In the movie Total Recall, Arnold Schwarzenegger (Gov. of California) runs through a security check point corridor operating using X-Ray technology. That film was released in 1990. Today that technology is being installed around the world at airports, border check points, marine ports and high risk security environments such as court buildings. They are currently being assessed or used in Canada, the U.S., U.K., Russia, Japan, and Australia. Some countries, such as India, have outright rejected them based on privacy and considered too offensive to passengers. Significant concern is being raised as to the long term medical impacts to humans going through the devices.
In Canada, the Canadian Air Transport Security Agency (CATSA) organization has completed some field trials at smaller airports (Kelowna, B.C.) and is looking to purchase a half dozen of the machines to continue further assessment. There are approximately 18 airports in the U.S. using them. In the U.K. several airports now have them including Manchester. Testing in several countries has been going since 2004. In the U.S. the Transportation Security Administration began field trials in 2007. The technology offers security details to process passengers quickly and determine if weapons or other contraband is on a person without doing physical body search. Such technology would significantly improve the detection of hidden materials.
The type of X-ray used in these machines is called backscatter, because it sees an image radiated back to device from one side of the person. Health concerns have emerged. Early designs of the device could penetrate 4 inches of solid steel. For human screening purposes the levels are significantly less at 0.005 millirems of radiation. But what about frequent flyers? They may have significant concerns about the use of this technology and higher than average use compared to the casual holiday traveler. According to the U.S. Nuclear Regulatory Commission, the average exposure to radiation a human absorbs is 360 millirems per year from all sources.
The last issue is privacy. Many argue that it can be maintained and still satisfy privacy regulators. The Government of Ontario's Privacy Commissioner has released a report assessing backscatter technology specifically regarding usage at airports. In it, the primary requirement is ensuring that the proper software is installed to maintain body privacy and still ensure proper operation of the machine. Canada's Federal Privacy Commission does have concerns on how long data is stored and if it is categorized to passenger manifests. Those issues have yet to be fully resolved in Canada.
The American Civil Liberties Union (ACLU) has been against the use of this technology as far back as 2006 and has not changed its position.
In the U.S., the Transportation Security Agency has yet to come out with regulations or rules with respect to backscatter technology and data collected. The TSA states that the agency adheres to the U.S. Privacy Act of 1974.
Additional resources: Privacy Commissioner of Canada Privacy Impact Assessment