National Toxicology Program

National Toxicology Program

Testing Status of Acetaminophen (4-hydroxyacetanilide) - 10127-H


CASRN: 103-90-2

Formula: C8-H9-N-O2

Synonyms/Common Names

  • APAP
  • 4'-Hydroxyacetanilide
  • N(4-Hydroxyphenyl)-Acetamide

Known Uses

Manufacture of azo dyes, analgesic, intermediate for pharmaceuticals (HSDB 1990); derivative of p-aminophenol. 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)

Short-Term Toxicity

  • 2 days (Gavage)  (C55801E)  Completed 
    • Rats: F344/N
    • Dose: RATS ONLY: 0, 50, 150, 1000, OR 2000 MG/KG; 6/GROUP.
  • 14-Day (Dosed-Feed)  (C55801)  Completed 
    • Rats: F344/N; Mice: B6C3F1
  • 13-Week (Dosed-Feed)  (C55801)  Completed 
    • Rats: F344/N; Mice: B6C3F1
    • Dose: R&M:0,0.08,2.50%/10 PER GROUP.

Long-Term Carcinogenicity

  • 2 years (Dosed-Feed)  (C55801)  Report Complete 
    • TR-394 (NIH Number: 90-2849)  (Peer Review Approval 11/19/1990A )
      Toxicology and Carcinogenesis Studies of Acetaminophen (CASRN 103-90-2) in F344 Rats and B6C3F1 Mice (Feed Studies)
    • Rats: F344/N; Mice: B6C3F1
    • Carcinogenesis Results
      • Male Rats No Evidence 
      • Female Rats Equivocal Evidence 
      • Male Mice No Evidence 
      • Female Mice No Evidence 
    • Dose: R&M:0,.06,.3,.6%/60 PER GROUP.

Special Studies

  • C. elegans  (S0943)  Completed 
    • C. elegans

Genetic Toxicology

  • In Vitro Cytogenetics (CA/SCE)  (034886)  Completed 
    • Sister Chromatid Exchange Positive 
    • Chromosome Aberrations Positive 
  • Salmonella  (413793)  Completed 
    • Citation: Haworth, S., Lawlor, T., Mortelmans, K., Speck, W., and Zeiger, E. Salmonella mutagenicity test results for 250 chemicals Environ. Mutagen. Vol. 5 (Suppl 1) (1983) 3-142
    •  Negative 

Organ Systems Toxicity

  • 120 day minimum Continuous Breeding (Legacy) (Dosed-Feed)  (RACB83079)  Completed 
    • Citation: Final Report - Acetaminophen: Reproduction and Fertility Assessment In CD-1 Mice When Administered in the Feed
    • Male and Female Mice: Swiss
    • Dose: 0,.31,.62,1.25,2.5,5.0%; 0,.25,.5,1%; N/A; 0,1%.
NTP is located at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.