If you’ve flown anywhere in the past several years, you probably saw, or had to go through, a full-body scanner at the security checkpoint.  There are two technologies in use there.  One is a circular chamber that low powered millimeter waves, to see if you’re hiding anything under your clothes (this is referred to as a millimeter wave scanner).  There’s really little risk associated with this type of scanner, it’s not a big deal at all.  The other technology has you walk between two large blue or gray boxes, and uses low levels of ionizing radiation to perform the same function (this is referred to as a backscatter scanner).  A more detailed comparison of the two technologies can be viewed here.

So what’s the big deal?  Well, the problem is that the backscatter scanners have never been independently tested and shown to be safe.  The government says they’re safe (with little evidence to support that), while the scientific and medical community has serious concerns about their safety.  Apart from the lack of testing, there’s the basic principle in radiation safety that people should never be x-rayed unless there’s a medical benefit.  The risk is real enough that it’s believe that some number of people will get cancer every year from this (the exact number is unknown, but probably less than 100).

So, given that there is a safer alternative, why use backscatter technology at all?  Good question.  Europe has banned them altogether.   Thankfully, there’s now a bill in Congress that would require an independent study on the health and safety of these body scanning technologies.  In a perfect world they’d do the study BEFORE spending money buying and deploying so many of these, but hey, better late than money.  The reality is that lobbyists and corporate interests seem to be heavily influencing the use of these technologies in our country.

In the meantime, what can you do?  If you’re lucky, you can choose to fly to and from airports that are using the millimeter wave technology instead; there’s a very detailed list of what technologies are used at various airports over at flyertalk.com.  You may also find that airports that have the backscatter scanners installed only rarely use them, instead funneling people through traditional metal detectors.