Mobile phones are pretty much ubiquitous. And so are discussions on the adverse health effects of electromagnetic fields associated with cell phone radiation.

To address this concern, the World Health Organization (WHO) established the International Electromagnetic Fields Project in 1996. This project was designed to assess the scientific evidence and conduct a risk assessment of all studied health outcomes from radiofrequency electromagnetic field (RF-EMF) exposure; this study should be ready by 2016.

Meanwhile, many studies have addressed this issue, attempting to determine if the use of cell phones can indeed be harmful. This is of obvious relevance: given the massive number of mobile phone users, this is a matter of public health with tremendous impact.

Despite many epidemiological studies, there is still no consensus.

Radiofrequency electromagnetic fields

Exposure to RF-EMF occurs not only from using cell phones, but also from using cordless phones, Bluetooth or Wi-Fi, and from mobile phone base stations, broadcast antennas, and even medical applications, for example. But the highest exposure normally comes from transmitters close to the body, such as mobile phones.

The exposure to the low-powered radiofrequency transmitted by phones decreases rapidly with increasing distance from the handset. This means that texting, accessing the Internet, or using a hands-free device entails a much lower exposure to RF-EMF than holding the phone against the head. Using a hands-free kit decreases the radiation exposure to the brain by around 90%; but logically, it increases exposure to other parts of the body.

Despite their higher power, exposure to RF-EMF from rooftop or tower-mounted base stations and from TV and radio stations is significantly lower than that from global system for mobile communications (GSM) devices. Also, third-generation (3G) phones emit a significantly lower amount of RF energy than GSM phones, while Bluetooth wireless hands-free kits have a much lower emission than mobile phones in general.

Although the most relevant factors determining the induced EMFs in the human body are the distance of the radiofrequency source from the body and the output power level, other factors such as the direction of wave incidence on the body, anatomical features, including height, body-mass index, posture, and properties of the tissues also contribute to EMF generation.

EMFs generated by radiofrequency sources induce electric and magnetic fields in our body. However, unlike X-rays or gamma rays, RF waves and EMFs are non-ionizing radiation. This means that this type of radiation doesn’t have enough energy to break chemical bonds and therefore can’t damage DNA and shouldn’t directly cause cancer.

Health effects of mobile phones

A large number of studies have been performed to assess the health risks of mobile phone radiation. WHO’s factsheet on electromagnetic fields and public health, last reviewed in October 2014, states that, to date, no adverse health effects have been definitely established as being caused by mobile phone use.

Most studies have quite naturally mostly focused on the effects of RF-EMF on the brain. Tissue heating is the main consequence of RF-EMF in the body, but at the frequencies used by mobile phones, most of the energy is absorbed by the skin and other superficial tissues, with little or no impact on the brain’s temperature.

The short-term effects of RF-EMF on brain electrical activity, cognitive function, sleep, heart rate and blood pressure have been studied and, again, no consistent evidence of adverse health effects has been found so far.

In what concerns long-term effects of RF-EMF exposure, a link is hard to determine since many cancers are not detectable until many years after the induction of the tumor, and mobile phones have only been widely used since the early 1990s. Nevertheless, animal research studies have consistently invalidated an increased cancer risk due to long-term exposure to RF-EMF.

The largest retrospective case-control study to date, INTERPHONE, was coordinated by the International Agency for Research on Cancer (IARC) and was designed to assess any possible links between cell phone use and head and neck cancers in adults. IARC gathered data from 13 countries and found no increased risk of glioma or meningioma with mobile phone use of more than 10 years.

However, they did find some indications of an increased risk of glioma for those with the highest cumulative hours of cell phone use. Still, there was no consistent trend of increasing risk with longer use.

Although they concluded that the strength of the gathered data was insufficient to ascertain a causal link, IARC classified RF-EMF as possibly carcinogenic to humans, placing it in a category that considers that a causal association is credible, but that chance, bias or confounding factors cannot be ruled out. So, no certainty.

These findings match the conclusions of a systematic review published in 2014. This study reviewed all the epidemiologic data of glioma, meningioma, and acoustic neuroma in relation to mobile phone use published by the end of 2012, and carried out a consistency analysis of the results. It was found that short-term use or non-regular use of mobile phones had no association with the development of brain tumors.

Long-term use on the other hand, was shown to possibly lead to a 19–40% increase in the incidence of glioma, but the data was highly heterogeneous and not statistically significant. So, again, no certainty.

Overall, the available data indicates that a modest increase in brain cancer risk cannot yet be excluded among heavy or long-term cell phone users. The risks of longer lifetime uses of cell phones are still to be studied. Also, the use of mobile phones at increasingly younger ages may make a difference: the average RF energy deposition in the brain and in the bone marrow of the skull is higher in children than in adults. Studies investigating potential health effects in children and adolescents are also in progress.

We’ll see what the WHO has to say next year.

References

Baan R, Grosse Y, Lauby-Secretan B, El Ghissassi F, Bouvard V, Benbrahim-Tallaa L, Guha N, Islami F, Galichet L, Straif K, & WHO International Agency for Research on Cancer Monograph Working Group (2011). Carcinogenicity of radiofrequency electromagnetic fields. The Lancet. Oncology, 12 (7), 624-6 PMID: 21845765

Christ A, Gosselin MC, Christopoulou M, Kühn S, & Kuster N (2010). Age-dependent tissue-specific exposure of cell phone users. Physics in medicine and biology, 55 (7), 1767-83 PMID: 20208098

INTERPHONE Study Group (2010). Brain tumour risk in relation to mobile telephone use: results of the INTERPHONE international case-control study. International journal of epidemiology, 39 (3), 675-94 PMID: 20483835

INTERPHONE Study Group (2011). Acoustic neuroma risk in relation to mobile telephone use: results of the INTERPHONE international case-control study. Cancer epidemiology, 35 (5), 453-64 PMID: 21862434

Lagorio S, & Röösli M (2014). Mobile phone use and risk of intracranial tumors: a consistency analysis. Bioelectromagnetics, 35 (2), 79-90 PMID: 24375548

The World Health Organization. Electromagnetic fields and public health: mobile phones. Fact sheet N°193, Reviewed October 2014

Image via ARENA Creative / Shutterstock.