1,4-Dioxane Quickview (CASRN 123-91-1)

Status of Data for 1,4-Dioxane

File First On-Line: 08/22/1988; Last Significant Revision: 08/22/1988

Category (section)	Status	Last Revised
Oral RfD Assessment	No data
Inhalation RfC Assessment	No data
Carcinogenicity Assessment	On-line	09/01/1990
Under Re-Assessment

Synonyms

123-91-1 Diethylene oxide 1,4-Dioxane Dioxane, 1,4-

Diethylene dioxide p-Dioxane Dioxane

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:
  • Induction of nasal cavity and liver carcinomas in multiple strains of rats, liver carcinomas in mice, and gall bladder carcinomas in guinea pigs.
  • 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
1.1 x10-2 per mg/kg-day	Linearized multistage procedure, extra risk

Drinking Water Unit Risks
3.1x10-7 per µg/L

Risk Level	Concentration
E-4 (1 in 10,000)	3x102 µg/L
E-5 (1 in 100,000)	3x101 µg/L
E-6 (1 in 1,000,000)	3 µg/L

• Dose-Response Data (Carcinogenicity, Oral Exposure)
  • Tumor Type: Squamous cell carcinoma of the nasal turbinates
  • Test Species: Rat/Osborne-Mendel, male
  • Route: Oral, Drinking water
  • Reference: NCI, 1978

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Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

• Not Assessed under the IRIS Program.