By Calvin Biesecker
New research by a professor and student at the Univ. of California-San Francisco (UCSF) and the Univ. of California-Berkeley respectively suggests that the risks of people getting cancer by going through backscatter X-ray-based whole body imagers at the nation’s airports is so low that there is no reason for concern.
The radiation doses the machines subject a person to “are low–extremely low,” Rebecca Smith-Bindman, M.D., a professor of radiology at UCSF, said in a statement this week. “The amount of radiation in these scans is so low that you don’t have to be concerned about it.”
Smith-Bindman and Pratik Mehta, an undergraduate student at UC-Berkeley, conducted the research and published an article on March 28 online in the Archives of Internal Medicine. The researchers assume that the backscatter-based Advanced Imaging Technology (AIT) machines work as designed.
Compared to the radiation exposure a person receives from the sun during a six-hour airplane flight, the radiation that person gets when passing through the backscatter AIT system is less than 1 percent, the researchers say.
“The suggestions that individuals who may be particularly vulnerable to radiation effects may want to avoid the scans are unwarranted concerns,” the research article says. “The flights themselves may expose them to a small increased exposure to ionizing radiation, but the scans will further increase that exposure by only a very small amount.”
The Transportation Security Administration (TSA) uses backscatter-based AIT machines supplied by OSI Systems [OSIS] Rapiscan Systems division. The agency also uses millimeter wave-based AIT systems provided by L-3 Communications [LLL] which have not raised any health concerns.
The newly published research by Smith-Bindman and Mehta stands in contrast to concerns raised last year by four other UCSF faculty members regarding the health effects of the backscatter AIT systems, particularly on a person’s skin and underlying tissue. The four UCSF professors sent a letter to the White House expressing their concerns and called for an “impartial panel of experts” to review the relevant data about the effects on people of the radiation emitted by the body scanners.
The Obama administration’s reply, crafted by TSA and the Food and Drug Administration, stated that the health risks from the backscatter imagers are “miniscule” (Defense Daily, Nov. 12, 2010).
In response UCSF said it would review the details of the administration’s response. The school’s newsroom said yesterday that the four faculty members are currently writing a paper on the matter and are withholding interviews until it is published.
TSA has deployed nearly 500 AIT machines to airports in the United States, with the majority supplied by Rapiscan. The agency plans to deploy another 500 AIT systems this year and has requested funding for 275 more systems in FY ’12.
Smith-Bindman said that there may still be safety risks associated with the use of AIT machines, such as human errors or mechanical malfunctions that cause the system to expose people to higher levels of radiation. She added that TSA should allow the systems to go through additional testing and give scientists access to them for independent testing, citing the earlier concerns of her four colleagues at UCSF.
She may have a point.
Earlier this month TSA disclosed that it had found inaccuracies in the test results its contractors have performed on the various types of X-ray imaging equipment–including AIT machines–related to the radiation they emit (Defense Daily, March 14). However, the agency said its own follow-up review found that the various pieces of equipment still meet all national safety standards.
TSA’s disclosure prompted Sen. Susan Collins (R-Maine) to question the confidence people can have in TSA’s data after she had been repeatedly assured by the agency that the AIT systems do not pose a health risk.