National Toxicology Program

National Toxicology Program
http://ntp.niehs.nih.gov/go/ts-98839

Testing Status of alpha-Methylstyrene - 98839

 

CASRN: 98-83-9

Formula: C9-H10

Synonyms/Common Names

  • Benzene, (1-methylethenyl)- (9CI)
  • Isopropenylbenzene

Known Uses

alpha-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.

Chemical Properties

Toxicity Effects (HSDB)

Nomination Background

Short-Term Toxicity

  • 2 weeks (Inhalation)  (C88006)  Completed 
    • Rats: F344/N; Mice: B6C3F1
  • 13 weeks (Inhalation)  (C88006B)  Completed 
    • Rats: F344/N; Mice: B6C3F1/N
    • Dose: R&M: 0, 75, 150, 300, 600 OR 1000 PPM; R: 20/SEX M: 10/SEX.

Long-Term Carcinogenicity

  • 2 years (Inhalation)  (C88006B)  Report Review 
    • TR-543 (NIH Number: 08-4474)  (Peer Review Approval 06/12/2006A )
      Toxicology and Carcinogenesis Studies of α-Methylstyrene (CASRN 98-83-9) in F344/N Rats and B6C3F1 Mice (Inhalation Studies)
    • Rats: F344/N; Mice: B6C3F1/N
    • 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 (Gavage; Inhalation; Intravenous)  (S0632)  Completed 
    • Male Rats: F344/N

Genetic Toxicology

  • In Vitro Cytogenetics (CA/SCE)  (235924)  Completed 
    • Sister Chromatid Exchange Positive 
    • Chromosome Aberrations Negative 
  • 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 
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