Radioactive capsule remains lost in Western Australia

A tiny capsule containing a potentially deadly radioactive substance remains lost in the Western Australian desert, after it fell from storage on a transport truck somewhere between a mine site north of Newman in the Pilbara region and a depot in Perth, 1400 km away. Emergency services are now searching for the capsule and are asking the public to be alert and report anything that looks like the missing material, which has been described as small (6 mm diameter and 8 mm tall), round and silver.

The capsule contains a small quantity of radioactive Caesium-137, a substance used in mining operations. The truck bearing the capsule left the mine on 12 January and arrived in Perth on 16 January, but the capsule wasn’t discovered missing until nine days later, on 25 January, when the container was unpacked for inspection. The state government made an announcement to the public two days later.

Dr Andrew Robertson, WA Chief Health Officer and Radiological Council Chair, said the capsule had been packed in accordance with radiation safety and transport regulations inside a box bolted onto a pallet. It is believed that a bolt was dislodged as a result of vibrations during the trip and the capsule fell through the bolt hole.

A large-scale search for the capsule is now underway, coordinated by WA’s Department of Fire and Emergency Services (DFES) — the state’s lead agency for hazardous materials. Robertson said the immediate focus was to find and safely contain the material and to warn the public of the health dangers, with the capsule emitting the equivalent radiation of 10 X-rays if you were to stand within one metre of the capsule for one hour.

“Exposure to this substance could cause radiation burns or severe illness — if people see the capsule or something that looks similar, stay away from it and keep others away from it too,” Robertson said.

“Do not touch or pick it up. The public is asked to report it immediately by calling 13 DFES (13 33 37).

“If you have touched the material, or have been close to it for an extended period, contact your local health practitioner or visit a hospital emergency department and tell them that you think you may have been exposed to radioactive material.”

Various experts have commented on the potential dangers surrounding the capsule. Dale Bailey, a Professor of Medical Imaging Science at the University of Sydney and Royal North Shore Hospital, noted, “There are two main hazards to humans from this material: (a) contamination of the skin, or worse, ingestion after making physical contact with the source if the container is ruptured; and (b) exposure to the gamma rays that the source is emitting.

“By far the most serious concern is contamination. The beta particles, in particular, will cause serious damage to any surface that they coat. There would be initial reddening of the skin or tissue and, in severe cases, ulceration and potentially death of the tissues (necrosis). If swallowed, it would potentially cause bleeding in the gut and ulceration, which can lead to significant complications.”

Ivan Kempson, an Associate Professor in Biophysics at the Future Industries Institute, University of South Australia, added, “If someone is too close to a concentrated source of radiation, like this capsule, for too long then it will cause problems from radiation toxicity. The worst-case scenario is that someone picks up the capsule, finds it curious and keeps it in a pocket, which has happened overseas before.

“The impact from radiation will be worse the closer you are, and the longer you are exposed to a concentrated source. If you were close to this capsule for a minute or two there is little reason for concern. There will be greatly diminished risk if you are more than tens of metres away from it.”

Dr Pradip Deb, a senior lecturer in Medical Radiations and Radiation Safety Officer at RMIT University, added that capsules of Cs-137 are normally well sealed, meaning that it should not contaminate the soil or environment so long as this seal is not broken.

“Such an incident could happen though if, for example, a truck were to run over the capsule,” Bailey said. And with Cs-137 having a half-life of about 30 years — meaning the capsule will be somewhat radioactive for the next 300 years — there would be a definite risk in giving up the search and simply hoping the capsule is undisturbed at least until its radiation levels drop.

Bailey concluded, “Finding this lost source will not be easy; given the large distance involved (1400 km), it will be akin to finding a needle in a haystack. Radiation detectors on moving vehicles can be used to detect radiation above the natural levels, but the relatively low amount of radiation in the source means that they would have to ‘sweep’ the area relatively slowly — certainly not at 100 km/h.

“Today, any mobile phone can be turned into a radiation detector by installing an app and covering the camera lens, hence enabling any potential citizen scientists to help in the search for this lost radioactive material. Anyone detecting radiation levels above the normal background should identify and seal off the potential site location with appropriate signage, maintain a large distance from the source ... minimise the amount of time monitoring the radiation emitted and call the local EPA.”