A dose-response relationship between organic mercury exposure from thimerosal-containing vaccines and neurodevelopmental disorders

Int J Environ Res Public Health. 2014 Sep 5;11(9):9156-70. doi: 10.3390/ijerph110909156.

Abstract

A hypothesis testing case-control study evaluated concerns about the toxic effects of organic-mercury (Hg) exposure from thimerosal-containing (49.55% Hg by weight) vaccines on the risk of neurodevelopmental disorders (NDs). Automated medical records were examined to identify cases and controls enrolled from their date-of-birth (1991-2000) in the Vaccine Safety Datalink (VSD) project. ND cases were diagnosed with pervasive developmental disorder (PDD), specific developmental delay, tic disorder or hyperkinetic syndrome of childhood. In addition, putative non-thimerosal-related outcomes of febrile seizure, failure to thrive and cerebral degenerations were examined. The cumulative total dose of Hg exposure from thimerosal-containing hepatitis B vaccine (T-HBV) administered within the first six months of life was calculated. On a per microgram of organic-Hg basis, PDD (odds ratio (OR) = 1.054), specific developmental delay (OR = 1.035), tic disorder (OR = 1.034) and hyperkinetic syndrome of childhood (OR = 1.05) cases were significantly more likely than controls to receive increased organic-Hg exposure. By contrast, none of the non-thimerosal related outcomes were significantly more likely than the controls to have received increased organic-Hg exposure. Routine childhood vaccination may be an important public health tool to reduce infectious disease-associated morbidity/mortality, but the present study significantly associates organic-Hg exposure from T-HBV with an increased risk of an ND diagnosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Attention Deficit Disorder with Hyperactivity / chemically induced
  • Attention Deficit Disorder with Hyperactivity / epidemiology
  • Case-Control Studies
  • Child
  • Child Development Disorders, Pervasive / chemically induced
  • Child Development Disorders, Pervasive / epidemiology
  • Child, Preschool
  • Developmental Disabilities / chemically induced
  • Developmental Disabilities / epidemiology*
  • Dose-Response Relationship, Drug
  • Female
  • Hepatitis B Vaccines / administration & dosage
  • Hepatitis B Vaccines / adverse effects*
  • Humans
  • Infant
  • Male
  • Preservatives, Pharmaceutical / administration & dosage
  • Preservatives, Pharmaceutical / adverse effects*
  • Thimerosal / administration & dosage
  • Thimerosal / adverse effects*
  • Tic Disorders / chemically induced
  • Tic Disorders / epidemiology
  • United States / epidemiology

Substances

  • Hepatitis B Vaccines
  • Preservatives, Pharmaceutical
  • Thimerosal