WEDNESDAY, June, 1 (HealthDay News) -- Can using a cellphone increase the risk of cancer?

The World Health Organization (WHO) says that it might.

After a group of scientists from 14 countries, including the United States, analyzed peer-reviewed studies on cellphones, the team announced Tuesday that there was enough evidence to categorize personal exposure as "possibly carcinogenic to humans."

This puts cellphones in the same category as lead and auto exhaust. The WHO report noted that there wasn't enough evidence to prove the radiation from cellphones is linked to cancer, but enough to alert consumers to a possible connection.

Dr. Michael Schulder, vice chairman of neurosurgery and director of the brain tumor institute at North Shore Long Island Jewish School of Medicine in Hempstead, N.Y., said the category into which WHO is putting cellphones is one that asserts there may be a concern. "That's fairly weak as a concern goes," he addded.

According to the U.S. Federal Communications Commission (FCC), which regulates radiation from cellphones, "there is no scientific evidence to date that proves that wireless phone usage can lead to cancer or a variety of other health effects, including headaches, dizziness or memory loss."

But, Schulder said, "commonsense would tell you that since a cellphone is a microwave generator and emits radiation, it has the potential to alter DNA. And it should be used in moderation."

Proving a causal relation between cellphone use and brain tumors is very hard to do, Schulder added. "It [would] take following many patients over many years to try to draw a connection," he said. "Even if a connection exists, it will be very hard to prove."

That's partly because the radiation emitted by cellphone includes very low level microwave radiation, a type of non-ionizing radiation which is absorbed near the skin. It's not ionizing radiation such as that emitted by an X-ray or CT scan. So-called ionizing radiation -- a known cause of cancer -- has enough energy to break down chemical bonds by knocking electrons off atoms or molecules (thus "ionizing" them and making them unstable).

However, to be on the safe side, Schulder recommends not speaking for long periods with the phone held to the ear. In addition, he suggests using an earpiece or speaker whenever possible. Both will keep the phone away from your head, he pointed out.

"If you use these methods, then any risk of brain tumor formation from the phone will be essentially eliminated," Schulder said.

Dr. Otis Brawley, chief medical officer for the American Cancer Society, added: "Given that the evidence remains uncertain, it is up to each individual to determine what changes they wish to make, if any, after weighing the potential benefits and risks of using a cellphone."

If some feel the potential risk outweighs the benefit, they can take actions, including limiting cellphone use or using a headset, he said. "Limiting use among children also seems reasonable in light of this uncertainty," Brawley said.

"On the other hand," Brawley said, "if someone is of the opinion that the absence of strong scientific evidence on the harms of cellphone use is reassuring, they may take different actions, and it would be hard to criticize that," he said.

Brawley also noted that many common exposures -- even coffee drinking --are classified by WHO as potentially concerning.

For those who want to know how much radiation their phone emits, the FCC recommends contacting the manufacturer.

The FCC noted that earpieces will indeed "significantly reduce the rate of energy absorption" in a user's head, but that if the phone is attached to the waist or another part of the body, "then that part of the body will absorb [radiofrequency] energy."

Besides ear pieces, there are other devices (such as metal cellphone shields) that claim to protect users from cellphone radiation or reduce it, but the FCC is skeptical of them.

"Studies have shown that these devices generally do not work as advertised," an FCC official statement cautioned. "In fact, they may actually increase radio frequency absorption in the head due to their potential to interfere with proper operation of the phone, thus forcing it to increase power to compensate," the agency stated.

Another expert, Dr. Roberto Heros, a professor of neurological surgery at the University of Miami Miller School of Medicine, has a different take on cellphone safety.

"Our culture has become a slave to the cellphone," he said. "We feel we cannot be out of touch for one minute, and we have to be connected by the cellphone."

Heros thinks people should limit the time they spend on the devices. But, he said, "they should use it when necessary. They should not [hesitate to] make calls that are necessary, because of any fear or panic about radiation," he said.

"If you really want to save lives, then don't use the cellphone while you're driving," Heros said. "Not because of brain cancer, but because of immediate death from an accident."

More information

For more information on cell phone safety, visit the U.S. Food and Drug Administration.