Emerging Contaminant -1,4 Dioxane
April 2008
FACT SHEET
At a Glance
* Flammable liquid and a fire hazard.
Potentially explosive if exposed to
light or air.
* Classified as a Group B2 (probable
human) carcinogen.
* Should be handled as a carcinogen
- with extreme caution.
* Contact may cause eye and skin
irritation and burns, coughing, or
shortness of breath.
* Can migrate considerably ahead of
other ground water contaminants.
* Short-lived in the atmosphere, may
leach readily from soil to ground
water, migrates rapidly in ground
water, and is relatively resistant to
biodegradation in the subsurface.
* May be regulated as hazardous
waste when used as a solvent
stabilizer.
* No federal drinking water standards
have been established. Many
states and EPA regions have set
guidelines and action levels.
* Modifications to existing sample
preparative procedures may be
needed to achieve increased
sensitivity for dioxane detection.
High temperature sample
preparation techniques improve the
recovery of dioxane.
* Common treatment technologies
include advanced oxidation
processes and ex situ
bioremediation.
Introduction
An "emerging contaminant" is a chemical or material that is
characterized by a perceived, potential or real threat to human health or
the environment or lack of published health standards. A contaminant
may also be "emerging" because of the discovery of a new source or a
new pathway to humans, or a new detection method or treatment
technology has been developed (DoD 2006). This fact sheet, developed
by the U.S. Environmental Protection Agency (EPA) Federal Facilities
Restoration and Reuse Office (FFRRO), provides a brief summary for
1,4-dioxane, including physical and chemical properties; environmental
and health impacts; existing federal and state guidelines; detection and
treatment methods; and additional sources of information. This fact
sheet is intended for use by site managers faced with addressing 1,4-
dioxane at a cleanup site or in drinking water supplies and for those in a
position to consider whether 1,4-dioxane should be added to the
analytical suite for site investigation.
What is 1,4-dioxane?
* A synthetic industrial chemical that is completely miscible in water
(EPA 2006).
* Synonyms include dioxane, dioxan, p-dioxane, diethylene dioxide,
diethylene oxide, diethylene ether, and glycol ethylene ether
(Mohr2001).
* Unstable at elevated temperatures and pressures. Potentially
explosive if exposed to light or air (Alexeeff 1998).
Exhibit 1: Physical and Chemical Properties of 1,4-Dioxane
(CHEMFATE 2003)
1
r
Property
CAS Number
Physical Description (room temperature)
Molecular weight (g/mol)
Water solubility (mg/L)
Boiling point (C)
Vapor pressure at 25°C (mm Hg)
Specific gravity
Log octanol-water partition coefficient (log K0
Log organic carbon partition coefficient (log Koc)
Henry's law constant (atm m /mol)
000123-91-1
Flammable liquid with a
faint, pleasant odor
88.10
Soluble in water
101.1 "Cat 760 mm Hg
38.0
1.033
-0.27
1.23
4.88X10"
Notes:
g/mol - gram per mole; mg/L - milligrams per liter; °C - degrees Celsius;
mm Hg - millimeters of mercury.
United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5106P)
1
EPA 505-F-07-004
April 2008
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What is 1,4-dioxane? (continued)
Used as a stabilizer for chlorinated solvents
such as 1,1,1-trichloroethane (TCA); a solvent
for impregnating cellulose acetate membrane
filters; a wetting and dispersing agent in textile
process; and as a laboratory cryoscopic solvent
for molecular mass determinations (ATSDR
2006; EPA 2006).
Used in many products, including paint strippers,
dyes, greases, varnishes, and waxes. Found as
an impurity in antifreeze and aircraft deicing
fluids and in some consumer products
(deodorants, shampoos, and cosmetics)
(Mohr 2001; ATSDR 2006; EPA 2006).
Also a by-product in the manufacture of
polyethylene terephthalate (PET) plastic and
used as a purifying agent in the manufacture of
Pharmaceuticals (Mohr 2001).
Residues may be present in manufactured food
additives, dioxane-containing food packaging
materials, or on food crops treated with
pesticides that contain dioxane, such as vine-
ripened tomatoes (USDHHS 2002).
Likely contaminant at many federal facilities
because of its widespread use.
Potential exposure could occur during its
production and use as a stabilizer or solvent
(USDHHS 2002).
What are the environmental impacts of 1,4-dioxane?
Typically found at solvent release sites and PET
manufacturing facilities (Mohr 2001).
Identified at 27 of the 1,662 sites on EPA's
National Priorities List (NPL); potentially present
but not analyzed for at many others (ATSDR
2006).
