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I'm not normally a scaremonger, but this analysis of possible health risks on the new backscatter x-ray systems raises some interesting issues. I'm curious if those of you with lots of physics and/or biology knowledge have any thoughts on this.
From the letter:
From the letter:
Unlike other scanners, these new devices operate at relatively low beam energies (28keV). The majority of their energy is delivered to the skin and the underlying tissue. Thus, while the dose would be safe if it were distributed throughout the volume of the entire body, the dose to the skin may be dangerously high.
The X-ray dose from these devices has often been compared in the media to the cosmic ray exposure inherent to airplane travel or that of a chest X-ray. However, this comparison is very misleading: both the air travel cosmic ray exposure and chest X- rays have much higher X-ray energies and the health consequences are appropriately understood in terms of the whole body volume dose. In contrast, these new airport scanners are largely depositing their energy into the skin and immediately adjacent tissue, and since this is such a small fraction of body weight/vol, possibly by one to two orders of magnitude, the real dose to the skin is now high.
The X-ray dose from these devices has often been compared in the media to the cosmic ray exposure inherent to airplane travel or that of a chest X-ray. However, this comparison is very misleading: both the air travel cosmic ray exposure and chest X- rays have much higher X-ray energies and the health consequences are appropriately understood in terms of the whole body volume dose. In contrast, these new airport scanners are largely depositing their energy into the skin and immediately adjacent tissue, and since this is such a small fraction of body weight/vol, possibly by one to two orders of magnitude, the real dose to the skin is now high.
So the beam is at a lower frequency (less chance of cell damage) and the radiation only touches a small part of the body (less chance of cell damage) but the radiation intensity near the skin is much higher (much higher chance of cell damage). Who knows what the numbers balance out to.
I poked around a bit and didn't find any animal studies. Surely they would have taken a population of rats and given them several hundred scans each before subjecting millions humans to it?
I don't really care about them seeing me nude; in fact I'm tempted to write "HI TSA!" on my chest with aluminum tape. I understand the TSA has an excellent sense of humor.
I poked around a bit and didn't find any animal studies. Surely they would have taken a population of rats and given them several hundred scans each before subjecting millions humans to it?
I don't really care about them seeing me nude; in fact I'm tempted to write "HI TSA!" on my chest with aluminum tape. I understand the TSA has an excellent sense of humor.
