Common environmental contact allergens in Singapore.

Contact allergens produce three types of reactions. The commonest reaction is allergic contact dermatitis (ACD). The commonest contactants in Singapore causing ACD are, in decreasing order of importance, nickel, fragrances, neomycin, lanolin, colophony, flavine, rubber chemicals, paraphenylenediamine, clioquinol and chromates. Another type of allergic contact reaction is immunologic contact urticaria (ICU). ICU is an IgE mediated mechanisms. Contact allergens causing ICU in Singapore are proteinaceous foodstuffs and rubber latex products. Photoallergic contact dermatitis is occasionally seen in Singapore. The commonest agent is Musk Ambrette, a perfume fixature found in male colognes.