The Senate will be holding a hearing Monday investigating a link between cell phones and cancer. 
    
The key issue is whether cell phone radiation actually seeps into the skull and causes brain cancer among users.
    
A Senate panel will be considering a new study suggesting that cell phone use for 10 years or more increases a person's risk for rare brain tumors by 50 to 90 percent. 

They say children are especially at risk, because their skulls are thinner and therefore absorb twice the radiation of an adult.  Also, according to the Senate panel, different cell phones emit different levels of radiation. 

For instance, the study said the T-Mobile Touch 3G is one of the highest emitters, while the Samsung Impression is one of the lowest.

T-Mobile says their phones meet federal safety guidelines and says scientific evidence indicates cell phones do not pose a public health risk.

So far, the FDA has found no link between cell phones and cancer.