Thimerosal is a mercuric derivative of thiosalicylic acid used as a preservative in vaccines, cosmetics, tattoo inks, eye drops and contact lens solutions as well as a disinfectant (e.g. merthiolate).  https://www.sciencedirect.com/topics/medicine-and-dentistry/thiomersal I'm ultimately agreeing with you, but thimerosal is a disinfectant