Mobile phone radiation and health

A cell phone is a wireless portable telephone that 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 cell phones in a cell communicate with that cell's antenna. Both the cell phone and the cell 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.

Cell 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. Cell phone 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 cell 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 cell 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 cell phone transmitter, which is held close to the user's face when talking, is a much greater source of human exposure than the cell tower transmitter, which is typically at least hundreds of meters away from the public on a cell tower. A user can reduce their exposure by using a headset and keeping the cell phone itself further away from their body.

Next generation 5G cellular networks, which began deploying in 2019, use higher frequencies in or near the millimeter wave band, 24 to 52 GHz.[8][9] Millimeter 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.

Users of wireless 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) mobile 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 mobile 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 Wi-Fi hotspot, they will receive the same dose of radio waves as if they had made a 20-minute call on a mobile phone.[10]

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.[11]

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.[12] However, wireless laptops are typically used close to people. WiFi had been anecdotally linked to electromagnetic hypersensitivity[13] but research into electromagnetic hypersensitivity has found no systematic evidence supporting claims made by sufferers.[14][15]

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."[16] 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".[17] Michael Clark of the HPA says published research on mobile phones and masts does not add up to an indictment of WiFi.[18][19]

A 2010 review stated that "The balance of experimental evidence does not support an effect of 'non-thermal' radiofrequency fields" on the permeability of the blood-brain barrier, but noted that research on low frequency effects and effects in humans was sparse.[20] 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".[21][22] However, several animal studies have demonstrated damage to the blood-brain barrier from phone radiation.[23][24]

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 cell phone use and cancer. In 2011 a World Health Organization working group classified cell phone use as "possibly carcinogenic to humans"[25]. The CDC states that no scientific evidence definitively answers whether cell phone use causes cancer.[21][26]

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".[6][27]

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".[28]

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.[29]

A decline in male sperm quality has been observed over several decades.[30][31][32] Studies on the impact of mobile radiation on male fertility are conflicting, and the effects of the radiofrequency electromagnetic radiation (RF-EMR) emitted by these devices on the reproductive systems are currently under active debate.[33][34][35][36] 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".[37][38] 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.[39]

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 recognised medical diagnosis.[40]

According to the National Cancer Institute, two small studies exploring whether and how cell phone radiation affects brain glucose metabolism showed inconsistent results.[21]

In 2000, the World Health Organization (WHO) recommended that the precautionary principle could be voluntarily adopted in this case.[53] 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.[54] They involve recommendations such as the minimization of cellphone usage, the limitation of use by at-risk population (e.g., children), the adoption of cellphones 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.[55]

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.[56]

Some national radiation advisory authorities, including those of Austria,[57] France,[58] Germany,[59] and Sweden,[60] 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.[61] However, measurements for the (then) UK Department of Trade and Industry[62] and others for the French Agence française de sécurité sanitaire environnementale[63] 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.[64]

Several nations have advised moderate use of mobile phones for children.[65] 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.[66]

Products have been advertised that claim to shield people from EM radiation from cell 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."[67]

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."[67] The FTC has enforced false advertising claims against companies that sell such products.[68]