IRIS

Heptachlor

CASRN 76-44-8

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (14 pp, 122 K) last updated: 09/30/1987

System RfD (mg/kg-day) Basis PoD Composite UF Confidence
Hepatic 5 x 10-4 Liver weight increases in males NOEL : 1.5 x 10-1
mg/kg-day
300 Low

 


Reference Concentration for Inhalation Exposure (RfC) (PDF) (14 pp, 122 K)
Not assessed under the IRIS Program.

 

Cancer Assessment

Weight of Evidence for Cancer (PDF) (14 pp, 122 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 (US EPA, 1986)
Basis:
  • Inadequate human data, but sufficient evidence exist from studies in which benign and malignant liver tumors were induced in three strains of mice of both sexes. 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, 122 K)

Oral Slope Factor: 4.5 per mg/kg-day
Drinking Water Unit Risk: 1.3 x10 -4 per µg/L
Extrapolation Method: Linearized multistage procedure, extra risk
Tumor site(s): Hepatic
Tumor type(s): Hepatocellular carcinomas (Davis, 1965; NCI, 1977)



Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (14 pp, 122 K)

Inhalation Unit Risk: 1.3 x10 -3 per µg/m3
Extrapolation Method: Linearized multistage procedure, extra risk
Tumor site(s): Hepatic
Tumor type(s): Hepatocellular carcinomas (Davis, 1965; NCI, 1977)


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