Rio Tinto has confirmed that a tiny but dangerous radioactive capsule that got lost on a 1400km journey across the WA outback came from one its mines.

January 28, 2023

Rio Tinto has confirmed that a missing potentially deadly radioactive capsule that’s triggered a massive search in the West Australian outback came from one of its mines.

The world’s second-largest miner says it contracted an expert radioactive materials handler to “package the capsule and transport it safely” 1400km from the Pilbara to a depot in the Perth suburb of Malaga.

“Rio Tinto was informed of the missing capsule by a contractor on January 25,” a spokesman said on Saturday.

Emergency services believe the tiny solid capsule, that can cause nasty skin burns, radiation sickness and cancer, likely fell off the back of the truck along the busy freight route after a bolt worked loose.

They’ve issued a radioactive substance health warning and launched an urgent search for the 8 by 6 millimetre unit that was last seen on January 10 at the mine site north of Newman.

“We are starting to comb roads and other areas in the search zones, specifically Great Northern Highway in Perth’s northeast,” David Gill, a Department of Fire and Emergency Services superintendent, told reporters on Friday.

Experts are using radiation detectors to try and find the unit and may have to perform tests along the entire 1400km transport route to find it.

Rio Tinto said it was working with the Radiological Council, the contractor that lost the capsule and emergency services to help find it.

The small silver cylinder is a 19-becquerel caesium 137 ceramic source commonly used in radiation gauges.

Chief Health Officer Andrew Robertson said the unit emits the equivalent of having 10 X-rays in an hour and members of the public should stay at least five metres away from it.

“If you have contact or close to you, you could either end up with skin damage, including skin burns … and if you have it long near you it could cause acute radiation sickness,” he said.

Long-term exposure could also cause cancer, however, experts say the capsule cannot be weaponised.

“Our concern is someone will pick it up, not knowing what it is, think this is something interesting (and) keep it … not knowing what they are actually dealing with,” Dr Robertson said.

“This is a source we have to be very careful of … It is quite a large radiation dose.”

Authorities believe the container the capsule was in collapsed due to road vibrations and the unit fell through a bolt hole.

Extensive testing at the mine site and a depot in Perth have failed to find the capsule.