Mutagenicity of urine from psoriatic patients undergoing treatment with coal tar and ultraviolet light

The possible percutaneous absorption of the mutagens from patients receiving crude coal tar (CCT) and ultraviolet light was investigated. Urine samples were collected from nonsmoking volunteers, smoking, and nonsmoking psoriatic patients. Patients were treated with 1% CCT U.S.P. or 1 to 10% CCT in petrolatum in the evening. The following morning, patients received coal tar baths and then ultraviolet light (mainly 290-320 nm, UVB). Nonpolar organics in urine samples were extracted by adsorption onto XAD-2 resin and the extracted organics assayed in the Ames Salmonella/Microsome test. TA98 was the most sensitive bacterial strain to detect mutagenicity. Except for smoking psoriatic patients, the addition of liver homogenate was necessary to see mutagenicity. No increase in the number of revertants was observed when B-glucuronidase was added to the assay. Of 14 patients studied 12 had at least one mutagenic urine sample. Typical values for nonsmoking psoriatics treated with CCT ranged from 42 to 496 his +/20 ml of urine after the subtraction of spontaneous his + counts (26 +/- 6). Two nonsmoking normal volunteers were found to excrete mutagenic urines. Smoking psoriatic patients ranged from 213 to 1,100 his +/20 ml urine. This study demonstrates the percutaneous absorption of mutagens from CCT and indicates that its effects may not be limited to the skin.