified a lack of sufficient evidence relating to children and this is still the case. ... Given that no long-term prospective study has looked at this issue to date this research need remains a high priority. For cancer in particular only one completed case-control study involving four European countries has investigated mobile phone use among children or adolescents and risk of brain tumour; showing no association between the two (Aydin et al. 2011). ... Given this paucity of information regarding children using mobile phones and cancer ... more epidemiological studies are needed.
Base stations
Cellular Mobile and UHF Antenna Tower with multiple Antennas
Experts consulted by France considered it was mandatory that the main
antenna axis should not to be directly in front of a living place at a
distance shorter than 100 metres. This recommendation was modified in 2003
to say that antennas located within a 100-metre radius of primary
schools or childcare facilities should be better integrated into the
city scape and was not included in a 2005 expert report.
The Agence française de sécurité sanitaire environnementale as of 2009,
says that there is no demonstrated short-term effect of electromagnetic
fields on health, but that there are open questions for long-term
effects, and that it is easy to reduce exposure via technological
improvements. A 2020 study in Environmental Research found that "Although direct causation of negative human health effects from (radio frequency radiation)
from cellular phone base stations has not been finalized, there is
already enough medical and scientific evidence to warrant long-term
liability concerns for companies deploying cellular phone towers" and thus recommended voluntary setbacks from schools and hospitals.
Safety standards and licensing
To
protect the population living around base stations and users of mobile
handsets, governments and regulatory bodies adopt safety standards,
which translate to limits on exposure levels below a certain value.
There are many proposed national and international standards, but that
of the International Commission on Non-Ionizing Radiation Protection
(ICNIRP) is the most respected one, and has been adopted so far by more
than 80 countries. For radio stations, ICNIRP proposes two safety
levels: one for occupational exposure, another one for the general
population. Currently there are efforts underway to harmonize the
different standards in existence.
Radio base licensing procedures have been established in the
majority of urban spaces regulated either at municipal/county,
provincial/state or national level. Mobile telephone service providers
are, in many regions, required to obtain construction licenses, provide
certification of antenna emission levels and assure compliance to ICNIRP
standards and/or to other environmental legislation.
Many governmental bodies also require that competing
telecommunication companies try to achieve sharing of towers so as to
decrease environmental and cosmetic impact. This issue is an influential
factor of rejection of installation of new antennas and towers in
communities.
The safety standards in the US are set by the Federal Communications Commission
(FCC). The FCC has based its standards primarily on those standards
established by the National Council on Radiation Protection and
Measurements (NCRP) a Congressionally chartered scientific organization
located in the WDC area and the Institute of Electrical and Electronics Engineers (IEEE), specifically Subcommittee 4 of the "International Committee on Electromagnetic Safety".
Switzerland has set safety limits lower than the ICNIRP limits for certain "sensitive areas" (classrooms, for example).
In March 2020, for the first time since 1998, ICNIRP updated
radiation requirements for mobile phones using 5G. Admitting that the
network is generally safe, the Commission, at the same time, restricted
the exposure of the whole body and greater exposure of small parts of
the body to frequencies above 6 GHz.
Lawsuits
In the US, personal injury lawsuits have been filed by individuals against manufacturers (including Motorola, NEC, Siemens, and Nokia) on the basis of allegations of causation of brain cancer and death. In US federal courts, expert testimony relating to science must be first evaluated by a judge, in a Daubert hearing, to be relevant and valid before it is admissible as evidence. In a 2002 case against Motorola,
the plaintiffs alleged that the use of wireless handheld telephones
could cause brain cancer and that the use of Motorola phones caused one
plaintiff's cancer. The judge ruled that no sufficiently reliable and
relevant scientific evidence in support of either general or specific
causation was proffered by the plaintiffs, accepted a motion to exclude
the testimony of the plaintiffs' experts, and denied a motion to exclude
the testimony of the defendants' experts.
Two separate cases in Italy, in 2009 and 2017, resulted in pensions being awarded to plaintiffs who had claimed their benign brain tumors
were the result of prolonged mobile phone use in professional tasks,
for 5–6 hours a day, which they ruled different from non-professional
use.
Precautions
Precautionary principle
In 2000, the World Health Organization (WHO) recommended that the precautionary principle could be voluntarily adopted in this case. It follows the recommendations of the European Community for environmental risks.
According to the WHO, the "precautionary principle" is "a risk
management policy applied in circumstances with a high degree of
scientific uncertainty, reflecting the need to take action for a
potentially serious risk without awaiting the results of scientific
research." Other less stringent recommended approaches are prudent avoidance principle and as low as reasonably practicable.
Although all of these are problematic in application, due to the
widespread use and economic importance of wireless telecommunication
systems in modern civilization, there is an increased popularity of such
measures in the general public, though also evidence that such
approaches may increase concern.
They involve recommendations such as the minimization of usage, the
limitation of use by at-risk population (e.g., children), the adoption
of phones and microcells with as low as reasonably practicable levels of
radiation, the wider use of hands-free and earphone technologies such as Bluetooth
headsets, the adoption of maximal standards of exposure, RF field
intensity and distance of base stations antennas from human habitations,
and so forth.
Overall, public information remains a challenge as various health
consequences are evoked in the literature and by the media, putting
populations under chronic exposure to potentially worrying information.
Precautionary measures and health advisories
In May 2011, the World Health Organization's International Agency for Research on Cancer
announced it was classifying electromagnetic fields from mobile phones
and other sources as "possibly carcinogenic to humans" and advised the
public to adopt safety measures to reduce exposure, like use of
hands-free devices or texting.
Some national radiation advisory authorities, including those of Austria, France, Germany, and Sweden, have recommended measures to minimize exposure to their citizens. Examples of the recommendations are:
- Use hands-free to decrease the radiation to the head.
- Keep the mobile phone away from the body.
- Do not use telephone in a car without an external antenna.
The use of "hands-free" was not recommended by the British Consumers' Association in a statement in November 2000, as they believed that exposure was increased. However, measurements for the (then) UK Department of Trade and Industry and others for the French Agence française de sécurité sanitaire environnementale showed substantial reductions. In 2005, Professor Lawrie Challis and others said clipping a ferrite bead onto hands-free kits stops the radio waves travelling up the wire and into the head.
Several nations have advised moderate use of mobile phones for children. A journal by Gandhi et al. in 2006 states that children receive higher levels of Specific Absorption Rate (SAR). When 5- and 10-year olds are compared to adults, they receive about 153% higher SAR levels. Also, with the permittivity
of the brain decreasing as one gets older and the higher relative
volume of the exposed growing brain in children, radiation penetrates
far beyond the mid-brain.
5G
In the beginning of the year 2020 Slovenia stopped the deployment of the 5G technology as a precaution due to health concerns.
During the 2019–20 coronavirus pandemic, misinformation circulated claiming that 5G networks contribute to the spread of COVID-19.
Bogus products
Products have been advertised that claim to shield people from EM radiation from mobile phones; in the US the Federal Trade Commission
published a warning that "Scam artists follow the headlines to promote
products that play off the news – and prey on concerned people."
According to the FTC, "there is no scientific proof that
so-called shields significantly reduce exposure from electromagnetic
emissions. Products that block only the earpiece – or another small
portion of the phone – are totally ineffective because the entire phone
emits electromagnetic waves." Such shields "may interfere with the
phone's signal, cause it to draw even more power to communicate with the
base station, and possibly emit more radiation." The FTC has enforced false advertising claims against companies that sell such products.
