In fact, radiation is a far less potent carcinogen than other toxic substances. Studies of more than 80,000 survivors of the Hiroshima and Nagasaki blasts have found that about 9,000 people subsequently died of some form of cancer. But only about 500 of those cases could be attributed to the radiation exposure the people experienced.
The average amount of radiation that victims in Hiroshima and Nagasaki were exposed to would increase the risk of dying from lung cancer by about 40 percent, Boice said. Smoking a pack of cigarettes a day increases the risk of dying of lung cancer by about 400 percent.
"Radiation is a universal carcinogen, but it's a very weak carcinogen compared to other carcinogens," Boice said. "Even when you are exposed, it's very unlikely you will get an adverse effect. But fear of radiation is very strong."