For over 150 years there has been a debate between the American Dental Association, the Environmental Protection Agency, and Complementary and Alternative Medicine about whether or not amalgam dental fillings are safe. Amalgams are the silver fillings we have in our teeth. After the dentist has prepared the cavity in your tooth for filling, he prepares the amalgam filling. This prepared by combining a powdered alloy composed of silver, tin and copper with liquid mercury. Almost 50% of dental amalgam is elemental mercury. Amalgam releases low levels of mercury vapor that can be inhaled, especially when they are older and starting to erode. High levels of mercury vapor are associated with adverse effects in the brain, kidneys, nerves, and immune system.