As I mentioned in my blog post
I am a radiation protection professional. I will tell you that any radiation exposure, no matter how slight, can increase your risks of health problems. Is it likely? No. But over time the use of the backscatter machines will result in some additional cancers and deaths among the flying public. It may be an additional 1 per million, or it could be 10 per million. I don't know and it will take years before any meaningful data can be accrued. There is much to take seriously from the arguments from experts regarding the localized skin exposure. There are also questions about machine malfunctions which could cause excessive radiation dose rates.
All that said, as a radiation protection professional I will endure using the machine over being given a hernia exam. I understand the risks. I will also say that I am much more concerned about kids and those otherwise more sensitive to radiation using the machines - and let's be honest, the current protocol is meant to drive people to use the machines.