Electromagnetic fields and public health: mobile phones

Mobile or cellular phones are huge part of our modern daily lives. In many countries, over half the population use mobile phones and the market is growing rapidly. In 2014, there were estimated to be 6.9 billion subscriptions worldwide. Mobile phones are so wide spread that in some areas they are the only phones in use thus, in other words, more reliable than landline phones. Given the large number of mobile phone users, it is important to investigate, understand and monitor any potential public health impact of new technologies and electromagnetic fields.

Mobile phones work in a way that they communicate by transmitting radio waves through a network of antennas called base stations. Radiofrequency waves are electromagnetic fields, and unlike ionizing radiation (such as X-rays or gamma rays) can neither break chemical bonds nor cause ionization in the human body.

Mobile phones are low-powered radiofrequency transmitters, operating at frequencies between 450 and 2700 MHz with peak powers in the range of 0.1 to 2 watts. The handset only transmits power when it is turned on. The closer the device comes to our body, the higher the power of radiation becomes, and vice versa when increasing distance. The person who is texting, using internet or using a “hands free” device, will be exposed to the radiofrequency fields at a lower rate than a person who is using the device to make calls by holding it pressed against their head.

In addition to using “hands free” devices, which keep mobile phones away from the body while making calls, we can reduce the exposure by making the calls shorter. If we use the phone in areas with good reception, we can reduce the exposure since phones use less power to transmit the calls. In areas with low quality reception mobile phones use more power to transmit and therefore cause higher exposure to radiofrequency fields. Mobile phones are prohibited in hospitals and on airplanes since the radiofrequency signals may interfere with some medical devices or navigation systems.

Short term effects include tissue heating as result of interaction between radiofrequency energy and the human body. With the current frequencies used by current mobile phones most of the energy is absorbed by the skin and other superficial tissues, resulting in temperature rise in the brain or any other organs of the body. Many studies have investigated the effects of RF fields on brain electrical activity, cognitive function, sleep, heart rate and blood pressure. To date research does not suggest that short time exposure has adverse health effects to levels of radiation below that that causes tissue heating.

Moreover, Epidemiological research examining potential long-term risks from radiofrequency exposure have mostly looked for association between brain tumors and mobile phone use. However, because many cancers are not detectable until many years after the interactions (that led to the tumor) and since mobile phones were not widely used until the early 1990s, epidemiological studies at present can only assess those cancers that become evident within shorter time periods.

Several large multinational epidemiological studies have been completed or are ongoing, including case-control studies and prospective cohort studies examining a number of health endpoints in adults. “Interphone“, The largest retrospective case-control study to date on adults coordinated by the International Agency for Research on Cancer (IARC), was designed to determine whether there are links between the use of mobile phones and head or neck cancers in adults.

The international pooled analysis of data gathered from 13 participating countries found no increased risk of glioma or meningioma with mobile phone use of more than 10 years. There are some indications of an increased risk of glioma for those who reported the highest 10% of cumulative hours of cell phone use, although there was no consistent trend of increasing risk with greater duration of use. The researchers concluded that biases and errors limit the strength of these conclusions and prevent a causal interpretation.

Based largely on these data, IARC has classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B), a category used when a causal association is considered credible, but when chance, bias or confounding cannot be ruled out with reasonable confidence.

While an increased risk of brain tumors is not established, the increasing use of mobile phones and the lack of data for mobile phone use over time (periods longer than 15 years) warrant further research of mobile phone use and brain cancer risk. In particular with the recent popularity of mobile phone use among younger people, therefore a potentially longer lifetime of exposure. The World Health Organization has promoted further research on this group. Several studies investigating potential health effects in children and adolescents are underway.

Source: WHO official web page