Biological mercury measurements before and after administration of a chelator (DMPS) and subjective symptoms allegedly due to amalgam.

The aim of the study was to explore multivariately the relationship between subjective symptoms allegedly due to amalgam and mercury measurements before and after administration of a chelator. Of 120 participants, the mercury concentrations in urine (U-Hg) and plasma (P-Hg) before and after a chelating agent or placebo were determined as were the numbers of fillings and symptoms allegedly due to subjective symptoms. The dental status was charted. Blood was analysed on 13 parameters. The analysis revealed neither the parameters in blood nor the subjective symptoms to be associated with a dimension dominated by 'mercury indicators'. The final analysis was therefore performed with 'number of subjective symptoms' and enabled to distinguish two subsamples. One subsample was characterised by > 2 subjective "symptoms", highest scores for U-Hg, P-Hg and filled surfaces, and chewing gum for > 1 h a day. The other subsample comprised the subjects with few filled surfaces and low U-Hg and P-Hg, but was not characterised by "no subjective symptoms". The chelator was considered neither to invalidate nor to improve these findings and was concluded not to be helpful in diagnosing "symptoms". The chelator caused side effects in 42% of the subjects and the placebo in 27%. A relationship between amalgam fillings and subjective symptoms could not be shown. Therefore, the mere fact of knowing to have amalgam fillings was assumed to be the reason why subjective symptoms were attributed to amalgam and side effects were ascribed to the treatment.