DIANE SAWYER (ABC NEWS)(OC): And there was surprising medical news here at home today about all those x-rays we all get at dentists' offices. The Yale School of Medicine released a study concluding that a lot of x-rays, especially when we're children, may double the risk of a brain tumor. We asked ABC's medical editor Dr Richard Besser to brief us on what this means.
DOCTOR RICHARD BESSER (ABC NEWS)(VO): It's scary because we all get them. Dental x-rays are the most frequent source of manmade radiation in your life. The researchers compared adults who have had a brain tumor with those who haven't. And here's what they found.
DOCTOR RICHARD BESSER (ABC NEWS)(VO): Those who had a meningioma, the most common form of brain tumor, were two to five times as likely to have had frequent dental x-rays when they were children.
DOCTOR RICHARD BESSER (ABC NEWS)(OC): What is it about kids that makes them more sensitive to x-rays?
DOCTOR SAMUEL ZEICHNER (DIR OF MAXILLOFACIAL RADIOLOGY COLUMBIA UNIV): Children are still growing. During the growth process, their cells are sensitive to radiation.
DOCTOR RICHARD BESSER (ABC NEWS)(VO): The study was based only on patients' memory of how many x- rays they had as a child, not a reliable method. Doctors say we will need better studies to truly know whether these x-rays caused the tumors. Still, here's what we do know.
DOCTOR RICHARD BESSER (ABC NEWS)(VO): A dental x-ray, even ten years ago, sent about 388 microseiverts of radiation through your head. Today's machines use a tenth of that, they're much safer. And keep in mind we're all exposed to about 3,000 microseiverts a year just from natural sources.
DOCTOR SAMUEL ZEICHNER (DIR OF MAXILLOFACIAL RADIOLOGY COLUMBIA UNIV): I would say the benefits outweigh the risks.
DIANE SAWYER (ABC NEWS)(OC): So walk us through this, Rich. So how many x-rays a year is safe?
DOCTOR RICHARD BESSER (ABC NEWS)(OC): Okay, so if you have a healthy child with no dental problems, no more than one per year.
DOCTOR RICHARD BESSER (ABC NEWS)(VO): If you're a healthy adult, again, no dental problems, one every two years. You may be able to go even longer.
DOCTOR RICHARD BESSER (ABC NEWS)(OC): But the bottom line, don't let this scare you away from going to the dentist, but whenever they want to give you an x-ray, ask them, do I need this one. It's not easy, but it's important.
DIANE SAWYER (ABC NEWS)(OC): And I have found sometimes they're not even aware how many you've had.
DOCTOR RICHARD BESSER (ABC NEWS)(OC): I don't think they are.
DIANE SAWYER (ABC NEWS)(OC): So, if you can keep track of it, be sure to ask them do I need another one, is there another way to get that information.
DOCTOR RICHARD BESSER (ABC NEWS)(OC): That's a great point.