Problems with the connection between thimerosal and autism

An excerpt from Tabloid Medicine: How the Internet is Being Used to Hijack Medical Science for Fear and Profit.

by Robert Goldberg, PhD

From the beginning, there were two problems with the connection between thimerosal and autism. The first problem with was that thimerosal, while about half mercury, contains ethyl mercury, for which there were no exposure guidelines. So the scientists used the ones for methyl mercury. However, the ethyl mercury has different properties, including being processed out of the body more quickly. The second problem was that children receive more mercury from breast milk in their first year then they do from vaccines.

Scientists were divided on whether the use of thimerosal was even a potential problem and many believed that the US government had reacted to the issue too hastily, allowing political concerns to overwhelm scientific ones.

The worries that the withdrawal had been undertaken precipitously were quickly born out. While the move to eliminate thimerosal from vaccines was intended to calm fears and reassure the public while scientists looked further into the issue, many people interpreted it as an admission of guilt. Why, they wondered, would thimerosal be taken out of vaccines if it was safe? And why would the government and the medical establishment keep reporting that there was no danger when this seemed belied by their actions? The next logical leap was that the scientists and doctors must be hiding something. Anti-vaccination activists, parents with autistic children who needed someone to blame, and others who saw an opportunity for profit began to coalesce into a movement that promoted the theory that immunizations caused autism using websites trumpeting the dangers of vaccines and the evil of doctors, scientists, and national health agencies callously concealing a threat that were damaging millions of children.

With the waxing of this movement came the creation of a legion of anti-vaccination ‘experts’ dispensing their dubious wisdom online and in the media. One was Barbara Loe Fisher, co-founder of the National Vaccine Information Center, and an anti-vaccine crusader since the early 1980s after her son supposedly sustained brain damage from the diphtheria, tetanus, and pertussis (DTP) immunization. Despite having no medical scientific credentials, she was able to successfully portray herself as a vaccine expert in the media, in politics, and later on the internet, which provided a new and highly effective medium for her message. This model of the media and Web savvy if scientifically ignorant ‘expert’ would be repeated many times in the anti-vaccine movement.

Another ‘expert’ who emerged during the early stages of the debate was another parent, Lyn Redwood. She was a nurse practitioner but it was emotion rather than reason that convinced her that thimerosal was behind her son’s autism and made her a fervent convert to the anti-vaccine movement. In 2000, Redwood linked up with another parent of an autistic son, Sallie Bernard, who had never studied medicine but as owner of a market research company was well-versed in promoting a message. Together they wrote and published an article claiming that autism was really mercury poisoning in a low-circulation journal called Medical Hypotheses. The piece, “Autism: A novel form of mercury poisoning,” continues to be frequently cited on the internet by anti-vaccine activists. Bernard and Redwood concluded that the symptoms of the two conditions are identical and that therefore autism could be treated with chelators, drugs used to remove heavy metals from the body.

Subsequent study would contradict Bernard and Redwood’s assertion that the symptoms of autism and mercury poisoning are exactly the same. In 2003, Karin B. Nelson and Margaret L. Bauman published a rebuttal in Pediatrics that noted that classic symptoms of mercury poisoning are reduced field of vision, ataxia (lack of muscle coordination), dysarthria (slow, poorly articulated speech), muscle weakness and spasticity, peripheral neuropathy (circulation problems in extremities), and often toxic psychosis. None of these are characteristic of autism nor do conditions known to be caused by mercury, like Minamata’s disease, significantly resemble autism.

None of this mattered a bit to the anti-vaccine movement. When their flawed article did not produce the desire results, Bernard and Redwood created an Web-based organization to spread their message called Sensible Action for Ending Mercury-Induced Neurological Disorders, known as Safe Minds, which would become one of the leading groups online and off in promoting the theory that thimerosal was implicated in autism, as well as a champion for a variety of bizarre and risky ‘cures.’

Like Barbara Loe Fisher, both women presented themselves, and were accepted, as experts in autism and were interviewed in print and on television, frequently with scientists or doctors excluded. When asked about the fact that many doctors doubted that there was a connection, instant experts were dismissive; “Oh them,” Fisher responded in one article, ”They have been attacking parents who have been talking about vaccine safety concerns.”

By 2002, in the US, only some flu shots and a few rarely used vaccines still had more than a trace amount of thimerosal in them. ..((But) fears were reinforced by the work of two unscrupulous scientists, Mark and David Geier. The pair, a father and son, had already built their livelihoods on dubious medical research and lawsuits against drug companies and saw autism as a rich new frontier. In 2003, they published an article in the journal Experimental Medicine and Biology that concluded that the Vaccine Adverse Event Reporting System (VAERS) demonstrated that thimerosal was implicated in autism, as well as mental retardation and speech disorders.

It was soon followed by two more articles, including one that purported to show that autistic children treated with chelator drugs excreted greater amounts of mercury than non-autistic children, in the Journal of American Physicians and Surgeons, a credible sounding new publication that in fact promoted a strong anti-vaccine and anti-government bias. Both articles were deeply methodologically flawed. In particular, what parents who heard about these studies did not know is that anyone can send a report to VAERS and they are not checked to remove duplicates or determine whether they are true. And the Geiers were not about to tell them.

Robert Goldberg is co-founder and vice president of the Center for Medicine in the Public Interest and author of Tabloid Medicine: How the Internet is Being Used to Hijack Medical Science for Fear and Profit.

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