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THIMEROSAL

Description

Thimerosal is an organomercury compound that has been used as a preservative in various medical and cosmetic products since the 1930s. Its primary function is to prevent the growth of bacteria and fungi in multi-dose vials of vaccines, eye drops, and some skincare formulations. Thimerosal is composed of ethylmercury and thiosalicylate, which give it its antimicrobial properties.

In skincare, thimerosal has been utilized in concentrations ranging from 0.001% to 0.01% to extend product shelf life. However, its use has significantly decreased due to concerns about potential mercury toxicity and allergic reactions. Studies have shown that a small percentage of individuals may experience contact dermatitis when exposed to thimerosal-containing products.

Regulatory bodies, including the FDA and EMA, have restricted thimerosal use in many applications. It has been largely phased out of vaccines and is now rarely found in over-the-counter skincare products. Alternative preservatives are typically preferred in modern formulations. When still present, thimerosal must be clearly listed on product labels to inform consumers with known sensitivities.