National Toxicology Program

National Toxicology Program
https://ntp.niehs.nih.gov/go/28749

Target Organs and Levels of Evidence for TR-543

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

Chemical (Study Title)
CASRN
Peer Review DatePrimary UsesRoute/Exposure LevelsStudy Laboratory
alpha-Methylstyrene
98-83-9
06/12/2006alpha-Methylstyrene is used in the production of acrylonitrile-butadiene-styrene resins and copolymers, which improve the impact and heat-resistant properties of polymers, specialty grades of plastics, rubber, and protective coatings. alpha-Methylstyrene also moderates polymerization rates and improves product clarity in coatings and resins. Low molecular weight liquid polymers are used as plasticizers in paints, waxes, adhesives, and plastics. Monomer for poly(alpha-methylstyrene). Associated with tobacco: reported either as a natural component of tobacco, pyrolysis product (in tobacco smoke), or additive for one or more types of tobacco products.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
TypeOrgan/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
TypeOrgan/Tissue (Lesion)
Non-Neoplastic Lesions
  • NASAL CAVITY: EPITHELIAL HYPERPLASIA; BASAL CELL EPITHELIAL DEGENERATION
Male Mice: Equivocal Evidence
TypeOrgan/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
TypeOrgan/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


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