London: Full-body airport scanners are just as likely to kill you as a terrorist's bomb blasting your plane in the sky.

The controversial machines that have been brought in at major airports across the globe are evoking fears that the increased exposure to radiation may cause cancer.

Now a physics professor has claimed that scanners are redundant because you are just as likely to contract cancer from the radiation as you are to die in a terrorist bomb on your flight.

Peter Rez from Arizona State University in the US said the probability of dying from radiation from a body scanner and that of being killed in a terror attack are both about one in 30 million, reports the Daily Mail.

"The thing that worries me the most is not what happens if the machine works as advertised, but what happens if it doesn't. A potential malfunction could increase the radiation dose," he said.

Rez has studied the radiation doses of backscatter scanners using the images produced by the machines. He discovered the radiation dose was often higher than the manufacturers claimed.

Rez suggested the statistical coincidence means there is really no case to be made for deploying any kind of body-scanning machine -- the risk is identical.

Critics say the low level beam used delivers a small dose of radiation to the body but because the beam concentrates on the skin -- one of the most radiation-sensitive organs of the human body, that dose may be up to 20 times higher than first estimated.

A number of scientists have already written to the Food and Drug Administration to complain that the safety aspects have not been properly addressed before the nationwide rollout of the scanners.

Biochemist John Sedat from the University of California and his colleagues said that most of the energy from the scanners is delivered to the skin and underlying tissues.

"While the dose would be safe if it were distributed throughout the volume of the entire body, the dose to the skin may be dangerously high," they wrote.