BACKGROUND: The aim of this study was to investigate the effect of fetal exposure to 4-n-octylphenol (OP) on the induction of mammary tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) in rats. MATERIALS AND METHODS: All rats which showed vaginal plugs or sperm by vaginal smear test after mating were fed a normal diet only, or a diet mixed with 10, 100, 1000 ppm OP throughout the pregnancy period and from day 13 of pregnancy to the end of the pregnancy. No abnormal pregnancy was seen in any of the rats. Pups were given 10 mg DMBA by gastric intubation 50 days after birth. RESULTS: Uterine weight decrease was observed in pups with fetal exposure to 1000 ppm OP throughout the pregnancy period. No endocrine disrupting conditions, such as persistent estrus, anovulatory ovaries or abnormal lactation in the mammary glands were seen in pups with fetal exposure to OP. However, fetal exposure to 100 and 1000 ppm OP throughout pregnancy period enhanced the early incidence and number of mammary carcinomas (MCs) while it did not enhance the incidence and number of benign proliferative lesions (PLs) which consisted of solid masses (fibroadenoma and lobular hyperplasia) and gross cysts. CONCLUSION: These results suggest that fetal exposure to the very weak estrogenicity of OP could enhance the induction of MCs but not affect the induction of PLs.
BACKGROUND: The aim of this study was to investigate the effect of fetal exposure to 4-n-octylphenol (OP) on the induction of mammary tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) in rats. MATERIALS AND METHODS: All rats which showed vaginal plugs or sperm by vaginal smear test after mating were fed a normal diet only, or a diet mixed with 10, 100, 1000 ppm OP throughout the pregnancy period and from day 13 of pregnancy to the end of the pregnancy. No abnormal pregnancy was seen in any of the rats. Pups were given 10 mg DMBA by gastric intubation 50 days after birth. RESULTS: Uterine weight decrease was observed in pups with fetal exposure to 1000 ppm OP throughout the pregnancy period. No endocrine disrupting conditions, such as persistent estrus, anovulatory ovaries or abnormal lactation in the mammary glands were seen in pups with fetal exposure to OP. However, fetal exposure to 100 and 1000 ppm OP throughout pregnancy period enhanced the early incidence and number of mammary carcinomas (MCs) while it did not enhance the incidence and number of benign proliferative lesions (PLs) which consisted of solid masses (fibroadenoma and lobular hyperplasia) and gross cysts. CONCLUSION: These results suggest that fetal exposure to the very weak estrogenicity of OP could enhance the induction of MCs but not affect the induction of PLs.