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Do Vaccines Cause Autism?

People who voice their concerns regarding the safety and efficacy of vaccines are often brushed aside bucase their concerns are not grounded in science. I want to determine if this is indeed the case. I started by looking at if there are any researches done to determine a link between vaccines and autism.

Below are a list of researches reported in medical and medical-related journals that established a link between vaccines and autism, and I give a summary of the findings. You can click on the links to download and read the full papers from the respective journal websites.

  1. T.M. Burbacher, D.D. Shen, N.Liberato, K.S. Grant, E. Cernichiari and T. Clarkson, “Comparison of Blood and Brain Mercury Levels in Infant Monkeys Exposed to Methylmercury or Vaccines Containing Thimerosal“, Environmental Health Perspectives, Vol. 113, No. 8 (Aug., 2005)

    Thimerosal is an effective preservative that has been used in the manufacturing of vaccines since the 1930s. It contains 49.6% mercury by weight and breaks down in the body into ethyl-mercury and thiosalicylate.

    This study compares the blood and brain levels of Hg (mercury) in infant non-human primates exposed orally to MeHg or via intramuscular injections of vaccines containing thimerosal. The routes of administration were chosen to mimic the two routes of Hg exposure for humans. The dosages and schedule of administration were chosen to be comparable with the immunization schedule for human newborns.

    This study finds Hg in the blood of the infants within 48-72 hour after vaccination. The blood concentrations of thimerosal-exposed monkeys are within the range of those reported for human infants after vaccination. Inorganic Hg is also detected in the brain of the monkeys.

  2. M.R. Herbert, “Autism: A Brain Disoerder or a Disorder that Affects the Brain?“, Clinical Neuropsychiatry, 2003

    Among observations made in this study is that for each 1000 lb of environmentally released mercury, there was on average a 43% increase in the rate of special education services and 61% increase in the rate of autism.

  3. Robert Nataf, Corinne Skorupka, Lorene Amet, Alain Lam, Anthea Springbett, Richard Lathe (2005) “Porphyrinuria in childhood autistic disorder: Implications for environmental toxicity“, Toxicology and Applied Pharmacology
    Volume 214, Issue 2, 15 July 2006, Pages 99–108

    Several studies have explored the body burden of heavy metals to address an environmental contribution to autistic spectrum disorder (ASD). Porphyrinuria is excessive excretion of one or more porphyrins in the urine. Porphyrins are derivative of the heme synthesis pathway and afford an independent measure of adverse exposure.

    To address the heavy metal burden of ASD children, this study carried out a retrospective study of level of specific urinary porphyrins in 269 French children with a primary diagnosis of autism or other neurodevelopmental disorders. Pentacarboxyporphyrin is a marker of heavy metal toxicity. Levels of this porphyrin, and its immediate precursors (hepta- and hexa-carboxyporphyrins), were elevated in urines of ASD children.

    The fraction of subjects with porphyrinuria was dependent on the specific parameter investigated, but in autistic disorder group 53% exceeded the internal control group. Porphyrin excess in autism was also markedly and significantly reduced by treatment of children with a chelating agent that removes heavy metals, suggesting a causal relationship.

    This study concludes that porphyrinuria, which is a reliable marker of environmental toxicity, is significantly over-represented in a large group of French children with autistic disorder. Given evidence for increasing population exposure to heavy metals including mercury, suggestions of increasing prevalence of autistic disorder and a statistical association between mercury release and autism rates, it is suspected that environmental toxicity, combined with genetic susceptibility contributes to ASD development.

  4. Donald R. Branch (2009), “Gender-selective toxicity of thimerosal“, Experimental and Toxicologic Pathology, Volume 61, Issue 2, March 2009

    Thimerosal is an organic compound that contains mercury and has been used historically as a preservative in vaccines and pharmaceutical products. The breakdown product, ethyl mercury, in thimerosal-preserved childhood vaccines has been suggested to be neurotoxic and to contribute to the etiology of neurodevelopmental disorder, including autism.

    The organomercurial preservative thimerosal has been used in various vaccines and immunoglobulin preparations for use in humans since the 1930s to help prevent potentially life-threatening contamination with harmful microbes. Recent attention due to the mercury contained in thimerosal molecule has focused on the potential impact of thimerosal use on the development of autism.

