Could talking too much on your cell phone now cause you to develop cancer in 15 years?
The largest study ever to look at links between cell phones and health was launched Thursday in Europe.
The study is different than previous ones because it really focuses on long-term effects of cell phone use, as well as whether how you carry your phone has an effect.
Up until now, most research has found that cell phones are perfectly safe, but critics say these studies haven't gone past 10 years and that cancer symptoms can take as long as 15 years to appear.
European researchers are trying to figure out if how often you use your cell phone, what you use the device for and where you carry it are risk factors for developing cancer and other neurological diseases.
On Thursday, five European countries launched the Cohort Study on Mobile Communications (COSMOS). It's the largest project of its kind looking at the cell phone habits of more than 250,000 people ages 18 to 69 in Britain, Finland, the Netherlands, Sweden and Denmark.
The study will focus on long-term use, monitoring participants for up to 30 years.
Researchers are working with mobile providers to track how often users make calls, send texts or download data.
They'll also look at how users carry their phone -- whether it's in their pants or chest pocket -- and if they use a hands-free device.
Groups like the World Health Organization, the American Cancer Society and the National Institutes of Health have all concluded that there is no data supporting connections between cell phone use and health problems.
But critics like Houlihan say these studies have only looked at 10 year data.
The researchers are tracking participants by having them fill out an ongoing online questionnaire that includes questions about their phone use, health and lifestyle.
Findings from the study will be announced as it progresses.