Mehmet Oz hosts a popular TV show that reaches millions of people. He offers a constant stream of medical advice, and he is popular because he makes his topics sound dramatic, or exciting, or surprising, or all three.
Unfortunately, Dr. Oz sometimes demonstrates a poor understanding of science. At least I hope so, because he promotes so many outrageous treatments, with such enthusiasm, that the only other explanation I can think of is that he is simply a fraud. I don’t think that’s true, so let’s give him the benefit of the doubt and assume that when he makes a mistake, he is simply ignorant of the truth. His latest startling revelation is that the metal fillings in your teeth are very, very bad for you. Or are they?
Last week, Dr. Oz hosted a show called “Toxic Teeth: Are Mercury Fillings Making you Sick? The show looked at silver amalgam fillings, which contain a small amount of mercury chemically bound within them. Mercury is indeed a toxin. Should you worry?
One problem with taking a skeptical look at a Dr. Oz’s show is that he packs each episode with scientific claims, coming at you thick and fast, and it would take hours to critique them all. Instead, I’ll just pick a few, which illustrate Oz’s lack of concern for accuracy, and his apparent ignorance of the underlying science about dental fillings.
Dr. Oz opens his show with a dramatic claim about mercury:
“This thermometer contains mercury,” he says, holding up a very small thermometer. “If I were to drop it, we would have to evacuate this entire studio immediately!”
Now, this is complete nonsense. If you drop a mercury thermometer, you should carefully clean up the mercury, which beads up into nice little silver-colored balls. No one in the room is in danger, unless perhaps they try to inhale it.*
This opening salvo should set off anyone’s skeptical alarm bells. Here’s a guy who doesn’t seem to mind exaggerating to make a point. Why trust anything he says in the rest of the show? I suspect, though, that after watching this episode, thousands of Oz’s loyal viewers raced to the phone and made appointments to have the silver fillings in their teeth removed.
Dr. Oz continues his introduction by explaining that mercury is contained in silver tooth fillings. No one knew, he claims, that mercury vapor could be released from these fillings, but this news:
“sparked a firestorm 30 years ago [here the show cuts to a graphic of a fireball exploding] when major news reports brought to light the potential TOXICITY of mercury fillings. … Now there’s mounting new evidence showing mercury is released when you eat, and even when you brush your teeth.”
Quick, run to the dentist! Get this toxic mess out of my mouth!
But hang on a minute. Why aren’t people dropping like flies from the fillings in their teeth? With little effort, I determined that, contrary to Dr. Oz’s statements, nothing new has been discovered lately about silver tooth fillings. I found studies going back to the 1970s that shown that we’ve long known for decades that mercury is released from these fillings. But Oz ignores all these. He even announces, a few minutes into the show, that
“for the first time ever, I’m going to show you what happens when you brush your teeth with mercury fillings.”
No, this is not the “first time ever.” As a scientist, I find it worrisome that Oz seems quite comfortable claiming, incorrectly, that he’s the first person ever to tell the world about this.
Perhaps the most outrageous – and unintentionally funny – segment of the show is the “demonstration,” where Oz introduces an Oz-certified expert on mercury vapor, David Wentz, who has a gizmo that looks like it was built by a sideshow huckster. The device is a plexiglass box that looks like it was meant to handle biohazards, with black rubber gloves that let you manipulate its contents. In the box: a set of fake teeth containing… silver fillings! And a toothbrush!
As he walks over to the device, Oz says “I work with Dave Wentz and his Ph.D. dad.” This goes by really fast, so you would be excused for not realizing that Dave Wentz himself doesn’t have a Ph.D., and for not knowing whether he has any credentials at all. Dr. Oz conveniently omits the fact that Wentz and his father run a highly profitable nutritional supplements company, USANA, which happens also to donate money to Oz’s nonprofit corporation, HealthCorps. Hmm.
