The TSA argues that the amount of radiation that is received is considerably less than the additional radiation that one will receive just by flying. The the TSA’s data like much of the data our government produces, is questionable. But here is the issue, radiation even small amounts can cause cancer. It is a probably issue which may be hard for many people to understand. X rays are like Hamas sending unguided missiles into Israel. Most of the time they just land on some dirt somewhere but every once in while they find a house, car or even a person. The more sent the greater the chance of hitting something. So while the chances of any one individual getting cancer from a body scan at the airport is very small the chances of someone being hit is very high. I don’t really know that they increase changes are but lets say that having a whole body scan give one a risk of cancer that is one in million. Then if a million people are scanned, the chances of someone getting radiation one. So there are a billion scans there would be a 1000 incidents of cancer (this may be much higher or lower in my example in reality). There is a reasonable chance that more people will die from the scanners than would die if a plan blew up.