Agreed. As a doctor, I shudder at the thought of the Xray backscatter machines. It is IONIZING radiation, capable of ejecting an electron from your DNA (creating an ion) that then can cause DNA bases to behave in very odd fashions -- crosslinking, etc., which your body can repair using special DNA repair enzymes correctly (good) or incorrectly (potentially bad). The bad repair results in a DNA mutation, which can lead to cell death (not too bad) or cancer (much, much worse.)

The risk of cancer is low, true. Humans are very bad at understanding low risks -- I look at an analogy here to the lottery. You would have to play the lottery for many lifetimes to expect to be a big winner, yet somebody wins the multistate lottery quite often. Similarly, the scanners, even if "totally safe for a lifetime of scans" may realistically cause cancer in a significant amount of people.

I take issue to the "equivalent to xxx minutes of plane flight." Another good analogy I like to use is a laser pointer. It is probably equivalent to a couple milliseconds of light of being outside on a bright day. Yet, would you let me shine it at your face with your eyes open? It depends on the tissues being affected. Similarly, the "soft" x-rays are primarily absorbed by the skin, and are scanned around the body AFAIK in a raster format.

Another analogy of this is that being outside is certainly safe on a bright day. However, would you let me take a magnifying glass and hold it four inches above your skin? Same energy, very different outcome. To make a blanket comparison of xray exposure is nonsensical. I don't know how the collimator in the x-ray is arranged, or how it is calibrated.

I can't really tell the risks, as I just don't have enough data. TSA is not saying. The scans, however, make me extremely nervous, and I always opt out, and strongly encourage my family and friends to also. Lately many of the "cancer boxes" seem to be powered off though (probably because of the busy weekend?)

Moreover, all of the people that take car transportation instead of flying increase their risk of death. I, for one, dislike the hassle of the new measures so much it may make me think twice about one or two short-haul trips.