At about 1:30 am on Tuesday, two armed carjackers knocked on the window of a white 2007 Volkswagen truck parked near a gas station in Tepojaco, a town in Mexico's Hidalgo State, north of Mexico City. When the driver, awakened, rolled down the window, the thieves demanded the keys to the truck, tied up the driver and his assistant, and drove off, sparking a frenzied two-day manhunt involving Mexico's civil authorities and military.
The truck, equipped with a mobile crane on the back, was carrying about 60 grams of highly radioactive cobalt-60 from a Tijuana hospital, where it had been used in discontinued cancer-treating equipment, to a storage facility. Wednesday evening, Mexico's National Commission on Nuclear Safety and Safeguards (CNSNS) said the cobalt-60 had been found — forcibly removed from its protective casing — in a field about half a mile from the truck.
Cobalt-60 is one of the materials that could be used to make a "dirty bomb," a crude radioactive weapon that could kill people but also spread chaos and panic if detonated in a heavily populated area. A dirty bomb made with cobalt-60 would "pose a threat mainly because even a fraction of a gram emits a huge number of high-energy gamma rays," the Congressional Research Service said in a 2011 report.
The good news for the public is that the potentially deadly cache of cobalt-60 appears to be safe, guarded by armed soldiers while the CNSNS begins the delicate two-day process of getting the radioactive waste back into a safe container. The bad news for the thieves is that they are probably doomed.
"I believe, definitely, that the thieves did not know what they had, they were interested in the crane, in the vehicle," said Mardonio Jimenez, a physicist and high-ranking CNSNS official. "The people who handled it will have severe problems with radiation," he added. "They will, without a doubt, die." CNSNS director Juan Eibenschutz offered a similar prognosis: "It's almost absolutely certain that whoever removed this material by hand is either already dead or about to die."
The bad news for the public is that such deadly material appears so easy to steal. Cobalt-60 is used in radiation-therapy equipment and some industrial tools, but large quantities are also used to sterilize some types of food. Mexico reports about a half-dozen thefts of radioactive material each year — all apparently incidental, aimed at nabbing the vehicle or other cargo — and the International Atomic Energy Agency gets more than 100 reports of theft or other unauthorized activity with radioactive materials each year.
And to get a sense of how dangerous this week's stolen cache was, compare it with an incident in Thailand in 2000. When scrap collectors unwittingly bought a teletherapy unit being stored outside a hospital, and the scrap yard they sold it to cut it open, three people died, seven others were made very ill, and about 1,900 people nearby were exposed to elevated radiation levels. That device held 425 curies, or radioactive units, worth of cobalt-60; the Mexican cache contained almost 3,000 curies, the CNSNS tells AFP.
And that's just from one piece of machinery from one hospital in Mexico. AFP also reports that the Mexican facility where the cobalt-60 shipment was headed "is surrounded by a white fence topped with barbed wire, but no armed guards were visible outside."
This is a major reason that U.S. ports and land border entry points are equipped with sensitive radioactive scanners. But it's also worth noting that radioactive dirty bombs are a prospective terrorist device because they sew terror, not because they are particularly deadly. Here's the U.S. Nuclear Regulatory Commission on dirty bombs and other radiological dispersal devices (RDDs):
Most RDDs would not release enough radiation to kill people or cause severe illness — the conventional explosive itself would be more harmful to individuals than the radioactive material. However, depending on the situation, an RDD explosion could create fear and panic, contaminate property, and require potentially costly cleanup.... The cloud of radiation from a nuclear bomb could spread tens to hundreds of square miles, whereas a dirty bomb's radiation could be dispersed within a few blocks or miles of the explosion. A dirty bomb is not a "Weapon of Mass Destruction" but a "Weapon of Mass Disruption," where contamination and anxiety are the terrorists' major objectives. [NRC]
That's small comfort to a pair of carjackers dying somewhere in central Mexico. But it's something to think about.