Seattle Times 
May 27, 2010
A group of doctors and professors from UC San Francisco are raising new concerns about the safety of a type of airport full-body scanner built by Torrance, Calif.-based Rapiscan Inc.
To reveal weapons hidden under a traveler’s clothes, the scanner relies on “backscatter technology,” which uses the ricochets from low-level X-rays to create what looks like a nude image of the person.
The experts said they fear that the scanners may expose the skin to high doses of X-rays that could increase the risk of cancer and other health problems, particularly among people with weak immune systems.
But officials at the Department of Homeland Security say there is no need to worry.
“The risk is so low it’s almost negligible,” said Dr. Alexander Garza, the assistant secretary for health affairs and chief medical officer for the department.