There are parents who believe that autism is caused by vaccinations containing a mercury compound which 'stabilises' that vaccine.
Exposure to mercury can cause immune, sensory, neurological, motor, and behavioral dysfunctions similar to traits associated with autism.
Thimerosal, a preservative added to many vaccines, has become a major source of mercury that exceeds safety guidelines. But, that’s not the only questionable ingredient used in vaccines (1)
Here is a list of other common ingredients: