Dangerous nuclear compounds were stolen from the back of an unlocked ute in the Melbourne suburb of Dandenong earlier this year, and remain at large despite a police investigation, according to the annual report of the Radiation Advisory Committee.

A senior research fellow in the Department of Biological Sciences at Macquarie University, Mr Janusz Gebiki, described the isotype contained in the stolen equipment, caesium-137, as “a highly dangerous emitter of penetrating gamma rays”.

Gebiki said there have been several injuries caused by exposure to lost, stolen or discarded caesium: “Because it is water soluble and behaves chemically like potassium, it is easily absorbed by organisms.” The biological half life was about 70 days, he said.

The ute belonged to an employee of a Melbourne environmental and engineering company, the name of which is being kept confidential by the committee. The committee could not say what the repercussions against the company would be.

The equipment was to be used on a job the next day, but was left in the ute, parked outside the employee’s home. Both the ute and the box in which the equipment was contained were unlocked. Dandenong police investigated the theft, and the Australian Federal Police and Australian Radiation Protection and Nuclear Safety Agency were advised.

The Secretary of the Radiation Advisory Committee, Julian Marwick, confirmed last week that the equipment had not been recovered. He said the material could be dangerous if handled incorrectly, but was not at the high end of risk: “I guess it’s all relative as to how it’s used… If it’s handled correctly it’s not terribly dangerous.”

Marwick said the committee had been in touch with all those licensed to have similar equipment to make sure it was locked and secure: “There are pretty strict requirements and we do conduct inspections.”

The theft is the most serious incident in the report, which includes another 33 cases where people were exposed to levels of radiation, most often as the result of medical error.

The committee also reported on research which had established “unequivocally” that ultraviolet tanning machines cause both skin and eye melanomas, and had been elevated to “top-most cancer risk category” by the International Agency for Research on Cancer.

Another issue considered by the committee was the use of security scanning in prisons, which could expose staff and prisoners to significant doses of radiation. So far as prisoners were concerned “there were benefits indicated in terms of detection of contraband materials that could result in harm to the person carrying them or others.” The committee recommended that dose meters be used to monitor the levels of exposure by staff.

All but one of the cases of medical exposure involved levels of radiation well below those that cause radiation sickness or increased risk of cancer. But in one case a cancer patient excreted radioactive “seeds” that had been implanted as part of his treatment. He picked them up and carried them in a plastic container in his trouser pocket.

He received a radiation dose double that which can cause increased cancer. When the patient brought the seeds back to the doctor, they were left for more than three days unshielded, and less than a metre from a desk used by medical staff, who would have been exposed to low doses as a result.

Another case involved the incorrect CT scanning of a patient because two people who both had the surname ‘Smith’ were confused with each other. Fortunately the dose of radiation received by the patient was low.

Also, a patient who had been previously diagnosed with breast cancer and received a full CT scan of bones, brain and pelvis was later discovered to be pregnant. The foetus received a low dose of radiation.

And a pregnant radiographer went in to a room where a CT scan was being performed to calm a patient. She has since claimed the scan was not properly paused while she was in the room, and as a result she was exposed.

The Radiation Advisory Committee is part of the Department of Health, and advises on radiation safety and risk. A copy of the report is claimed to be available online, but at the time of writing, the most recent report on the website was 2008.