Thimerosal (sometimes spelled as thimerosol) (trade name: Merthiolate) is an organometallic compound containing mercury, commonly used as a preservative. It is found in some vaccines, most controversially including those widely administered to children. Its chemical formula is C₉H₉HgNaO₂S. It has been in use since the 1930s.

Despite a lack of empiric evidence, some have hypothesized a relationship between thimerosal exposure from childhood vaccines and autism. In a 2001 report, the Institute of Medicine concluded "that the evidence is inadequate to either accept or reject a causal relationship between thimerosal exposure from childhood vaccines and the neurodevelopmental disorders." [1] (http://www.fda.gov/cber/vaccine/thimerosal.htm#saf) The National Institute of Allergy and Infectious Diseases concluded that the "only known side-effects of receiving low doses of thimerosal in vaccines have been minor reactions such as redness and swelling at the injection site." [2] (http://www.niaid.nih.gov/factsheets/thimerosal.htm) Concerns about mercury toxicity have nevertheless led to the production of many thimerosal-free vaccines.

External links

• http://pediatrics.aappublications.org/cgi/content/full/112/6/1394 paper showing no harm from thimerosal.
• http://www.testfoundation.org/thimerosal.htm A site campaigning against thimerosal in vaccines
• First Coast News a site alleging a CDC coverup. (http://www.firstcoastnews.com/health/news-article.aspx?storyid=14764)
• A site detailing the lack of connection between thimerosal and developmental disorders. (http://www.quackwatch.org/03HealthPromotion/immu/thimerosal.html)
• Neurotoxic effects of postnatal thimerosal are mouse strain dependent (http://www.nature.com/cgi-taf/DynaPage.taf?file=/mp/journal/vaop/ncurrent/full/4001529a.html) (pay site) Paper showing thimerosal link to neurologic effects, including some reminicent of autism, in a specific strain of mice; the lead author, Dr. Mady Hornig of Columbia, believes "autism is a constellation of syndromes that almost certainly has many different causes." Dr. Steven Goodman of the Johns Hopkins School of Medicine, a member of the Institute of Medicine commission said that the commission was aware of the research at the time of its report, and characterized it as insufficient evidence to overturn the "tremendous amount of human work that doesn't find a clue of a connection" [between the use of thimerosal in human vaccines and autism].