Thimerosal and Autism Studies
Thimerosal, an ethylmercury-containing preservative in vaccines, was employed in the 1930s to prevent contamination of vaccines in some multi-dose vials to fight bacteria and fungi. In 1997, The FDA Modernization Act called for the FDA to review and assess the risk of all mercury containing food and drugs. As part of this effort, the FDA conducted a review of mercury content in vaccines.
The FDA's review found no evidence of harm caused by doses of thimerosal except for minor local reactions. Unlike methylmercury, the kind of mercury found in the crust of the earth, ethylmercury is quickly excreted from the body. Nevertheless, in July 1999, the Public Health Service agencies, the American Academy of Pediatrics, and vaccine manufacturers agreed that thimerosal levels in vaccines should be reduced or eliminated as a precautionary measure.
This step was undertaken in part to achieve the broader goal of reducing exposure to mercury where feasible to do so and in part to avoid a false perception of risk from vaccines that could result in parents avoiding life-saving vaccines. It is important to note that data has shown that autism levels continue to rise despite the removal of thimerosal.
During the past several years, a series of biological and epidemiological studies have examined thimerosal and found no evidence that the preservative causes harm to infants or children.
Below are several studies that have examined thimerosal and found no evidence that the preservative caused harm to infants or children.
Prenatal and Infant Exposure to Thimerosal From Vaccines and Immunoglobulins and Risk of Autism
- Pediatrics, Cristofer S. Price, ScM, William W. Thompson, PhD et al. (September 13, 2010)
Continuing Increases in Autism Reported to California's Developmental Services System
- Archives of General Psychiatry, Robert Schechter, MD, MSc and Judith K. Grether, PhD (January 2008)
"Early Thimerosal Exposure and Neuropsychological Outcomes at 7 to 10 Years"
- New England Journal of Medicine, Thompson WW, Price C, Goodson B, et al. (September 27, 2007)
"Lack of Association Between Rh Status, Rh Immune Globulin in Pregnancy and Autism"
- American Journal of Medical Genetics, Judith H. Miles and T. Nicole Takahashi (May 2007)
"Thimerosal Exposure in Infants and Developmental Disorders: A Prospective Cohort Study in the United Kingdom Does Not Support a Causal Association"
- Pediatrics, John Heron and Nick Andrews, PhD and Jean Golding, DSc (September 2004)
"Association Between Thimerosal-Containing Vaccine and Autism"
- Journal of the American Medical Association, Anders Hviid, MSc (October 2003)
"Thimerosal and the Occurrence of Autism: Negative Ecological Evidence from Danish Population-Based Data"
- Pediatrics, Kreesten M. Madsen, MD (September 2003)
"Autism and Thimerosal-Containing Vaccines: Lack of Consistent Evidence for an Association"
- American Journal of Preventive Medicine, Paul Stehr-Green, DrPh, MPH (August 2003)
"Thimerosal and Autism?"
- Pediatrics, Karen Nelson, MD (March 2003)
"Mercury concentrations and metabolism in infants receiving vaccines containing thiomersal: A descriptive study"
- The Lancet, Michael Pichichero, MD (November 2002)