National Toxicology Program

National Toxicology Program

Testing Status of Methyl parathion - 10608-X


CASRN: 298-00-0

Formula: C8-H10-N-O5-P-S

Synonyms/Common Names

  • O,O-Dimethylphosphorothoic acid-o-(4-nitrophenyl)ester (9CI)

Known Uses

Insecticide. 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

  • 13 weeks (Dosed-Feed)  (C02971)  Completed 
    • Rats: F344/N; Mice: B6C3F1
    • Dose: R: 0,10,50, M: 0,20,500 PPM/5 PER GROUP.

Long-Term Carcinogenicity

  • 2 years (Dosed-Feed)  (C02971)  Report Complete 
    • TR-157 (NIH Number: 79-1713)  (Peer Review Approval 12/15/1978A )
      Bioassay of Methyl Parathion for Possible Carcinogenicity (CASRN 298-00-0)
    • Rats: F344/N; Mice: B6C3F1
    • Carcinogenesis Results
      • Male Rats Negative 
      • Female Rats Negative 
      • Male Mice Negative 
      • Female Mice Negative 
    • Dose: R: 0,20,40, MM: 0,35,77 (AVG), FM: 0,62.5,125 PPM/50 PER GROUP.

Special Studies

  • C. elegans  (S0903)  Completed 
    • C. elegans
    • Dose: feed: (0,.002,.0032,.005,.0079,.013,.02,.032,.05,.079,.13,.2) mM 2/19/06; repro: (0,.004,.005,.0063,.0079,.01,.013,.02,.025,.032,.04) mM 02/24/06 growth: (0,1,1.6,2.5,4,6.3,10,16,25,40,63,100) uM 07/09/07.

Genetic Toxicology

  • In Vitro Cytogenetics (CA/SCE)  (433667)  Completed 
    • Sister Chromatid Exchange Positive 
    • Chromosome Aberrations Negative 
  • Salmonella  (049060)  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
    •  Positive 
NTP is located at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.