Maryland officials are searching for a device stolen from a Bethesda construction site Monday that contains a small amount of cesium-137, a radioactive substance that, in a larger quantity, could be used as a component in a “dirty bomb,” according to experts. Montgomery County police spokeswoman Joyce Utter said yesterday that several other items were stolen from the construction site, in the 7300 block of River Road. The gauge is owned by Engineering Consulting Services in Frederick.
The moisture density gauge, which is in a 40-pound transport case the size of a footlocker, contains a small amount of cesium-137, which is common in medical devices and food irradiation machines. Physicists and nuclear proliferation experts have voiced concern in recent months that the element, even in very small quantities, is not tracked closely enough by federal and state authorities. The stolen device is used to measure moisture and compaction in soils and other aggregates. It poses no immediate public health risk as long as the cesium-137 is not dispersed, said Richard McIntire, spokesman for the Maryland Department of the Environment.
A January report by the Center for Nonproliferation Studies at the Monterey Institute of International Studies called for closer oversight of the tens of thousands of radioactive devices used for medical diagnostics and food irradiation that contain cesium-137 and cobalt-60. The gauge stolen Monday had 10 millicuries of cesium-137 -- an amount that Charles Ferguson, a physicist and co-author of the report, said “would probably pose very little harm.”
But, Ferguson said, he and others have voiced increased concern since Sept. 11, 2001, that terrorists could assemble enough small quantities of cesium-137 to create a bomb that uses conventional explosives to disperse a radioactive cloud.
There are 101 users licensed to own and operate moisture density gauges in Maryland, and the machines have been regulated in the state since 1971, McIntire said. He said one “goes missing” about once a year, and the state is required to report each disappearance to the Nuclear Regulatory Commission.
Any information should be directed to the Montgomery police at 301-657-0112.