LONG-TERM USE OF NICOTINE CHEWING GUM AND MERCURY EXPOSURE FROM DENTAL AMALGAM FILLINGS

In experimental studies, chewing gum has been shown to increase the re lease rate of mercury vapor from dental amalgam fillings. The aim of t he present study was to investigate the influence of long-term frequen t chewing on mercury levels in plasma and urine. Mercury levels in pla sma (P-Hg) and urine (U-Hg), and urinary cotinine were examined in 18 subjects who regularly used nicotine chewing gum, and in 19 referents. Age and number of amalgam surfaces were similar in the two groups. To tal mercury concentrations in plasma and urine were determined by mean s of cold vapor atomic absorption spectrometry. Urinary cotinine was d etermined by gas chromatography-mass spectrometry. The chewers had bee n using 10 (median) pieces of gum per day for the past 27 (median) mon ths. P-Hg and U-Hg levels were significantly higher in the chewers (27 nmol/L and 6.5 nmol/mmol creatinine) than in the referents (4.9 nmol/ L and 1.2 nmol/mmol creatinine). In both groups, significant correlati ons were found between P-Hg or U-Hg on the one hand and the number of amalgam surfaces on the other. in the chewers, no correlations were fo und between P-Hg or U-Hg and chewing time per day or cotinine in urine . Cotinine in urine increased with the number of pieces of chewing gum used. The impact of excessive chewing on mercury levels was considera ble.