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Endrin Quickview (CASRN 72-20-8)

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.

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Status of Data for Endrin

File First On-Line: 09/07/1988; Last Significant Revision: 10/01/1989

Category (section)
Last Revised
Oral RfD Assessment Yes 09/07/1988
Inhalation RfC Assessment No
Carcinogenicity Assessment Yes 10/01/1989
  • 72-20-8
  • Endrin
  • Mendrin, 1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4(a)5,6,7,8,8a-octahydro-endo
Endrin 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 for this information.
Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Critical Effect
Point of Departure*
Mild histological lesions in liver, occasional convulsions NOEL : 2.5 x10-2 mg/kg-day 100 3 x10-4 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
    • D (Not classifiable as to human carcinogenicity)
  • Weight-of-Evidence Narrative:
    • Oral administration of endrin did not produce carcinogenic effects in either sex of two strains of rats and three strains of mice. An NCI bioassay was suggestive of responses in male and female rats although NCI reported a no evidence conclusion. The inadequacies of several of the bioassays call into question the strength of the reported negative findings. These inadequacies and the suggestive responses in the NCI bioassay do not support a Group E classification; rather a Group D classification best reflects the equivocal data.
    • 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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