Scan or Grope?

[Beest]

Originally Posted by Nirvana

If the rumors are right and they scramble DNA

I haggis'd, the made sure to do my background reading.
http://www.hpa.org.uk/Topics/Radiati.../BodyScanners/

I am a radiation safety professional, you're getting more radiation on the flight, than going through the scanner.

[monster]

Originally Posted by Beest

I am a radiation safety professional.

he says that to all the chicks......

[Shawnee123]

Originally Posted by monster

he says that to all the chicks......

[glatt]

Originally Posted by Beest

I am a radiation safety professional, you're getting more radiation on the flight, than going through the scanner.

What I have read elsewhere is that it's comparing apples to oranges when it comes to radiation dosage. A typical x-ray machine in a doctor's office will give you a set amount of radiation and that's averaged out over your whole body to come up with the exposure number. The backscatter machines use a certain amount of radiation, and when they publish that number, they average it out over your whole body as well. But what I've read is that this is a bad comparison because the backscatter machine only penetrates a couple of millimeters. So when you average out the total radiation over the actual tissue that's being radiated, it's orders of magnitude higher for that tissue. The published numbers are simply wrong, according to what I've read. And for men, especially boys with smaller ones, the vital tissue that's being radiated at these high levels are the testicles.

I don't pretend to be knowledgeable about this, I only know what I've read. So I could be wrong, but what I've read about this leaves me with unsettled questions. I'm not confident that they have been proven safe, but based on what I know now, I would not let my son go through one.

Once some trusted entity other than the TSA shows them to be safe, I'll change my tune. But I don't trust the TSA at all to tell the truth.

[Beest]

Originally Posted by glatt

Once some trusted entity other than the TSA shows them to be safe, I'll change my tune. But I don't trust the TSA at all to tell the truth.

The source I linked was the UK Health and Safety Authority (OSHA equivalent), I tried to lookup the NRPB (national Radiological Protection Board) where I did my training but it looks like it's been absorbed into the HSA.

It's the same stuff about exposure at altitiude.

This is the FDAs response to the letter from the PhDs concerning 'skin dose', it's a point by point smackdown.

The stated concern was, “The majority of their energy is delivered to the skin and the underlying tissue.” We agree. However, the concern that “the dose to the skin may be dangerously high” is not supported. The recommended limit for annual dose to the skin for the general public is 50,000 µSv. The dose to the skin from one screening would be approximately 0.56 µSv when the effective dose for that same screening would be 0.25 µSv. Therefore the dose to skin for the example screening is at least 89,000 times lower than the annual limit.

Other specific concerns expressed in the letter are based on the assumption that a screening results in skin or other organ doses that are orders of magnitude higher than the effective dose per screening. The dose to other organs is less than, equal to, or at most approximately three times the effective dose for the deployed product. The annual dose limit for security screening is the same as the NCRP recommendations for the annual effective dose limit for the general public including special populations. An individual would have to receive more than 1000 screenings to begin to approach the annual limit.

The testing by the FDA and NIST calculates very carefully how much skin exposure you get and it's a lot less than by natural sources. One fun thing to do is to turn on my Geiger counter, which makes a beep every time some radiation passes, it will beep away merrilly every few seconds just about anywhere, cosmic rays pass thorugh us all the time

One teensy caveat, the whole field of relating radiation exposure to health risk is based on studying accidental exposures, you can't just irradiate a bunch of people and see who gets cancer (well not any more, see the military personell at early bomb tests). The biggest study group is Japanese victims of the Nagasaki and Hiroshima detonations, also early bomb test where a lot of military perosnell were exposed. A couple of years ago they halved all the exposure limits when they figured out the humidty of the air over Hiroshima was different to what had been previously thought so the basic exposure data was wrong.

[glatt]

Thanks Beest. I appreciate your pulling this information together. I didn't understand that the term "effective" dose meant that they were already taking into consideration the different tissues being irradiated vs. the entire body.

I'm more receptive to information from the FDA than the TSA, although they still aren't my ideal of a trusted authority. But I skimmed the report you linked and saw that Johns Hopkins had also reviewed one of these scanners, and I went to their report too:
http://www.tsa.gov/assets/pdf/jh_apl_v2.pdf

It says basically the same thing. So I guess I trust that these are basically safe. It's better to limit exposure to radiation where you can, but at the same time, the scanner is a lot more convenient than getting groped. I think after skimming the FDA report and the John's Hopkins report, I'd probably choose the scanner after all.