SANTOWHITE Powder was fed at dietary levels of 0, 1,000, 2,500, 5,000 and 10,000 ppm (parts per million) for approximately four weeks to groups of ten rats of each sex. The neat test material and test diets were stable. The diets were homogeneously prepared and near their target con- centrations. There were no significant clinical signs and all animals survived to the terminal sacrifice. Reduced food intake and lower body weights were noted for both sexes at the three highest dietary levels throughout the study. The liver appeared to be the target organ in this study. Upon gross examination, livers were abnormally colored and there were increased absolute and relative hepatic weights for both sexes at all dietary levels. Microscopically, all dietary levels showed hepa- tocellular vacuolation (lipid accumulation). In addition, the three highest dietary levels also showed hepatocellular hypodegeneration/necrosis. A no-observed-effect-level (NOEL) was not achieved for this study but was considered to be lower than 1,000 ppm in the diet of rats for four weeks.