Dental Fillings May Increase Mercury Levels
People with more than eight amalgam dental fillings have more mercury in their blood than those with none, according to a new study from the University of Georgia.
More than eight amalgam dental fillings could cause increased levels of mercury in your blood system, according to a new study.
(Photo: Daniel Huszar)
The average American has three dental fillings, while 25 percent of the population has 11 or more fillings. The study found those with eight or more had about 150 percent more mercury in their blood. Dental fillings composed of dental amalgam, a mixture of mercury, silver, tin and other metals, have been a concern for some time.
The research, which studied nearly 15,000 individuals, is the first to demonstrate a relationship between dental fillings and mercury exposure. The results were published online last week and will be in the print edition of the journal Ecotoxicology and Environmental Safety in December.
“Tooth decay is one of the most prevalent chronic diseases,” said Lei Yin, a scientist in the department of environmental health science and the study’s lead author. “I think a majority of people have experienced dental fillings, but the kind of materials the dentist uses isn’t something that’s really discussed.”
Mercury exposure from dental fillings is not a new concern, but previous studies were inconsistent and limited, according to Xiaozhong “John” Yu, assistant professor of environmental health science and co-author.
“This study is trying to provide the most accurate levels of exposure, which will form the scientific basis to make future risk assessment,” Yu said, adding that the study was the first to also control for age, education, ethnicity, race, gender, smoking and seafood consumption, which is a known contributor to mercury levels in the body.
Xiaozhong “John” Yu and Lei Yin from the University of Georgia conducted research that shows dental amalgam can contribute to prolonged mercury levels in the body. (Photo: University of Georgia)
The researchers analyzed exposure by specific types of mercury and found a significant increase in methyl mercury, the most toxic form, related to dental fillings. Yu said this suggests the human gut microbiota, a collection of microorganisms living in the intestines, may transform different types of mercury.
Dental amalgam has been the go-to filling material for more than 150 years, because it is affordable and durable. However, about half of the compound contains mercury, a heavy metal known to be toxic at high levels, causing brain, heart, kidney, lung and immune system damage. New research suggests that methyl mercury may cause damage even at low levels.
“As toxicologists, we know that mercury is poison, but it all depends on the dose. So, if you have one dental filling, maybe it’s OK. But if you have more than eight dental filings, the potential risk for adverse effect is higher,” Yu said. People with numerous dental fillings who are also exposed to mercury from other sources, such as seafood or work environments, are most at risk.
According to its website, the U.S. Food and Drug Administration considers dental amalgam fillings safe for adults, but says, “pregnant women and parents with children under six who are concerned about the absence of clinical data as to long-term health outcomes should talk to their dentist.”
The study also looked at composite resins, a mercury-free alternative for dental fillings that can release small amounts of bisphenol A, or BPA, which may cause developmental or reproductive damage. The results found no association between dental fillings and urinary BPA, but further research is needed to understand BPA exposure from resin-based materials.
“It’s important for doctors and patients to be informed in their selections,” Yin said. “We now have an excellent starting point to evaluate the potential risk of dental material on human health.”
Article by Elizabeth Fite, University of Georgia
