[Longitudinal study of the excretion of 1-hydroxypyrene in urine after external treatment with coal tar]

In order to study the dermal uptake, time course, and urinary excretion of polycyclic aromatic hydrocarbons, the concentration of 1-hydroxypyrene in urine was determined by means of high performance liquid chromatography with fluorescence detection before, during, and after the topical treatment with coal tar in 19 patients suffering from prurigo simplex subacuta, microbial eczema, atopic dermatitis, eczematization after scabies, exanthematous lichen ruber, pityriasis lichenoides and cutaneous sarcoidosis. Beginning with a value of 6.04 +/- 2.06 micrograms 1-hydroxypyrene/g creatinine before treatment, the urinary excretion significantly increased during the therapy with coal tar (p < 0.0001 at 3rd, 5th, and 6th day of therapy). A maximum was reached at day 8 of topical treatment with a value of 584.35 +/- 191.96 micrograms 1-hydroxypyrene/g creatinine (p < 0.002). Already during treatment at day 10 there was a beginning decrease of 1-hydroxypyrene to 361.63 +/- 170.13 micrograms/g creatinine. After the end of treatment, the excretion further decreased reaching a value of 5.31 +/- 2.85 micrograms 1-hydroxypyrene/g creatinine at the 10th day after therapy. Skin carcinomas due to therapeutical use of coal tar occur extremely rarely and only after vergoten, non-controlled use. We suggest that the duration of exposure is the most important factor for the carcinogenic effect of coal tar.