Comparative study of the carcinogenic effect of BHP and BAP on NMRI mice.

The carcinogenic effects of N-bis(2-hydroxypropyl)nitrosamine (BHP) and N-bis(2-acetoxypropyl)nitrosamine (BAP) were studied in NMRI mice treated subcutaneously once weekly for life. The highest incidences of tumours were found in the lung (73-100%), in the liver (67-100%) and nasal cavity (0-33%) in both sexes of mice. Data were similar in animals treated with BHP or BAP. These tumours were adenomas, adenocarcinomas and squamous cell carcinomas (nasal cavity and lung) as well as hemangio-endotheliomas and hemangioendotheliosarcomas (liver). The lung tumours were found in the control mice (27-50%) 20 weeks later than in the experimental animals. The rate of malignant neoplasms rose with increasing survival and decreasing dose levels.