Severe Phototoxic Burn Following Celery Ingestion

To the Editor.—  Because of a research project, we recently reviewed the article by Ljunggren¹ in the October 1990 issue of the Archives. Our recalculations showed a psoralen concentration in celery root that was 50% lower than that reported in the article. According to Ljunggren's method, a 10-g portion of celery root was homogenized and extracted. The extracted material was again dissolved in 5 mL of acetone. The concentration of psoralen in this solution was then determined to be 0.01%. Therefore, there was a total of 0.5 mg (and not 1 mg) of psoralen in the 5-mL acetone solution and, consequently, in the 10 g of celery root from which the psoralen was extracted. As a result, the 450 g of celery root that was eaten by the patient contained 22.5 mg of psoralen instead of the reported 45 mg of psoralen.Since this very original article will likely