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Are Dental X-Rays Safe?

February 18, 2014 by Michael Greger M.D. in News with 30 Comments

Are Dental X-Rays Safe?

Every year, doctors cause an estimated 29,000 cancers a year dosing patients with X-rays during CAT scans (see Cancer Risk from CT Scan Radiation). What about dentists? 100 million Americans are exposed to dental X-rays every year, but don’t the lead apron and thyroid shield protect our vital organs? All our vital organs except one, our brain!

A study entitled “Dental X-Rays and Risk of Meningioma,” was recently published. The objective was to explore the association between dental X-rays—the most common artificial source of high-energy radiation—and the risk of intracranial meningioma, the most common type of brain tumor.

The researchers found that those who report ever having a bitewing X-ray had twice the odds of a brain tumor, and those that got a panoramic series—the full mouth X-rays—before age 10 had nearly 5 times the odds (see my 3-min video Do Dental X-Rays Cause Brain Tumors? for details).

While more research is needed, the bottom line is the benefits and risks of radiation exposure must always be carefully weighed. Dentists should consider the justification for every exposure. Furthermore, dentists should not prescribe routine dental X-rays at preset intervals for all patients (such as every 6 months or year, etc.). Says who? Says the official recommendations of the American Dental Association. There is little evidence to support irradiating people looking at all the teeth in search of hidden problems in asymptomatic patients. Accordingly, dentists should select patients wisely—only take X-rays when there is patient-specific reason to believe there is a reasonable expectation the X-rays will offer unique information influencing diagnosis or treatment.

The last time I was at at the dentist for my check-up I was again offered a set of full mouth X-rays (because I was “due”). Normally when I refuse routine dental X-rays I’ve just explained that I try to minimize my radiation exposure, but this time I was able to refuse “as per the official recommendation of the American Dental Association!” I just got a blank stare.

More on avoiding brain tumors in:

This is the third in a five part video series on preventing and mediating the adverse effects of radiation exposure. The first, Fukushima and Radioactivity in Seafood, described the natural and artificial sources of radioactive isotopes in our diet. The previous video, Cancer Risk from CT Scan Radiation detailed the estimated 29,000 cancers that doctors cause with CAT scans every year. I also have videos on Mediating Radiation Exposure from Air Travel, in which I talk about those full-body scanners in airports. And I close out with ways to mediate all these risks with Reducing Radiation Damage With Ginger And Lemon Balm.

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death and More Than an Apple a Day.

Image credit: bolandrotor / Flickr

How Risky are CT Scans?

February 13, 2014 by Michael Greger M.D. in News with 26 Comments

Cancer Risk from CT Scan Radiation

The greatest radiation exposure risk comes not from the Fukushima fallout or the polonium naturally found in all seafood (see my last video, Fukushima and Radioactivity in Seafood), but from doctors.

This was the study that originally shook things up: “Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CAT scans.” Researchers concluded that the best available risk estimates suggest that pediatric CAT scans (also known as CT scans) will result in significantly increased lifetime radiation risk. How increased? In the United States, of the approximately 600,000 abdominal and head CT scans annually performed in children under the age of fifteen, 500 of these individuals might ultimately not just get cancer but die from cancer attributable to the CAT scan radiation. In response to this revelation, the editor-in-chief of the leading radiology journal admitted that radiologists have not been watching out for children.

The cancer estimates were based on data from Japanese atomic bomb survivors, in terms of how many deaths one can expect from what kind of radiation dose. However, there’s never been a study able to actually document the excess cancers—until now. It turns out that the X-rays released by CAT scanners may be twice as carcinogenic as the higher energy gamma rays released from atomic bombs. Just a few CT scans may triple the risk of brain tumors and leukemia in children.

Other studies are being performed around the world to quantify the risk and should be out in the next few years. Until then, what can we do? First of all, we should get X-rays only when absolutely necessary. Good evidence suggests that between a fifth and a half of CAT scans aren’t necessary at all—they could be replaced with another type of imaging or not performed at all. That’s a lot of added cancer risk for no added benefit.

If you check out my 4-min video Cancer Risk From CT Scan Radiation, you can see the risk of developing cancer for different groups after getting one CT scan. The risk of developing cancer after a single CT scan may be as high as 1 in a 100 for a baby girl. It can take years for cancer to develop, though, which is why the risk is lower in the elderly since they have fewer years left to live. The diagnostic medical radiation dealt out in one year is estimated to cause 2,800 breast cancers among women in the United States, and 25,000 other cancers. That’s doctors causing a lot of cancer.

One chest CT scan is like getting 400 chest X-rays, and a stress test heart scan can be like getting over a thousand X-rays. Doctors need to communicate the risks of these procedures, using relatable analogies. For example, the risk of a chest CT is like the risk of having a car crash during 2500 miles of highway driving or of smoking 700 cigarettes. You pick up a pack of cigarettes and there’s a warning label, but then you go in for thallium heart scan, and no one minds telling you that the risk corresponds to smoking 1400 cigarettes. One in every 270 middle-aged women that get an angiogram may get cancer because of that one test.

The risk associated with the thallium heart scans shocked me. By eating healthy, we may not only eliminate the death and disability associated with heart disease and its treatment (such as open heart surgery), but the risks associated with heart disease diagnosis as well. See these videos for my advice on preventing heart disease:

As I explain in my full-length live presentation on preventing, arresting, and reversing the 15 top killers (Uprooting the Leading Causes of Death), adverse drug reactions from prescription drugs are estimated to cause more than 100,000 deaths in the United States every year, making doctors the sixth leading cause of death. And that’s not counting other “iatrogenic” (physician-caused) harm, such as these radiation risks or medication errors or infections acquired in hospitals. My profession needs to do a better job of offering fully informed consent, clearly and comprehensively explaining the risks and benefits of each alternate course of action.

What about getting X-rays at the dentist? I’ve got a video about that too: Do Dental X-Rays Cause Brain Tumors?. And cell phone radiation? See my video Do Cell Phones Cause Cancer?

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death and More Than an Apple a Day.

Image credit: thesmokingsection / Flickr

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