Mercury

The element mercury has been shown to damage the human nervous system. Yet, since 1856, mercury amalgam is "the" filling dentists have used to repair our teeth. Now a study in the journal Chemical Research in Toxicology [indicates:shows] that mercury fillings actually lose their toxic potential over time. Canadian [scientists:researchers] used x-ray spectroscopy to compare new mercury amalgams to those about 20 years old. After two decades, 95 percent of the elemental mercury on the surface of a filling had gone through a chemical reaction. It became [beta-mercury:hydrogen] sulfide, a black-colored solid. Which [explains:confides] why fillings dull with age. And the compound isn't [absorbed:digest] by the body, which means it can't affect the body the way elemental mercury can.