TSA officials maintain the machines are safe. They say with security machines, unlike medical X-rays, most of the radiation does not enter the body, but bounces off the skin's surface.
The dose of radiation from a full-body scanner is 2000 times less than a chest X-ray and 200,000 times less than a CT scan. Still, scientists who have studied the issue extensively urge caution.
"People have different sensitivities to radiation," said David Brenner from Columbia University's Center for Radiological Research. "Children in general are more sensitive than adults to radiation and the developing embryo and fetus in pregnancy are the most sensitive of all."
While scientists debate how dangerous the radiation in the full body scanners is, Cleary and other pilot advocates are urging pilots not to take the health risk.
Cleary told pilots that their stance against the scanners and the patdowns is a "fight to restore the dignity we deserve as the last line of defense against terrorists who would use airplanes as weapons of mass destruction. We are not the enemy and we will not stand for being treated as such before each duty period."