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Hexachlorobenzene Quickview (CASRN 118-74-1)

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 Hexachlorobenzene

File First On-Line: 09/26/1988; Last Significant Revision: 03/01/1991

Category (section)
Last Revised
Oral RfD Assessment Yes 09/26/1988
Inhalation RfC Assessment Message 03/01/1991
Carcinogenicity Assessment Yes 03/01/1991
  • 118-74-1
  • Granox
  • Pentachlorophenyl chloride
  • Perchlorobenzene
  • Hexachlorobenzene
Hexachlorobenzene Source Documents
Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Critical Effect
Point of Departure*
Liver effects NOAEL : 8 x10-2 mg/kg-day 100 8 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)

Information reviewed but value not estimated. See IRIS Summary.

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Carcinogenicity Assessment for Lifetime Exposure
  • Weight-of-Evidence Characterization
    • B2 (Probable human carcinogen - based on sufficient evidence of carcinogenicity in animals)
  • Weight-of-Evidence Narrative:
    • Hexachlorobenzene, when administered orally, has been shown to induce tumors in the liver, thyroid and kidney in three rodent species.
    • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure

Oral Slope Factor(s)
Extrapolation Method
1.6 per mg/kg-day Linearized multistage, extra risk
Drinking Water Unit Risks
4.6x10-5 per µg/L
Risk Level
E-4 (1 in 10,000) 2 µg/L
E-5 (1 in 100,000) 2x10-1 µg/L
E-6 (1 in 1,000,000) 2x10-2 µg/L

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

Inhalation Unit Risk(s)
Extrapolation Method
4.6 x10-4 per µg/m3 Linearized multistage, extra risk

Inhalation Concentrations at Specified Risk Levels

Risk Level
E-4 (1 in 10,000) 2x10-1 µg/m3
E-5 (1 in 100,000) 2x10-2 µg/m3
E-6 (1 in 1,000,000) 2x10-3 µg/m3

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