Lately some attention has been given to a letter written in April by University of California-San Francisco professors to OSTP Director John P. Holdren, the President’s science advisor, about the issue of full body scanners being deployed at airports and the X-ray radiation emitted by these machines. Dr. Holdren responded with an e-mail to the authors noting that the issue had been studied extensively for many years by the Food and Drug Administration (FDA), Department of Health and Human Services, and Department of Homeland Security (DHS) but also acknowledging the need for a clear and detailed explanation of the science around X-ray backscatter screening. Dr. Holdren wrote:

“In the interest of greater transparency and to minimize the spread of misinformation, I have asked representatives in FDA and DHS to work with OSTP to craft a detailed and clear description of the evidence for the safety of the devices in question, addressing all of the points raised in your letter.”

Recently, representatives from the FDA and DHS provided that detailed description in a letter to Dr. Holdren, which he shared with the UCSF professors. The response letter is available here or here in PDF, and the FDA has a website dedicated to the topic.