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Methidathion Quickview (CASRN 950-37-8)

Health assessment information on a chemical substance is included in IRIS only after a comprehensive review of toxicity data by U.S. EPA health scientists from several Program Offices, Regional Offices, and the Office of Research and Development.

Disclaimer: This QuickView represents a snapshot of key information. We suggest that you read the IRIS Summary to put this information into complete context.

For definitions of terms in the IRIS Web site, refer to the IRIS Glossary.

Status of Data for Methidathion

File First On-Line: 08/22/1988; Last Significant Revision: 05/01/1989

Category (section)
Status
Last Revised
Oral RfD Assessment On-line 08/01/1990
Inhalation RfC Assessment No data
Carcinogenicity Assessment On-line 10/01/1993
Synonyms
  • 950-37-8
  • Ciba-Geigy GS 13005
  • DMTP
  • ENT 27193
  • Fisons nc 2964
  • Geigy 13005
  • GS 13005
  • Methidathion
  • Methidathion 50s
  • OMS 844
  • o,o-Dimethyl-s-(2-methoxy-1,3,4-thiadiazol-5(4h)-onyl-(4)-methyl) phosphorodithioate
  • more...
Methidathion Source Documents
Revision History
Date Section Description
04/01/1997 III., IV., V. Drinking Water Health Advisories, EPA Regulatory Actions, and Supplementary Data were removed from IRIS on or before April 1997. IRIS users were directed to the appropriate EPA Program Offices.
Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Critical Effect
Point of Departure*
UF RfD
Liver toxicity NOEL : 1 x10-1 mg/kg-day 100 1 x10-3 mg/kg-day

* The Point of Departure listed serves as a basis from which the Oral RfD was derived. See Discussion of Conversion Factors and Assumptions for more details.

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Reference Concentration for Chronic Inhalation Exposure (RfC)

Not Assessed under the IRIS Program.

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Carcinogenicity Assessment for Lifetime Exposure
  • Weight-of-Evidence Characterization
    • C (Possible human carcinogen)
  • Weight-of-Evidence Narrative:
    • Increased incidence of liver adenomas, carcinomas, and combined adenomas and carcinomas in male mice. There was no shortening of time to tumor. Short-term tests and structure/activity study were not supportive of a higher classification.
    • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure

  • Not Assessed under the IRIS Program.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

  • Not Assessed under the IRIS Program.

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