Hexachlorodibenzo-p-dioxin (HxCDD), mixture of 1,2,3,6,7,8-HxCDD and 1,2,3,7,8,9-HxCDD Quickview (CASRN 57653-85-7, 19408-74-3)

Status of Data for Hexachlorodibenzo-p-dioxin (HxCDD), mixture of 1,2,3,6,7,8-HxCDD and 1,2,3,7,8,9-HxCDD

File First On-Line: 03/31/1987; Last Significant Revision: 01/01/1991

Category (section)	Status	Last Revised
Oral RfD Assessment	No data
Inhalation RfC Assessment	No data
Carcinogenicity Assessment	On-line	03/01/1991

Synonyms

19408-74-3 57653-85-7 Dibenzo-p-dioxin, 1,2,3,6,7,8-hexachloro- Dibenzo-p-dioxin, 1,2,3,7,8,9-hexachloro- 1,2,3,6,7,8-Hexachlorodibenzo-p-dioxin

1,2,3,7,8,9-Hexachlorodibenzo-p-dioxin Hexachlorodibenzo-p-dioxin, mixture Hexachlorodibenzo-p-dioxin HXCDD Hexachlorodibenzo-p-dioxin, mixture (HxCDD)

Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Not Assessed under the IRIS Program.

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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
  • B2 (Probable human carcinogen - based on sufficient evidence of carcinogenicity in animals)
• Weight-of-Evidence Narrative:
  • Hepatic tumors in mice and rats by gavage
  • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

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Quantitative Estimate of Carcinogenic Risk from Oral Exposure

Oral Slope Factor(s)	Extrapolation Method
6.2 x103 per mg/kg-day	Linearized multistage procedure, extra risk

Drinking Water Unit Risks
1.8x10-1 per ug/L

Risk Level	Concentration
E-4 (1 in 10,000)	6x10-4 ug/L
E-5 (1 in 100,000)	6x10-5 ug/L
E-6 (1 in 1,000,000)	6x10-6 ug/L

• Dose-Response Data (Carcinogenicity, Oral Exposure)
  • Tumor Type: Liver tumors (adenomas and carcinomas; neoplastic nodules and hepatocellular carcinomas)
  • Test Species: Mouse/B6C3F1, male; rat/ Osborne-Mendel, female
  • Route: Oral, Gavage
  • Reference: NTP, 1980a

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Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

Inhalation Unit Risk(s)	Extrapolation Method
1.3 per ug/m3	Linearized multistage procedure, extra risk

Inhalation Concentrations at Specified Risk Levels

Risk Level	Concentration
E-4 (1 in 10,000)	8x10-5 ug/m3
E-5 (1 in 100,000)	8x10-6 ug/m3
E-6 (1 in 1,000,000)	8x10-7 ug/m3

• Dose-Response Data (Carcinogenicity, Inhalation Exposure)
  • Tumor Type: Liver tumors (adenomas and carcinomas; neoplastic nodules and hepatocellular carcinomas)
  • Test Species: Mouse/B6C3F1, male; rat/ Osborne-Mendel, female
  • Route: Oral, Gavage
  • Reference: NTP, 1980a