Do Amalgam Fillings Affect Mercury Levels in Urine? A Canadian Study

Canadians are not exposing themselves to unsafe levels of mercury due to their dental amalgam restorations, according to a study¹ published in BMC Oral Health.

Using data from the 2007/09 Canadian Health Measures Survey (CHMS) the research team assessed the relationship between mean urinary mercury concentration in the general Canadian population and the number of amalgam surfaces. The researchers also reviewed data on mercury levels for males and females and for different age groups.

The results show that overall mean mercury concentration was well below levels associated with any health risks, regardless of the number of amalgam surfaces. Overall, approximately 98% of participants had mercury levels that were lower than levels considered to pose a health risk. In general, the mean urinary mercury concentration tended to increase with the number of amalgam surfaces, appeared to be influenced by age, and was slightly higher in females compared to males.

One of the study’s authors, Dr. Carlos Quiñonez, assistant professor and program director of dental public health at the University of Toronto’s faculty of dentistry, puts the results into context: “Our research comes into line with studies conducted in the US and Europe, demonstrating that dental amalgams are not a hazardous source of elemental and inorganic mercury in human beings.”

“If patients are worried that dental amalgam is unsafe, there is now current Canadian data that can help ease their concerns,” says Dr. Quiñonez.

The study authors acknowledge that the levels of mercury they measured could not be attributed to dental amalgam alone, since other sources of mercury, such as contaminated fish and seafood, could also contribute to the mercury levels they observed.

Urinary mercury concentrations are expressed as µg Hg per gram creatinine or µg Hg per litre of urine. Mercury levels considered to be safe are 5 µg Hg/g Cr or 7 µg Hg/L.