[something]

the UCSF letter explains why this is not a valid comparison. the ambient radiation absorbed in flight and the radiation of the mwbs are not in the same part of the spectrum so they are not comparable using simple agregate statistics. the stopping power of your (or any) body is function of the energy of the incident radiation (or particle) and this not considered in the mrem comparison.

[jessriedel]

If you demand that human trials be done for every possible permutation of conceivable risk---throwing out as incomparable all data that is taken in even remotely different circumstances--then you can claim health risks about every single thing. And it's pretty much impossible to satisfy you because of the cost of human trials.

The concerns raised in the UCSF letter are strained beyond belief. Further, a number of points (like the breast-cancer bullet point) are clearly there to influence emotions rather than critical reasoning.

I'll just explain this one. As the UCSF letter states, the radiation is being deposited on a volume smaller than usual by a factor possibly as large as "one to two orders of magnitude". That means that at absolute worst this is like radiation dose of 1 mrem (still less than the flight tiny compared to your yearly dose), and that's assuming that all of the risk of cosmic radiation comes from skin cancer (which is wildly wrong).

[something]

i agree that demanding perfect testing is ridiculous in most scenarios, especially when talking about human trials. however, that's not what i'm suggesting should happen. i also don't deny that the UCSF letter has a sensationalist or alarmist tone. i'm not touting their concerns, just suggesting it as a place that explains the difference between cosmic xrays and the xrays in these scanners. i guess my point is that it's very easy to mislead people that have no appreciation for these very real differences. glossing over details and nuance that have not yet been proven insignificant, and doing so with the goal of making concerned people stop asking questions about their own safety- that's not cool. when it's our own government it's even less cool.

there are so many issues swirling around this subject- privacy, security, safety, fear, "terror"... i guess i'm just wanting the science of the safety to be completely objective, open, reviewed, failsafes and failure modes known... all that jazz. as a member of the public it seems like these things were just thrown out there. the tsa is covering their butt by doing whatever is possible, a few scanner manufacturers are having a good year, and we're just supposed to leave it like that, keep calm, carry on... i can't say that makes me feel great.