The effect of time on the incidence of carcinomas obtained by the implantation of paraffin wax pellets into mouse bladder.

Paraffin wax pellets were implanted surgically into the mouse bladder lumen and animals killed after 40-50, 70-80 and 100-110 weeks. The number and malignancy of bladder carcinomas increased considerably with the time after implantation. Pellets containing 1-phenylazo-2-naphthol significantly increased at each time the incidence of bladder carcinomas relative to that observed with paraffin wax. Pellets containing N-2-fluorenylacetamide or its metabolites gave very similar incidences or carcinomas whether or not they were carcinogenic by oral or parenteral administration.