Possible carcinogenic hazards of several tars and of locacorten‐tar ointment (spectro‐fluorescent investigations and experiments in animals)

The content of benz (a)pyrene (BP) in some tars and the carcinogenic effect of the ointment, Locacorten‐Tar, has been investigated in our laboratory. The determination of BP was performed by the spectrofluorescence technique based on Shpolsky's effect in frozen crystalline solution of normal paraffins. The concentration of BP in wood tars varied from 0 to 338.2 μg/g, whereas that of BP in coal tars is about 15 times higher (5,000μg/g). In Locacorten‐Tar it was 225 μg/g. Locacorten‐Tar ointment was tested in C57 X CBA mice by skin application. By the end of the treatment (after one year) all surviving animals had malignant skin tumours (carcinomas and sarcomas), which metastasized and were transplantable. BP estimation can apparently serve as an indicator of the carcinogenicity of tars and ointments. The determination of its content may serve as one of the criteria for selecting constituent compounds for ointments.