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.