Thiomersal

Thiomersal.svg

Thiomersal, also known as thimerosal and merthiolate, is an organomercury compound used as a preservative in vaccines, antiseptics, and cosmetics. It is a well-known antimicrobial agent that has been used since the 1930s to prevent bacterial and fungal contamination in multi-dose vials of vaccines.

Chemical Properties

Thiomersal is an organomercury compound with the chemical formula C₉H₉HgNaO₂S. It is a sodium salt of ethylmercurithiosalicylate. The compound is a crystalline powder that is soluble in water and alcohol.

Uses

Thiomersal has been widely used as a preservative in vaccines to prevent contamination by bacteria and fungi. It is particularly important in multi-dose vials, where the risk of contamination is higher. Thiomersal is also used in some antiseptics and cosmetics.

Safety and Controversy

The use of thiomersal in vaccines has been the subject of controversy due to concerns about mercury poisoning and its potential link to autism. Numerous studies and reviews by public health organizations, including the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), have found no credible evidence linking thiomersal in vaccines to autism or other neurodevelopmental disorders. Despite this, its use has been reduced or eliminated in many vaccines as a precautionary measure.

Regulatory Status

In the early 2000s, thiomersal was removed or reduced to trace amounts in most vaccines given to young children in the United States and European Union as a precautionary measure. However, it is still used in some multi-dose vials of vaccines, particularly in developing countries, due to its effectiveness as a preservative.

See Also

• Vaccine controversy
• Mercury poisoning
• Autism
• Preservative