Autism, Vaccination, Science, and the Media

Is there an "epidemic" of autism? Are vaccinations or dental fillings to blame?

Lately the media has loudly featured, with more noise than facts, the increase in reported cases of autism and the unproved allegation that the mercury derivatives in some vaccines and dental fillings have caused this increase.

We seek ways to improve the condition of those with autism, but enthusiasm mustn't imperil sound science. Wrong answers can make things worse, wasting time and squandering resources.

Reasoning Gone Astray, and the Right Way to Test

Unfortunately, few understand the scientific method. Scientific thinking has strict rules intended to reduce error as much as possible. These rules are complex and not always easy to learn. The requirements of scientific thinking are not clearly taught in our schools. Neither are they generally understood by the media. The result is a scientifically naive population easily deceived by advertisers, charlatans, quacks, politicians, and well-meaning but poorly informed activists. The media's scientific illiteracy is especially unfortunate. Their focus too often is on sensation, and they fill the air with erroneous interpretations of scientific reports as well as outright pseudo-science.

Two important scientific maxims, which we will apply to the autism controversy:

1) Anecdotes and testimonials are unreliable.

2) Correlation does not equal causation.

Anecdotes are stories and claims by individuals about medical incidents. The charge that vaccination and fillings have caused the current "epidemic" of autism is mostly based on anecdotes. However, anecdotes are firmly rejected by scientific thinking, and for good reason. A parent may claim that symptoms of autism appeared following her child's vaccination. But the teller of this anecdote may have misinterpreted what happened, may have forgotten the details, may have allowed emotions to color recollection. These are some of the reasons why anecdotes are rejected as scientific evidence.

Also, the fact that symptoms appeared after vaccination does not necessarily mean they were caused by vaccination. "Correlation does not equal causation." Correlation generates speculation, but better evidence is needed for conclusions. Autistic symptoms often occur at the same age that vaccinations are given, but data indicates that these symptoms appear in the same frequency regardless of whether vaccinations have been given.

Science provides methods to develop sounder conclusions; these are called experiments and studies, and they have strict rules to avoid false conclusions. Valid experiments must be "double blind" when possible: that is, the subjects are split up at random into two groups "experimental" and "control" (one receiving and one not receiving the substance that is being tested for side effects) and, in order to eliminate the effects of bias, neither the experimenters nor the subjects know who is in which group. Such studies have not demonstrated any connection between vaccination, fillings, and autism.

What Media Ought to Teach About the Autism Controversy

The media would be more helpful if they supplied better information about the various forms in which mercury is found. For example, methyl mercury (found in canned tuna) is highly toxic, while the mercury in dental fillings is not. Furthermore, the data on autism rates does not even show that there is an epidemic of autism to be explained. Although reported autism has increased, for instance, it appears that at the same time the reported incidence of mental retardation has decreased. It is likely that today "autism" is a diagnosis more socially acceptable than "mental retardation," and many who previously would have been diagnosed as mentally retarded are now more accurately being classified on the autism spectrum. Moreover, medical and educational personnel are becoming more aware of autism, and the diagnostic criteria have been greatly expanded, leading to active investigation and increased discovery of the condition. These factors not an "epidemic" may be enough to account for the increase in reported autism.

The anecdotes of interested parties do not conform to the requirements of scientific evidence, nor do they constitute a controlled "significant sample." The arguments against vaccination and fillings rely on anecdotes, unsupported assertions, and faulty interpretation of data. Worried parents misled by these assertions might refuse to have their children vaccinated. To avoid an illusory hazard, parents may put their children at real risk of the many serious diseases prevented by vaccination.

Caution is necessary before embracing any alleged therapy for autism. The families of those suffering from autism, sometimes desperate for help, are too easily exploited by quacks and charlatans. Dental quacks for many years have offered methods to "cleanse" the body of mercury, including removing perfectly good fillings (which is a mutilation, not a treatment) and using "detoxifying" chemical agents. Now we may expect to see the quacks offering to "neutralize" the alleged harmful effects of vaccination.

Dr. Marvin J. Schissel is a dentist and an advisor to the American Council on Science and Health, the National Council Against Health Fraud, and the Committee for Scientific Investigation of Claims of the Paranormal.


