Does prolonged cell phone use cause brain tumors?

It could just be coincidental, but a neurologist friend again saw a relatively young patient recently with a brain tumor. This patient, just like the few previous ones we mentioned in this column, was also a heavy user of cellular phones.

Sometime last year, we reported a case of a sales manager who was found on CT scan to have a brain tumor. He logged in at least an hour of calls made and received in his cell phone daily due to his job as a national sales manager. His tumor was in the right side of his brain and he usually placed his cell phone on the right ear when he used it.

The major concern about cell phones is that they are a source of radiation because they transmit radio frequency (RF) waves, a form of energy located on the electromagnetic spectrum between FM radio waves and microwaves. Although theoretically, this type of radiation—called nonionizing—doesn’t have enough energy to directly damage the cell’s DNA, the cumulative effect of years of heavy cell phone use might have adverse effects that could predispose one to tumor formation.

Cell phone radiation

The cell phone’s antenna is the major source of RF waves. Most phones now don’t have any visible external antennas, and in these phones, the antenna is part of the body of the hand-held phone. The RF waves are strongest therefore at the body part of the phone, which is usually held against the side of the head when one makes or receives a call. Theoretically, the closer the antenna—which is in the phone’s body—is to the user’s head, the greater is the exposure to cell phone radiation. For heavy cell phone users, hands-free devices, allowing the cell phone to be away from the head or face, is therefore recommended.

The last time that we reviewed the scientific literature on the relationship between cell phone usage and brain tumor, there was no clear link between the two. A pooled analysis of around 30 studies evaluating possible links showed that:

Patients with brain tumors do not report more cell phone use compared to the controls.

There is no “dose-response relationship”—a tendency for the risk of brain tumors to increase with increasing cell phone use, although these studies only considered usual or regular cell phone usage.

There is also no clear link between the side of the head on which the brain tumor occurred and the side on which the cell phone was generally used.

Limitations

All the studies included in this pooled analysis had one limitation—they have not been able to follow people for long periods of time. Experts raised the possibility that exposure to irradiation may cause development of tumors many years or even decades after the exposure. Cell phones have only been around for less than 25 years so we still cannot be sure of their possible long-term health effects.

Another argument worth noting about previous studies was that  the largest data source was a series of studies called the Interphone studies, which were funded by the wireless communications industry. Conducted in 13 countries, the Interphone studies concluded that cell phone exposure did not increase the risk of brain tumors. However, many experts questioned the findings because of possible bias associated with industry funding, plus the vital flaw that the duration of cell phone use was of short duration.

We reviewed the scientific literature again for any updates and we came accross a well-designed study published early this year in the Journal of Computer Assisted Tomography suggesting that long-term exposure to microwaves from cellular phones may lead to an increased risk of brain tumors.

“We conclude that the current standard of exposure to microwave during mobile phone use is not safe for long-term exposure and needs to be revised,”  the study authors concluded.

Some precautions

The authors suggested some precautions to reduce exposure to cell phone and cordless phone radiation:

The number and length of phone calls should be limited.

Children’s cell phone use should be restricted because they appear to have a higher risk.

Communicating by text instead of voice should be preferred.

Use of hands-free devices is also recommended, but the group specifically recommended a special “air tube” headset (not a regular wired headset).

Newer phones and other technologies with reduced exposure mechanisms are also recommended.

Perhaps it’s about time that the government should step in and mandate precautionary measures to protect cell phone users, especially children and adolescents. The unlimited promotional offers of telecom companies are also encouraging people to call instead of just texting their messages. Just like in the cigarette packaging, it may not be a bad idea to require all cell phones to have this label: “Prolonged usage of this device may be hazardous to one’s health.”