Lost Radioactive Caesium-137 Capsule Sparks Search Efforts in Western Australia: Expert Advice on Potential Health Risks

Finding a small silver capsule, measuring 8mm by 6mm, is like searching for a needle in a haystack in the vast desert highways of Australia's largest state. The capsule, no bigger than a coin, is believed to have fallen off a truck while being transported along the Great Northern Highway, which is 1400 kilometers (870 miles) long, a distance greater than the coastline of California, as reported by CNN.

The reason it's so crucial to locate it is because it contains Caesium-137, a highly radioactive substance that is dangerous and potentially lethal. It emits gamma and beta rays, which is why authorities in Western Australia are so determined to find it. The mining company, Rio Tinto, issued an apology on Monday for the lost capsule and stated that they are supporting the efforts of the state government to find it.

The capsule was used in a density gauge at the Gudai-Darri iron ore mine and was collected by a contractor for transport to Perth, the state capital. Rio Tinto has checked all the roads in and out of the remote mine in Western Australia where the device was located. However, authorities have warned that the chances of finding the small capsule are low due to its tiny size and the vast distances involved.

State authorities in Western Australia are searching for a tiny radioactive capsule believed to have fallen off a truck.
State authorities in Western Australia are searching for a tiny radioactive capsule believed to have fallen off a truck. Department of Fire and Emergency Services/AP


Missing Radioactive Capsule

There are concerns that the capsule has been carried further away from the search zone, which could create a radioactive health hazard for anyone who comes into contact with it for up to 300 years. The state authorities issued a warning informing residents of a radioactive spill in the southern part of the state, including the northeastern suburbs of Perth, which is home to approximately 2 million people. According to the authorities, the capsule was placed inside a package on January 10 and collected by a contractor from Rio Tinto's Gudai-Darri mine site on January 12.

The vehicle took four days to reach Perth and was unloaded for inspection on January 25, when the loss of the capsule was discovered. The Department of Fire and Emergency Services (DFES) reported that when the package was opened, it was broken apart, with one of the four mounting bolts missing, the source, and all screws on the gauge. They believe that the strong vibrations caused by the bumpy roads damaged the package, causing a mounting bolt to come loose.

Experts have warned that Caesium-137 can pose serious health risks, such as skin burns from close exposure, radiation sickness, and potentially fatal cancer risks, especially for those unknowingly exposed for extended periods. Radiation Services WA, a company specializing in radiation protection advice, has stated that standing within a meter of the capsule for one hour would result in exposure to 1.6 millisieverts, equivalent to 17 chest X-rays. The company also warned that picking up the capsule would cause severe harm to the fingers and surrounding tissue. Ivan Kempson, an Associate Professor of Biophysics at the University of Southern Australia, stated that the worst-case scenario would be if a curious child picked up the capsule and put it in their pocket.

An illustration provided by Western Australia's Department of Health shows the size of the capsule compared to a coin.
An illustration provided by Western Australia's Department of Health shows the size of the capsule compared to a coin. Western Australia's Department of Health

Failure of Control Measures

He also mentioned that while it is a rare occurrence, it has happened before, and there have been cases of people suffering radiation poisoning after finding similar items, although they were stronger than the current missing capsule. Kempson emphasized that while everyone is exposed to a certain level of radiation from the environment and food, the primary concern now is the potential impact on the health of the person who may find the capsule.

CNN stated that the loss of the radioactive capsule has shocked experts as handling such materials is usually strictly regulated and overseen by strict protocols for transportation, storage, and disposal. Rio Tinto, which used the capsule, stated that it regularly deals with dangerous goods and hires expert contractors to handle radioactive materials. Despite this, Radiation Services WA says the failure of the control measures used for the capsule's transportation is unusual, as radioactive substances are typically transported throughout Western Australia without issue.

Pradip Deb, a radiation safety officer at RMIT University in Melbourne, also noted that the loss was "very unusual" as safety regulations require these materials to be transported in highly protective cases. Rio Tinto has not disclosed the name of the logistics company used for transportation. Authorities are searching along the truck's route, from the metropolitan areas of Perth in the south to a small town near the mine site in the north, as NBC reported.

The Search Difficulties

The search vehicles are equipped with specialized radiation detection equipment and drive slowly along the highway at 50 kilometers an hour in both directions. The slow speed is necessary for the equipment to detect radiation from the missing capsule. The search teams have covered more than 660 kilometers and are expected to complete the entire route by Friday. If someone comes across the capsule before it's found, they have been advised to stay at least 16.4 feet away.

It would be difficult to see it from a distance. Authorities are using radiation detectors to locate the capsule, not their eyesight. However, there are concerns that it may no longer be in the search zone. The capsule may have been carried away by another vehicle's tire or dispersed by wild animals. There are many uncertainties about what could happen, and a nuclear policy analyst has expressed concern about the potential impact on the environment. The capsule needs to be recovered and secured, but the variables involved make it unclear what could happen.

BBC mentioned that Caesium-137 has a half-life of around 30 years, meaning that its radioactivity will decrease by half after 30 years and continue to do so every 60 years. The capsule's radioactivity could last for up to 300 years. If the capsule remains intact and is not broken, it will not spread its radioactivity into the environment or soil. According to experts, if the missing capsule is found in an isolated area, it is unlikely to have much impact. Rio Tinto, one of the largest mining companies in the world, operates 17 iron ore mines in Western Australia and has faced controversy for its activities, including the destruction of ancient rock shelters in 2020.

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