KANSAS CITY, Mo. - There are five billion cell phone subscribers in the United States, and 303 million are from the United States, according to the National Cancer Institute.
The institute also says the amount of people using a cell phone each day and the length of the calls has increased.
Many of those users are women, and for the sake of convenience, women often store a cellular device in their bra strap.
"So they put it somewhere convenient and since there are no pockets they keep it in their bra close to their chest," said Jennifer Klemp, PhD, with the University of Kansas Cancer Center.
And retailers are catering to that audience, with bras on the market equipped with a built-in pocket to store a phone.
Tiffany Frantz, a Pennsylvania resident, said she was diagnosed with breast cancer at 21 and strongly believes it was connected to her cell phone habits.
"I kept it in my bra so that it was easy to feel on vibrate. It was easy to hear," said Frantz.
Klemp said there are no definitive studies right now that can link breast cancer to cell phones.
"It's totally case study. It's totally anecdotal, and there is very little evidence to support that carrying a cell phone close to the chest increases the risk of breast cancer," Klemp said.
Although the research isn't there, Klemp said the World Health Organization has ranked cell phones as "possibly carcinogenic to humans."
Klemp notes it's important to know how much radiation your phone is releasing. That is measured by the specific absorption rate, known as the SAR.
According to CNET, the Blackberry Curve 9310 is one of the highest on the list for emissions at 1.58 watts per kilogram. The site also says in the United States, the highest Rate allowed is 1.6 watts per kilogram. The popular iPhone 5 is listed at 1.18 watts per kilogram.
Klemp said although a connection can't be proven, it can't hurt to be more careful.
"I would just limit the exposure. Just be smart about it. I wouldn't wear it attached to me all day long," she said.
If you would like to see how much radiation your phone emits, you can check out the Federal Communications Commission website: http://fcc.us/10Ltfol