Caesium-137 gamma sources have been involved in several radiological accidents and incidents.
1987 Goiânia, Goiás, Brazil
In the Goiânia accident of 1987, an improperly disposed of radiation therapy system from an abandoned clinic in Goiânia, Brazil, was removed then cracked to be sold in junkyards, and the glowing caesium salt sold to curious, unadvised buyers.[32] This led to four confirmed deaths and several serious injuries from radiation contamination.[33][34]
1989 Kramatorsk, Donetsk, Ukraine
The Kramatorsk radiological accident happened in 1989 when a small capsule containing highly radioactive caesium-137 was found inside the concrete wall of an apartment building in Kramatorsk, Ukrainian SSR. It is believed that the capsule, originally a part of a measurement device, was lost in the late 1970s and ended up mixed with gravel used to construct the building in 1980. Over 9 years, two families had lived in the apartment. By the time the capsule was discovered, 4 residents of the building had died from leukemia and 17 more had received varying doses of radiation.[35]
1997, Georgia
In 1997, several Georgian soldiers suffered radiation poisoning and burns. They were eventually traced back to training sources abandoned, forgotten, and unlabeled after the dissolution of the Soviet Union. One was a caesium-137 pellet in a pocket of a shared jacket that put out about 130,000 times the level of background radiation at 1 meter distance.[36]
1998 Los Barrios, Cádiz, Spain
In the Acerinox accident of 1998, the Spanish recycling company Acerinox accidentally melted down a mass of radioactive caesium-137 that came from a gamma-ray generator.[37]
2009 Tongchuan, Shaanxi, China
In 2009, a Chinese cement company (in Tongchuan, Shaanxi Province) was demolishing an old, unused cement plant and did not follow standards for handling radioactive materials. This caused some caesium-137 from a measuring instrument to be included with eight truckloads of scrap metal on its way to a steel mill, where the radioactive caesium was melted down into the steel.[38]
March 2015, University of Tromsø, Norway
In March 2015, the Norwegian University of Tromsø lost 8 radioactive samples including samples of caesium-137, americium-241, and strontium-90. The samples were moved out of a secure location to be used for education. When the samples were supposed to be returned the university was unable to find them. As of 4 November 2015 the samples are still missing.[39][40]
March 2016 Helsinki, Uusimaa, Finland
On 3 and 4 March 2016, unusually high levels of caesium-137 were detected in the air in Helsinki, Finland. According to STUK, the country's nuclear regulator, measurements showed 4,000 μBq/m3 – about 1,000 times the usual level. An investigation by the agency traced the source to a building from which STUK and a radioactive waste treatment company operate.[41][42]
May 2019 Seattle, Washington, United States
Thirteen people were exposed to caesium-137 in May 2019 at the Research and Training building in the Harborview Medical Center complex. A contract crew was transferring the caesium from the lab to a truck when the powder was spilled. Five people were decontaminated and released, but 8 who were more directly exposed were taken to the hospital while the research building was evacuated.[43]
January 2023 Western Australia, Australia
Further information: Western Australian radioactive capsule incident
Public health authorities in Western Australia issued an emergency alert for a stretch of road measuring about 1,400 km after a capsule containing caesium-137 was lost in transport on 25 January 2023. The 8 mm capsule contained a small quantity of the radioactive material when it disappeared from a truck. The State Government immediately launched a search, with the WA Department of Health's chief health officer Andrew Robertson warning an exposed person could expect to receive the equivalent of "about 10 X-rays an hour". Experts warned, if the capsule were found, the public should stay at least 5 metres away. The capsule remains unrecovered.[44]
