Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Toxicology of Neurodevelopmental Disorders
  • Published:

The role of mercury in the pathogenesis of autism

Molecular Psychiatry volume 7, pages S42–S43 (2002)Cite this article

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder of unknown etiology in most cases. Studies of monozygotic twins report an average 60% concordance rate, indicating a role for both genetic and environmental factors in disease expression.1 Recent reviews in environmental health have suggested that early exposure to hazardous substances may underlie some cases of neurodevelopmental disorders, including ADHD, learning disabilities, and speech/language difficulties.2 In 1999, thimerosal used as a vaccine preservative was identified as a widespread source of organic mercury exposure in infants.3 Mercury (Hg), a heavy metal, is considered highly neurotoxic.4 The amount of mercury in vaccines, while small, exceeded USEPA safety guidelines on a cumulative basis.3 Certain individuals may exhibit severe adverse reactions to low doses of Hg which are otherwise largely benign to the majority of those exposed.5 Some individuals with idiopathic autism spectrum disorder may represent such a sensitive population. As summarized in this paper, disease characteristics suggest this possibility: (a) ASD traits are known to arise from mercury exposure; (b) onset of ASD symptoms is temporally associated with administration of immunizations; (c) the reported increase in the prevalence of autism in the 1990s closely follows the introduction of two mercury-containing vaccines; and (d) elevated mercury has been detected in biological samples of autistic patients. Since ASD may now affect as many as one in 150 US children,6 and since thimerosal is still used in many products worldwide, confirmation of thimerosal as an environmental agent in autism pathogenesis has important societal and patient implications.

Thimerosal is comprised of 49.6% ethylmercury (EtHg) by weight. Until early 2001, it was a component of most Hepatitis B, Haemophilus influenzae type B (HiB), and Diphtheria/Tetanus/Pertussis (DTP or DTaP) vaccines. These vaccines were routinely administered to infants at birth and at ages 2, 4, 6, and 15–18 months. The cumulative amount of mercury injected in the first 6 months of life was 187.5 μg.3 Although the pharmacokinetics of EtHg have not been well studied, its toxicity is believed to be similar to MeHg,3 for which pharmacokinetic models have been developed to estimate the risk of adverse outcomes based on Hg levels in standard biomarkers of hair or blood. Using such a model, the EtHg from the recommended vaccines is predicted to raise hair mercury levels above USEPA guidelines of 1 ppm for up to one year and, in some infants, to elevate Hg levels to 10 ppm, which is the lowest threshold for adverse outcomes in children exposed prenatally to MeHg.4,7 That thimerosal-containing vaccines can significantly raise blood Hg levels in infants has been demonstrated in vivo.8 Endpoints for adverse effects at low doses of MeHg have been in domains characteristic of ASD and include lowered performance on tests of attention, memory, language, and fine motor skills.9,10,11 A CDC analysis of computerized HMO medical records found statistically significant associations between increased exposure to thimerosal from infant immunizations and attention deficit disorder, speech/language delay, and tics.12 Traits characteristic of these disorders are common features of ASD.10,11

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

References

  1. Bailey A et al. J Child Psychol Psychiatry 1996 37: 89–126

  2. Goldman LR, Koduru S . Environ Health Perspect 2000 108 (Suppl 3): 443–448

  3. Ball LK et al. Pediatrics 2001 107: 1147–1154

  4. National Academy of Sciences Committee on the Toxicological Effects of Mercury, National Research Council. Toxicological Effects of Methylmercury National Academy Press: Washington, DC 2000

  5. Warkany J, Hubbard DH . J Pediatrics 1953 42: 365–386

  6. Centers for Disease Control. Prevalence of Autism in Brick Township, New Jersey, 1998: Community Report April 2000 www.cdc.gov/nceh/cddh/dd/rpttoc

  7. Redwood L et al. J Neurotox (in press)

  8. Stajich GV et al. J Pediatr 2000 136: 679–681

  9. Grandjean P et al. Environ Res 1998 77: 165–172

  10. Filipek P et al. J Autism Dev Disord 1999 29: 439–484

  11. Dawson G, Watling R . J Autism Dev Disord 2000 30: 415–422

  12. Stehr-Green PA . Review of Vaccine Safety Datalink Information on Thimerosal-Containing Vaccines presentation to the Advisory Committee on Immunization Practices, June 7–8 2000

    Google Scholar 

  13. Bernard S et al. Medical Hypotheses 2001 56

  14. Kanner L . The Nervous Child 1942–1943 2: 217–250

  15. Gilberg C, Wing L . Acta Psychiatr Scand 1999 99: 399–406

  16. Bristol M et al. J Autism Dev Disord 1996 26: 121–157

  17. Teitelbaum P et al. Proc Natl Acad Sci U S A 1998 95: 13982–13987

  18. Baranek G . J Autism Dev Disord 1999 29: 213–224

  19. Amin-Zaki L et al. Br Med J 1978 March 1: 613–616

  20. Johansson U et al. Int Arch Allergy Immunol 1998 116: 295–305

  21. Comi AM et al. J Child Neurol 1999 14: 388–394

  22. Cave S . Testimony before the Committee on Government Reform and Oversight, US House of Representatives June 18 2000 http://www.house.gov/reform/hearings/healthcare/00.07.18/cave.pdf

  23. Bradstreet J . Testimony before the Committee on Government Reform and Oversight, US House of Representatives April 25 2001 http;//www.gnd.org/Testimony/testimony.htm

Download references

Author information

Authors and Affiliations

  1. Safe Minds, Cranford, NJ, USA

    S Bernard, A Enayati, H Roger, T Binstock & L Redwood

Authors
  1. S Bernard
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. A Enayati
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. H Roger
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. T Binstock
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. L Redwood
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to S Bernard.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Bernard, S., Enayati, A., Roger, H. et al. The role of mercury in the pathogenesis of autism. Mol Psychiatry 7 (Suppl 2), S42–S43 (2002). https://doi.org/10.1038/sj.mp.4001177

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/sj.mp.4001177

This article is cited by

Search

Advanced search

Quick links