Thiomersal and vaccines
[8] Thus, major scientific and medical bodies such as the Institute of Medicine[9] and World Health Organization[10] (WHO) as well as governmental agencies such as the Food and Drug Administration[11] (FDA) and the Centers for Disease Control and Prevention (CDC)[12] reject any role for thiomersal in autism or other neurodevelopmental disorders.
[21] Thiomersal (also spelled thimerosal, especially in the United States) is an organomercury compound used as a preservative in vaccines to prevent bacterial and fungal contamination.
[11] Following a mandated review of mercury-containing food and drugs in 1999, the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) determined that under the existing vaccination schedule "some children could be exposed to a cumulative level of mercury over the first 6 months of life that exceeds one of the federal guidelines on methyl mercury.
[24] It was introduced as a preservative in the 1930s to prevent the growth of infectious organisms such as bacteria and fungi, and has been in use in vaccines and other products such as immunoglobulin preparations and ophthalmic and nasal solutions.
[29] A review of the data showed that while the vaccine schedule for infants did not exceed FDA, Agency for Toxic Substances and Disease Registry (ATSDR), or WHO guidelines on mercury exposure, it could have exceeded Environmental Protection Agency (EPA) standards for the first six months of life, depending on the vaccine formulation and the weight of the infant.
In the process of forming the response to this information, the participants attempted to strike a balance between acknowledging possible harm from thiomersal and the risks involved if childhood vaccinations were delayed or stopped.
[33] In 2004 Quackwatch posted an article saying that chelation therapy has been falsely promoted as effective against autism, and that practitioners falsified diagnoses of metal poisoning to "trick" parents into having their children undergo the process.
First, methylmercury had for decades been the subject of widespread environmental and media concern after two highly publicized episodes of poisonings in the 1950s and 1960s in Minamata Bay, Japan from industrial waste and in the 1970s in Iraq from fungicide contamination of wheat.
[24] Advocates of a thiomersal-autism link also relied on indirect evidence from the scientific literature, including analogy with neurotoxic effects of other mercury compounds, the reported epidemiologic association between autism and vaccine use, and extrapolation from in vitro experiments and animal studies.
[18] This research by Geier has received considerable criticism[39] for methodological problems in his research, including not presenting methods and statistical analyses to others for verification,[40] improperly analyzing data taken from Vaccine Adverse Event Reporting System,[9][40] as well as either mislabelling or confusing fundamental statistical terms in his papers, leading to results that were "uninterpretable".
[18] Further support for the association between autism and thiomersal appeared in an article by Robert F. Kennedy Jr. in the magazines Rolling Stone and Salon.com[43] alleging a government conspiracy at a CDC meeting to conceal the dangers of thiomersal to protect the pharmaceutical industry, and a book written by David Kirby, Evidence of Harm, dramatizing the lives of parents of autistic children, with both authors participating in media interviews to promote their work and the controversy.
[42] Media attention and polarization of the debate has also been fueled by personal injury lawyers who took out full-page ads in prominent newspapers and offered financial support for expert witnesses who dissented from the scientific consensus that there is no convincing evidence for a link between thiomersal and autism.
[13] These parents share the viewpoint that autism is not just treatable, but curable through "biomedical" interventions and have been frustrated by the lack of progress from more "mainline" scientists in finding this cure.
These websites use emotional appeals to gather support and frame the controversy as an adversarial dispute between parents and a conspiracy of doctors and scientists.
McCarthy has published a book describing her personal experience with her autistic son and appeared on The Oprah Winfrey Show to promote the hypothesis of vaccines causing autism.
These findings show that the assumptions that originally led to concern about the toxicity of ethylmercury, which were based on direct comparison to methylmercury, were flawed.
[51] A retrospective cohort study on 109,863 children in the United Kingdom found no association between TCVs and autism, but a possible increased risk for tics.
[52] Another UK study based on a prospective cohort of 13,617 children likewise found more associated benefits than risks from thiomersal exposure with respect to developmental disorders.
[53] Because the Danish and UK studies involved only diphtheria-tetanus-pertussis (DTP) or diphtheria-tetanus (DT) vaccines, they are less relevant for the higher thiomersal exposure levels that occurred in the U.S.[38] In North America, a Canadian study of 27,749 children in Quebec showed that thiomersal was unrelated to the increasing trend in pervasive developmental disorders (PDDs).
In fact, the study noted that rates of PDDs were higher in the birth cohorts with no thiomersal when compared to those with medium or high levels of exposure.
[9] [bold in original]Further evidence of the scientific consensus includes the rejection of a causal link between thiomersal and autism by multiple national and international scientific and medical bodies including the American Medical Association,[59] the American Academy of Pediatrics,[60] the American College of Medical Toxicology,[61] the Canadian Paediatric Society,[62] the U.S. National Academy of Sciences,[9] the Food and Drug Administration,[11] Centers for Disease Control and Prevention,[12] the World Health Organization,[10] the Public Health Agency of Canada,[63] and the European Medicines Agency.
[32] Similarly, a study found that the number of hospitals who failed to properly vaccinate infants of hepatitis B seropositive mothers rose by over 6 times.
[66] Although critics of using chelation therapy as an autism treatment point to a lack of any evidence to support its use, hundreds of doctors prescribe these medications despite possible side effects including nutritional deficiencies as well as damage to the liver and kidney.
[18] The popularity of this therapy caused a "public health imperative" that led the U.S. National Institute of Mental Health (NIMH) to commission a study about chelation in autism by studying DMSA, a chelating agent used for lead poisoning, despite worries from critics that there would be no chance it would show positive results and it would be unlikely to convince parents to not use the therapy.
[68] In the one case which received compensation, the U.S. government agreed to pay for injury to a child that had a pre-existing mitochondrial disorder who developed autism-like symptoms after multiple vaccinations, some of which included thiomersal.
[69][70] In February 2009, this court also ruled on three autism-related cases, each exploring different mechanisms that plaintiffs proposed linked thiomersal-containing vaccines with autism.
