Thimerosal Thimerosal
Centers for Disease Control and Prevention

Infant and Environmental Exposures to Thimerosal and Neuropsychological Outcomes at Ages 7 to 10 Years

CDC conducted the Infant and Environmental Exposures to Thimerosal and Neuropsychological Outcomes at Ages 7 to 10 Years study to investigate possible associations between prenatal and early childhood exposure to thimerosal-containing vaccines and/or immunoglobulins and deficits in neuropsychological functioning.

The study engaged a panel of independent external consultants to advise on the study design, selection of the neuropsychological test battery, interpretation of results, and editing of the draft manuscript. The consultants have expertise in the fields of toxicology, epidemiology, biostatistics, vaccine safety, and also included a representative from the autism advocacy community. The external consultants provided their individual input into the study protocol and the analysis plan.

The study evaluated 1,047 children between the ages of 7 to 10 years who received vaccines during the 1990s when thimerosal was used as a preservative in many childhood vaccines.

The study found only a few statistically significant associations or consistent patterns between exposure from thimerosal and neuropsychological functioning. The weight of the evidence from this study does not support an association between early ethyl mercury exposure from thimerosal-containing vaccines and/or immunoglobulins and neuropsychological functioning at ages 7 to 10 years.