Pager-sized protection

Travelers entering the United States face a new inspection: radiation tests. The new Bureau of Customs and Border Protection says new pager-sized detectors will help screen for terrorist activity. They may keep out a dirty bomb, a suitcase nuke, or some other source of nasty radiation.

Inspectors carry the small gizmos on their belts and use them at all U.S. points of entry. Some passengers may not even notice them unless they beep or vibrate when radiological activity is spotted. The scanners cost about $2,500 each, and Customs plans to distribute them to all 9,000 of its inspectors.

Scanners aren't foolproof, however. Their range is limited, and they can sound alerts for innocuous radiation, like that from people who recently had an X-ray or chemotherapy treatment. The potassium in bananas can set them off too. To prevent false positives, some inspectors have other devices that signal what the radioactive material is. Bigger scanners examine vehicles.

Customs spokesman Dean Boyd said officials know that all technology has limits: "The pagers-they are not a silver bullet. They are one piece of technology that we use, and we use a broad range of technologies to detect radiation."