News Review from Harvard Medical School – Radiation When You Fly

Whole-body scanning at airports has become more popular over the past few years. Some are concerned that the radiation from these scans can be a health risk. One type of scanner does not expose people to radiation. But the other type does expose people to a small amount. Experts point out that millions of people will undergo whole-body scanning. But there are many other sources of radiation that people are exposed to each day. Experts also recommend that airports choose scanners with millimeter wave technology, which does not expose people to radiation.


The articles appear in the April issue of the journal Radiology.

By Robert H. Shmerling, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

There’s been heightened concern about radiation exposure this week. Given the events in Japan over the last week, worries about radiation are understandable.

But even if you don't live near a damaged nuclear power plant, you're exposed to radiation every day. And you may be getting more radiation exposure now due to a new source: security scanners at the airport.

The Transportation Security Administration (TSA) began installing whole-body scanners in airports in 2007. But the number of airports using them increased dramatically after a failed plot in 2009. That’s when a terror suspect attempted to detonate explosives hidden in his underwear as his flight landed in Detroit.

According to the TSA, 78 airports are now using body scanners to search for hidden explosives. The TSA has declared these scanners safe. Still, many are concerned, especially those who are scanned often. This includes airline or airport employees and anyone who flies frequently.

However, there are 2 types of scanners are being used in U.S. airports. One uses millimeter wave technology, which produces no harmful radiation. About half of the scanners are of this type. The other half use backscatter X-rays. These do expose people to a small amount of radiation.

Two new reports on the safety of airport scanners have just been published. They provide useful information on this important subject.

In these new reports, experts point out that:

Though the risk of having a security scan at the airport is minimal, millions of people will be exposed to this risk over time. And that could cause health problems for a substantial number of people. However, this is unproven as it's possible that tiny amounts of radiation are truly harmless.

The amount of radiation exposure associated with body scanners may be acceptable when considering other sources of radiation we accept every day (see below).

There’s no proof that the tiny amounts of radiation exposure associated with airport scanners add up to cause any health problems. Most risks are assumed based on much higher exposures (such as survivors of the atomic bomb in Hiroshima).

Airport scanners should have well-defined limits on the amount of radiation they produce. Frequent monitoring is needed to ensure compliance with these limits.

The risks and benefits of airport scanners should be reviewed regularly. To do this, we need more information not only on radiation risk, but also on the effectiveness of these scanners.

Going forward, the first choice of scanners should be those using millimeter wave technology. They apparently provide similar images and do not cost more than backscatter X-ray scanners.

I think it's important that we ask questions about the safety of airport scanners. But the answers must be understandable to the average air traveler. The TSA should put the risks of airport scanners into context. Perhaps the best way is to compare it them to other everyday risks.

What Changes Can I Make Now?

Understand that radiation exposure is impossible to avoid. For example, the radiation exposure associated with having an airport scan is:

30,000 times less than the average person in the U.S. gets from natural radiation sources (such as cosmic rays) in one year

1,300 times less than a mammogram and 1,000 times less than a chest X-ray

30 times less than flying in an airplane at 30,000 feet for an hour

6 times less than sitting in Grand Central Terminal in New York City for an hour (due to radiation from granite walls there)

Though the occasional airport scan is probably harmless, it makes sense to take some precautions. For example:

Find out from airport personnel whether your airport uses backscatter X-rays or millimeter wave technology. If you have a choice of airports, choose one that uses the latter.

When you have medical X-rays, wear a lead apron to protect areas not being X-rayed. And let the X-ray technician know if you're pregnant.

If you work near radiation, follow your employer's safety rules and regulations.

If you’re concerned about how frequently you're having body scans at the airport, you can request a “pat down” instead.

Of course, if you really want to avoid radiation associated with airport scanners, don't fly! Find another way to travel, such as a train or bus.

What about taking iodine tablets prior to going through airport security? I don't recommend it! While taking iodine can limit radiation exposure to the thyroid gland, it's not recommended unless radiation exposure is much higher than one gets in an airport scanner. And, iodine tablets can cause side effects.

What Can I Expect Looking to the Future?

Concerns about radiation exposure are not the only objections raised about airport body scanners. Many have questioned their effectiveness. And even more have complained that the detailed anatomic images produced by body scanners are a humiliating invasion of privacy. In many airports, there has been far more concern over these issues than over safety.

So, you can expect continued debate about the merits and risks of airport scanners. You can also expect ongoing research into the risks of small amounts of radiation. And just last week, TSA officials announced that it will begin publishing the results of radiation test results from screening equipment.

In the meantime, you have a choice: accept the TSA at their word that current airport scanners are safe or avoid the scanners altogether.
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Harvard Medical School (HMS) is one of the graduate schools of Harvard University. It is currently ranked first among American research medical schools by U.S. News and World Report, and ranked 21st among research medical schools in the amount of competitive grants received from the NIH.[2][3]
Located in the Longwood Medical Area of the Mission Hill neighborhood of Boston, Massachusetts, H.M.S. is home (as of Fall 2006) to 616 students in the M.D. program, 435 in the Ph.D. program, and 155 in the M.D.-Ph.D program.[1] HMS' M.D.-Ph.D program allows a student to receive an M.D. from HMS and a Ph.D from either Harvard or the Massachusetts Institute of Technology (see Medical Scientist Training Program) Picture: Gordon Hall, Harvard Medical School.