Dr. Oz then reaches into the box, and while the audience watches in hushed excitement, he brushes the teeth, right on top of those silver fillings! Right on cue, Wentz proclaims that the mercury vapor reading hits 61 in just a few seconds.
“Anything over zero is toxic,” Wentz proclaims. “And we’re at 61.”
“Oh my goodness, 61!” Dr. Oz exclaims.
“That mercury is coming off the fillings, into your mouth, going across the blood-brain barrier, into your brain,” says Wentz dramatically.
Wow. I’ve been brushing my teeth (which have several fillings) for years. How can I not be dead?
As Dr. Oz should know, “the dose makes the poison.” Even water can kill you if you drink too much of it. Wentz is clearly wrong to say that “anything over zero is toxic.”
How much mercury is safe, then?
According to the EPA, 0.1 micrograms of mercury per kilogram of body weight per day is safe. For an adult who weighs around 150 pounds, that’s about 7 micrograms. A 6-ounce can of tuna has about 20 micrograms of mercury, about 3 times the safe amount per day. Scientists do have real concerns that mercury in tuna and other fatty fish might present a health hazard.
Dr. Oz’s device seemed to show that 61 micrograms of mercury were released from brushing teeth, which would be about 9 times the exposure that is considered safe. Is there really a risk here?
Well, no. The EPA has found that “nearly all methylmercury exposures in the U.S. occur through eating fish and shellfish.” (Admittedly, though, this is not mercury vapor.) The precise question that Oz claims to be explaining “for the first time” has been examined in multiple studies, and the evidence is that silver fillings are harmless. (See the FDA summary here.)
A thorough scientific review in 2004 concluded that:
“The current data are insufficient to support an association between mercury release from dental amalgam and the various complaints that have been attributed to this restoration material. … Individuals with dental amalgam-attributed complaints had neither elevated HgU nor increased prevalence of hypersensitivity to dental amalgam or mercury when compared with controls. The findings of these studies suggested that individuals with complaints self-attributed to dental amalgam should be screened for underlying dental, physical, and psychiatric conditions.”
So no, there’s no evidence that mercury from silver fillings causes any health problems. None.
But what about that device on Dr. Oz’s show, which showed 61 micrograms being released in just a few seconds of brushing the teeth? My conclusion is that the device in Dr. Oz’s studio was either wildly inaccurate or simply fraudulent. The setup was almost a parody of what real scientific instruments look like, and nothing about it gave me any confidence that it was reliable. I would suggest to Oz that before making a claim like this, he should ask rigorously trained scientists to make the measurements using properly calibrated equipment. A TV studio is no substitute for a real lab.
But wait: Mehmet Oz is a Professor of Surgery at Columbia University – he must know his science! Plus he has an M.D. from the University of Pennsylvania, and he did his undergrad studies at Harvard. By all appearances, he is a very smart guy. If his show were about heart surgery – his specialty – it would no doubt be professional, accurate, and probably far too technical to attract an audience.
Here’s the rub: despite his credentials, Oz is not an expert on mercury amalgam fillings. He probably could have read and understood the science, but he appears to be unaware, or too busy to be bothered by, the many scientific studies on this subject. Had he done his homework, he might not have presented such a spectacularly overblown episode that seems intended to scare people into removing the silver fillings from their teeth.
So there’s no need to go out and get your silver fillings replaced. It’s too bad that a highly educated surgeon like Mehmet Oz, with such a big audience, prefers to present wild exaggerations rather than telling people the truth. Perhaps, though, the truth just isn’t that exciting.
*Note added on followup: Even swallowing is rarely harmful. From J. Dodes: “Acute toxic exposures to elemental mercury are rare but there have been cases of elemental mercury being accidentally released directly into the bloodstream from broken rectal thermometers and when elemental mercury had been swallowed intentionally in an attempt at suicide. In all these cases there was no long-term effects from the mercury.” Dodes, JE. The Amalgam Controversy:an evidence-based analysis. JADA, 132:348-56, 2001.
The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.