title: Modifying effects of prepubertal exposure to potassium perchlorate and tetrabromobisphenol A on susceptibility to N-bis(2-hydroxypropyl)nitrosamine- and 7,12-dimethylbenz(a)anthracene-induced carcinogenesis in rats.
abstract: Early life exposure to certain kinds of chemicals is of concern because of a possible increase in cancer risk, but relevant data are limited. In the present experiment, modifying effects of prepubertal administration of potassium perchlorate (KClO(4)) and tetrabromobisphenol A (TBBPA) on susceptibility to multi-organ carcinogenesis were evaluated. F344 dam rats were administered 0% (control), 0.01%, 0.1% or 1% TBBPA in diet or 0.01% KClO(4) in drinking water after parturition. Their weaned offspring in each group were treated for 2 weeks in the same manner. From 6 weeks of age, all offspring were treated with N-bis(2-hydroxypropyl)nitrosamine in drinking water for 4 weeks. In addition the females at 7 weeks of age were gavaged once with 7,12-dimethylbenz(a)anthracene. At weeks 39 and 47 of age, the males and females, respectively, were euthanized and the liver, kidney, lung, esophagus, thyroid, urinary bladder, testis, epididymis, ovary and mammary gland were histopathologically examined. The incidences of thyroid follicular adenomas in 1% TBBPA females (p<0.05) and of transitional cell papillomas in the urinary bladder of 0.01%, 0.1% and 1% TBBPA females were increased (p<0.05) as compared to the controls. These results indicate that prepubertal exposure to TBBPA raises susceptibility to thyroid and urinary bladder tumorigenesis in rats. Although causes of the effect on thyroid carcinogenesis might be direct and/or indirect hormonal actions, further studies are needed for confirmation.
authors.affiliation: Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan. imai@nihs.go.jp
authors.forename: Toshio
authors.initials: T
authors.lastname: Imai
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Takami
authors.forename: Young-Man
authors.initials: YM
authors.lastname: Cho
authors.forename: Masao
authors.initials: M
authors.lastname: Hirose
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Nishikawa
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity*; D000367:Age Factors; D000818:Animals; D015197:Carcinogenicity Tests; D003043:Cocarcinogenesis; D005260:Female; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000473:pathology; D009374:Neoplasms, Experimental / Q000139:chemically induced* / Q000473:pathology; D009602:Nitrosamines / Q000633:toxicity*; D010472:Perchlorates / Q000633:toxicity*; D011075:Polybrominated Biphenyls / Q000633:toxicity*; D017680:Potassium Compounds / Q000633:toxicity*; D051381:Rats; D011916:Rats, Inbred F344; D013964:Thyroid Neoplasms / Q000139:chemically induced / Q000473:pathology
chemical_list: D009602:Nitrosamines; D010472:Perchlorates; D011075:Polybrominated Biphenyls; D017680:Potassium Compounds; C009006:potassium perchlorate; C012457:diisopropanolnitrosamine; D015127:9,10-Dimethyl-1,2-benzanthracene; C020806:tetrabromobisphenol A