Air Force halts use of 1950s-era missile test kits after finding potentially carcinogenic residue

Airmen who work with the nation’s intercontinental ballistic missiles were told to immediately stop using a 1950s-era test kit after an inspection found potentially carcinogenic residue on some of the components.

Maj. Gen. Colin Connor, commander of 20th Air Force, issued the order Aug. 26, a Global Strike Command spokesperson said Monday. It applies to all 20th Air Force equipment and airmen.

The order was prompted after an airman at F.E. Warren Air Force Base in Cheyenne, Wyo., was exposed to residue while doing a routine inspection on an AN/PRM-10 test oscillator set, Global Strike Command said in a statement Friday.

Tests confirmed that the residue contained polychlorinated biphenyls, or PCBs, the command said.

The system is a signal generator used to test intercontinental ballistic missile communications systems. The airman received medical attention and returned to duty with no adverse effects, the command statement said.

The 20th Air Force, which oversees the service’s three intercontinental ballistic missile wings, ordered a review of all oscillator sets across Air Force Global Strike Command and issued updated safety warnings, officials said.

The Wyoming installation is one of three Air Force bases that house intercontinental ballistic missiles. The other two are Minot Air Force Base in North Dakota and Malmstrom Air Force Base in Montana.

Residue may have been found on six of eight oscillator sets, officials said. Those samples are being tested for PCBs and the results are pending, the command said.

In the meantime, airmen were directed to stop using the testing systems and switch to a modern, PCB-free replacement device.

1st Lt. Claire Waldo sits inside a launch control center at Vandenberg Air Force Base, California, Feb. 3, 2020. Air Force Global Strike Command has directed airmen to stop using a communications test kit at its ICBM bases after inspectors found potential residue of PCBs, a cancer-linked chemical, on the equipment. (Aubree Milks/U.S. Air Force)

The service is working to dispose of the old test kits, which were built from 1952 to 1958, and identify any other test components that may contain PCBs, officials said.

The Global Strike Command mission overseeing the Air Force’s intercontinental ballistic missiles and nuclear bombers has not been affected by the ongoing review, according to the command.

“We remain vigilant for issues like these and will continue to aggressively and immediately take the appropriate actions,” said Gen. S.L. Davis, who leads the command.

PCBs are toxic chemicals that may cause cancer and other serious adverse health effects. They were commonly used in electronics, including the test kits to maintain the Minuteman III missiles, until they were banned in the U.S. in the late 1970s. 

For years, the Air Force’s nuclear bases have been dealing with PCBs, which do not easily break down and may remain in the environment for a long time.

An ICBM patch worn at F.E. Warren Air Force Base, Wyoming, March 11, 2026. F.E. Warren, where the AN/PRM-10 exposure occurred, is also where the Air Force is preparing to transition from the Minuteman III weapon system to its Sentinel replacement. (Michael A. Richmond/U.S. Air Force)

In 2024, an Air Force memorandum documented the presence of PCBs at missile facilities based on an environmental survey. The guidance noted that PCBs persisted at low levels despite comprehensive removal efforts in the 1990s.

Earlier this year, the service released additional findings from its ongoing Missile Community Cancer Study. It showed that personnel working around ICBM bases have higher rates of Hodgkin lymphoma and testicular cancer than those in other career fields.