A missing shipment of radioactive cobalt-60 has been found near where the stolen truck transporting the material was abandoned in central Mexico state, the country's nuclear safety director said.
The highly radioactive material was found Wednesday in an empty lot about a kilometre from Hueypoxtla, an agricultural town of about 4,000 people, but it poses no threat or a need for an evacuation, said Juan Eibenschutz, director general of the National Commission of Nuclear Safety and Safeguards.
"Fortunately there are no people where the source of radioactivity is," Eibenschutz said.
The cargo truck hauling the extremely dangerous cobalt-60 that had been used in medical equipment was stolen from a gas station early Tuesday, and authorities had put out an alert in six central states and the capital looking for it. Police and the military joined in the hunt.
The truck was taking the cobalt to a nuclear waste facility in the state of Mexico, which is adjacent to Mexico City.
Eibenschutz said direct exposure to cobalt-60 could result in death within a few minutes. He said hospitals near the area were asked to report if they treat anyone exposed to radioactivity.
"This is a radioactive source that is very strong," Eibenschutz told The Associated Press.
But, he added, the material poses no threat to human life if kept at least 500 metres away.
Eibenschutz didn't know the exact weight of cobalt, but said it was the largest amount stolen in recent memory, and the intensity of the material caused the alert.
The material was used in obsolete radiation therapy equipment that is being replaced throughout Mexico's public health system. It was coming from the general hospital in the northern border city of Tijuana, Eibenshutz said.
Before the container was found, he said the thieves most likely wanted the white 2007 Volkswagen cargo vehicle with a moveable platform and crane.
Eibenschutz said there was nothing to indicate the theft of the cobalt was intentional or in any way intended for an act of terrorism.
The truck marked "Transportes Ortiz" left Tijuana on November 28 and was headed to the storage facility when the driver stopped to rest at a gas station in Tepojaco, in Hidalgo state north of Mexico City.
The driver, Valentin Escamilla Ortiz, told authorities he was sleeping in the truck when two men with a gun approached about 1:30am. Tuesday. They made him get out, tied his hands and feet and left him in a vacant lot nearby.
When he was able to free himself, he ran back to the gas station to get help.
On average, a half dozen thefts of radioactive materials are reported in Mexico each year and none have proven to be aimed at the cargo, Eibenschutz said. He said that in all the cases the thieves were after shipping containers or the vehicles.
Unintentional thefts of radioactive materials are not uncommon, said an official familiar with cases reported by International Atomic Energy Agency member states, who was not authorised to comment on the case. In some cases, radioactive sources have ended up being sold as scrap, causing serious harm to people who unknowingly come into contact with it.
In a Mexican case in the 1970s, one thief died and the other was injured when they opened a container holding radioactive material, he said.
The container was junked and sold to a foundry, where it contaminated some steel reinforcement bars made there. Eibenschutz said all foundries in Mexico now have equipment to detect radioactive material.