Iraqi jihadists have grabbed 88 pounds of uranium compounds from a Mosul University science lab, but U.S. and international weapons experts are downplaying the possibility the deadly toxins could be used to make a so-called “dirty bomb.”

The material, believed to be low-grade, unenriched uranium mixed with other elements, was taken from a science lab at Mosul University by ISIS, the terrorist group that took over Iraq’s second-largest city last month and has vowed to attack Baghdad. Iraq notified the UN in a July 8 letter which sought international help to “stave off the threat of their use by terrorists in Iraq or abroad,” according to Reuters, which saw the letter.

Although the material is not believed to be weaponized, and ISIS does not have known missile delivery capability, the theft stoked fear that a dirty bomb – a primitive explosive used to disseminate radioactive material – could be fashioned from the uranium compounds.

“There is theoretically the potential for a dirty bomb.”

- Daryl Kimball, Arms Control Association

“There is theoretically the potential for a dirty bomb,” Daryl Kimball, of the Arms Control Association in Washington, told FoxNews.com, explaining that such bombs are more effective at scaring people than killing them. “It explodes and the terrorist is banking on the fear factor of radiation. That’s what we are looking at here at worst.”

Iraq’s Foreign Ministry said the compounds were used at Mosul University labs in “very limited quantities” for research, and that they were slated for destruction before ISIS took over the city.

Former International Atomic Energy Agency chief inspector Olli Heinonen said that if the material came from a university it most likely is laboratory chemicals consisting of natural or depleted uranium.

“You cannot make a nuclear explosive from this amount, but all uranium compounds are poisonous,” Heinonen told Reuters. “This material is also not ‘good’ enough for a dirty bomb.”

The letter was sent by Iraq’s UN Ambassador Mohamed Ali Alhakim to UN Secretary-General Ban Ki-moon.

Pentagon spokesman Col. Steve Warren said the U.S. is aware of the situation, but does not believe the uranium is weaponized. 

“We do not believe that there is weaponized or enriched uranium in Iraq,” Warren said. “Obviously we’ve seen the letter that the Iraqi government has sent to the United Nations. We cannot independently confirm who has control of this uranium.

“It’s important to note that in 2004 the U.S. Department of Energy worked with the Iraqis to remove all enriched uranium from Iraq,” Warren added. “So we believe that the enriched uranium has all been removed from Iraq and that this material that is being discussed I think came from a university so it’s more of an academically oriented material.”

David Albright, of the Washington-based Institute for Science and International Security, said the likelihood of fashioning a dirty bomb from the stolen materials was remote, noting uranium is not very radioactive.

“However, any uranium in the hands of a terrorist group is concerning, since it shows interest in nuclear material and their interest is unlikely to be for peaceful purposes,” Albright, a former IAEA weapons inspector, told FoxNews.com.

Russian Foreign Ministry spokesman Alexander Lukashevich also said the seizure likely posed no direct threat. But, he said the development is troubling.

“The sheer fact that the terrorists … show unmistakable interest in nuclear and chemical materials is, of course, very alarming,” Lukashevivh said.

Mark Hibbs of the Carnegie Endowment think tank told Reuters UN inspectors had previously scoured Mosul, including several universities following the Gulf War. He said what remained was uranium liquid wastes, sources, uranium oxides and uranium tetrafluoride.

“Some of these items are still there, but there’s no enriched uranium,” he said.

Earlier this week, Iraq’s U.N. envoy said that the government had lost control of a former chemical weapons facility near Baghdad to “armed terrorist groups.”