New study shows no link between thimerosal and autism
On Monday, September 13, 2010, the journal Pediatrics published the results of a scientific investigation that explored whether mercury exposure, through the vaccine preservative thimerosal, resulted in an elevated risk of autism. Using a case-control design, this study found no association between thimerosal exposure and autism, autism spectrum disorder, or regressive autism.
This study is unique from previous reports because it interviewed parents and used direct observations of child behavior to identify subgroups of autism, including regressive autism. All individuals who were included in the study, including those without autism, were screened using a tool called the Social Communication Questionnaire; thus, children with mild adverse neurodevelopmental outcomes that were not diagnosed as autism were not included. In order to calculate thimerosal exposure, the investigators documented thimerosal exposure through child and maternal medical charts and medical records. The analysis conducted also controlled for a wide variety of preexisting medical co-morbidities and potential confounding factors that were discussed and agreed upon by an external advisory committee.
No significant increase in risk of autism or regressive autism was observed with elevating levels of thimerosal exposure during any of the four time periods analyzed, including the prenatal period. The results of this study add to a large body of literature showing that thimerosal is not associated with a higher risk for autism. Thimerosal has now been removed from childhood vaccinations due to public concern over the preservative. . Details about the study, including rationale for the adjusted analyses and confounding variables, and additional analyses can be found on the website of the independent agency contracted to conduct the study.
For more information, please read Autism Speaks statement on the vaccines and autism.