A two-generation reproductive toxicity study of n-butylbenzene in rats.

N-butylbenzene (n-BB), which is suspected of having endocrine disrupting effects, was administered orally by gavage at dose levels of 0, 30, 100, and 300 mg/kg/day to groups of Crj: CD (SD) IGS rats (24 males and 24 females per group) over 2 generations, and the effects on fertility of the parental animals and development/growth of the offspring were investigated. In the F0 and F1 parental animals, n-BB at the doses of 30 mg/kg/day and above increased the liver weights, and the doses of 100 and 300 mg/kg/day increased the kidney weights and caused histopathological changes in the liver and kidney. Moreover, the dose of 300 mg/kg/day also increase adrenal gland weights and there was a tendency for inhibition of body weight gain. With respect to effects on fertility, no significant findings were noted in the F0 parental males and females. Furthermore, it was concluded that n-BB did not induce serious reproductive toxicity in the F1 parental animals and no effects on the endocrine system were recognized. In the F1 and F2 offspring, n-BB at 300 mg/kg/day increased the thymus weights.