Pearl White and Bismuth

"Pearl white" was a preparation that had originally been made from actual ground-up pearls -- a very expensive and luxurious cosmetic at a time when cultured pearls were not yet known. By the Edwardian era, bismuth was usually used in its place.

However, bismuth was believed at the time to be poisonous, as it is a related substance to lead. The Scientific American Cyclopedia admonished that "the use of bismuth cannot be too strongly reprehended" and claimed it would produce "paralysis of [skin's] minute vessels." (Although the editors of said book still freely provided powder recipes which used the substance, nonetheless.) Bismuth actually has unusually low toxicity for a heavy metal, and is considered nowadays to be generally safe in cosmetics.