Science / Medicine : Additive Could Make Guns Visible in X-Ray

<i> Times science writer Thomas H. Maugh II reports from the 197th national meeting of the American Chemical Society in Dallas</i>

Plastic explosives and guns would be visible in airport X-ray machines if a newly discovered additive were incorporated during their manufacture, according to polymer chemist Johannes Smid of the State University of New York at Syracuse. Small quantities of the additive, called triphenylbismuth, make plastic materials opaque to radiation, he said.

The compound could also be added to a variety of plastic items that are used in the body, including catheters, implants, bone adhesives, sutures and artificial veins, to make it easier to see them on X-rays. When such items degenerate or slip out of position now, surgery is required to pinpoint their location. The additive could also be used in items small enough to be swallowed, such as dentures and parts of toys.

The new additive, Smid said, mixes completely and permanently with most plastics without interfering with their manufacture and is heat stable and water insoluble. It produces an opacity similar to that of aluminum.