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.