Studies on the allergenicity of Baltic amber

Baltic amber is a fossil resin deposited 36-7 million years ago and one source may be the extinct tree Pinites (Pinus) succinifer. Palaeobotanical studies of amber have an extensive literature, but the aspect of allergenicity has not been addressed before. The aim of our study was to present the results from sensitization studies with Baltic amber and to discuss these in view of possible cross-reactivity with contact allergens in colophony. It is concluded that allergens found in colophony can also be present in Baltic amber. The main resin acids were identified in an ether-soluble extract of amber. Amber suspended in petrolatum caused positive patch test reactions in patients with contact allergy to colophony. Furthermore, animals sensitized to colophony showed positive reactions to amber, but animals induced with amber did not react when challenged with amber. A use test with an amber necklace in patients with positive test reactions to amber and colophony was negative, which supports the view that amber in personal ornaments is not a clinical problem.