Dental amalgam fillings contain the element mercury, which has been associated with adverse effects in the brain and kidneys, reports the U.S. Food and Drug Administration. These amalgam fillings can release low levels of mercury that can enter the mouth as vapor and be inhaled into the lungs.
Based on a review of the best available scientific evidence, the FDA has determined that the amount of mercury released from high-quality amalgam fillings is not enough to cause harm to dental patients over 6 years of age, the FDA explains.
Developing fetuses and children under 6 years of age are much more susceptible to the neurotoxic effects of mercury vapor, advises the FDA, and there is very little clinical data regarding its long-term effects. For this reason, some women who are pregnant or plan on getting pregnant may elect to have their amalgam fillings removed and replaced with composite fillings.
The FDA has determined that nursing mothers need not worry that their amalgam fillings will cause their milk to be contaminated with mercury. The estimated amount of the element that enters the milk from that source is well below the general levels for oral intake that the Environmental Protection Agency considers to be safe, according to the FDA.