The CDC on Thimerosal in Vaccinations & Autism

The Centers for Disease Control and Prevention provides much information about the controversial concerns about connections between the mercury-based preservative thimerosal in childhood vaccines and autism. Since 1999 both the CDC and the U.S. Food and Drug Administration have conducted numerous studies and found no link between thimerosal and autism. Since 2001, thimerosal has been removed from nearly all childhood vaccines. The CDC states, "We are committed to understanding what causes autism, how it can be prevented and how it can be recognized and treated as early as possible."

Autism

• According to the CDC, estimates show that 1 in 150 children have an autism spectrum disorder, which is considerably more than estimates from the early 1990s. The CDC states that many people believe that the rise in cases of autism is directly related to the elevated number of childhood vaccinations that were administered that contained the preservative thimerosal. The CDC says that evidence gathered from many scientific studies does not support the claims that vaccine usage caused changes in autism frequency. The CDC is currently funding the largest U.S. study to help identify the possible causes that may put children at risk of developing an autism spectrum disorder. The multi-year study is called SEED or Study to Explore Early Development.

Thimerosal

• Thimerosal is a mercury-based preservative that has been used in some vaccines and other products since the 1930s. Thimerosal is used to prevent the growth of bacteria and fungi in multi-dose vaccines. If germs contaminate vaccines it is possible that they could cause serious reactions, illness and even death. Thimerosal does not stay in the body for an extended period of time, nor does it build up to reach dangerous levels. After entering the body, it breaks down and is eliminated.

Safety

• According to studies by the CDC and FDA, low doses of thimerosal are safe. There is no research or evidence that supports claims that thimerosal causes autism. In 2001, thimerosal was removed from most childhood vaccines, excluding some flu vaccines. The CDC states that since its removal, "autism rates have gone up, which is the opposite of what would be expected if thimerosal caused autism."

Side Effects

• The possible most common side effects of thimerosal are redness and swelling at the injection site. According to the CDC, there is a rare chance of an allergy to thimerosal, though research shows that most people who are allergic will not have a reaction when thimerosal is injected under the skin.

Mercury

• Mercury is a naturally occurring mineral. According to the FDA, a potentially toxic form of mercury is called methyl mercury. Methyl mercury can be found in household products and in mercury-contaminated fish. It is possible for extreme levels of methyl mercury to cause toxicity in the body. Thimerosal contains a different kind of mercury called ethyl-mercury, which is not harmful. The FDA, the EPA and the Agency for Toxic Substance and Disease Registry developed guidelines for safe methyl mercury levels in products and foods. Following concerns about the safety of thimerosal, a review found that some infants could be exposed to levels of ethyl mercury that exceeded the standards set for methyl mercury after receiving vaccinations. Since there were no guidelines for ethyl mercury, experts agreed that all mercury-containing products should not exceed established levels that were set for methyl mercury. So in 2001, thimerosal was removed from most childhood vaccines. The FDA states, "No children or infants were receiving toxic levels of mercury from vaccines, but FDA still believed it appropriate to pursue alternatives to using thimerosal as a preservative in vaccines."

MMR Vaccine

• Despite claims otherwise, the MMR or measles, mumps and rubella vaccine does not now and or ever contained thimerosal. Other vaccines that have never contained thimerosal are the varicella (chickenpox), inactivated polio (IPV) and pneumococcal conjugate vaccines. The FDA lists all vaccines that do and do not contain thimerosal. Also, a health care provider or pharmacist can supply you with package inserts that list a vaccine's ingredients and possible adverse reactions.