Mercury is one of the most toxic elements and a persistent traveler through our environment. So, who's the travel agent for this elemental poison? Coal fired power plants? Most definitely. Mining operations? Of course. Your neighborhood dental office? Surprisingly, yes.

The United Nations Environment Program reports that 10% of global mercury usage is for amalgam tooth fillings. This results in up to 340 tons of dental mercury journeying into the environment each year. In the United States, dentists are currently the second largest users of elemental mercury. This accounts for roughly 32 tons of mercury used yearly to place amalgam restorations, otherwise known as silver fillings. Although the number of amalgams placed has decreased over the last few decades, dentists still use amalgam without precautions. So, the threat of mercury exposure continues.

Dental mercury travels many pathways on its journey back into the environment. It starts when a dentist receives pre-capsulated dental amalgam. In each capsule, up to 900 mg of elemental mercury is separated from the other alloys. To make the final product, the capsule is vigorously shaken in a triturator to thoroughly mix all the elements. Occupational safety concerns arise because this heats the mercury, creating thousands of micrograms of mercury vapor which are released upon opening the capsule. The used amalgam capsule still contains a small amount of mercury. So, the ADA recommends the capsules to be stored in an airtight container and collected by a hazardous waste company. Unfortunately, a majority of dentists toss the capsules into the trash. This mercury-contaminated trash will eventually travel to a landfill where mercury will continue its trip down into the soil.

Back at the dental office, a freshly mixed amalgam is placed into the tooth. The dentist then carves away any excess material while patients swallow some amount of waste. Most is suctioned out and flows to the filtration system. But this system only captures a small percentage of the larger pieces. The vast majority and much smaller pieces escape into the wastewater. A similar scenario plays out when dentists replace amalgam fillings. Many dentists aren’t realizing the environmental harm and clean out their filtration systems by dumping the captured mercury-tainted sludge down the drain. A study funded by the ADA estimated that amalgam fillings contributed to 50% of the mercury found in wastewater. This contaminated water then flows to publicly owned water treatment plans. While efforts are made to remove the mercury from wastewater, most of it settles down into the sewage sludge, which is then taken and spread on land as fertilizer or deposited in a landfill. In both scenarios, the mercury constantly off gases into the atmosphere and seeps into the ground. A percentage of the sewage sludge is also sent packing to incinerators. With over 200 tons of dental mercury continually off gassing mercury vapor in the mouths of Americans, even exhaling is a contributor of mercury to our atmosphere. Additionally, people with amalgam fillings serve as hosts for mercury's passage back into our environment through the excretion of human waste. Mercury's ride continues even after death. Crematories which are unregulated and contain no filtration processes are a drawing vehicle for transporting mercury back into the atmosphere. And all the various pathways are accounted for.

Dental mercury from the United States contributes roughly 28 and a half tons into the environment each year. The governments of the world are actively working together to reduce the amount of mercury released globally to protect human health. The first and most powerful step to eliminating mercury release from dental amalgam is to discontinue the use of this toxic material. With the threats so great and solutions so simple, it’s time to restrict mercury's passport.