February 13, 2003

Dear Dr. Schissel

Most parents of late onset autistic children do not blame vaccines per say as the cause of autism. These parents point to the mercury additive in the vaccines as the cause. These parents believe that vaccines containing mercury administered to a woman before or during pregnancy may result in brain damage to the fetus resulting in the newborn child exhibiting autismlike symptoms at birth or that vaccines containing mercury administered according to the Government's Vaccination Schedule results in a cumulative insult to the child's autoimmune system. The latter scenario may give one of three results: (1) the child seems to be unaffected, (2) the child's gut and brain are affected, resulting in mercury poison symptoms, or (3) the autoimmune symptom is cumulatively comprised to a point that the mercury travels to the brain upon receipt of the MMR vaccine.

The good doctor Schissel's argument that the parent's anecdotal conclusions are to be discounted brings to mind a recent case in which years of testimony, all anecdotal, was denied and discounted by the manufacturers, were finally proven to be correct. And that is the case of cigarette smoking being a real cause of cancer.

I ask the dentist in denial of the effects of mercury this simple question: If thousands of parents suspect and have concluded that their children were poisoned by the mercury preservatives in vaccines, why not administer mercury-free vaccines until these mercury-spiked vaccines are proven benign? To continue to administer the mercury-laden vaccines until they are proven harmful seems irresponsible to me. Your logic seems to me to be erring on the side of risk.

You conveniently omitted the fact that thousands of parents have removed and are removing the mercury from the bodies of their children using chelation, whereupon the children's health and behavior return to normal.

The same argument applies to the mercury-laden dental filling material that the dental profession calls silver or amalgam filling material. Thousands of adults have had remarkable improvement in their health and wellbeing after having this suspect filling material carefully removed. Now that amalgam is suspect, the same argument stated above should prevail: desist using the suspect material until it is proven safe.

My good doctor, I'd like your response to two hypotheticals:

(1) On the day your wife informs you that she just found out she was in her first month of pregnancy, she also announces that her dentist discovered that she has thirty-two fissures in her teeth, one in each tooth. Would you recommend she be treated with amalgam or a mercury-bonding material?

(2) You attend the birthing, and within the first two hours the pediatrician tells you he is about to inoculate your child with the hepatitis B vaccine. Would you insist that a thimerosal-free vaccine be injected?

Please send your response to

Paul Shapiro

February 21, 2003

Dear Mr. Shapiro,

I am a parent of an autistic child, and I assure you I experience a parent's heartache and desire to find answers. But, unlike you, I think the best road to answers lies in the machinery of science, not in emotional responses to poor information. Resources are limited, and to misdirect them is wasteful and self-defeating.

The dire scenario you paint about how the presence of mercury might (!) damage a child is based on imaginative speculation and anecdote. In defense of anecdotes you state, correctly, that early suspicions about smoking were based on anecdotes. But as soon as valid data was developed, from early on, the data led to firm conclusions about the hazards of smoking. This is not the case with vaccinations, with or without mercury-containing thimerosal, where the data, early and recent, do not support the anecdotes, and where reliance on the anecdotes may induce parents to deny their children the proven essential benefits of vaccination. Of course, science is not engraved in stone but responds to new information, and at the moment the best information indicates that vaccination, with or without thimerosal, is safe and essential. If future studies indicate problems with vaccination, then current vaccination programs and methods would of course have to be revised, and I would strongly support efforts to do this. But I prefer that we wait for solid answers rather than jump to possibly hazardous conclusions. Moreover, you may not be aware that in this country, in response to anecdotes and the clamor of some parents, thimerosal has not been used in vaccines for several years.

It seems you have been taken in by proponents of quackery. You make the oft-heard but never supported assertion that the health of "thousands" has improved when amalgam fillings have been removed or the body cleansed of mercury by chelation. There is not a shred of scientifically valid evidence that mercury-containing amalgam fillings are dangerous when properly used. The removal of sound amalgam fillings for alleged reasons of health is not a treatment but a mutilation, and as a dentist I condemn this quackery in the strongest terms. The same might be said of the fraudulent use of chelation to "detoxify" the body. Chelation is condemned by every responsible medical authority.

You ask me two "hypotheticals": What would I use to fill all the teeth of my pregnant wife, and would I insist on a thimerosal-free vaccine for my newborn son? To answer, I would use an esthetic plastic material to fill the front teeth, and would use amalgam for the back teeth. And I would not insist on a thimerosal-free vaccine.

I hope we continue to develop effective scientific information and methods. We can't afford to sidetrack our efforts because of emotional attitudes based on misinformation and a poor understanding of science.

Marvin J. Schissel, DDS
ACSH Advisor