Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Povidone-iodine (PVP-I) is a stable chemical complex of polyvinylpyrrolidone (povidone, PVP) and elemental iodine. It contains from 9.0% to 12.0% available iodine, calculated on a dry basis. This unique complex was discovered at the Industrial Toxicology Laboratories in Philadelphia by H. A. Shelanski and M. V. Shelanski. They carried out tests in vitro to demonstrate anti-bacterial activity, and found that the complex was less toxic than tincture of iodine in mice. Human clinical trials showed the product to be superior to other iodine formulations. It was first sold in 1955, and has since become the universally preferred iodine disinfectant.