Lack of neuropathological changes in rats after exposure to butyl benzyl phthalate

Butyl benzyl phthalate (BBP; Santicizer 160 Plasticizer) was fed to 3 groups of 10 male and 10 female Charles River CD rats for 6 wk at target doses of 500, 1500, and 3000 mg/kg/d. Control groups of 6 males and 6 females received untreated diets for the same period. Body weight gains were decreased at the 1500 and 3000 mg/kg/d levels. Hindlimb stiffness was noted at the 3000 mg/kg/d level and was more prevalent in males. Stiffness was apparently reversed after withdrawal from BBP exposure for 2 d. Microscopic examination of central and peripheral nervous system tissues did not reveal any compound-related pathological changes. Thus, there were no morphological changes in the nervous system that could be related to the apparently reversible hindlimb stiffness.