Dibenzo [cd,jk] pyrene (anthanthrene), considered to be noncarcinogenic, was examined for carcinogenicity in a comparative study with other polycyclic hydrocarbons. Anthanthrene induced benign and malignant epidermal neoplasms in female Swiss mice after repeated skin application. The incidence of these tumors (47%) was lower and the latency longer than those found after benzo[a]pyrene or dibenzo[a,h]pyrene treatment. Since the proportion of malignant neoplasms was similar (60%) in these three groups, the results indicate that anthanthrene is a relatively strong carcinogen. A rationale accounting for previous negative results in percutaneous experiments with this compound is suggested.
Forty male MRC-W rats were treated chronically with 1-(2-hydroxyethyl)-1-nitrosourea in drinking water (total dose, 330 mg/rat). Fifteen rats (38%) developed osteogenic osteosarcomas or chondrosarcomas of the lower vertebrae. This was the first time that an orally administered organic compound induced a high incidence of these tumors.
Two peritoneal mesotheliomas were induced in rats during a carcinogenicity study of 1-nitroso-5,6-dihydrouracil (NO-DHU) injected intraperitoneally. A review of literature concerning experimental induction of such tumors indicated that they seldom produced with organic compounds and rarely occur spontaneously. In the present study, several reports of chemically induced mesotheliomas of the testes are analyzed and the diagnoses critically reviewed along with other differential diagnoses.
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