Though an effective preservative for vaccines, thimerosal is derived from mercury, a known neurotoxin. It is also a strong antigen (capable of producing allergic reactions) and can suppress the immune system. Though several agencies, including the EPA (Environmental Protection Agency), the FDA (Food and Drug Administration), and the WHO (World Health Organization) have set maximum safe levels for mercury ingestion (which vary from group to group, and are intended for adults), some scientists claim that there is no acceptable, safe amount of thimerosal for children. Infants, especially, have immature body systems, and their kidneys are less able to remove this toxin than the kidneys of adults.
Thimerosal has gotten a bad reputation and received blame from some scientists and parent groups as a cause of autism. Government authorities have denied that there is evidence of any link between the two, but have recommended that it be removed from pediatric vaccines as a precaution. A recall was never issued, so thimerosal-containing pediatric vaccines remained on doctors’ shelves until they were used up or expired. Even today, thimerosal is present in some vaccines, including flu vaccines and the Rhogam injection Rh-negative women usually receive during pregnancy (though a thimerosal-free version is available).
Does Thimerosal Cause Autism?
The majority of the medical community claims that there is no solid evidence of a link, but many parents whose lives have been shattered by a child’s illness insist that the child was developing normally until receiving immunizations. Some doctors counter that what appears to be a link may actually be a coincidence, since the symptoms of autism are likely to begin at the same time as children are getting vaccinated. Many people believe that the two are linked, but their relationship is complex and associated with other risk factors that make effective studies difficult.
A careful look at both sides of the issue reveals studies that seem to be contradictory and arguments by both sides that are almost equally convincing. However, the more research parents may do into the history and current state of pediatric vaccination in the United States, the more it may seem that something is not right.