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https://ntp.niehs.nih.gov/go/479

Toxic equivalency factor evaluation (PCB Mixture; PCB 126/PCB 118): Target Organs and Levels of Evidence for TR-531

Toxicology and Carcinogenesis Studies of a Binary Mixture of 3,3',4,4',5-Pentachlorobiphenyl (PCB 126) (CASRN 57465-28-8) and 2,3',4,4',5-Pentachlorobiphenyl (PCB 118) (CASRN 31508-00-6) in Female Harlan Sprague-Dawley Rats (Gavage Studies)

Chemical (Study Title)
CASRN 		Peer Review Date Primary Uses Route/Exposure Levels Study Laboratory
TEF Evaluation (PCB Mixture; PCB 126/PCB 118)
TEFPCBMIX 		12/09/2004 One of 2 dioxin-like compounds plus mixtures being tested to determine if the TEFs for these chemicals would be predictive of rodent carcinogenicity. This mixture consists of PCB 118 (2,3',4,4',5- pentachlorobiphenyl) & PCB 126 (3,3',4,4',5- pentachlorobiphenyl) Mixtures were produced commercially before 1977 for the electric industry as dielectric insulating fluids for transformers & capacitors Gavage
Female rats only (PCB 118/PCB 126): 0, 7, 22, 72, 216, or 360 ng/kg; 50/dose 		Battelle Columbus Laboratory

Levels of Evidence

Female Rats: Clear Evidence
Type Organ/Tissue (Lesion)
Neoplastic Lesions
  • Liver: Cholangiocarcinoma 0/53 0/51 5/53 19/53 28/53 12/65 19/50 adenoma 2/53 1/51 0/53 4/53 17/53 5/65 1/50 carcinoma 0/53 0/51 0/53 0/53 1/53 0/65 0/50
  • Lung: Cystic keratinizing epithelioma 0/53 0/51 0/53 20/53 49/53 41/66 12/50
  • Oral Cavity: Gingival squamous cell carcinoma 1/53 1/51 2/53 4/53 0/53 1/66 1/50
May Have Been Related
  • Liver: Hepatocholangioma 0/53 0/51 0/53 1/53 1/53 1/65 1/50 cholangioma 0/53 0/51 0/53 1/53 0/53 0/65 0/50
Non-Neoplastic Lesions
  • Liver: hepatocyte hypertrophy; multinucleated hepatocyte; hepatocyte glandular structure; pigmentation; toxic hepatopathy; diffuse fatty change; nodular hyperplasia; centrilobular fibrosis; necrosis; oval cell hyperplasia; bile duct cyst; bile duct hyperplasia; portal fibrosis; cholangiofibrosis; eosinophilic focus; focal fatty change; centrilobular degeneration; metaplasia
  • Lung: alveolar epithelium metaplasia bronchiolar; squamous metaplasia; serosal fibrosis; keratin cyst
  • Oral cavity: gingival squamous hyperplasia
  • Thymus: atrophy; severity of atrophy
  • Thyroid gland: follicular cell hypertrophy
  • Adrenal cortex: atrophy; cytoplasmic vacuolization
  • Pancreas: acinus cytoplasmic vacuolization; chronic active artery inflammation; acinus atrophy; chronic active inflammation
  • Kidney: nephropathy; severity of nephropathy
  • Heart: cardiomyopathy; coronary artery chronic active inflammation; epicardium inflammation
  • Mandibular lymph node: hemorrhage
  • Mediastinal lymph node: hemorrhage
  • Mesenteric lymph node: hemorrhage
  • Mesentery: artery chronic active inflammation
  • Brain: hemorrhage
  • Forestomach: squamous hyperplasia
  • Spleen: lymphoid follicle atrophy
  • Nasal cavity: inflammation; respiratory epithelium hyperplasia; olfactory epithelium metaplasia