Documents obtained through a Freedom of Information Act request show that the Transportation Security Administration dismissed concerns from its employees about the radiation emitted by body imaging machines at airport security checkpoints.

In an email sent to a TSA official in May 2010, the leader of a Boston-based TSA union said that a growing number of security officers had been diagnosed with cancer. To investigate the matter, she asked for dosimeter devices to monitor how much radiation the security officers were being exposed to.

"[The security officers] would like these dosimeters to be periodically sent out to a non-TSA third party medical facility for data results gathering which could later be periodically released to our workforce," the union's president, AJ Castilla, wrote.

The email (PDF) was obtained by the Electronic Privacy Information Center (EPIC).

The Department of Health and Human Services later responded (PDF) to the TSA union, saying that it was unlikely that the cancers reported were associated with exposure to the body scanning machines.

"There were a variety of cancers reported among TSA employees, and they were among the most common types diagnosed in the United States," they said. "No cases of thyroid cancer or leukemia were reported (the thyroid and bone marrow are the most radiosensitive organs)."

In March, the American Federation of Government Employees (AFGE), the exclusive union for Transportation Security Administration employees, called on the TSA to implement a nationwide radiation monitoring program for its employees.

The TSA has held that there are no harmful radiation emissions from body scanners used at security checkpoints, but the TSA union thinks more studies are needed.

"AFGE has suggested that the National Institute for Occupational Safety and Health (NIOSH) conduct a comprehensive study that we firmly believe is needed," AFGE National President John Gage said in March. "We are encouraged to learn from press reports that TSA intends to ask NIOSH to update its 2008 study, in which it recommended a nationwide, mandatory radiation monitoring program. TSA did not act on that recommendation, and there has never been a better time to implement it."

Another email (PDF) obtained by EPIC says that Homeland Security mischaracterized the National Institute of Standards and Technology (NIST) by suggesting that they had "affirmed the safety" of body scanners.

NIST stated that they had measured the amount of radiation being emitted by the machines and made sure it did not exceed known standards, but did not conduct studies of its possible health effects.

Dr. David J. Brenner claimed that the U.S. should be concerned about the long-term consequences of an extremely large number of people being exposed to a radiationn an article published in the April issue of Radiology. He is the Director of the Center for Radiological Research at Columbia University Medical Center in New York.

"The risks for any individual going through the X-ray backscatter scanners are exceedingly small," Dr. Brenner said. "However, if all air travelers are going to be screened this way, then we need to be concerned that some of these billion people may eventually develop cancer as a result of the radiation exposure from the X-ray scanners."

"As someone who travels just occasionally, I would have no hesitation in going through the X-ray backscatter scanner," he added. "Super frequent fliers or airline personnel, who might go through the machine several hundred times each year, might wish to opt for pat-downs. The more scans you have, the more your risks may go up — but the individual risks are always going to be very, very small."

Despite the concerns over radiation exposure, scientists have complained that there is still very limited data on the safety of body scanner machines because of a lack of independent testing. An article published in the Archives of Internal Medicine on June 27 claims "there is good reason to believe that the procedures used by National Institute of Standards and Technology (NIST), John Hopkins Applied Physics Laboratory (JHL), and the Transportation Security Administration (TSA) lead to underestimates of exposure."