The Mexican government has put civil protection agencies in five southern states and some federal agencies on alert following the theft of radioactive medical material from a vehicle on Monday.

CBS News partner network UNO TV reported the iridium-192, a radioactive compound used in mobile medical radiography work, was stolen from a vehicle in Tabasco state, near Mexico's border with Guatemala.

According to the report, the material is classified as Category 2 under the international nuclear watchdog's (IAEA) rating scale. While the iridium-192 was safely encased when stolen, UNO TV said a Category 2 material could cause serious lesions or even death within a day of exposure if removed from its protective casing.

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The alert issued to authorities included the states of Tabasco, Campeche, Chiapas, Oaxaca and Veracruz.

According to UNO TV, the alert called on any local authorities who were to locate the radioactive material not to try and handle it, but rather to establish a secure perimeter around it of approximately 90 feet, and report it to federal officials.

This week's incident was at least the second time in recent years that dangerous radioactive material has been stolen from a vehicle in Mexico.

A decommissioned and safely encased cobalt-60 medical teletherapy unit is seen being lowered into a wooden box for transport to radioactive waste facility in Mexico. CNSNS/Handout

In December 2013, thieves made off -- apparently unwittingly -- with a container full of cobalt-60, also used in medical equipment, from a vehicle transporting it for safe disposal.

The cobalt, which is a Category 1 source under the IAEA's ranking system and thus more dangerous than the iridium stolen this week, was found in a field abandoned by thieves days later. Several people were treated for radiation exposure after its discovery.

There was no indication as of Thursday morning that the thieves behind the iridium's disappearance in Tabasco were anything other than misguided bandits, as turned out to be the case in 2013, but it will again pique the interest of security forces who worry about criminal and terrorist groups trying to obtain such materials.

In an article posted on the Bulletin of the Atomic Scientists after the 2013 theft was resolved, two nuclear experts -- one of whom is a former IAEA employee -- wrote that medical sources of radioactivity like cobalt are more dangerous to those who handle them in their undiluted form than they would be "if spread using a radiological dispersal device such as a so-called 'dirty bomb.' Nonetheless, had the Mexican source been used in a dispersal device, the economic consequences could have been extremely significant."

The scientists urged greater accountability by national authorities in reporting to the IAEA incidents of theft like the ones in Mexico.

They also suggested establishing global standards for the transport and handling of radioactive medical materials, saying it "would be an important step toward enhancing the global nuclear security regime," but admitting it was a tall order, "given the difficulty of negotiating and implementing binding international instruments."