The U.S. Food and Drug Administration has issued a warning on its website which informs about the potential safety issues of mercury-based dental fillings. Amalgam fillings are a mixture of mercury and silver, as well as several other metals in lesser quantities. The FDA was forced to display the warning as part of a settlement which stemmed from a lawsuit filed by several groups which allege that amalgam releases mercury.

The FDA warning only applies to pregnant women and children. While in theory having amalgam fillings and chewing on them might release a small quantity of mercury, studies have found no evidence of health hazards. Amalgam is very stable chemically and kills bacteria. It is also much more resistant than polymer-based fillings.

It is generally not a good idea to replace amalgam fillings with polymer ones, as the latter last almost half the number of years. FDA Deputy Commissioner Randall Lutter told AP that the regulator still ponders what to do next. The FDA is reluctant to ban amalgam as long as there is no solid evidence of health risks.

They are backed by dentists. For example, Dr. Edmond Hewlett, a dental professor at the University of California, Los Angeles, and an American Dental Association adviser, told AP that the groups arguing against amalgam are making use of "junk science."

However, neurologists warn that while most people are not exposed to any kind of risk, there are some categories who might be. Safety must come first, they say, pointing out the negative effects of mercury on the nervous system.