Subchronic toxicity was evaluated in 2 groups of 20 Charles River albino rats (10 male and 10 female) ingesting Santicizer 160 (butyl benzyl phthalate) via the diet for 13 weeks. The first group ingested test article at a dietary concentration of 0.5% throughout the treatment period. The second group received weekly adjustments in dietary levels, starting at 0.5% and increasing incrementally by 0.5% until a concentration of 2.0% was reached; animals were then maintained at this level for the remainder of the test. Mortality was observed in 3 males in the control group, in one female in the 0.5% dose group, and in one male in the 2.0% dose group during the treatment period. A statistically significant (analysis of variance, p < 0.05) decrease in body weight gain was observed in males and females in the 2.0% dose group, but not in the 0.5% dose group. Liver to body weight, and kidney to body weight ratios were significantly (p < 0.05) increased in males and females in the 2.0% dose group; however, the investigators attributed this to the decreased (see above) body weight of these animals. Necropsy of animals that died or survived to the end of the 90 day treatment period did not reveal gross pathology that could be attributed to the effect of the test articl e. Additionally, microscopic analysis of the liver, spleen, kidneys, adrenals, stomach, and large and small intestines did not reveal test article induced pathology.