U.S. regulators are looking into how radio frequencies emitted by cellphones and other wireless devices affect people amid lingering concerns about the risks of cellphone radiation.

The Federal Communications Commission said on Friday it is seeking comment from other agencies and health experts on whether it should update its standards limiting exposure to phones’ electromagnetic fields, as they apply to children in particular.

The FCC last reviewed those standards in 1996, before the ubiquitous use of mobile devices. But the agency’s officials say they have no reason to believe the current standards are inadequate and called the proceeding, which was announced in documents posted online on Friday, a routine review.

Scientists have been unable to determine whether radio waves emitted by mobile devices pose threats to the brain or other parts of the human body but studies continue as the number of mobile devices Americans own, already in the hundreds of millions, continues to grow.

(Reporting by Alina Selyukh; Editing By Todd Eastham)