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At the Yamagata Sports Center, residents of Fukushima are screened for radiation when they check into the displaced persons center. Here, Yukiko Fushimi, center, gets checked along with her two grandchildren, but none of them showed elevated levels.
MCT photo
Don’t worry too much about the hint of radiation reaching U.S. shores from the damaged nuclear reactors in Japan, experts say.
So far, it’s much less than we’d get from a chest X-ray.
But consider this: Every day, all day long, we’re bathed in low levels of radiation — cosmic rays from outer space, radon in our houses, uranium deposits in the soil, radio signals from every AM and FM station in range, airport full-body scanners, dental X-rays, cellphones, even tiny hints lingering from the A-bomb tests of the 1940s and ’50s.
And remember that radiation is cumulative. Most scientists agree there’s no such thing as a harmless dose.
Now relax. It’s less scary than it sounds.
“It’s absolutely true there’s no safe dose. But we’re likely to be OK if we remain vigilant,” says Dr. Nagy Elsayyad, a radiation oncology expert at the University of Miami Sylvester Comprehensive Cancer Center.
Not all radiation is equal. What comes from medical X-rays, airport scanners, leaking nuclear plants and similar sources is ionizing radiation — the dangerous kind, capable of causing cancer, increasingly so as time and dosage increase. But much of the radiation around us, from radio waves to cellphone signals to leaky microwave ovens, is the non-ionizing type never proven to cause illness, say scientists — well, most scientists.
World War II newsreel footage from Hiroshima and Nagasaki shows the doomsday effects of nuclear bombs exploding over cities, killing hundreds of thousands from the immediate blast and tens of thousands more later on, from high-dose radiation poisoning. And the current nuclear crisis in Japan has prompted new fears of radiation contamination.
But lower, everyday levels we experience routinely are less easy to grasp. For example, the U.S. Federal Aviation Administration estimates an airline pilot spending a 25-year career flying at 30,000 feet between Chicago and New York will experience enough extra cosmic radiation through the thinner atmosphere to increase his or her cancer risk by about 0.3 percent.
Another natural source, radon, is an invisible, odorless, radioactive gas emitted from soil.
In all, natural sources expose the average earthling to about 6.2 millisieverts (mSv) of radiation annually. The millisievert is the common unit for measuring radiation exposure; one millisievert equals about 10 chest X-rays. There are other ways of measuring radiation, but the millisievert is the most widely used.
The trick is to limit our exposure to ionizing radiation above that universal 6.2 mSv, Elsayyad says. The National Council on Radiation Protection recommends we get no more than one additional unit per year.
To put it in perspective, measuring in millisieverts, a chest X-ray adds 0.1, a mammogram adds 0.7, a high-altitude, cross-country airplane flight adds 0.05 and a medical CAT scan adds 10. The new full-body scanners at airports may be intrusive, but their radiation level is low — far less than 0.1 mSv, according to the American Cancer Society.