When the fall semester ends, many Columbia students will be heading to the airports. Increased security measures by the Transportation Security Administration, or TSA, includes the use of new body-scanning X-ray technology. But the question many have been asking: is it safe?

CTV News spoke with Columbia University radiation expert Dr. David Brenner, Head of Columbia's Center for Radiological Research.

"If you went through an airport two years ago, you would go through a little archway. That was basically a metal detector, so it would detect a gun or a knife or something like that. Post the 2009 Christmas bomber, the homeland security - the TSA - decided to implement a new generation of Advance Imaging Technology (AIT) devices. One is called a millimeter wave scanner: millimeter waves are radiations that are similar in energy to a microwave. Basically, you are flooded with low fluence of these millimeter waves and the machine looks for the reflectents in the detectors. From that, they can figure out whether there are any explosives on you," said Brenner.

"The second type also uses the same technique of bouncing radiation off you, but here the radiation is X-rays; that's usually called the X-ray Backscatter System. They both work on much the same principle of bouncing some radiation off you and looking at the reflected radiation. Our concern is that one of these two devices - the X-ray device - uses ionizing radiation, which we know to have significant potential cancer risks."

Dr. Brenner points out that the levels of radiation are relatively low. The main concern is not for college students - who fly less frequently - but for pilots, flight attendants and the TSA workers themselves who are exposed to radiation everyday.

"Your risk of cancer going through the scanner once is probably about 1 in 10 million, so from the point of view of someone who doesn't fly very often and goes through the scanner only occasionally, I don't think there are any real health concerns that I would be worried about.

"There are a couple of scenarios that we do worry about. The first is the very frequent fliers, air flight personnel also go through many times. An air host or hostess is going through maybe 300 times a year. We take that very small risk and if you go through it a hundred times, your risk will be multiplied by a hundred, if you go through it three hundred times, your risk will be multiplied by three hundred.

"That being said, even if you multiply a very small risk of 1 in 10 million by 300, it's still a very small risk. Where the real issue occurs is that these machines are now front-line screening technology, with the goal of everybody going through these scanners, and that's a lot of people. The number of enplanements - the number of times people get on airplanes - in the U.S. last year was about 730 million, and by 2020 it's going to be 1 billion, so that's an awful lot of scans. Take that very small risk of 1 in 10 million and then multiply that by a billion - the number of potential scans - and what you end up with is the conclusion that probably, some years down the line, some people will develop cancer as a result of these X-ray scans," Brenner added.

It is still too early to identify the long-term impacts of using X-ray technology on large segments of the population. Regardless, Dr. Brenner concedes that in a post-September-11 world, exposure to low-levels of radiation outweighs the risk of a security threat in the air.