Natural radiation link to childhood leukaemia in region

NATURAL gamma rays could be responsible for around 40 cases of childhood leukaemia in the UK each year, research suggests.

Scientists found a small but significant link between the risk of the illness and exposure to gamma radiation from the environment.

Higher levels of gamma radiation – found in South Yorkshire, Cornwall, the Isles of Scilly and the Scottish borders – were associated with a greater likelihood of children developing leukaemia. Powys in mid-Wales, Dorset and Wiltshire had the lowest measured rates.

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The findings contradict the widely held belief that very low radiation doses have little or no effect on cancer rates.

They follow separate results published last week suggesting low-dose radiation from CT scans can triple risks of children developing leukaemia or brain cancer.

Gamma rays are essentially a highly penetrating form of invisible light that form part of the natural background radiation everyone is exposed to. The main sources of natural gamma rays are radioactive isotopes of uranium, thorium and potassium. These can be found in the soil, rocks, drinking water and even building materials. Another source is cosmic radiation from outer space.

Study leader Gerald Kendall, from the Childhood Cancer Research Group at Oxford University, said: “What is new in our findings is the direct demonstration that there are radiation effects at these very low doses and dose-rates. In terms of preventing childhood cancers caused by natural gamma-rays, there’s not a lot you can do.”

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Researchers, writing in the journal Leukaemia, said the study was the largest ever conducted on links between childhood cancer and background radiation.

The team analysed radiation exposures for almost 27,500 children diagnosed with cancer between 1980 and 2006, including more than 9,000 with leukaemia.

No significant links were discovered between natural gamma rays and other childhood cancers.

Nor was a link found between any kind of cancer and radon, a radioactive gas produced by certain rocks.

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Co-author Prof Richard Wakeford, of Manchester University, said: “Naturally occurring gamma-rays provide an ever-present, very low-level source of exposure to radiation, but this very large epidemiological study suggests that even at these very low levels there is a very small risk to health.”