CSD:
Bottom line WRT the risk level of these two types of machines(1) is that TSA has not released enough data to rule out significant risk. The released data leave large holes for assumptions & estimates, not to mention the means in which they are applying the radiation in question. Anyone with only the data that has been released who says, "no worries" is no more valid than those saying there is significant risk(2) & (3).
FTR, my degree is in physics and I do a bit of work with RF, IR, and other non-visible wavelength emitters & detectors. To be more specific, I model them. To do so, I need some pertinent bits of information about them. Without those bits, I can not determine their effects/effectiveness. In the current brouhaha, I could do some of the pertinent calculations...given the data.
Right now we have the TSA saying "trust me" after the EPA can ruled x-ray radiation a cancer risk and with little understanding of the effects of mm wave radiation on humans.
(1) That I know of. Backscatter X rays and millimeter wave.
(2) A couple of fellows I know who left my employer for greener pastures liken the risk of death by cancer from one of the x-ray devices as roughly equivalent to being killed by a terrorist. Pretty darned small. BUt, if one is doing risk analysis, the net to the flying public is a wash: no reduction in total risk, just trade cancer risks down the road for lower death by terrorist risk toady (assuming the x-ray device completely eliminates the risk of death by terrorists for that flight).
(3) The risks for the mm wave devices is a BIG unknown. There has been little testing done, but the simulations show some ugly results. Much more testing on live critters really ought to be done before subjecting the general public to
thalidomide mm wave radiation.
This might help: