SAN FRANCISCO (CBS 5) -- The public outcry over those new and revealing full body scans at the nation's airports seems to have died down. But even though passengers may not be thinking about them, some scientists are voicing new concerns.
Over the holidays, some airline passengers were enraged about new security procedures, including screeners who can see images of their body parts. But what about what you can't see?
"It concerns me a great deal," said UCSF Professor Robert Stroud. At his biophysics lab Professor Stroud has been analyzing data on the new so-called backscatter body scanners. They emit very low level X-rays that bounce off a person's body, allowing screeners to see through clothes.
The manufacturer, Rapiscan, claims they are safe, and compliant with all U.S. regulations and standards. But Stroud said, "We simply don't know enough about low intensity radiation."
Stroud said the low intensity radiation appears to mostly concentrate in the skin. "Skin is where a lot of this particular radiation probably will be most damaging," he said.
He believes eyes could also be sensitive to any kind of radiation. "If you have typically 3 head X-rays for example you increase your risk of cataracts significantly," Stroud said. "I would imagine in time we will all be presented with some type of glasses."
Stroud and three other UCSF colleagues wrote a letter to the White House. The White House wrote back, saying "we are confident that full body X-ray security products and practices do not pose a significant risk to the public health."
But the scientists at UCSF believe what is being offered up as scientific proof of the body scanners' safety is not convincing.
A recent study was commissioned by the feds and carried out by researchers at Johns Hopkins University. "The document is heavily redacted," said Stroud. "Also there are no names on the document."
Stroud also said vital information is missing. "Never in this document for example is the X-ray current for the actual machine listed."
He also said another problem was the way the test was conducted. "The scientists from Johns Hopkins were not presented with a machine to investigate in their labs, rather they were invited to witness experiments carried out by the manufacturers in their own lab," Stroud said.
Transportation Security Administration spokeswoman Sarah Horowitz said sections of the study were blacked out for a reason. "Obviously there are studies that contain security sensitive information," Horowitz said.
Bottom line, Horowitz said, the study proves the scanners are safe. "We have worked with federal agencies and third parties including universities and they have convinced us of the safety of the technology," said Horowitz. "There is minuscule amount of radiation being emitted by the scanners."
A spokeswoman for Johns Hopkins said its study is being misinterpreted, stating in an email to CBS5: "The laboratory's expertise is systems engineering, not how something affects the human body. So it would be outside of our expertise to say whether or not a radiation level is safe."
It's one more reason to make Professor Stroud doubt. "I do think it's time for an independent investigation," he said.
The TSA recently agreed to exempt all airline flight crew from the full body scanners. But more and more passengers are going through 247 machines at 38 U.S. airports at last count.
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