Phthalic acid dermatitis caused by an organostannic compound, tributyl tin phthalate.

We report a case of primary irritant contact dermatitis caused by an organostannic insecticide, tributyl tin phthalate, which has been thought to be stable and safe. A factory worker has been in contact with raw tributyl tin phthalate on one leg. Soon after taking a hot-water bath, he developed severely painful erythema on this leg. Patch tests and chemical analysis revealed that hot water hydrolyzed tributyl tin phthalate and produced concentrated phthalic acid. Since phthalic acid, a weak acid, was then concentrated, an acute irritant reaction appeared in this patient.