There are two types of scanners at the airport; the MILLIMETRE WAVE SCANNER and the BACK-SCATTER X-RAY SCANNER.
Both emit ‘high-energy’ radiation and both are dangerous. There is no “safe” dose of radiation.
Also known as the 'Terahertz Wave Body Scanner'. Terahertz waves don’t travel far inside the body but they rip apart DNA. Exposure may cause skin cancer, breast cancer, testicular cancer, brain tumours and foetal damage in pregnant women.
Low-level X-rays produce the same kind of "see-through" images that millimetre wave technology produces. Backscatter images resemble a chalk etching. Unlike medical X-rays, the X-rays used in backscatter technology bounce off the skin, revealing what's under your clothes, but not what's under your skin. Safe exposure levels differ from person to person. Airport workers in proximity to these machines need to wear protective clothing or shelter behind lead shielding when the scanner is operational. The wearing, and regular testing, of radiation badges is also recommended.
X-rays are ionising (penetrating) radiation. Ionising radiation in any dose causes genetic mutations, which lead to cancer. Cancers associated with X-rays include leukaemia, breast, bladder, colon, liver, lung, oesophagus, ovarian, multiple myeloma, prostate, nasal cavity/sinuses, pharyngeal, laryngeal, pancreatic and stomach cancers. A person undergoing a backscatter scan receives approximately 25 -45 millirems of radiation. 25millirems per year from a single source is regarded as the upper limit of safe radiation exposure. Widespread overuse of body scanners, and variations in radiation caused by different machines, could lead to many thousands of new cancer cases and deaths.
AGENCE FRANCE-PRESSE. Friday November 12th 2010
WASHINGTON — US scientists warned Friday that the full-body, graphic-image X-ray scanners that are being used to screen passengers and airline crews at airports around the country may be unsafe.
"They say the risk is minimal, but statistically someone is going to get skin cancer from these X-rays," Dr Michael Love, who runs an X-ray lab at the department of biophysics and biophysical chemistry at Johns Hopkins University school of medicine, told AFP. "No exposure to X-rays is considered beneficial. We know X-rays are hazardous but we have a situation at the airports where people are so eager to fly that they will risk their lives in this manner," he said.
A group of scientists at the University of California, San Francisco (UCSF) raised concerns about the "potential serious health risks" from the scanners in a letter sent to the White House Office of Science and Technology in April. Biochemist John Sedat and his colleagues said in the letter that most of the energy from the scanners is delivered to the skin and underlying tissue. "While the dose would be safe if it were distributed throughout the volume of the entire body, the dose to the skin may be dangerously high," they wrote.
The Office of Science and Technology responded this week to the scientists' letter, saying the scanners have been "tested extensively" by US government agencies and were found to meet safety standards. But Sedat told AFP Friday that the official response was "deeply flawed."