In fact, the ADA bestows the dentists' seal of approval, frequently seen on toothpaste, on dozens of amalgam products. The patent resulted from developmental work at NIST supported by the National Institute of Dental Research to find an alternative to mercury-containing dental restoratives. At the other extreme are dentists who believe the mercury in amalgam causes severe health problems ranging from Alzheimer's disease to leukemia. They think the ADA is biased because it is paid for the endorsements. Somewhere in the middle are dentists like Hepps, who turned to alternative fillings partly because they could not get a definite answer about mercury's safety or their liability for problems traced to mercury.
Studies abound about mercury's toxicity, second only to uranium as a human poison.
But fillings are so small that many scientists consider them irrelevant. The few studies that seriously evaluate fillings reach conflicting conclusions about exposure. Some say fish, water and perhaps air all transport far more mercury into the human body than fillings do. Others, including a 1997 report by the U.S. Environmental Protection Agency, say nothing deposits more inorganic mercury into the body than fillings. Environmental toxicologist William Pease reviewed much of the literature on mercury fillings in connection with Proposition 65 litigation.