Abstract
Koa wood is an important forest product resource of the Hawaiian islands. The wood is used in furniture, bowl-turning, flooring, veneer, cabinetry, and is also exported for similar uses. Three patients, all woodworkers, who developed an allergic contact dermatitis to the sawdust of koa wood (Acacia koa), are described. The patients showed positive patch tests to the koa sawdust, which was applied neat and in 1%, 3%, and 20% suspensions in petrolatum. Sensitizers isolated from an Australian acacia tree species (Acacia melanoxylon), closely related to koa, are two quinones and a stronger sensitizer, melacacidin, a hexahydroxyflavan. Chemical extraction of Acacia koa revealed that the two quinones were not detectable. However, the hexahydroxyflavan, melacacidin, was detected and isolated. All three patients showed positive patch test reactions to the melacacidin.
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