While attempting to understand the association between cellphone use and cancer risk, researchers established that the brain's dominant side may choose which ear to use while talking on a cellphone.

A person's speech and language center is found on the dominant side of the brain. Ninety-five percent of the population's language center is on the left side, and these people tend be right handed. Those who are left handed tend to have their centers on the right side of the brain. Researchers found that about 70 percent of people surveyed held their phone up to the ear that was on the same side as their dominant hand, HealthDay News reported.

This study, which is published in the May issue of JAMA Otolaryngology — Head & Neck Surgery, was motivated by the possibility that doctors could be able to quickly locate a patient's language center before conducting a risky brain surgery. Naturally, the language center should be avoided and preserved during surgery for fear of damage to the area.

"In essence this could be used as a poor man's Wada test," Dr. Michael Seidman, director of the division of otologic/neurotologic surgery at the Henry Ford Health System in West Bloomfield, Mich., said. "[The Wada test] is the standard test used today to determine exactly where a surgical patient's language center is located, which is critical information to have if you want to carefully preserve a person's language abilities."

But Seidman described the test as "risky" and said, "By looking at how a person uses their cellphone, which side they listen to, you can get a shorthand insight into brain dominance. It's not a foolproof guarantee, but I would say it's a pretty reliable and safe way of going about it."

Researchers analyzed answers from over 700 surveys in which people gave information regarding their cellphone use; their favored hand for completing tasks such as writing, throwing, and cellphone handling; and any hearing-loss issues. The researchers were also informed of any history of brain, head, or neck tumors as well. All of those surveyed were members of a web-based otology (hearing) discussion group, or patients already undergoing Wada and MRI testing for other purposes.

They found that 90 percent of the people were right handed, and 68 percent of them used their right ear, while 25 percent used their left ear and 7 percent used both ears.

The results were almost identical for left-handed people: 72 percent used their left ear, 23 percent used their right ear, and 5 percent used both ears.

The team concluded that the cellphone handling habits of the participants corresponded to the side our brains which is most dominant.

"The next question is if this information may help us figure out whether or not cellphone use is associated with cancer risk," Seidman said.

However, Seidman acknowledges that if such an association existed, there would be more brain, neck, and head cancer on the right side of the brain than there currently is.

"But the question of cancer risk and cell phone use is very controversial," he said. "We just don't know yet. Much more work needs to be done."

There is no research to date that proves cellphones cause cancer. In one case-control study, there were no significant increases in brain or central nervous system cancers related to cellphone use. Although one analysis showed a modest increase in the risk of glioma among the participants who said they spent the most time on their phones, researchers decided the data was inconclusive because the amount of reported cell phone use was unlikely. Other participants who reported using their cellphones for shorter periods appeared to have a reduced risk of brain cancer, according to the National Cancer Institute.

Still, Dr. Joe Verghese, a professor of neurology at the Albert Einstein College of Medicine in New York City, believes there could be other variables influencing the way people use their phones.

"It could also be that right-handed people, for example, simply reach for their cellphone with their dominant hand, and then naturally feel more comfortable continuing to keep it and use it on their right side because it would feel awkward to pick up a phone with your right hand and then switch it over to your left side," he said. "If that's the case, this could actually be about motor dominance more than auditory or language dominance."

Sources:

M Seidman, B Siegel, P Shah, S Bower. Hemispheric Dominance and Cell Phone Use. JAMA Otolaryngology — Head & Neck Surgery. May 2013.

E Cardis, I Deltour, M Vrijheid, E Combalot, et al. Brain Tumour Risk in Relation to Mobile Telephone Use: Results of the INTERPHONE International Case-control Study. International Journal of Epidemiology. 2010.