https://ntp.niehs.nih.gov/go/28749

Target Organs and Levels of Evidence for TR-543

Toxicology and Carcinogenesis Studies of ?-Methylstyrene (CASRN 98-83-9) in F344/N Rats and B6C3F1 Mice (inhalation studies)

Chemical (Study Title)
CASRN		 Peer Review Date Route/Exposure Levels Study Laboratory
alpha-Methylstyrene
98-83-9		 06/12/2006 Inhalation
R: 0, 100, 300, OR 1000 PPM M: 0, 100, 300, OR 600 PPM; 50/SEX/SPECIES		 Battelle Northwest Laboratory

Levels of Evidence

Male Rats: Some Evidence
Type Organ/Tissue (Lesion)
Neoplastic Lesions
  • Kidney Tubular Cell: ADENOMA (STANDARD EVALUATION) 0/50 0/50 1/50 0/50 (STANDARD AND EXTENDED EVALUATIONS COMBINED) 1/50 2/50 2/50 5/50 ADENOMA OR CARCINOMA (STANDARD EVALUATION) 0/50 0/50 2/50 2/50 (STANDARD AND EXTENDED EVALUATIONS COMBINED) 1/50 2/50 3/50 7/50
May Have Been Related
  • Hematopoietic System: MONONUCLEAR CELL LEUKEMIA 26/50 32/50 29/50 38/50
Non-Neoplastic Lesions
  • KIDNEY: PAPILLA MINERALIZATION; TUBULAR HYPERPLASIA
  • NASAL CAVITY: EPITHELIAL HYPERPLASIA; BASAL CELL EPITHELIAL DEGENERATION
Female Rats: No Evidence
Type Organ/Tissue (Lesion)
Non-Neoplastic Lesions
  • NASAL CAVITY: EPITHELIAL HYPERPLASIA; BASAL CELL EPITHELIAL DEGENERATION
Male Mice: Equivocal Evidence
Type Organ/Tissue (Lesion)
May Have Been Related
  • Liver: ADENOMA OR CARCINOMA 28/50 36/50 33/50 37/50
Non-Neoplastic Lesions
  • NASAL CAVITY: EPITHELIAL METAPLASIA; BOWNAM'S GLANDS HYPERPLASIA, ATROPHY
Female Mice: Clear Evidence
Type Organ/Tissue (Lesion)
Neoplastic Lesions
  • Liver: ADENOMA 10/50 20/50 21/50 23/50 CARCINOMA 3/50 9/50 6/50 18/50 ADENOMA OR CARCINOMA 13/50 26/50 24/50 33/50
Non-Neoplastic Lesions
  • LIVER: EOSINOPHILIC FOCUS
  • NASAL CAVITY: EPITHELIAL METAPLASIA; BOWMAN'S GLANDS HYPERPLASIA
  • KIDNEY: NEPHROPATHY, SEVERITY OF NEPHROPATHY