The Transportation Security Administration (TSA) last Friday said it plans to contract with the National Academy of Sciences to examine the health effects of backscatter X-ray-based Advanced Imaging Technology (AIT) machines that the agency uses to screen passengers at some aviation security checkpoints.

The Academy will convene a committee to review previous studies done to examine the health effects of the backscatter AIT machines and also review the processes that TSA and equipment manufacturers use to estimate radiation exposure to people who are screened by the machines.

TSA currently uses two types of AIT systems to screen passengers at airport security checkpoints, the backscatter systems, which are made by OSI Systems [OSIS], and millimeter wave-based technology systems, which are made by L-3 Communications [LLL]. There are no concerns being raised about the health effects of the millimeter wave AIT systems, which don’t emit ionizing radiation.

While the backscatter AIT systems do emit ionizing radiation, TSA and the Department of Homeland Security (DHS) have maintained, and trotted out various studies to prove their case, that these systems are harmless to travelers.

Earlier this year, the DHS Inspector General reported that TSA is in compliance with standards that have been established to verify the safe radiation dose emitted by the backscatter body scanners and that these systems deliver minimal amounts of radiation (Defense Daily, Feb. 29). TSA has cited numerous other studies previously in defense of its use of these machines.

More recently, the European Commission in the spring issued a report by its scientific group saying the backscatter X-ray machines, which are also being used at a number of airports worldwide, present the same risks to radiation as from naturally occurring sources in the environment. However, the report did say that there may be potential concerns with certain groups of people such as children and pregnant women.

Last year researchers from two universities in California also published their findings that the risks to people of getting cancer by going through the backscatter AIT systems are so low as to be of no concern (Defense Daily, March 30, 2011).

Despite the various studies showing little to no health risks to passengers who are screened by the backscatter AIT systems, Sen. Susan Collins (R-Maine) introduced legislation requiring TSA to conduct an independent study of the health effects of these systems.

Collins, who is the ranking member of the Senate Homeland Security and Governmental Affairs Committee, said in a statement on Monday that she is “pleased” that the National Academy of Sciences is going to investigate the health effects on passengers and TSA screeners of the backscatter AIT machines.

“While TSA has told the public that the amount of radiation emitted from these machines is small, passengers and some scientific experts have raised questions about the impact of repeated exposure to this radiation,” Collins said. “Pregnant women, children, the elderly, and as much as five percent of the adult population, are more sensitive to radiation exposure. This independent study should help us to finally answer those questions.”