National Toxicology Program

CASRN: 98-83-9

Formula: C9-H10

Synonyms/Common Names:

• BENZENE, (1-METHYLETHENYL)- (9CI)
• ISOPROPENYLBENZENE

Known Uses:

MONOMER FOR POLY(ALPHA-METHYLSTYRENE). (TDB)

Nomination Background

Short-Term Toxicity

• 2-WEEK (Inhalation)  (C88006) Completed 
  • Rats: F344/N; Mice: B6C3F1
• 13-WEEK (Inhalation)  (C88006B) Completed 
  •   (Peer Review 06/12/2006) Citation: Toxicology and Carcinogenesis Studiies of ?-Methylstyrene (CAS No. 98-83-9) in F344/N Rats and B6C3F1 Mice (inhalation studies)
  • Rats: F344/N; Mice: B6C3F1
  • Dose: R&M: 0, 75, 150, 300, 600 OR 1000 PPM; R: 20/SEX M: 10/SEX

Long-Term Carcinogenicity

• 2-YEAR (Inhalation)  (C88006B) Report Review 
  • TR-543   (Peer Review 06/12/2006)
    Toxicology and Carcinogenesis Studiies of ?-Methylstyrene (CAS No. 98-83-9) in F344/N Rats and B6C3F1 Mice (inhalation studies)
  • Rats: F344/N; Mice: B6C3F1
  • Carcinogenesis Results
  • Male Rats Some Evidence 
  • Female Rats No Evidence 
  • Male Mice Equivocal Evidence 
  • Female Mice Clear Evidence 
  • Dose: R: 0, 100, 300, OR 1000 PPM M: 0, 100, 300, OR 600 PPM; 50/SEX/SPECIES

Special Studies

• Absorption Disposition Metabolism Elimination (Intravenous; Gavage; Inhalation)  (S0632) Completed 
  • M Rats: F344; M Rats: F344; M Rats: F344
  • Dose: iv: 10 mg/kg gavage: 1000 mg/kg inhalation: 300 and 900 ppm

Genetic Toxicology

• In Vitro Cytogenetics (CA/SCE)  (235924) Completed 
  • Chromosome Aberation Negative 
  • Sister Chromatid Exchange Positive 
• Micronucleus  (A36497) Completed 
  • Mice: B6C3F1
  • Male Negative 
  • Female Positive 
• Salmonella  (338665) Completed 
  • Citation: Zeiger, E., Anderson, B., Haworth, S., Lawlor, T., and Mortelman, K. Salmonella Mutagenicity Tests V. Results from the Testing of 311 Chemicals Environ. Molec. Mutagen. Vol. 19 (Suppl 21) (1992) 2-141
  •  Negative