Anecdotal Evidence

Everybody brought up to believe in the scientific method knows that anecdotal evidence is not proof. What you observed might have been a rare occurrence.

I get it. I worked at Scientific American in the ‘60s when it was a great magazine. I edited the internal weekly at UCSF Medical Center for many years. I pledge allegiance to The Scientific Method.

But Capital-M Medicine can be too dismissive of all phenomena not acknowledged in peer-reviewed journals, i.e., “the literature.” At the height of the AIDS epidemic, UCSF professor Donald Abrams applied to the National Institute on Drug Abuse for a grant to study the impact of marijuana on appetite and nausea. In explaining why he was turned him down, NIDA honcho Allan Leshner smirked, “The plural of anecdote isn’t evidence.” All the AIDS patients who’d been able to overcome nausea and hold down food thanks to the illegal herb… In NIDA’s eyes they counted for zip.

Many anti-vaxxers, I assume, have seen anecdotal evidence with their own eyes and generalized from it.

In the mid-’90s I knew a couple who had a normal, sweet, 11-month-old boy. N was in her 30s, R was pushing 60, and the baby had given them great, unexpected joy. He was just starting to walk and say a few words when N brought him to the pediatrician for his second or third “DTP shot” ( a three-vaccine combo to prevent Diphtheria, Tetanus, and Pertussis). ”Almost overnight,” N said, “he changed.” He regressed. He stopped smiling and building his vocabulary. He wouldn’t make eye contract with a visitor (me).

In due course the parents were given an autism diagnosis. R died of a heart attack and I lost track of N. I heard they blamed the little boy’s altered personality on Thimerasolol, a preservative added to the three antigens in the DTP shot. Thimerasol contains mercury, a known neurotoxin. No matter how many parents attributed their kids’ dramatic regression to their DTP shots, Capital-M Medicine denied a causal relationship

I asked Jeffrey Hergenrather, MD, his thoughts about infants being exposed to Thimerasol. He recalled Dr. John Gofman’s line on human exposure to radiation: “there is no safe threshold.” Billions of cosmic rays might zoom harmlessly through your body, and then one might hit a cell’s nucleus in such a way that it divides, and metastasizes.

Is it possible that a small number of newborns are genetically disposed to have a strong, adverse reaction to Thimerasol? Many such genetic predispositions are being revealed, thanks to advancing technology. (It appears that a very small percentage of marijuana users are genetically disposed to Cannabinoid Hyperemesis Syndrome.)

The drug manufacturers cut back on its use because so many people thought they saw Thimerasol do serious harm to children. The US Food and Drug Administration website gives no credit to the bereaved families whose concerns about Thimerasol seemingly led to this reform:

“Under the FDA Modernization Act (FDAMA) of 1997, the FDA conducted a comprehensive review of the use of thimerosal in childhood vaccines. Conducted in 1999, this review found no evidence of harm from the use of thimerosal as a vaccine preservative, other than local hypersensitivity reactions (Ball et al. 2001).

As part of the FDAMA review, the FDA evaluated the amount of mercury an infant might receive in the form of ethylmercury from vaccines under the U.S. recommended childhood immunization schedule and compared these levels with existing guidelines for exposure to methylmercury, as there are no existing guidelines for ethylmercury, the metabolite of thimerosal. At the time of this review in 1999, the maximum cumulative exposure to mercury from vaccines in the recommended childhood immunization schedule was within acceptable limits for the methylmercury exposure guidelines set by FDA, the Agency for Toxic Substances and Disease Registry, and the World Health Organization. However, depending on the vaccine formulations used and the weight of the infant, some infants could have been exposed to cumulative levels of mercury during the first six months of life that exceeded Environmental Protection Agency (EPA) recommended guidelines for safe intake of methylmercury.

Other than allergic responses in some individuals, there was no known health risk from thimerosal-preservative at the concentration used in vaccines, but in 1999, the Public Health Service (including the FDA, National Institutes of Health (NIH), CDC, and Health Resources and Services Administration (HRSA)), along with the Amer1ican Academy of Pediatrics (AAP) and the American Academy of Family Physicians (AAFP) concluded that becau1se of scientific uncertainty at the time, as a precautionary measure, that it was prudent to reduce childhood exposure to mercury from all sources, including vaccines, to the extent feasible. On July 1, 1999, the FDA sent a letter to all manufacturers of U.S.-licensed vaccines requesting their plans to remove thimerosal from their U.S. licensed vaccines. This step was taken because the elimination or reduction of mercury in vaccines was a feasible means of reducing an infant’s total exposure to mercury in a world where other environmental sources of mercury are challenging to eliminate…”

In case we, the people, didn’t get the point, the FDA site reiterates in boldface type:

“No Link Between Thimerosal in Vaccines and Autism

“Although all vaccines routinely recommended for children 6 years of age and younger in the U.S. are available in formulations that do not contain thimerosal, thimerosal has a long record of safe and effective use in preventing bacterial and fungal contamination of vaccines, with no ill effects established other than hypersensitivity and minor local reactions at the site of injection.

“There is a robust body of peer-reviewed, scientific studies conducted in the United States and countries around the world that support the safety of thimerosal-containing vaccines. The scientific evidence collected over the past 20+ years does not show any evidence of harm, including serious neurodevelopmental disorders, from use of thimerosal in vaccines. Specifically, the Institute of Medicine (now known as the National Academy of Medicine), and others have concluded that the evidence favors rejection of a link between thimerosal and autism. Scientific studies of the risk of other serious neurodevelopmental disorders have failed to support a causal link with thimerosal.”

Some weasel words are underlined… Whatever happened to “First, do no harm?”