Wednesday, December 8, 2010

The Whole-Body Scanners

Are they safe?
In the recent weeks TSA started to aggressively steer people towards the whole-body scanners, which are capable of producing "naked" images of people. This policy was introduced without much public debate, raising numerous concerns about privacy, legality, civil rights, etc. In this article we’ll concentrate on safety of these screening devices.

TSA and a number of officials from FDA have issued assurances that these scanners are safe, claiming that a number of experts have reviewed the radiation exposure data and agrees that the doses of radiation travelers get from being scanned are well within exposure limits established as safe. However, the technical specifications, details of operation and construction, and other data necessary for an independent review of safety of these devices are not published.

What is known is that there are two different types of scanners – one uses scattering of "soft" X-rays, and another uses the terahertz (millimeter) microwaves to form an image. We will discuss the X-ray scanners first.
The general public is well aware of danger of exposure to X-rays; this danger is being forcefully underlined by the usual safety procedures of clinical radiologists donning lead vests and retreating before turning the X-ray machines on. Unlike high-intensity radiation, low-intensity X-rays do not kill or burn cells outright, but the energetic photons can and do damage DNA in the cells. Most DNA damage is not critical, and is repaired by the cells; however some damage remains unrepaired – crippling cellular mechanisms, or disabling them completely when enough damage is accumulated. One of these mechanisms, called apoptosis, or programmed cellular death, prevents cells in our bodies from multiplying uncontrollably. Once this mechanism is disabled, the cell becomes cancerous. (Radiation exposure was also recently found to increase mortality from cardiovascular diseases).

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