Several chlorinated acetones have been identified in drinking water and these as well as a number of chlorinated acroleins are produced by chlorination of humic acid solutions. Many of these chlorinated compounds and the brominated acrolein analog were positive in the Ames assay in the laboratory. To determine if carcinogenic activity was associated with these chemicals halogenated acetone derivatives were applied topically to SENCAR mice at the various dose levels. Doses were applied six times over a two-week period in 0.2 ml ethanol per application. Control animals received 0.2 ml ethanol per application as single dose or multiple doses to match corresponding study. Two weeks after final dose, 1.0 micro g TPA in 0.2 ml acetone was applied three times weekly for 20 weeks. After 24 weeks the percent of animals with tumor for dose groups above were reported. The data show that 1,3-DCA, CAC, and BAC, when applied topically, initiate tumors in the mouse skin. These chemicals administered orally in a 2% emulphor solution, at doses described in table 3, did not initiate tumors in the mouse skin.