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To be added to food, this additive must achieve 99% purity. However, this leaves room for small amounts of potential contaminants like lead, arsenic, or mercury (1Trusted Source).

Rebecca Capua is an assistant conservator in the Paper Conservation Department at the Metropolitan Museum of Art since 2009. She received an MA in art history and an Advanced Certificate in art conservation from the Conservation Center, Institute of Fine Arts, New York University in 2007. Her primary area of research is on the materials of American artists of the late 19th and early 20th century. Address: The Sherman Fairchild Center for the Conservation of Works on Paper, Metropolitan Museum of Art, 1000 Fifth Avenue, New York, NY 10028. Email: rebecca.capua@metmuseum.org.