PERTH, Australia (AP) — Authorities in Western Australia on Wednesday recovered a tiny but dangerous radioactive capsule that fell off a truck while being transported along an 870-mile Outback highway last month in what an official said was like finding the needle in the haystack.

Officials said the capsule the size of a pea was found south of the mining town of Newman on the Great Northern Highway. It was detected by a search vehicle traveling at 43 miles per hour when specialist equipment picked up radiation emitting from the capsule.

Portable search equipment was then used to locate it 6.5 feet from the side of the road.

“This is an extraordinary result … they have quite literally found the needle in the haystack,” said Emergency Services Minister Stephen Dawson.

Chief Health Officer Andy Robertson said the capsule did not appear to have moved and no injuries had been reported.

It contains the caesium 137 ceramic source, commonly used in radiation gauges, which emits dangerous amounts of radiation, equivalent of receiving 10 X-rays in an hour. It could cause skin burns and prolonged exposure could cause cancer.

Search crews had spent six days scouring the entire length of the highway.

The capsule measures 8 millimeters by 6 millimeters, and people have been warned it could have unknowingly become lodged in their car’s tires.

A government investigation has been launched into how the capsule fell off the truck and a report will be provided to the health minister.

Defense officials were verifying the identification of the capsule, which has been placed into a lead container for safety. It will be stored in a secure location in Newman before being transported to a health facility in the city of Perth.

The capsule got lost while being transported between a desert mine site and Perth on Jan. 10. The truck transporting the capsule arrived at a Perth depot on Jan. 16. Emergency services were notified of the missing capsule on Jan. 25.

The chief executive of the mining giant Rio Tinto Iron Ore, Simon Trott, has apologized for the incident and expressed gratitude for the find.

“A pretty incredible recovery when you think of the distances involved, and also the remoteness of the terrain, and I think that really speaks to the tenacity of all those who were involved in the search,” Trott said.

“The simple fact is this device should never have been lost. We’re sorry that that has occurred and we’re sorry for the concern that that has caused within the Western Australian community,” Trott added.

Robertson said the investigation of the mishap could lead to a prosecution.

“We have the ability to prosecute under the Radiation Safety Act and we will certainly look at such prosecutions, and we’ve done that in the past,” Robertson said.

Prime Minister Anthony Albanese said a 1,000 Australian dollar ($708) fine was an inadequate maximum penalty for mishandling radioactive material.

“It shouldn’t have been lost, that’s the first thing. And second, yeah of course that figure is ridiculously low,” Albanese said.

Dawson said the state government was reviewing the penalties under the Radiation Safety Act.