IRIS

1,4-Dioxane

CASRN 123-91-1 | DTXSID4020533

Toxicological Review (PDF) (419 pp, 3.69 M)
IRIS Summary (PDF) (32 pp, 291 K)

Key IRIS
Values
Chemical
Documents
Other EPA
Information

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (32 pp, 291 K) Last Updated: 08/11/2010

System	RfD (mg/kg-day)	Basis	PoD	Composite UF	Confidence
Hepatic, Urinary	3 x 10^-2	Liver and kidney toxicity	NOAEL : 9.6 mg/kg-day	300	Medium

Reference Concentration for Inhalation Exposure (RfC) (PDF) (32 pp, 291 K) Last Updated: 09/20/2013

System	RfC (mg/m³)	Basis	PoD	Composite UF	Confidence
Nervous, Respiratory	3 x 10^-2	Atrophy and respiratory metaplasia of the olfactory epithelium	LOAEL (HEC): 32.2 mg/m³	1000	Medium

Cancer Assessment

Weight of Evidence for Cancer (PDF) (32 pp, 291 K) Last Updated: 09/20/2013

WOE Characterization	Framework for WOE Characterization
Likely to be carcinogenic to humans	Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005)

Basis:

In accordance with the Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005), 1,4-dioxane is characterized as "likely to be carcinogenic to humans."
This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (32 pp, 291 K)

Oral Slope Factor: 1 x 10^-1 per mg/kg-day
Drinking Water Unit Risk: 2.9 x 10^-6 per µg/L
Extrapolation Method: Log-logistic model with linear extrapolation from the POD (BMDL_50HED) associated with 50% extra cancer risk.
Tumor site(s): Hepatic
Tumor type(s): Hepatocellular adenoma and carcinoma (Kano et al. 2009)

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (32 pp, 291 K)

Inhalation Unit Risk: 5 x 10^-6 per µg/m³
Extrapolation Method: Multi-tumor dose-response model with linear extrapolation from the POD (BMDL_10HED) associated with 10% extra cancer risk.
Tumor site(s): Reproductive, Other, Hepatic, Urinary, Gastrointestinal, Respiratory
Tumor type(s): Multiple (nasal, liver, kidney, peritoneal, mammary gland, and Zymbal gland) (Kasai et al. 2009)

Additional EPA toxicity information may be available by visiting the following sites:

Human Health Benchmarks for Pesticides (HHBP). This database provides human health benchmarks for pesticides that may be present in drinking water.
Office of Pesticide Programs Pesticide Chemical Search. This database provides links to health effects information and registration status for pesticides.
Chemistry Dashboard. This database provides information on chemical structures, experimental and predicted physicochemical, and toxicity data.

Sep 2013: IRIS Toxicological Review of 1,4-Dioxane (With Inhalation Update) (Final Report) (Report)

Jul 2013: IRIS Toxicological Review of 1,4-Dioxane (with Inhalation Update) (Interagency Science Discussion Draft) (Report)

Sep 2011: IRIS Toxicological Review of 1,4-Dioxane (with Inhalation Update) (External Review Draft) (Report)

May 2011: IRIS Toxicological Review of 1,4-Dioxane (Interagency Science Consultation Draft) (Report)

Aug 2010: IRIS Toxicological Review of 1,4-Dioxane (Final Report, 2010) (Report)

Apr 2009: IRIS Toxicological Review of 1,4-Dioxane (External Review Draft, 2009) (Report)

Apr 2005: IRIS Toxicological Review of 1,4-Dioxane (Interagency Science Discussion Draft) 2010 (Report)

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