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Propolis or bee-glue, a resinous bee-hive product, is the cause of an increasing number of cases of allergic contact dermatitis. Formerly only observed in bee-keepers, propolis allergy today is mainly seen in individuals who use propolis in bio-cosmetics and self treatment of various diseases. Nearly 200 cases are summarized in an overview, including the first description of 'poplar bud' contact dermatitis from 1887. As practically all flavonoid aglycones and most of the other phenolics present in propolis are identical with the bud secretion of poplars, evidence is given that the poplar bud constituents are responsible for propolis hypersensitivity.
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Hausen et al. (1987) studied this question.
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