title: Metabolism of [14C]1,2,7,8-tetrachlorodibenzo-p-dioxin in a ruminating Holstein calf.
abstract: 1. [UL-7,8-ring 14C]-1,2,7,8-tetrachlorodibenzo-p-dioxin (1278-TCDD) was administered orally to a ruminating Holstein bull calf (43.6 kg; 1.2 mg kg(-1) body weight). Urine and faeces were collected daily for 96 h, while blood was sampled at multiple time points. Tissues were removed for combustion analysis. 2. Each tissue contained < 0.65 of the dose at 96h. Tissues with highest levels of 1278-TCDD, as a percentage of administered dose, were the large and small intestine, rumen, liver and carcass. 3. Urinary excretion accounted for 10.6% of the dose, and faecal excretion accounted for 81.6% of the administered dose. The major urinary and faecal metabolites were isolated and characterized by mass spectrometry and 1H-NMR. 4. Plasma levels of 14C peaked at 24h, and decreased to near background at 96 h. Detectable plasmal levels of 1278-TCDD were observed by 2 h. 5. A hydroxylated metabolite of 1278-TCDD was detected in calf plasma, which has the potential to interfere with thyroid hormone homeostasis.
authors.affiliation: US Department of Agriculture, Agricultural Research Service, Biosciences Research Laboratory, Fargo, ND 58105, USA. hakkh@fargo.ars.usda.gov
authors.forename: H
authors.initials: H
authors.lastname: Hakk
authors.forename: G L
authors.initials: GL
authors.lastname: Larsen
authors.forename: V J
authors.initials: VJ
authors.lastname: Feil
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002417:Cattle; D002845:Chromatography; D004785:Environmental Pollutants / Q000493:pharmacokinetics*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013058:Mass Spectrometry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics*; D013723:Teratogens / Q000493:pharmacokinetics*; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; D013723:Teratogens; C445379:1,2,7,8-tetrachlorodibenzo-p-dioxin; C014980:1-amino-2,3,7,8-tetrachlorodibenzo-p-dioxin