CN Digital Studio (Airport security | CN Digital Studio)

Winter escapes.

They’re great once you’re paddle-boarding across crystalline Caribbean waters or powering through powder in Vail. But getting there? Not so much. The packing, the crowds, and the delays have always been annoying. But lately air travel has become controversial, even a bit worrisome, and that’s before lift-off. Over the past year a steady drip of headlines hinting at a possible link between new security scanners and cancer has made me wonder if I should make my next trip by sea.

“We don’t know if there will be long-term effects on frequent fliers or flight crews,” says Ken Spaeth, M.D., director of the Occupational and Environmental Medical Center of the North Shore–Long Island Jewish Health System. The radiation emitted is “a low dose, but it penetrates the skin,” notes Spaeth, who is helping a New York congressman fight for an investigation. “It’s fair to ask: Is this safe, and how can we be sure?”

The Transportation Security Administration official I contacted assured me that the TSA “would never use technology that could jeopardize the health of passengers or our employees” and gave me a list of agencies and institutes that have deemed them safe, including the FDA. But the ranks of the unconvinced are growing.

Put into wider use in 2010, the back-scatter X-ray machines, the ones that look like big black boxes and scatter high-intensity X-rays quickly over your body, earned the nickname “naked” or “strip-search” scanners from critics. Personally, I’m less concerned about what a random stranger may or may not see than the idea that these machines—which are now in nearly 40 U.S. airports—could be emitting more radiation than we think. (Europe, seemingly always ahead of the curve when it comes to such issues, has already banned them, citing health concerns.)

A group of scientists at the University of California, San Francisco, petitioned the White House in 2010 for urgent research to better quantify radiation levels, but say they got nowhere. (The White House posted data in a response on its Web site but, according to the UCSF group, did not address the scientists’ key concerns.) They are particularly frustrated that, for security reasons, independent scientists are not getting access to evaluate the actual machines.

Judging by the quality of images produced, a single dose could be anywhere from ten to 45 times higher than what the TSA is reporting, according to an Arizona State University study published a year after the machines were introduced. Granted, even if the dose is 45 times higher, it would still be low, but the cumulative risks of low-dose exposure are not well known. Additionally, a machine malfunction could leave a beam on one part of the body much longer than is thought to be safe.

Even under perfect working conditions, the machines trouble some scientists. A 2011 Columbia University study calculated that one billion scans of passengers over a year could cause 100 cancers. “The true number could be less or it could be more; we really don’t know,” says study author David Brenner, Ph.D., director of the Center for Radio- logical Research at Columbia University. He’s less worried about single-time uses—and even e-mailed me a few days after going through one at JFK—and more the larger public health–policy issue, “particularly with the availability of equally efficient millimeter-wave scanners.” (Those look like glass phone booths and don’t use radiation.)

A bill has been introduced in the Senate to launch an independent investigation into the safety of the back-scatter machines and to require signs at airports letting passengers know their choices. And that’s just the point: We do have a choice. Until we get the independent research critics are asking for, I’ll be taking the old-school route and enduring the pat-down. Annoying? Perhaps. Safe? No doubt.