For years, there have been worries that cellphones can cause anything from cancer to brain tumours. Now, a study is sounding a new warning for cellphone users.

The small study is being presented Wednesday at a meeting of the American Academy of Otolaryngology-Head and Neck and Surgery Foundation in Washington, D.C. It suggests that long term cellphone use, particularly using the phone primarily on one ear, may cause inner ear damage.

The study comes at a time when even young children are carrying cellphones and using them for everything from gossip sessions to listening to music with the built-in MP3 players.

Dr. Naresh Panda from Chandigarh, India studied 100 young cellphone users and 50 people who had never used a cellphone. He found no significant difference of hearing abnormalities between those who regularly used the phones and those who didn't. But those who used the phone for more than 60 minutes a day for over four years had noticeable losses in high frequency hearing.

The hearing loss was greatest in the dominant ear -- the ear usually used for their cellphone conversations.

Panda admits he uses a cellphone himself but says he tries to keep it to a minimum.

"We should educate the public to only use them when necessary," he told CTV News.

Panda suspects microwave emissions from the phone may be damaging tissue in the ear.

"These microwaves may do harm because of the proximity to the ear," he says.

The problem with hearing loss is that it's slow and gradual and people may not hear the difference until it's serious. Panda says there appear to be warning signals that a cellphone is damaging hearing:

• Feeling warmth in the ear after a cell conversation
• A sense of fullness in the ear
• Or a ringing in the ear

Panda found that who experienced any of the above symptoms during cellphone use seemed to have more hearing loss than those who had no complaints.

He says follow-up studies are needed to see if the hearing changes noticed in the study are reversible after making changes to cellphone habits.

Toronto-based audiologist Marshall Chasin says listening to sounds at 85 decibels or higher, over many years, can cause some hearing loss. That is the reason any phone use can be potentially more damaging than face-to-face conversations, even though the conversations don't sound any louder than face-to-face.

"Listening to a cellphone for 60 minutes or longer can potentially be damaging," believes Chasin. "The reason I say that is we know the loudness coming out of a cellphone is about 85 decibels. If you listen to that long enough, over a week, over a year, or 10, it can cause hearing loss."

Whether it's the magnetic emissions that are damaging the ear, as Panda speculates, or simply the volume level, researchers say cellphone users can lessen the risk of hearing problems by:

• Switching ears regularly
• Using an ear piece, which would eliminate the risk of magnetic waves from the phones themselves
• Or better yet, using a speaker phone.

"If you listen to a speaker phone or hands-free system as opposed to using the cell phone in one ear, that essentially means the potential damage is one-quarter of what it would have been," says Chasin.

"My rule of thumb is moderation -- if you listen to anything loud enough, long enough, it can cause hearing loss."