US scientists are warning that radiation from controversial full-body airport scanners has been dangerously underestimated and could lead to an increased risk of skin cancer - particularly in children.

University of California biochemist David Agard said that unlike other scanners, the radiation from these devices is delivered at low energy beam levels, with most of the dose concentrated in the skin and underlying tissue.

“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,” Dr Agard said.

"Ionizing radiation such as the X-rays used in these scanners have the potential to induce chromosome damage, and that can lead to cancer."

Of further concern is that a failure in the device – like a power or software glitch - could cause an intense radiation dose to a single spot on the skin.

The warnings come ahead of the planned rollout of the scanners in Australia next year as part of the Federal Government’s crackdown on airport security.

David Brenner, the head of Columbia University’s Centre for Radiological Research, says the concentration on the skin – one of the most radiation-sensitive organs of the body – means the radiation dose is actually 20 times higher than the official estimate.

Dr Brenner says the most likely risk from the airport scanners is a type of skin cancer called basal cell carcinoma, which mainly occurs on the head and neck and is usually curable.

The researcher was consulted to write guidelines for the security scanners in 2002 but said he would not have signed the report had he known the devices were going to be used so widely.

"There really is no other technology around where we're planning to X-ray such an enormous number of individuals," he said. “While individual risks will be extremely small, the population risk has the potential to be significant.”

The research also shows children are more vulnerable to radiation damage, because they have more cells dividing at any one time than when fully grown and a radiation-induced mutation can lead to cancer in adulthood.

Officials from the US Transportation Security Administration and the Food and Drug Administration have tried to allay concerns by saying that it would take thousands of trips through the scanners to equal the dose from one X-ray scan in a hospital.

The recent concerns raised by Dr Brenner at the US Congressional Biomedical Caucus have not been officially addressed.

Dr Agard and fellow doctors John Sedat, a molecular biologist and the group's leader; Marc Shuman, a cancer specialist; and Robert Stroud, a biochemist and biophysicist, addressed their concerns to Dr John Holdren, science adviser to US President Barack Obama.

The scientists are calling for more research to be undertaken before the use of the scanners becomes commonplace.

Dr Brenner believes millimetre-wave scanners that use radio waves instead of X-rays would be better to use because they have no known radiation risks.

Full-body scanners no stranger to controversy

The full-body scanners have already caused controversy, with privacy concerns including whether scanned images may breach child pornography laws in various countries.

They have also been criticised as ineffective, with warnings they would be unlikely to detect many of the explosive devices used by terrorism groups.

In other trouble earlier this month, a US airport security screener was suspended for assaulting a colleague who joked about him having small genitalia after he walked through a scanner.

And in March a UK airport security worker said she would sue her bosses after a colleague leered at her “naked” image in a scanner.

Small penis taunt: Airport security officer beaten

Scanner ogling: Woman to sue

'Naked scanners': Child porn fears

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