The psoralens1 are furocoumarins to which most people in the United States have been exposed. Celery contains psoralen. Oil of bergamot, widely used in perfumes, contains 5-methoxypsoralen. Thus, there are few persons who have not ingested psoralen and probably no adult woman who has not applied a psoralen to her skin. Plants containing psoralen have been used to produce pigmentation for at least 3,000 years. Recently, oil of bergamot has been used for this purpose. Scientific investigation of the psoralens began when Kuske2 and, later, Fahmy and his group3 isolated the active chemicals from a variety of plants. Many physicians in different countries began to study these compounds. Lerner, Denton, and Fitzpatrick4 and Kelly and Pinkus5 initiated clinical evaluation in the United States.
The chemical alterations in the psoralesn which occur after oral ingestion or topical application to the skin are not known. Exposure of