A tiny radioactive capsule with the potential to cause nasty skin burns and serious illness has been lost as it was transported from a West Australian mine to Perth.
An urgent radioactive substance health warning has been issued along a 1400km truck route from the Pilbara to a depot in the Perth suburb of Malaga.
Hazardous material experts are searching for the 8mm by 6mm solid capsule, which is believed to have fallen off the back of a truck after a bolt worked loose.
"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.
Searches at the mine site and a depot in Perth have failed to find the potentially dangerous capsule, which was last seen on January 10 at the mine.
Chief Health Officer Andrew Robertson said the small silver cylinder was a 19-gigabecquerel caesium 137 ceramic source commonly used in radiation gauges.
"That may not mean a lot to people but probably more concerning is that it does emit a reasonable amount of radiation," he said.
Dr Robertson said the unit emits about two millisieverts of radiation per hour, which is the equivalent of having 10 x-rays in an hour.
"Two millisieverts is also the amount of natural radiation we would receive in a year just by walking around," he said.
"This is a source we have to be very careful of ... It is quite a large radiation dose."
Members of the public have been warned not to touch the dangerous device and stay at least five metres away, and contact emergency services if they find it.
"It emits both beta and gamma rays, so 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," Dr Robertson said.
"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."
The capsule cannot be weaponised or broken to spread the radioactive material, however, it can cause cancer, Dr Robertson warned.
Authorities believe the container the capsule was in collapsed due to road vibrations and the unit fell through a bolt hole.
They're using radiation detectors to try and find the unit, with Dr Robertson saying the entire 1400km route may need to be surveyed.
