The carcinogenic action of dibenzcarbazoles

Abstract

Naphthylamine is not carcinogenic when painted on the skin of animals, yet cancer of the bladder is relatively frequent among those concerned in its manufacture. The following substances, which might possibly be formed as impurities during the manufacturing process, were tested for carcinogenic activity by painting on mouse skin, [alpha][alpha]-and [beta][beta]-dinaphthylamine had no carcinogenic activity. 12:7:8-dibenzcarbazole produced only one papilloma and one epithelioma in 20 mice after 500 days treatment. 1:2: 5:6-dibenzcarbazole produced malignant skin changes in 250 days, 3:4:5:6-dibenzcarbazole in 180 days. Of the mice painted with the 3:4:5:6-compound, 80% of those surviving over 1 mo. showed well-marked hypertrophic biliary changes, i.e. after OS mgm. had been painted on. Most of those surviving over 200 days had nodules of altered liver cells resembling hepatomas, about 6 mgm. of the 3:4:5:6-dibenzcarbazole producing this effect. No metastases from the liver occurred, and in none of the expts. were neoplasms found in the urinary tract. Subcutan. injs. of the 3:4 decompound produced spindle-celled sarcomas at the site of inj., which have been successively grafted to the 5th generation.