As the search continues for a tiny radioactive capsule in Western Australia, the state's deputy premier says there needs to be a review into how it disappeared.
An urgent warning remains in place after the caesium-137 capsule, only 6 millimetres in diameter and 8mm long, was reported missing on January 25.
The tiny radioactive source was part of a radiation gauge used commonly to measure the density of materials used in processing plants.
It was lost in transit somewhere along a 1,400 kilometre journey between a Rio Tinto mine site in WA's north, and a depot in the suburb of Malaga about 11km north of Perth's CBD, between January 11 and January 16.
The Department of Emergency Services and Rio Tinto was only notified the capsule was missing when the container was unpacked for inspection on January 25.
Authorities believe it fell through a hole in the truck where a bolt had been dislodged after a container collapsed in transit due to vibrations.
'We want it recovered as soon as possible'
Deputy Premier Roger Cook said it the situation was extremely concerning and a review should be conducted into how it occurred.
"I understand there was stringent arrangements in place to protect and track this particular capsule … but the fact that it's missing is very concerning," he said.
"This is a very dangerous material and we want it to be recovered as soon as possible."
When asked if there would be any consequences for Rio Tinto, the deputy premier said it was not for him to decide.
"That's a matter for the chief health officer to decide with his colleagues on the Radiological Council," he said.
Rio Tinto investigating
Rio Tinto chief executive Simon Trott said the company was investigating how the capsule was lost, and was working with authorities in the search.
"We recognise this is clearly very concerning and are sorry for the alarm it has caused in the Western Australian community," he said.
"As well as fully supporting the relevant authorities, we have launched our own investigation to understand how the capsule was lost in transit."
Mr Trott said relevant safety measures were taken before the package left the Rio Tinto mine site.
"Rio Tinto engaged a third-party contractor, with appropriate expertise and certification, to safely package the device in preparation for transport," he said.
Prior to the device leaving the site, a Geiger counter was used to confirm the presence of the capsule inside the package."
'It's left my head in a bit of a spin'
On Saturday, Radiation Services WA general manager Lauren Steen described the situation as "highly unusual".
"Typically they're transported in highly protected casing that are subject to a certification verification stage. The housing is subjected to rigorous testing for vibrations, heat, high impact," she said.
"It's left my head in a bit of a spin," she said.
"If you were to stand one metre [away] … you would be receiving about the equivalent of 17 chest x-rays.
"If you were to hold the source in your hand for a substantial period of time, you would start to notice some radiation burns."
Authorities are urging anyone who encounters the capsule to stay at least five metres away and report it to the Department of Fire and Emergency Services.
A multi-agency incident management team is continuing to scour the search area with specialised equipment, but have previously said there was no certainty the capsule would be found.
Editor's note: This story has been edited to clarify that the radioactive source is commonly used to measure the density of materials.
