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Metribuzin

CASRN 21087-64-9 | DTXSID6024204

  • IRIS Summary (PDF) (14 pp, 117 K)
  • Status: EPA announced in a 2004 Federal Register Notice that chemicals used as pesticides would not be re-assessed by the IRIS Program. This entry in the IRIS database is preserved at the request of EPA program and regional offices. Additional toxicological information may be found under "Other EPA Information."

On this page:

  • IRIS Toxicity
    Values
  • Other EPA
    Information

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (14 pp, 117 K) Last Updated: 01/31/1987

System RfD (mg/kg-day) Basis PoD Composite UF Confidence
Hepatic, Urinary, Other 2.5 x 10 -2 Liver and kidney effects, decreased body weight, mortality NOEL : 2.5
mg/kg-day
100 Medium

Reference Concentration for Inhalation Exposure (RfC) (PDF) (14 pp, 117 K)

Not assessed under the IRIS Program.

Cancer Assessment

Weight of Evidence for Cancer (PDF) (14 pp, 117 K) Last Updated: 12/01/1993

WOE Characterization Framework for WOE Characterization
D (Not classifiable as to human carcinogenicity) Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1986)
Basis:
  • No human data and inadequate evidence ffom animal bioassays. Metribuzin did not increase the incidence of tumors in a lifetime dietary study using CD-1 mice when compared with both concurrent and historic controls. In a 2-year feeding study in Wistar rats, no significant differences in neoplastic findings between the test and control groups were found. Short-term studies in bacteria and mammalian systems suggest that metribuzin is not mutagenic.
  • This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (14 pp, 117 K)

Not assessed under the IRIS Program.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (14 pp, 117 K)

Not assessed under the IRIS Program.

Other EPA Information

Additional EPA toxicity information may be available by visiting the following sites:
  • Human Health Benchmarks for Pesticides (HHBP). This database provides human health benchmarks for pesticides that may be present in drinking water.
  • Office of Pesticide Programs Pesticide Chemical Search. This database provides links to health effects information and registration status for pesticides.
  • Chemistry Dashboard. This database provides information on chemical structures, experimental and predicted physicochemical, and toxicity data.

Related Links

  • EPA Chemicals Dashboard - Metribuzin
  • eChemPortal - Metribuzin

Critical Effects

Hepatic
Hepatic

Urinary
Urinary

Chemical Structure

Metribuzin

Synonyms

  • Bay 61597
  • Bay dic 1468
  • Bayer 6159h
  • Bayer 6443h
  • Bayer 94337
  • Dic 1468
  • Lexone
  • Metribuzin
  • Sencor
  • Sencoral
  • Sencorer
  • Sencorex
  • as-Triazin-5(4h)-one, 4-amino-6-tert-butyl-3-(methylthio)-
  • 1,2,4-Triazin-5(4h)-one, 4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-
  • 1,2,4-Triazin-5-one, 4-amino-6-tert-butyl-3-(methylthio)-
  • 21087-64-9
  • 4-Amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4h)-one
  • 4-Amino-6-tert-butyl-3-(methylthio)-1,2,4-triazin-5-on
  • 4-Amino-6-tert-butyl-3-methylthio-as-triazin-5-one
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