Urinary mercury concentrations associated with dental restorations in adult women aged 16-49 years: United States, 1999-2000

Background: Mercury amalgam dental restorations have been used by dentists since the mid 19th century and issues on safety continue to be periodically debated within the scientific and public health communities. Previous studies have reported a positive association between urine mercury levels and the number of dental amalgams, but this relation has never been described in a nationally representative sample in the United States. Aims and Methods: Using household interview, dietary interview, dental examination, and laboratory data from the 1999-2000 National Health and Nutrition Examination Survey ( NHANES), the association between mercury concentrations and dental restorations was examined in US women of reproductive age. Results: In women of childbearing age, approximately 13% of all posterior dental surfaces were restored with amalgams and the average urinary mercury level in women was low (1.34 mu g/l). It is estimated that an increase of 1.8 mu g/l in the log transformed values for mercury in urine would occur for each 10 dental surfaces restored with amalgam. Conclusions: Although the findings do not address the important issues of adverse health effects at low thresholds of mercury exposure, they do provide important reference data that should contribute significantly to the ongoing scientific and public health policy debate on the use of dental amalgams in the USA.