Dental amalgam controversy of mercury received by sewage treatment plants. The mercury contaminates the treatment plant sludge, which is typically disposed of by land application, landfilling or incineration. Several states, including New Jersey, New York, and Michigan, have required the installation of dental amalgam separators prior to 2017. EPA promulgated an effluent guidelines regulation in 2017 which prohibits most dental practices from disposing amalgam waste down the drain. Most dental offices nationwide are now required to use amalgam separators. The WHO reported in 2005 that in the United Kingdom mercury from amalgam accounted for 5% of total mercury emissions. In Canada, dental amalgam
Amalgam tattoo from pencil leads), and is sometimes termed a "graphite tattoo", although this is less common than tattooing with amalgam. The diagnosis is clinical. Amalgam tattoo can be distinguished from other causes of localized oral pigmentation because it does not change significantly in size or color, although it may appear to slowly enlarge for several months after the initial implantation of the metal particles. Some amalgam tattoos appear radio-opaque on radiographs (i.e. they show up on x-rays), although in many cases amalgam tattoos have no radiographic features since the responsible particle(s) of amalgam are very small even though clinically the area