For decades, researchers have been trying to quantify the risks of very low doses of ionizing radiation the kind that might be received from a medical scan, or from living within a few tens of kilometres of the damaged Fukushima nuclear reactors in Japan. So small are the effects on health if they exist at all that they seem barely possible to detect. A landmark international study has now provided the strongest support yet for the idea that long-term exposure to low-dose radiation increases the risk of leukaemia, although the rise is only minuscule (K. Leuraud et al. Lancet Haematol. http://doi.org/5s4; 2015).
The finding will not change existing guidelines on exposure limits for workers in the nuclear and medical industries, because those policies already assume that each additional exposure to low-dose radiation brings with it a slight increase in risk of cancer. But it scuppers the popular idea that there might be a threshold dose below which radiation is harmless and provides scientists with some hard numbers to quantify the risks of everyday exposures.
“The health risk of low-dose radiation is really very tiny, but the public is very concerned,” says Bill Morgan, who heads a systems-biology programme in low-dose radiation at the Pacific Northwest National Laboratory in Richland, Washington, and chairs the committee on radiation effects at the International Commission on Radiological Protection (ICRP) in Ottawa, Canada. That concern has driven a lot of investment in programmes trying to quantify the risk, he says. The European Commission, for example, has a 20-year road map to assess the problem. “We don’t do a very good job of explaining ourselves to the public, which finds it hard to put radiation risks in context some people go to radon spas to treat their rheumatism while others won’t board planes for fear of cosmic rays,” he adds……..