CARDENAS, Mexico, April 16 (UPI) -- Civil authorities and law enforcement agencies in southern Mexico were put on alert Thursday after radioactive material was stolen from a vehicle -- probably by thieves who didn't know what they were taking, investigators said.
The stolen material was identified as iridium-192, which is a compound used in medical and industrial radiography, officials said. It was removed from a vehicle in Cardenas in the state of Tabasco, near Mexico's border with Guatemala.
The Mexican government advised five southern states of the theft and warned anyone who might come across the radioactive material to notify authorities immediately -- without handling the iridium-192, which can be deadly upon exposure.
Iridium-192 is classified by the International Atomic Energy Agency as a Category 2 material -- defined by the regulatory firm as "industrial gamma radiography sources or high or medium dose rate brachytherapy sources."
"Category 1 sources are potentially the most dangerous and Category 5 sources are the most unlikely to be dangerous," the IAEA says regarding its classification of radioactive materials.
The agency says Category 2 materials, like iridium-192, are "very dangerous" to anyone who directly handles or is directly exposed to it.
"If not safely managed or securely protected, [Category 2 materials] could cause permanent injury to a person who handled it or who was otherwise in contact with it for a short time," the agency says. "It could possibly be fatal to be close to this amount of unshielded radioactive material for a period of hours to days."
However, contamination to populations via other methods, like fire or water, is extremely improbable.
"It would be virtually impossible for a source in Category 2 ... to contaminate a public water supply to dangerous levels," the IAEA said.
In addition to Tabasco, the states of Campeche, Chiapas, Oaxaca and Veracruz were also put on alert.
Investigators believe the material was likely taken by thieves who didn't know exactly what they were stealing. The iridium-192 was safely encased when it was removed from the vehicle. Officials instructed anyone who finds the material to establish a safe perimeter around it and contact local authorities.
This is the second time in the last two and-a-half years that radioactive material has been stolen out of a vehicle in Mexico. In December 2013, a canister of cobalt-60 -- a radioactive isotope produced in nuclear reactors -- was stolen and later found abandoned in a field.
Cobalt-60 is classified by the IAEA as a Category 1 material -- considered as "extremely dangerous" to anyone who handles or comes into direct exposure of it. In that case, investigators said the thieves took the cobalt-60 without knowing what it was.
Following the cobalt theft, six people were hospitalized for exposure but no serious or permanent effects were sustained by any of them.