Amalgam (dentistry) disposal. Dental amalgam is the largest source of mercury received by U.S. treatment plants. The U.S. Environmental Protection Agency (EPA) promulgated an effluent guidelines regulation in 2017 which prohibits most dental practices from disposing dental amalgam waste down the drain. Most dental offices in the U.S. are required to use an amalgam separator in their drain system. The separator captures the waste material, which is then recycled. The European Commission has issued a Waste Directive that classifies amalgam waste as a hazardous waste. The waste should be separated from other waste by fitting amalgam separators in all dental practices. Mercury
Women in chemistry the only woman to be award two Nobel prizes). Her prize in chemistry was for her "discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element." Irene Joliot-Curie, Marie's daughter, became the second woman to be awarded this prize in 1935 for her discovery of artificial radioactivity. Dorothy Hodgkin won the prize in 1964 for the development of protein crystallography. Among her significant discoveries are the structures of penicillin and vitamin B12. Forty five years later, Ada Yonath shared the prize with Venkatraman Ramakrishnan and Thomas