Do mobiles' magnetic fields harm humans?

Thursday December 18 2014

The Daily Telegraph reports that “mobile phones are unlikely to harm human health”, adding to the ongoing, and often conflicting, coverage of the potential health impact of environmental exposure to what some people have called “electromagnetic smog”.

This is a term used to refer to a mix of low-level electromagnetic fields that exist in the modern environment. This "smog" is not just generated by mobile phones, but also by Wi-Fi routers, tablets, laptops, power lines and cell towers. In the modern world, you are never far away from a manmade magnetic field.

Concerns regarding the impact of exposure to environmental magnetic fields on human health have existed for decades. While observational studies have suggested that there is an association between such exposure and certain diseases, no studies have demonstrated a direct causal link. Part of the difficulty in determining whether there is a direct effect is the lack of an established mechanism of action by which magnetic fields could plausibly bring about changes in the biochemical processes that occur in the body.

The most plausible mechanism of action is known as the radical pair mechanism. A "radical" is an atom or molecule that is chemically reactive due to the presence of an unpaired electron. Some biochemical processes produce brief radicals as an intermediate step in the longer process. Processes that involve, or are thought to involve, pairs of these radicals were used in this research.  

This latest study investigated whether exposure to weak magnetic fields (WMFs) alters processes in a class of enzymes known or thought to involve radical pairs, which could potentially damage cells. The researchers found that these reactions were not sensitive to magnetic fields.

Where did the story come from?

The study was carried out by researchers from the University of Manchester and was funded by the EMF Biological Research Trust, in the UK.

The study was published in the peer-reviewed Journal of the Royal Society – Interface.

The Daily Telegraph's reporting had several problems. In particular, its claim that, "the magnetic fields created by mobile phones and power lines are not harmful to human health, the University of Manchester has found". This overstates what was being researched and is not what was found.

Magnetic fields from mobile phones were not those that were studied, and the source of this incorrect link with mobiles is likely to be a press release from the University of Manchester.

On the plus side, the Telegraph stated that this was a lab-based study, and reported the need for further research to rule out other potential causal mechanisms.

What kind of research was this?

This was a lab-based study that systematically investigated the magnetic field sensitivity of one variety of enzymes. This research explored the impact of WMFs in cells under lab conditions, to test the hypothesis that biological processes involving radical pairs are a plausible mechanism of action by which environmental magnetic fields could affect biology.

It is important to note that the study did not assess the direct impact of WMFs on the development of human disease.

What did the research involve?

The researchers tested the effect of exposure to a range of weak to moderate static magnetic fields on chemical reactions involving a group of enzymes called flavin-dependent enzymes. These are responsible for a variety of essential biological processes, including energy production, DNA repair, regulating natural cell death, neural development and detoxification. Several radical pairs can temporarily occur during reactions initiated by these enzymes, and the researchers were interested in magnetically induced changes in these reactions arising from MF sensitivity.

What were the basic results?

The researchers found no magnetic field effects in the various reactions studied. They say that a number of conditions must be met for a radical pair reaction to be sensitive to magnetic fields, and that these conditions do not appear to be widespread in biology.

How did the researchers interpret the results?

The researchers concluded that we “should reconsider the likelihood of magnetic sensitivity as a result of the radical pair mechanism in biology”. This means that the mechanism of action thought to be most plausible in explaining the observed association between magnetic field exposure and human disease was not seen.


This study adds to the literature suggesting that environmental magnetic field exposure is unlikely to cause human disease. It's important to note, however, that this study did not examine disease states directly, but instead investigated a mechanism of action thought to be the most likely candidate to explain the observed link between MFs and certain medical conditions. The results of this study suggest that radical pair mechanism is not likely to be sensitive to magnetic fields.

Further potential mechanisms of action will need to be studied before drawing firm conclusions on the risk (or lack thereof) presented by mobile phones, power lines and other sources of manmade electromagnetic energy.

The results of this study do not conflict with the most recent guidance from the UK Health Protection Agency, which states that “there is no known mechanism or clear experimental evidence” that explains the association between MF exposure and diseases such as childhood leukaemia.

Other agencies have released similar guidance on magnetic field exposure. In 2002, the International Agency for Research on Cancer (IARC) categorised extremely low-frequency magnetic fields as "possibly carcinogenic [i.e. cancer-causing] to humans". A later report from the same agency concluded that there is inadequate evidence to confirm the impact of these fields on human health.

Analysis by Bazian
Edited by NHS Choices