IRIS

Heptachlor epoxide

CASRN 1024-57-3

  • IRIS Summary (PDF) (14 pp, 121 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."

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (14 pp, 121 K) last updated: 09/30/1987

System RfD (mg/kg-day) Basis PoD Composite UF Confidence
Hepatic 1.3 x 10-5 Increased liver-to-body weight ratio in both males and females LEL : 1.25 x 10-2
mg/kg-day
1000 Low

 


Reference Concentration for Inhalation Exposure (RfC) (PDF) (14 pp, 121 K)
Not assessed under the IRIS Program.

 

Cancer Assessment

Weight of Evidence for Cancer (PDF) (14 pp, 121 K) last updated: 09/30/1987

WOE Characterization Framework for WOE Characterization
B2 (Probable human carcinogen - based on sufficient evidence of carcinogenicity in animals) Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1986)
Basis:
  • Sufficient evidence exists from rodent studies in which liver carcinomas were induced in two strains of mice of both sexes and in CFN female rats. Several structurally related compounds are liver carcinogens.
  • This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (14 pp, 121 K)

Oral Slope Factor: 9.1 per mg/kg-day
Drinking Water Unit Risk: 2.6 x 10 -4 per µg/L
Extrapolation Method: Linearized multistage procedure, extra risk
Tumor site(s): Hepatic
Tumor type(s): Hepatocellular carcinomas (Davis, 1965; Velsicol, 1973)



Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (14 pp, 121 K)

Inhalation Unit Risk: 2.6 x 10 -3 per µg/m3
Extrapolation Method: Linearized multistage procedure, extra risk
Tumor site(s): Hepatic
Tumor type(s): Hepatocellular carcinomas (Davis, 1965; Velsicol, 1973)


Additional EPA toxicity information may be available by visiting the following sites, including the following:
  • Human Health Benchmarks for Pesticides (HHBP) information. The HHBP website provides toxicity reference values for a number of pesticides to help determine if there is a potential health risk when pesticides are detected in water. However, the toxicity information from the HHBP table may be useful for other purposes.
  • EPA Pesticide Program toxicity information. This link provides information from EPA's Pesticide Program on the derivation of toxicity reference values.
  • EPA's Chemistry Dashboard. This link provides information from EPA's National Center for Computational Toxicology (NCCT) on chemical structures, experimental and predicted physicochemical and toxicity data, and additional links to relevant websites and applications.
  • Contact us about pesticides

You will need Adobe Reader to view some of the files on this page. See EPA’s PDF page to learn more.