THIMEROSAL POSITIVITIES - THE ROLE OF SH-GROUPS AND DIVALENT IONS

For a better understanding of the mechanistic details of the interacti ons of organomercury compounds inside the skin, 32 subjects who previo usly had given positive patch-test reactions to thimerosal (TH) and ne gative reactions to thiosalicylic acid, were divided into 2 groups. 16 subjects were repatch tested to ethylmercury chloride (EtHgCl) and to solutions containing EtHgCl mixed with L-cysteine and glutathione, re spectively. The remaining 16 were repatch tested to EtHgCl and to solu tions containing EtHgCl mixed with chlorides of Zn, Mg, and Mn, respec tively. The results showed that whilst L-cysteine, glutathione and ZnC l2 were able to abolish or to reduce the positive reactions to EtHgCl, chlorides of Mg and Mn were unable to do so. Patch tests revealed tha t in causing positive reactions to TH, EtHg probably interacted with t hiol groups and with Zn ions, as in biological systems when causing to xic effects. The limited number of TH reactions in the general populat ion, the constant presence of concomitant positive reactions to EtHgCl and MeHgCl, and the lack of cross-reactivity with other organic or in organic mercury compounds, lead us to speculate that reactions to TH a re due to organomercury alkyl compounds, and that positive subjects ha ve a constitutively reduced capability to metabolize organomercury com pounds, rather than to reveal previous exposure.