    The result of this study demonstrates that there is a significant difference in the maximum tolerated does (MTD) of thimerosal depending on whether the test animal is male or female. It was found that in mice, using 10% dimethyl sulfoxide (DMSO) to dissolve the thimerosal prior to injection that the MTD of thimerosal in males was only 25.6 mg/kg compared to 76.8 mg/kg in females. Thus, thimerosal has a 3-fold increased toxicity in males compared to females. Regardless of the concentration of MDSO, only male mice were susceptible to severe thimerosal toxicity between the dose range of 38.4 – 76.8 mg/kg. This is the first report of gender-selective toxicity for thimerosal.

    As autism occurs much more frequently in males than in females, the findings of this study may relate to a potential selectivity of thimerosal for toxic effects in come male children, particularly in utero.

  5. Carolyn M. Gallagher & Melody S. Goodman (2010), “Hepatitis B Vaccination of Male Neonates and Autism Diagnosis“, Journal of Toxicology and Environmental Health, Part A, 73:24, 1665-1677

    A neonate is a newborn child, especially one less than a month old. Hepatitis B vaccination was recommended for US newborns in 1991. This study finds that boys vaccinated as neonates are three times more likely to be diagnosed with autism compared to boys never vaccinated or vaccinated after the first month of life. This article also refers other researches that look into the link between vaccines and autism.

    In 1999, the US Public Health Service (USPHS) called for vaccine manufacturers to eliminate or reduce the Hg (mercury) content in vaccines in response to the FDA assessment that US infants fully vaccinated during the first 6 months of life may have been exposed to cumulative Hg levels that exceed US EPA safety recommendation. Something to ponder: Why is mercury, which is a known toxin, used as an ingredient in vaccines?

  6. Helen V. Ratajczak (2011), Theoretical aspects of autism: Causes—A review, Journal of Immunotoxicology, 8:1, 68-79

    When autism was first described in 1943, its incidence is 4 to 5 per 10,000 children. Now, it is 1 per 10 in US and 1 per 64 in UK. A 10-fold increase in incidence in US was reported in 2001, with 1/120 in 1990 compared to 1/2500 in 1970s. The prevalence of autism is increasing at epidemic rates. This article examines causes of autism, one of which is vaccination.

    Data did not show any decrease in autism in California despite the exclusion of more than trace levels of thimerosal from nearly all childhood vaccines by 2002. However, in 2004, inactivated influenza vaccine containing thimerosal was recommended for all children 6 to 23 months old in US. Most inactivated influenza vaccines contain thimerosal despite its implication in autism.

    In 1988, two doses of MMR II were recommended to immunize those who did not respond to the first injection. A spike of incidence of autism accompanied the addition of the second dose of MMR II. The MMR II vaccine is contaminated with human DNA from the cell line. An additional increased spike in incidence of autism occurred in 1995 when the chicken pox vaccine was grown in human fetal tissue.

    The incidence and prevalence data indicate the timing of introduction of vaccines and changes in the type and increasing number of vaccines given at one time implicate vaccines as a cause of autism.

    There are many controversies about vaccines and autism, especially since many parents cite normal development of their children until they receive vaccines. The vaccine organism itself could be a culprit. For example, one hypothesis of the cause of autism is that the pertussis toxin in the DPT vaccine causes a separation of the G-alpha protein from retinoid receptors in genetically-at-risk children.

    Since 1930s, thimerosal, which has been implicated as a cause of autism, has been extensively used as an anti bacterial agent in vaccines. Not only is every major symptom of autism documented in cases of mercury poisoning but also biological abnormalities in autism are very similar to the side effects of mercury poisoning. Supporting this relationship are reports documenting that heavy metals are increased in the blood and urine of autistic subjects.

There you go. There are many researches (going back more than 10 years) that look into the link between vaccines and autism. Therefore, to accuse people who voice their concerns about vaccine safety as not being grounded in science is baseless. People who are labelled as anti-vaxers are not against vaccines per se. What they are campaigning for is more rigorous testing to ensure that vaccines are indeed safe and effective.