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https://ntp.niehs.nih.gov/go/9832

Toxic equivalency factor evaluation (Dioxin mixture): Target Organs and Levels of Evidence for TR-526

Toxicology and Carcinogenesis Studies of a Mixture of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) (CASRN 1746-01-6), 2,3,4,7,8-Pentachlorodibenzofuran (PeCDF) (CASRN 57117-31-4), and 3,3',4,4',5-Pentachlorobiphenyl (PCB 126) (CASRN 57465-28-8) in Female Harlan Sprague-Dawley Rats (Gavage Studies)

Chemical (Study Title)
CASRN		Peer Review DatePrimary UsesRoute/Exposure LevelsStudy Laboratory
TEF evaluation (Dioxin mixture)
TEFDIOXINMIX		02/17/2004The main sources of TCDD and PeCDF releases into the environment are from metal smelting, refining, & processing; combustion & incineration sources; chemical manufacturing & processing; biological & photochemical processes; and existing reservior sources that reflect past releases. Used as dielectric insulating fluids in transformers & capacitors and used in hydraulic fluids, plastics, & paints.Gavage
FEMALE RATS ONLY: 0, (TCDD) 3.3, 7.3, 15.2, OR 33 NG/KG; (PeCDF) 6.6, 14.5, 30.4, OR 66 NG/KG; (PCB 126) 33.3, 73.3, 153, OR 333 NG/KG; 100/DOSE		Battelle Columbus Laboratory

Levels of Evidence

Female Rats: Clear Evidence
TypeOrgan/Tissue (Lesion)
Neoplastic Lesions
  • Liver: ADENOMA 0/53 1/53 1/53 1/53 11/51 OR CHOLANGIOCARCINOMA 0/53 0/53 2/53 7/53 9/51
  • Lung: CYSTIC KERATINIZING EPITHELIOMA 0/53 0/53 0/53 2/53 20/53
May Have Been Related
  • Pancreas Acinar Cell: ADENOMA OR CARCINOMA 0/52 1/53 2/53 2/53 0/51
Non-Neoplastic Lesions
  • LIVER: HEPATOCYTE HYPERTROPHY; MULTINUCLEATED HEPATOCYTE; PIGMENTATION; INFLAMMATION; DIFFUSE FATTY CHANGE; BILE DUCT HYPERPLASIA; OVAL CELL HYPERPLASIA; NODULAR HYPERPLASIA; EOSINOPHILIC FOCUS; CHOLANGIOFIBROSIS; BILE DUCT CYST; NECROSIS; PORTAL FIBROSIS; MIXED CELL FOCUS; TOXIC HEPATOPATHY
  • LUNG: ALVEOLAR EPITHELIUM, METAPLASIA, BRONCHIOLAR; SQUAMOUS METAPLASIA
  • PANCREAS: ARTERIAL CHRONIC ACTIVE INFLAMMATION; ACINAR CYTOPLASMIC VACUOLIZATION; ACINAR ATROPHY; CHRONIC ACTIVE INFLAMMATION; DUCT DILATATION
  • ADRENAL CORTEX: HYPERPLASIA; CYSTIC DEGENERATION; ATROPHY; CYTOPLASMIC VACUOLIZATION
  • ORAL MUCOSA: GINGIVAL SQUAMOUS HYPERPLASIA
  • UTERUS: SQUAMOUS METAPLASIA
  • THYMUS: ATROPHY; SEVERITY OF ATROPHY
  • OVARY: CHRONIC ACTIVE INFLAMMATION
  • KIDNEY: NEPHROPATHY; SEVERITY OF NEPHROPATHY
  • HEART: CARDIOMYOPATHY
  • BONE MARROW: HYPERPLASIA
  • URINARY BLADDER: TRANSITIONAL EPITHELIAL HYPERPLASIA
  • MESENTERY: ARTERIAL CHRONIC ACTIVE INFLAMMATION
  • THYROID GLAND: FOLLICULAR CELL HYPERTROPHY