Long-term urinary platinum, palladium, and gold excretion of patients after insertion of noble-metal dental alloys

The aim of this study was to investigate to which extent noble-metal dental alloys contribute to the total platinum (Pt), palladium (Pd), and gold (Au ) body burden of the general population. The urinary Pt, Pd, and Au excreti on was determined in three nonoccupationally exposed volunteers before and up to 3 months after insertion of a high-gold dental alloy. The in-vitro re lease of Pt, Pd, and Au from four different types of dental alloys into eit her artificial saliva or 1% lactic acid solution was additionally investiga ted. The Pt, Pd, and Au concentrations were determined by sector field indu ctively coupled plasma mass spectrometry (SF-ICP-MS). Before insertion of t he high-gold dental alloy, the Pt excretion of the patients ranged between 1.0 and 7.4 ngl(-1) (0.6-3.3 ng g(-1) creatinine). In the immediate post-in sertion phase the Pt excretion rose to 10.5-59.6 ng l(-1) (14.5-33.2 ng g(- 1) creatinine). This is a mean increase by a factor of 12 compared with the average Pt excretion before insertion. Three months after insertion, the P t excretion was still elevated by a factor of 7. Contrary to Pt, the Au and Pd excretion in urine was not significantly increased after insertion of t his type of high-gold dental alloy. Our in-vitro investigations confirm the assumption that Pt, Pd, and Au are released from noble metal-containing de ntal alloys by corrosion. Under the applied conditions, the release was in the lower ng cm(-2) range. It can be concluded that the Pt release from den tal alloys can predominantly contribute to the Pt exposure of non-occupatio nally exposed persons. It can exceed the exposure from all other environmen tal sources including the Pt release from automobile exhaust catalysts.