State authorities in Western Australia are searching for a tiny radioactive capsule believed to have fallen off a truck.
CNN  — 

It’s like looking for a needle in a haystack – an 8mm by 6mm silver capsule, no bigger than a coin, believed to be lost somewhere along a stretch of vast desert highway in Australia’s biggest state.

The reason authorities are so determined to find it is that it contains Caesium-137, a highly radioactive substance that’s potentially lethal.

Authorities in Western Australia believe the capsule, which emits both gamma and beta rays, fell off the back of a truck as it was being transported along a 1,400-kilometer (870-mile) section of the Great Northern Highway – a distance longer than the Californian coastline.

Mining company Rio Tinto, which used the capsule in a density gauge at its Gudai-Darri iron ore mine, apologized on Monday, saying it was supporting state government efforts to find it.

Rio Tinto said it has checked all roads in and out of the mine in remote WA, where the device was located before a contractor collected it for the journey south to the state capital, Perth.

Due to the tiny size of the capsule and the huge distances involved, authorities warn the chances of finding it are slim.

And there are fears that it may have already been carried further from the search zone, creating a radioactive health risk for anyone who comes across it for potentially the next 300 years.

An illustration provided by Western Australia's Department of Health shows the size of the capsule compared to a coin.

How did it go missing?

State authorities raised the alarm on Friday, alerting residents to the presence of a radioactive spill across a southern swathe of the state, including in the northeastern suburbs of Perth, home to about 2 million people.

According to authorities, the capsule was placed inside a package on January 10 and collected from Rio Tinto’s Gudai-Darri mine site by a contractor on January 12.

The vehicle spent four days on the road and arrived in Perth on January 16 but it was only unloaded for inspection on January 25 – when it was discovered the capsule was missing.

“Upon opening the package, it was found that the gauge was broken apart with one of the four mounting bolts missing and the source itself and all screws on the gauge also missing,” said the Department of Fire and Emergency Services (DFES).

They believe that strong vibrations caused by bumpy roads damaged the package – dislodging a mounting bolt that held it in place.

How dangerous is it?

Experts have warned that Caesium-137 can create serious health problems for people who come into contact with it: skin burns from close exposure, radiation sickness and potentially deadly cancer risks, especially for those exposed unknowingly for long periods of time.

Radiation Services WA, a company that provides radiation protection advice, says standing within 1 meter (3.3 feet) of the capsule for an hour would deliver around 1.6 millisieverts (mSv), as much as around 17 standard chest X-rays.

Picking up the capsule would cause “serious damage” to your fingers and surrounding tissue, the company said in a statement.

Ivan Kempson, an associate professor in Biophysics from the University of Southern Australia, said the worst case scenario would be a curious child picking up the capsule and putting it in their pocket.

“This is rare but could happen and has happened before,” Kempson said. “There have been some past examples of people finding similar things and suffering radiation poisoning but they were much stronger than the current capsule that is missing.

“We are all exposed to a constant level of radiation from things around us and the foods we eat but the primary concern now is the potential impact on health of the person who would find the capsule.”

State authorities are searching for the capsule along a stretch of the Great Northern Highway in Western Australia.

How rare is it to lose a radioactive device?

The incident has come as a shock to experts who said that handling of radioactive materials like Caesium-137 is highly regulated with strict protocols for their transport, storage and disposal.

Rio Tinto said it regularly transports and stores dangerous good as part of its business and hires expert contractors to handle radioactive materials.

Radiation Services WA says radioactive substances are transported throughout Western Australia on a daily basis without any issues. “In this case, there seems to be a failure of the control measures typically implemented,” it said, adding that it had nothing to do with the capsule’s loss.

Pradip Deb, a lecturer and radiation safety officer at RMIT University in Melbourne, said the loss of the capsule was “very unusual” as Australian safety rules require them to be transported in highly protective cases.

The name of the logistics company used to transport the device has not been released, Rio Tinto said.

A conveyor belt transports iron ore at the Gudai-Darri mine operated by the Rio Tinto in the Pilbara region of Western Australia, June 21, 2022.

What’s happening with the search?

Authorities have been searching along