Short-lived in the atmosphere, with a six to ten
hour half life (Mohr 2001). Breakdown products
include aldehydes and ketones.
May migrate rapidly in ground water, ahead of
other contaminants, and does not volatilize
rapidly from surface water bodies (EPA 2006).
Weakly retarded by sorption to soil particles and
may move rapidly from soil to ground water
(EPA 2006).
Relatively resistant to biodegradation
(Mohr 2001; ATSDR 2006).
Does not bioconcentrate in the food chain
(Mohr 2001; ATSDR 2006).
What are the health effects of 1,4-dioxane?
Classified as a Group B2 (probable human)
carcinogen (EPA IRIS 2005; IARC 1999).
"Reasonably anticipated to be a human
carcinogen" (USDHHS 2002).
Carcinogenic Oral Slope Factor is 1.1E-2
milligrams/kilogram/day (mg/kg/day), with a
lifetime cancer risk of 1 in 10~4 for a drinking
water concentration of 0.3 parts per million
(ppm) (EPA IRIS 2005; ATSDR 2006).
Toxicity currently being reassessed under the
EPA Integrated Risk Information System (IRIS)
(EPA IRIS 2005).
Exposure may occur through inhalation of
vapors, ingestion of contaminated food and
water, or dermal contact (USDHHS 2002).
Inhalation is the most common route of human
exposure - readily adsorbed through the lungs,
skin, and gastrointestinal tract. Distribution is
rapid and uniform in lung, liver, kidney, spleen,
colon, and skeletal muscle tissue (ATSDR
2006).
Workers at industrial sites are at greatest risk of
repeated inhalation exposure (USDHHS 2002).
Exposure may result in irritation of the eyes,
nose, throat, and lungs, possible drowsiness,
vertigo, headache, and anorexia (ATSDR 2006).
Chronic exposure may result in dermatitis,
eczema, drying and cracking of skin, and
possible liver and kidney damage (EPA 1996;
ATSDR 2006).
Weakly genotoxic; reproductive effects are
unknown (ATSDR 2006).
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Are there any existing federal and state standards and guidelines for 1,4-dioxane?
Water Standards and Guidelines:
• May be regulated as hazardous waste when
used as a solvent stabilizer (EPA 1996).
• No federal drinking water standards
(USDHHS 2002). However, Maximum
Contaminant Level (MCL) is not necessary
to establish a cleanup level.
• EPA Regions 3 and 6 have calculated a
screening level of 6.1 parts per billion (ppb)
fordioxane in tap water, based on a 1 in 10~6
lifetime excess cancer risk. These
standards are not enforceable but provide a
useful gauge of relative toxicity (EPA 2007a
and b).
• State regulators often use drinking water
action levels and health advisories to
establish appropriate site cleanup goals
(EPA 2006).
• Cleanup guidelines vary by state, ranging
from 3 to 85 ppb in drinking water or ground
water. Only one state (Colorado) has
established an enforceable standard -
facilities need to have met a 6.1 ppb limit by
March 2005 and a 3.2 ppb limit by March
2010 (EPA 2006).
Workplace Exposure Limits:
• The Occupational Safety and Health
Administration (OSHA) airborne permissible
exposure limit (PEL) is 360 milligrams per
cubic meter (mg/m3) or 100 ppm
(EPA 1996; OSHA 1998).
• The American Conference of Governmental
Industrial Hygienists (ACGIH) threshold limit
value (TLV) for dermal exposure is 25 ppm,
and the recommended airborne exposure
limit is 20 ppm averaged over an 8-hour
work shift (EPA 1996; ACGIH 1998).
• The National Institute for Occupational
Safety and Health (NIOSH) has set 500 ppm
as the concentration that is immediately
dangerous to life or health (IDLH) and
recommended 1 ppm as the airborne
exposure limit (NIOSH 1997).
What detection and site characterization methods are available for 1,4-dioxane?
It is recommended that dioxane be analyzed for
in ground water samples where TCA is a known
contaminant.
As a result of the limitations in the analytical
methods used fordioxane, it has been difficult to
evaluate its occurrence in the environment
(EPA 2006).
Conventional analytical methods produced
sensitivity levels that were about 100 times
greater for dioxane as compared with those for
volatile organic compounds (VOC) (Mohr2001).
Modifications to existing sample preparative
procedures may be needed to achieve
increased sensitivity fordioxane detection (EPA
2006).
High-temperature sample preparation
techniques improve the recovery of dioxane.
