Search for radioactive capsule in outback

A radioactive sign
A radioactive capsule has gone missing as it was transported from a West Australian mine. -EPA

A tiny radioactive capsule with the potential to cause skin burns has gone missing as it was transported from a West Australian mine.

Hazardous material experts are searching for the 8mm by 6mm capsule which is believed to have fallen from a truck as it was travelling from the Pilbara to Perth.

Authorities are searching for the capsule which "does emit a reasonable amount of radiation".

"It's about receiving 10 X-rays in an hour," a health spokesman said, adding that more severe health conditions including cancer could stem from prolonged exposure.

The capsule is understood to have fallen from a truck during a 1400km journey, after vibrations worked loose a bolt, and the capsule fell through the bolt hole.

Emergency services were notified of the missing capsule on Wednesday.