There is no safe level of mercury. Mercury is the most toxic naturally occurring substance on the planet, yet, according to the EPA, there is currently over 1 ton of mercury from amalgam fillings in the mouths of Americans. Over 67 million Americans exceed the exposure of mercury vapors considered "safe" by the EPA because of the presence of amalgams in their teeth.
Ever since humans discovered fire, our activities have been releasing a "dog's breakfast" of unnatural chemistry. The list has grown to well over 75,000 free elements, compounds and pharmaceuticals. Many of these are acidic, electron-hungry oxidants and free radical generators.
New concern has been raised over the toxicity of dental composites, which have long been promoted as overall safer than mercury-based amalgams, to children’s psychosocial functioning. In fact, new research indicates that bisphenol-A based dental restorations may be more neurotoxic than the mercury ones they were designed to replace, resulting in even greater learning impairment and behavioral issues.