The preservative contains mercury which in high levels is unhealthy for brain function. “Thimerosal, a preservative used widely in vaccine formulations, contains ethylmercury. Thus it has been suggested that childhood vaccination with thimerosal-containing vaccine could be causally related to neurodevelopmental disorders…” (Hviid et al., “Association Between Thimerosal-Containing Vaccine and Autism”) Thimerosal is a preservative used in many vaccines and it contains ethylmercury. Some think that vaccines for children containing thimerosal are possibly related to neurodevelopmental