(Adds analyst comment, IAEA context)
MEXICO CITY, July 4 (Reuters) - Thieves in central Mexico on Thursday stole a pick-up truck carrying dangerous radioactive material, authorities said.
The load of iridium 192 was normally used in industrial radiography, Mexico's interior ministry said in a statement. It was housed in a specialized container and would only pose a health risk if the housing was tampered with, it said.
In December, thieves in Mexico made off with a truck containing dangerous radioactive medical material - Cobalt-60 - that the United Nations' nuclear agency said could provide an ingredient for a "dirty bomb", in which conventional explosives disperse radiation from a radioactive source.
The radioactive load was later found dumped by the thieves close to where it was stolen.
The U.N. International Atomic Energy Agency (IAEA), which has stepped up calls on member states to tighten security to prevent nuclear and radioactive materials from falling into the wrong hands, had no immediate comment on Friday.
Because radioactive material is regarded as less hard to find and the device easier to make, experts say a dirty bomb is a more likely threat than a nuclear bomb in a terrorist attack.
However, they say a dirty bomb carries more potential to terrorise than cause a large loss of life.
Nuclear expert Mark Hibbs of the Carnegie Endowment think-tank said Iridium-192, a common medical and industrial isotope with many applications, "in theory" could be used as a radiological weapon.
But, "the perpetrators would have to accumulate enough material to disperse it effectively which may be difficult since in many cases small amounts of Ir-192 are used in sources," he told Reuters in an e-mail.
"Unlike cobalt-60, which remains a dangerous source of radiation for many years, Ir-192's shorter half-life implies that perpetrators would have far less time to fashion it into a dispersion device," Hibbs added. (Reporting by Gabriel Stargardter; additional reporting Fredrik Dahl in Vienna; Editing by Nick Macfie/Ruth Pitchford)