title: Toxicity of 2,4,4'-trichlorobiphenyl in rats following 90-day dietary exposure.
abstract: The toxicity of 2,4,4'-trichlorobiphenyl (PCB 28) was investigated in rats after a 90-d dietary exposure. Groups of 10 male and 10 female weanling Sprague-Dawley rats were administered PCB 28 in the diet at 0, 0.05, 0.50, 5.0, or 50.0 ppm for 13 wk. Growth rate and food consumption were not affected by treatment, and no clinical signs of toxicity were observed. Mottled liver was noted in both control and PCB-treated males, but was found with increased incidence in the highest treatment group. Increased urinary ascorbic acid and hepatic microsomal ethoxyresorufin O-deethylase activity were observed in the 50.0 ppm group of both sexes. The vitamin A content in liver, lung, and kidney was not significantly affected by treatment. Analysis of brain biogenic amines showed a decreased dopamine concentration in the substantia nigra region of female rats receiving 0.5 ppm PCB 28 and higher doses. Female rats appeared to be more sensitive than males to the neurochemical effects of PCB 28. Dose-dependent histologic changes were observed in the thyroid and liver, with biologically significant changes occurring at 5.0 ppm and above. Based on these data, the no observable-adverse-effect level (NOAEL) for this PCB congener was considered to be 0.5 ppm in diet or 36 micrograms/kg body weight/d.
authors.affiliation: Environmental Health Directorate, Health Protection Branch, Ontario, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Chu
authors.forename: D C
authors.initials: DC
authors.lastname: Villeneuve
authors.forename: A
authors.initials: A
authors.lastname: Yagminas
authors.forename: P
authors.initials: P
authors.lastname: Lecavalier
authors.forename: R
authors.initials: R
authors.lastname: Poon
authors.forename: H
authors.initials: H
authors.lastname: Håkansson
authors.forename: U G
authors.initials: UG
authors.lastname: Ahlborg
authors.forename: V E
authors.initials: VE
authors.lastname: Valli
authors.forename: S W
authors.initials: SW
authors.lastname: Kennedy
authors.forename: A
authors.initials: A
authors.lastname: Bergman
authors.forename: R F
authors.initials: RF
authors.lastname: Seegal
authors.forename: M
authors.initials: M
authors.lastname: Feeley
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001205:Ascorbic Acid / Q000032:analysis / Q000652:urine; D019363:Cytochrome P-450 CYP1A1 / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000032:analysis; D004435:Eating / Q000187:drug effects; D005260:Female; D005502:Food; D006128:Growth / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000473:pathology; D008099:Liver / Q000187:drug effects / Q000473:pathology; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D009929:Organ Size / Q000187:drug effects; D011078:Polychlorinated Biphenyls / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013378:Substantia Nigra / Q000737:chemistry / Q000187:drug effects; D013961:Thyroid Gland / Q000187:drug effects / Q000473:pathology
chemical_list: C081766:2,4,4'-trichlorobiphenyl; D011078:Polychlorinated Biphenyls; D019363:Cytochrome P-450 CYP1A1; D001205:Ascorbic Acid; D004298:Dopamine