Mexican authorities say a truck containing “extremely dangerous” radioactive material used in medical imaging was stolen by two gunmen on Monday. According to the International Atomic Energy Agency the white Volkswagen work truck, taken from the central Hidalgo town of Tepojaco, was transporting a steel reinforced wooden crate which housed a source containing Cobalt-60 headed for a waste storage center.
The truck’s driver told authorities that two gunmen approached the truck while he was parked at a service station. They tied up the driver and drove away.
The IAEA has issued an international warning:
“At the time the truck was stolen, the source was properly shielded. However, the source could be extremely dangerous to a person if removed from the shielding, or if it was damaged.”
Mexico’s National Commission for Nuclear Safety and Safeguards (CNSNS) said the material posed no risk provided it was not broken or tampered with but experts agree that the material could theoretically be used to build a makeshift weapon.
Cobalt-60 has been a factor in several serious source accidents including fatalities. Of immediate concern is the fact that such material could in theory be put into a so-called “dirty bomb” designed to intentionally spread the radioactive material over a wide area.
In a 1987 incident in Goiania, Brazil a machine containing caesium-137, a substance very similar to cobalt-60, , was exposed after it was mistakenly dismantled for scrap value. The result was 85 contaminated homes and 249 people needing medical treatment. Twenty-eight people suffered radiation burns and 4 died including a 6 year old who came into direct contact with the material.
Mexican government officials are reporting that six people are in a hospital in Pachuca for possible radiation exposure and are suspects in this week’s radioactive cobalt-60 theft/heist. None are in grave condition.
Cobalt-60, 60Co, is a synthetic radioactive isotope of cobalt with a half-life of 5.27 years. It is produced artificially by neutron activation of the isotope 59Co.60Co decays by beta decay to the stable isotope nickel-60 (60Ni). The activated nickel nucleus emits two gamma rays with energies of 1.17 and 1.33 MeV, hence the overall nuclear equation of the reaction is 59
27Co + n → 60
27Co → 60
28Ni + e− + ν
e + gamma rays.
Cobalt is an element of steel alloys. Uncontrolled disposal of 60Co in scrap metal is responsible for the radioactivity found in several iron-based products.
In 2000, a disused radiotherapy head containing a 60Co source was stored at an unsecured location in Bangkok, Thailand and then accidentally was sold to scrap collectors. Unaware of the dangers, a junkyard employee dismantled the head and extracted the source, which remained unprotected for a period of days at the junkyard. Ten people, including the scrap collectors and workers at the junkyard, were exposed to high levels of radiation and became ill. Three of the junkyard workers subsequently died as a result of their exposure, which was estimated to be over 6 Gy. The source was safely recovered by the Thai authorities.
In August, 2012, Petco recalled several models of steel pet food bowls after US Customs and Border Protection determined that they were emitting low levels of radiation. The source of the radiation was determined to be 60Co that had contaminated the steel.
In May 2013 a batch of metal-studded belts sold by online retailer Asos were confiscated and held in a US radioactive storage facility after testing positive for cobalt-60.