“There are 244 full-body ‘backscatter’ X-ray scanners in use at 36 airports in the U.S. They operate almost nonstop, according to the TSA. A recent study reported that radiation from the machines can reach organs through the skin. The European Union has banned body scanners that use radiation; it is against the law in several European countries to X-ray people without a medical reason. Independent scientists say limited access has hampered their ability to evaluate the systems. In a letter to the federal Department of Health and Human Services dated Oct. 12, 2010, scientists said that ‘the casual nature for maintenance of these devices is alarming to us.'”
http://well.blogs.nytimes.com/2012/08/06/x-ray-scans-at-airports-leave-lingering-worries/