[Biomonitoring for the evaluation of a mercury burden from amalgam fillings. Mercury determination in urine before and after oral doses of 2,3-dimercapto-1-propanesulfonic acid (DMPS) and in hair].

The statistically significant correlation between mercury urine concentrations of 67 male volunteers aged 16 to 72 years (mean: 1.20 micrograms/l, range 0.1-5.0; 1.57 micrograms/24 h, range 0.1-7.8) and their amalgam filling index (r = 0.653; p < or = 0.0001) indicates that amalgam fillings burden the organism with mercury. Oral gavage of 300 mg DMPS (Dimaval) elevated mercury elimination in the urine by a factor of 9.2. The correlation between mercury elimination in the 24 h urine with and without DMPS is statistically highly significant (r = 0.89, p < or = 0.0001). This means that the information yield from mercury determination in urine is usually not improved by DMPS. For toxicological evaluation of mercury excretion in urine we propose to employ 1/20 of the BAT-level for inorganic mercury (200 micrograms/l). This approach is frequently used in setting MIK levels based on MAK levels. We refer to the resulting standard as BUT level (Biologischer Umweltstofftoleranzwert). The BUT level for inorganic mercury in urine is thus 10 micrograms/l. The mean determined in the cohort under investigation was ca. 10 times lower than the proposed threshold value. Therefore the present findings do not suggest a risk to health due to mercury in the volunteers examined here. Hair analysis of the same volunteers did not correlate with inorganic mercury burden from amalgam fillings. However, a weak correlation was found between hair mercury levels and fish consumption. Since fish are mainly a source of organic mercury, hair analysis may be useful for biological monitoring of this form of mercury.