These include purging at elevated temperature
(SW-846 Method 5030C); equilibrium
headspace analysis (SW-846 Method 5021);
vacuum distillation (SW-846 Method 8261A);
and azeotrophic distillation (SW-846 Method
5031) (EPA 2000; EPA 2006).
What technologies are being used to treat 1,4-dioxane?
Pump-and-treat (P&T) remediation is potentially
applicable when the ex situ treatment is tailored
for the unique properties of dioxane
(EPA 2006).
Common treatment technologies include:
• Commercially available advanced oxidation
processes (AOP) using hydrogen peroxide
with ultraviolet (UV) light or ozone
(EPA 1996; EPA 2006).
• Ex situ bioremediation using a fixed-film,
moving-bed biological treatment system
(EPA 2006).
Technologies being assessed include:
phytoremediation using hybrid poplar trees;
photocatalysis and in-well combined treatment
technologies that involve in situ air stripping; air
sparging; soil vapor extraction; enhanced
bioremediation; and dynamic subsurface ground
water circulation (EPA 2001; EPA 2006; Powell
2006; Odah and others 2005).
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Where can I find more information about 1,4-dioxane?
Agency for Toxic Substances and Disease
Registry (ATSDR). 2006. "lexicological Profile
for 1,4-Dioxane."
Alexeeff, G. 1998. Office of Environmental
Hazard Assessment. Memorandum: 1,4-
Dioxane Action Level.
www.oehha.ca.gov/water/pals/pdf/
PAL14DIOXAN.pdf.
American Conference of Governmental
Industrial Hygienists (ACGIH). 1998. Threshold
Limit Values (TLVs) for Chemical Substances
and Physical Agents Biological Exposure Indices
for 1998. Cincinnati, Ohio.
CHEMFATE. 2003. Database Listing for 1,4-
Dioxane. www.syrres.com/esc/chemfate.htm.
International Agency for Research on Cancer
(IARC). 1999. "Re-Evaluation of Some Organic
Chemicals, Hydrazine and Hydrogen Peroxide."
Monographs on the Evaluation of Carcinogenic
Risk of Chemicals to Man. Vol. 71. Pages 589-
602.
Mohr, T.K.G. 2001. "Solvent Stabilizers White
Paper." Prepublication Copy. Santa Clara
Valley Water District of California. San Jose,
California.
National Institute for Occupational Safety and
Health (NIOSH). 1997. "Pocket Guide to
Chemical Hazards." Cincinnati, Ohio. Page
120.
Occupational Safety and Health Administration
(OSHA). 1998. "Occupational Safety and
Health Standards, Toxic and Hazardous
Substances." 29 Code of Federal Regulations
1910.1000.
Odah, M.M., R. Powell, and D.J. Riddle. 2005.
"ART in-well technology proves effective in
treating 1,4-dioxane contamination."
Remediation Journal. Vol. 15 (3). Pages 51-
64.
Powell, T. 2006. Photo-Cat Case Histories &
Technology Briefing, www.purifics.com.
U.S. Department of Defense (DoD). 2006.
Emerging Contaminants.
www.denix.osd.mil/denix/Public/Library/MERIT/
merit.html.
U.S. Department of Health and Human Services
(USDHHS). 2002. 1,4-Dioxane, CAS No. 123-
91-1, Report on Carcinogens, 10th Edition.
U.S. Environmental Protection Agency (EPA).
1996. Solvents Study. Office of Solid Waste.
EPA 530-R-96-017, 52 pages.
EPA. 2000. "Method 8261. Volatile Organic
Compounds by Vacuum Distillation in
Combination with Gas Chromatography/Mass
Spectroscopy (VD/GC/MS)." In: SW-846 Draft
Update IVB.
EPA. 2001. "Brownfields Technology Primer:
Selecting and Using Phytoremediation for Site
Cleanup." EPA 542-R-01-006.
EPA Integrated Risk Information System (IRIS).
2005. "1,4-Dioxane (CASRN 123-91-1)."
EPA. 2006. "Treatment Technologies for 1,4-
Dioxane: Fundamentals and Field Applications."
EPA 542-R-06-009.
EPA. 2007a. Region 3. Human Health Risk
Assessment - Risk-Based Concentrations
Table, www.epa.gov/region3.
EPA. 2007b. Region 6. Human Health
Medium-Specific Screening Levels.
www.epa.gov/region6.
Additional information on 1,4-dioxane can be found at www.cluin.org/dioxane
Contact Information
If you have any questions or comments on this fact sheet, please contact: Mary Cooke, FFRRO, by phone at
(703) 603-8712 or by e-mail at cooke.maryt@epa.gov.
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