The radiation received by an individual in one scan is equivalent to a few minutes of flying at typical altitudes.
Here's an excellent, interesting report on x-ray scanners by ProPublica that came out a few weeks ago. It gives a lot of good information:
- The science says from 6 to 100 passengers a year will get cancer from U.S. scanners (of 100 million people who fly every year) -- which means an additional 6 to 100 people will get cancer if they are scanned compared to if they weren't. Without such scans these 100 M people will develop abut 40 M cases of cancer.
- In 1998 the inventor of the scanning machine thought it highly unlikely it would ever be widely used in the near future, and the FDA had serious reservations about them then. The FDA has never approved the machines because they're not classified as a medical device.
- TSA says no one will get cancer from the machines.
- the TSA...
"...skipped a public comment period required before deploying the scanners. Then, in defending them, it relied on a small body of unpublished [non peer-reviewed] research to insist the machines were safe, and ignored contrary opinions from U.S. and European authorities that recommended precautions, especially for pregnant women. Finally, the manufacturer, Rapiscan Systems, unleashed an intense and sophisticated lobbying campaign, ultimately winning large contracts."
- The radiation received from one scan is 10 microREMs, equivalent to about 0.001 chest x-rays.
- A 2006 study from the National Academy of Sciences found “no compelling evidence” that there is any radiation level with zero cancer risk.
So what to do? It's easy to resent anyone who makes you take an x-ray, and get all truculent at the airport. I wonder if the anti-floridation people are as opposed to these scanners as they are to THE GOVERNMENT putting fluoride in the water -- one of their arguments is that governments have no right to add a substance to something like the water supply. (Aside: I wonder how they feel about chlorine.)
On the other hand, I've had more x-rays than I can remember, especially in the last two years before and after my neck surgery. When my doctor ordered an x-ray I didn't think twice about it and got several of them, each time, over multiple visits.
On the third hand, at the hospital they at least protect your private parts with a lead apron.
On the fourth hand, which snowflake is it that finally breaks the branch?
Perhaps it it worth declining a scan at the airport, though, just to add weight to the argument that no one can expose you to ionizing radiation without your consent.