The TSA is so sure airport body scanners are safe -- the kind that Europe just banned because of "cancer risks -- are safe, that it's cancelling plans for a health and safety study.  After a ProPublica/PBS NewsHour investigation unearthed research showing that the scanners could lead to a number of cancer cases, TSA Administrator John Pistole agreed, out loud, in front of the Senate, to conduct a new independent study for further investigation. Now, Pistole is backing off, reports ProPublica's Michael Grabell. He told a different Senate committee, "My strong belief is those types of machines are still completely safe."