Dr. Oz takes a big bite of bad science

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 has 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 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 drink 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 http://www.usana.com/dotCom/about/index, 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.

Congress holds an anti-vaccine hearing

I was in my car yesterday listening to C-SPAN (yes, I do that sometimes), when to my stunned surprise I heard Congressman Dan Burton launch into a diatribe on how mercury in vaccines causes autism.  No, this was not a replay of a recording from a decade ago.  The hearing was held just a few days ago by the Committee on Oversight and Government Reform.

Congressman Burton used this hearing to rehash a series of some of the most thoroughly discredited anti-vaccine positions of the past decade.  Burton is a firm believer in the myth that vaccines cause autism, and he arrogantly holds the position that he knows the truth better than the thousands of scientists who have spent much of the past decade doing real science that proves him wrong.  

In a classic political move, the committee called on scientists Alan Guttmacher from the NIH and Colleen Boyle from the CDC to testify, but in fact the committee just wanted to bully the scientists.  Committee members lectured the scientists, throwing out bad science claims, often disguised as questions, thick and fast.  Alas, Guttmacher and Boyle weren't prepared for this kind of rapid-fire assault by pseudoscience.

Burton himself was the worst offender, offering anecdotes and bad science with an air of authority.  He stated bluntly: 

“I’m convinced that the mercury in vaccinations is a contributing factor to neurological diseases such as autism."

No, it isn't.  Dozens of studies, involving hundreds of thousands of children, have found the same thing: there is no link whatsoever between thimerosal and autism, or between vaccines and autism.  And Burton went off the deep end with this: 

"It wasn’t so bad when a child gets one or two or three vaccines… Mercury accumulates in the brain until it has to be chelated.” 

Bang bang, two false claims in 10 seconds.  First he claims that mercury from vaccines "accumulates in the brain", a statement with no scientific support at all. Then he claims that chelation therapy is the solution - a radical, potentially very harmful treatment that no sensible parent would ever force on their child.  Unfortunately, some quack doctors have experimented with chelation therapy on autistic children, despite that fact that it can cause deadly liver and kidney damage, and one of them caused the death of a 5-year-old boy in 2005.

Burton also claimed that single-shot vials would "eliminate the possibilty of neurological damage from vaccines" - a claim that was invented out of thin air by the discredited anti-vax doctor Andrew Wakefield, whose fraudulent 1998 study was the spark that started the current wave of anti-vax hysteria.

Congressman Bill Posey from Florida was just as bad as Burton, demanding a study of vaccinated versus unvaccinated children, a standard talking point of the anti-vax movement.  (Congressman Posey: do you even realize that your question is almost identical to what Jenny McCarthy asked five years ago, on the Larry King Live show?)  Here's his question to the CDC's Boyle:

"I wonder if the CDC has conducted or facilitated a study comparing vaccinated children with unvaccinated children yet - have you done that?"

Dr. Boyle wasn't prepared for this.  She tried to point out that many studies have been done looking at the relation between vaccines and autism, but she didn't get very far before interrupted, thus: 

Rep. Posey: “So clearly, definitely, unequivocally, you have studied vaccinated versus unvaccinated?” 

Dr. Boyle: “We have not studied vaccinated versus unvaccinated." 

Posey: “Never mind. Stop there. That was the meaning of my question. You wasted two minutes of my time."

Dr. Boyle simply wasn't prepared for a Congressman who was parroting anti-vax activists.  It's too late now, but her response should have been this:

Congressman Posey, only an extremely unethical scientist would consider conducting such a study.  To compare vaccinated versus unvaccinated children in the manner you suggest, one would have to withhold vaccines from young children.  We know from decades of evidence, involving tens of millions of children, that vaccines save lives.  Few if any medical interventions are more effective than vaccines. 

But Congressman, the scientific community has done observational studies of vaccinated versus unvaccinated children, comparing autism rates in children whose parents chose not to vaccinate.  Those studies show that autism rates were slightly higher in unvaccinated children.  That's right, vaccinated children had autism at a lower rate. 

So no, Congressman Posey, the CDC hasn't done a study of vaccinated versus unvaccinated children.  Only a corrupt dictatorship could impose a study like that on its people.  Is that what you want?

To make matters worse, the House committee invited Mark Blaxill to testify.  Blaxill is a well-known anti-vaccine activist whose organization, SafeMinds, seems to revolve around the bogus claim that mercury in vaccines causes autism.  His organization urges parents not to vaccinate their children, and giving him such a prominent platform only serves to spread misinformation among parents of young children.  

Blaxill's central claim is that that we're in the midst of an autism epidemic: 

"For a long time, reported U.S. autism rates were low, estimated at about 1 in 10,000. Then around 1990 something new and terrible happened to a generation of children. Autism rates didn’t just rise, they multiplied," claimed Blaxill in his written testimony.

His entire argument builds on this.  Yet multiple studies, looking carefully and objectively at the data, indicate that all or nearly all of the rise in autism cases is due to increasing diagnoses, which in turn is due to multiple factors: a dramatically broading of the definition of autism in the early 1990s, a greater awareness of the condition, and a greater willingness of doctors and parents to accept the diagnosis.  For an objective summary of the evidence, see the articles by neurologist Steven Novella here and here, which summarize a dozen epidemiological studies.  The weight of the evidence shows that the actual incidence of autism is either stable or possibly rising very slowly.  There is no "autism epidemic."

It's also worth pointing out that Blaxill is a conspiracy theorist who claims that the "CDC has actively covered up the evidence surrounding autism’s environmental causes."  

Congress has every right to conduct oversight into medical research at the NIH and the CDC.  But when Dan Burton, Bob Posey, and others decide in advance what the science says, and abuse their power to demand "answers" that validate their badly mistaken beliefs, people can be harmed. Over the past decade, the anti-vaccine movement has successfully convinced millions of parents to leave their kids unvaccinated, and the result has been serious outbreaks of whooping cough, haemophilus, measles, chicken pox, and mumps around the U.S. and Europe.  

Some anti-vax parents claim that these childhood illnesses aren't so bad.  I wish they would talk to the parents of young children who have died in recent whooping cough outbreaks.  These illnesses can be deadly.

Message to Congress: science isn't easy, and autism is complicated.  Don't criticize science when it doesn't give you the answer you thought you knew.  That's not how science works.  Thousands of scientists are now trying to identify the causes of autism, and they've made progress, especially on the genetic front.  The answer might not be simple, but we will find it.