RECOVERY OF SILVER FROM RADIOGRAPHIC FIXER

This study examined the silver content of 10 brands of dental x-ray fi lm that are commercially available in Japan. Kodak Ektaspeed EP-22 (Ea stman Kodak Co., Rochester, N.Y.) was found to have the highest silver content, and SD 100 Gold X-ray Film (San Dental Co., Ltd., Tokyo, Jap an) had the lowest content of silver. Electrolysis and ion exchange we re used as the methods of silver recovery from films in the general de ntal office. Ion exchange was more than 99% efficient in silver recove ry from the radiographic fixer and resulted in an 80% reduction in bio chemical oxygen demand and a 95% reduction in chemical oxygen demand. However, these levels and other environmental pollutants were still ab ove the limits set by the Japanese Pollutant Control law.