Radiation list to be expanded
Leigh Dayton
The Australian
THIS week a strange thing happened. The uranium industry and radiation health experts were as one.
The detente quickly evaporated into a dispute about the health risks posed by exposure to low-level radiation. But the combatants agreed the Australian National Radiation Dose Register should be expanded beyond the uranium mining and milling industry to include all people exposed to so-called ionising radiation at work.
"It's not often I find myself in agreement with the Australian Uranium Association," says public health physician and radiation specialist Tilman Ruff, from the Nossal Institute for Global Health at the University of Melbourne.
"But it makes good public health sense," he says of the AUA's call to expand the register.
The ANRDR is a centralised database maintained by the national regulator, the Australian Radiation Protection and Nuclear Safety Agency. It was set up in 2010 to collect, store, manage and share records of radiation doses received by workers exposed to harmful radiation.
As the AUA notes, responsibility for such matters resides with the states and territories, so enabling legislation was passed to allow operators such as Olympic Dam and Beverley mine in South Australia to register employee data. The Northern Territory government has introduced legislation to enable, for instance, Ranger mine to include data. Other jurisdictions are yet to follow.
"It's time now for the benefit of national dose data tracking to be extended beyond just uranium works," says AUA chief executive Michael Angwin.
An ARPANSA spokesperson says the regulator is already investigating options for inclusion of data for other exposed mining and milling industry workers, and agrees all exposed workers "regardless of employer" would benefit from the ability to access their long-term dose history.
Peter Karamoskos, a nuclear radiologist in Victoria and the public representative on ARPANSA's radiation health committee, says: "If you're exposed to radiation - and therefore at increased risk of cancer - it follows that it's in the interest of public health to ensure the ANRDR is expanded to all people exposed to workplace radiation."
Diverse industries are affected: nuclear research, radiopharmaceutical production, radiology, dentistry, veterinary medicine, mineral sands, uranium and rare earths mining and exploration, and even airlines.
The risk comes from ionising radiation emitted by cosmic rays and naturally radioactive materials such as uranium and radon. Ionising radiation is highly reactive, damaging molecules and DNA. "The effects of radiation exposure are cumulative," says Karamoskos, who - along with Ruff and ARPANSA occupational exposure section manager Paul Martin - explains that's why a centralised registry that follows employees from job to job or state to state is critical.
Martin adds: "The point is the safety of individual workers who can access their own data".
As Ruff notes: "It's important for them to know, to be able to make informed choices about work risks".
No argument there. "To me the safety and health of my charges, employees or people around is No 1," says the chairman of AUA's radiation protection working group, health physicist Frank Harris, who advises Rio Tinto and its subsidiary Energy Resources of Australia.
By law it has to be. As Martin says, an occupationally exposed person cannot experience a radiation dose of more than 20 millisieverts a year. Sieverts are a measure of biological effects of ionising radiation, as opposed to just the absorbed dose of radiation energy. This is where industry and science part company. Industry accepts 20mSv as safe; mainstream science does not.
"The AUA (implies) radiation exposure within regulatory limits involves no risk, which it does," says Ruff. "The largest ever study of radiation industry workers showed elevated rates of cancer incidence and mortality at average levels of exposure well within permitted levels." That study, conducted by the World Health Organization's International Agency for Research on Cancer, showed a cancer risk consistent with that of the Hiroshima and Nagasaki atomic bomb survivors among the 600,000 workers exposed to 19mSv.
Ruff, like Karamoskos, also cites the 2006 review of the US National Academy of Sciences Committee on the Biological Effects of Ionising Radiation, which found: "There is a linear dose-response relationship between exposure to ionising radiation and the development of solid cancers in humans.
"It is unlikely that there is a threshold below which cancers are not induced."
That's why societies, industries and individuals make cost-benefit decisions about whether a benefit, say an X-ray or uranium supply, is worth the increased risk of cancer.
Further, Karamoskos and Ruff worry that groups such as the AUA acknowledge the findings but play down the risks of radiation by airing the views of fringe researchers such as Canada's Doug Boreham, who claims low doses of radiation are "anti-carcinogenic" and that "low-dose radiation is like getting a suntan".
Harris says: "I'm not encouraging Doug's approach, but as a scientist you listen to all sides."