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Sunday, Oct. 9, 2011
Like Astro Boy, humans may be able to live with radiation
By ROWAN HOOPER
"It makes good media. It's the emotional pulling on the idea that radiation kills you. But you talk to our cancer patients: Radiation cures you."
The nuclear expert sitting in front of me was dismissive about the fears surrounding the public's perception of radiation. Gerry Thomas runs the Chernobyl Tissue Bank at Imperial College London, and she knows more than most about the measurable effects of exposure to radiation.
The Tissue Bank collects and stores tumors from patients exposed to radioactive iodine in childhood after the Chernobyl nuclear disaster in the Soviet Union (present-day Ukraine) in April 1986.
While of course she won't assert that radiation is safe — it can be terribly dangerous — she makes an important point: Radiation is natural.
Radiation is all around us. In the time it took me to write those five words, I had been bombarded by hundreds of cosmic rays, and the radioactive atoms in the air I breathed and the food I've eaten will have decayed in my body and released radiation. Thousands of gamma rays are streaming through me from the building I'm sitting in, and from the ground underneath.
This so-called background radiation is not something we worry about. Perhaps because we can't see it, we don't worry about it. And, of course, background radiation is very low level.
But here's the deeper reason we don't worry about it: We have evolved to cope with it.
Cancer patients at the Hammersmith Hospital in London where Dr. Thomas works, and at hospitals all over the world, are exposed to very high doses of radiation. Those levels are much higher than, say, the doses that workers at the crippled Fukushima No.1 nuclear power plant are receiving.
Of course, with radiation therapy the dose is focused on the patients' cancers, whereas at Fukushima the workers' whole bodies are being exposed.
But even with cancer therapy, inevitably the surrounding tissue is exposed to radiation, too. If radiation is so dangerous, then oncologists should expect to see cancers developing in that surrounding tissue.
"Yet we don't get a huge increase in secondary cancers as a result," says Thomas.
So what's going on? According to Thomas, the answer is simple: In some situations, radiation is less dangerous than we think.
After Chernobyl, excluding those who worked at the site itself to contain the disaster, the worst health effects were not directly due to exposure to radiation. In the wider, surrounding population, the most damaging health effects were psychological: depression, anxiety, thoughts of suicide.
Thomas wants to try and ensure that in Japan, post-Fukushima, a psychologically damaging level of fear about radiation doesn't build up.
After the Great Hanshin Earthquake in 1995, the Hyogo Institute for Traumatic Stress was set up to treat mental-health issues occurring among survivors, and Thomas is one of many experts who want Japan to take psychological issues more seriously.
Of course there are concerns about radiation in Japan, and those are understandable. But I thought of what Thomas said last month when I read a scientific paper that stood out from all the others discussing the damaging effects of ionizing radiation on the body and the measurements of radioactive cesium and iodine across Japan.
Gian Luigi Russo and colleagues at Italy's National Research Council found that hospital workers exposed over months and years to radiation from X-rays at permitted levels, had undergone changes at a cellular level. These changes may even be positive. In other words, this low, regular exposure to radiation could be good for the health.
Russo took blood samples from 10 cardiologists who are exposed to around 4 millisieverts of radiation per year. The cardiologists use X-ray-guided surgery, also known as Interventional Radiology (IR).
X-rays are used so the surgeon can identify the precise location of the problem. It means the hospital workers are exposed to slightly above the dose they would receive naturally, but still well below the U.S. Code of Federal Regulation's limit of 50 millisieverts per year.
When Russo's team looked at the blood of the cardiologists, they found that it had the distinctive mark of cell damage — higher-than-expected amounts of hydrogen peroxide. Also, their white blood cells showed signs of decreased life-expectancy. However, the blood also contained glutathione, a protective antioxidant, at twice the normal levels. The results are published in the European Heart Journal (DOI reference: 10.1093/eurheartj/ehr263).
Russo's is only a small sample, but this could be the first evidence that low doses of radiation can induce changes at a biochemical and cellular level. However, it remains to be seen whether the benefit of the dose outweighs the potential cost.
I'd love to know what Osamu "God of Manga" Tezuka would have made of all this. Tezuka, of course, created one of Japan's most iconic contemporary cultural figures: Tetsuwan Atom, also known as Astro Boy.
The peace-loving android was nuclear-powered, and Tezuka had interesting views on radiation. In the 1949 manga "Metropolis," he invented a radioactive metal he called Omotanium that had beneficial powers. How would he have responded to the ongoing disaster at the Fukushima No.1 nuclear power plant?
Of course we don't know, as he died — from stomach cancer — in 1989.
Rowan Hooper (@rowhoop on Twitter) is the News Editor of New Scientist magazine. The second volume of Natural Selections columns translated into Japanese is published by Shinchosha at ¥1,500. The title is "Hito wa Ima mo Shinka Shiteru (The Evolving Human)."