A controversy currently rages in the USA regarding radiation safety for low doses of ionising radiation. In a review of how science is used for regulatory purposes by the Environmental Protection Agency, a Senate committee has been hearing evidence from an hormesis (‘low doses of poison are good for you’) enthusiast, Edward Calabrese. I heard Calabrese speak at the Australasian Radiation Protection Society meeting in Hobart, Tasmania, in 2014. The main thrusts of his argument were allegations of scientific fraudulence in the Linear No Threshold (LNT) model -which asserts a risk of cancer induction proportional to radiation dose down to zero (no safe dose)- and an attack on the integrity of one of its founding proponents, Nobel laureate Hermann Muller.
There is nothing more undermining to good radiation safety practice than the belief or suspicion that it might be good for us after all.
I wrote about this in a recent editorial Both sides now1 in the journal Australasian Engineering and Physical Sciences in Medicine. The editorial acknowledged the importance of low dose radiobiological research, but argued that for regulatory purposes the LNT was the most responsible approach. It cited recent research into increased cancer incidence in children who had received CT scans, excess instances of leukaemia for radiation workers, and lung cancer from radon exposure in homes – the exposures in each case being just a few milli-Sieverts (mSv). This is significantly less than the 100-200 mSv generally held to as the lowest established level of radiation to cause an observed increase in cancer incidence. These findings support the extension of the solid line of certainty in the graph to close to zero.
The average annual dose per person from medical radiation (excluding radiotherapy) in the USA of 3 mSv, according to official figures2, is almost double that of Australia3 and seven times that of the UK4. In Both sides now I stated:
There is nothing more undermining to good radiation safety practice than the belief or suspicion “that it might be good for for us after all.”
In my opinion, this is neither the time to relax radiation regulations, nor to cease in our vigilance in optimising and limiting radiation exposures in medical practice.
- Both sides now: diagnostic imaging medical physics in two hemispheres, Editorial in Australasian Physical and Engineering Sciences in Medicine Volume 40, Issue 2, pp 269–27.