Mercury and amalgam sensitivity: Possible clinical manifestations and sources of contact sensitization a multicenter study of the German Contact Dermatitis Group (DKG)

Abstract

In 1993-1994 the German Contact Dermatitis Group (DKG) conducted a multicenter patch test study with eleven different mercury (Hg) and amalgam (A) substances. The objectives of the study were to determine cross-reactivities, the associated symptoms, the relevance of positive test reactions and the sources of sensitization. In a group of 368 patients (275 female, 93 males from 13 allergy centers), positive reactions to at least one Hg substance were detected in 89 cases (24 %). The patients were suffering from diverse stomatological, dermatological and internal illnesses. The four main Hg representatives gave only 12-15% positivity with the following cross-reactivity: 5% amalgam with ammoniated mercury (HgNH2Cl): 96 %, vice versa 55 %; HgNH2Cl with phenylmercuric salts 72 %, vice versa 63 %; thimerosal with all others approximately 50 %. Of the 41 patients with positive reactions to inorganic substances (HgNH2Cl plus 2-20 % amalgam), 25 showed localized skin symptoms and 28 had mucosal symptoms. The test reactions were clinically relevant in 19 of the 41 cases. A significant increase of positive reactions was seen in the following diagnostic groups: subjects with oral lichen planus or lichenoid lesions, leukoplakia, lichenoid dermatitis, mercury contact eczema, as well as in the following occupational groups: medical, clinical laboratory and nursing professions, laborers and tradesmen. The Hg hypersensitivity is most likely to be acquired via the skin. Recommended test substances are 1 % HgNH2Cl, 5 % (or 10 %) amalgam, phenylmercuric acetate 0.05 % and 0.05 % thimerosal, all suspended in petrolatum.