Rio Tinto Group Loses “Highly Radioactive” Cesium-137 Capsule on Western Australian Highway

In Western Australia, officials are urgently trying to locate a small capsule holding radioactive material that was misplaced along a huge stretch of road.[0] A “small silver cylinder” measuring 0.3 inches by 0.2 inches, the capsule holds cesium-137 and is part of a mining sensor.[1]

When the package was inspected by the Western Australian government, it was observed that it had been “disassembled, with one of the four mounting bolts missing and the source itself, as well as all screws on the gauge, also absent.”[2]

Vibrations from the truck's driving along the highway may have caused the bolt to become dislodged.[3] Simon Trott, Rio Tinto's iron ore chief executive, said in a statement issued Monday, “We are taking this incident very seriously. We recognise this is clearly very concerning and are sorry for the alarm it has caused in the Western Australian community.”[4]

Authorities in Australia reported that the capsule was securely stored on January 10.[5] The shipment traveled along the highway from January 11 to 14, before being held at a facility in Perth starting on January 16.[5] Nine days later, on 25 January, it was discovered missing when the package was unpacked for inspection.[6]

This capsule contains a ceramic source of cesium-137.[1] This is a standardized piece of equipment typically used in industrial mining operations and, according to Robertson, it would emit the equivalent of 10 x-rays into the human body every hour into someone who was near it.[7] The amount of radiation received in one hour is roughly equivalent to the amount absorbed by a person during a year of normal activities.[7]

The Rio Tinto Group is unable to find a capsule which is extremely radioactive, having lost it along an 870-mile long stretch of highway running through the Western Australian desert.[8] “We have offered our full and ongoing support to authorities in the search for the missing device. We have completed radiological surveys of all areas on-site where the device had been, and surveyed roads within the mine site as well as the access road leading away from the Gudai-Darri mine site,” Trott said.[9]

Exposure to Cs-137 may lead to an increased risk of cancer due to the high-energy gamma radiation it emits.[10]

0. “Warning Issued After Tiny Radioactive Capsule Is Lost in Australia” PEOPLE, 27 Jan. 2023,

1. “Australia is searching the desert for a dangerous radioactive capsule smaller than a penny” Boing Boing, 30 Jan. 2023,

2. “Rio Tinto apologises for losing radioactive capsule in Australia” BBC, 30 Jan. 2023,

3. “Radiation panic as experts hunt for deadly test capsule ‘the size of a grain of rice'” Daily Star, 30 Jan. 2023,

4. “Mining giant Rio Tinto apologizes for sparking radiation alert after losing device in Australia” CNBC, 30 Jan. 2023,

5. “Truck Drops Deadly Radioactive Pill in Australian Outback” Jalopnik, 27 Jan. 2023,

6. “What is the radioactive capsule missing in WA used for and how dangerous is it?” The Guardian, 30 Jan. 2023,

7. “Missing Tiny, Deadly Radioactive Capsule Spurs Nationwide Search in Australia” VICE, 27 Jan. 2023,

8. “Tiny ‘Highly Radioactive' Capsule Lost In Australian Desert Raises Alarm”, 30 Jan. 2023,

9. “Tiny radioactive capsule lost in Australian outback carries the equivalent of 10 X-ray blasts as fears mount it could be picked up by passing traffic” Fortune, 30 Jan. 2023,

10. “Radiation alert in Australia after Caesium-137 capsule goes missing, here's HOW it can hurt you” WION, 28 Jan. 2023,