Emerging Contaminant-
1,4-Dioxane
September 2009
FACT SHEET
At a Glance
* Flammable liquid and a fire hazard.
Potentially explosive if exposed to
light or air.
* Found at many federal facilities
because of its widespread use as a
stabilizer in chlorinated solvents,
paint strippers, greases, and
waxes.
* 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.
* Classified as a Group B2 (probable
human) carcinogen.
* Contact may cause eye and skin
irritation and burns, coughing, or
shortness of breath.
* No federal drinking water standards
have been established. Many
states and EPA regions have set
guidelines and action levels.
* Modifications to existing sample
preparation 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 a lack of published health standards. A contaminant
may also be "emerging" because a new source or a new pathway to
humans has been discovered, or a new detection method or treatment
technology has been developed (DoD 2008). This fact sheet, developed
by the U.S. Environmental Protection Agency (EPA) Federal Facilities
Restoration and Reuse Office (FFRRO), provides a brief summary of the
emerging contaminant 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.
1,4-Dioxane is a probable carcinogen and has been found in ground
water at sites throughout the United States. The physical and chemical
properties and behavior of 1,4-Dioxane create challenges for its
characterization and treatment. It is highly mobile and has not been
shown to readily biodegrade in the environment. This fact sheet is
intended for use by site managers faced with addressing 1,4-Dioxane at
cleanup sites 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 investigations.
What is 1,4-Dioxane?
»> 1,4-Dioxane is 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).
»> 1,4-Dioxane is unstable at elevated temperatures and pressures and
is potentially explosive if exposed to light or air (Alexeeff 1998).
»> It is 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
processes; and as a laboratory cryoscopic solvent for molecular
mass determinations (ATSDR 2006; EPA 2006).
»> It is used in many products, including paint strippers, dyes, greases,
varnishes, and waxes. 1,4-Dioxine is also found as an impurity in
antifreeze and aircraft deicing fluids and in some consumer products
(deodorants, shampoos, and cosmetics) (ATSDR 2006; EPA 2006;
Mohr2001).
»> 1,4-Dioxine is a likely contaminant at many federal facilities because
of its widespread use.
United States
Environmental Protection Agency
Office of Solid Waste and
Emergency Response (5106P)
1
EPA 505-F-09-006
September 2009
-------
Emerging Contaminant- 1,4-Dioxane
What is 1,4-Dioxane? (continued)
Residues may be present in manufactured food
additives, 1,4-Dioxane-containing food packaging
materials, or on food crops treated with pesticides
that contain 1,4-Dioxane (such as, vine-ripened
tomatoes) (DHHS 2002).
It is also a by-product in the manufacture of
polyethylene terephthalate (PET) plastic and is
used as a purifying agent in the manufacture of
Pharmaceuticals (Mohr2001).
Exhibit 1: Physical and Chemical Properties of 1,4-Dioxane (ATSDR 2006)
1 Property 1
CAS Number
Physical Description (physical state at room temperature)
Molecular weight (g/mol)
Water solubility (mg/L at 25°C)
Boiling point (°C)
Vapor pressure at 25°C (mm Hg)
Specific gravity
Octanol-water partition coefficient (log Kow)
Organic carbon partition coefficient (log Koc)
Henry's law constant (atm m3/mol)
^H KZnQ^I ^|
000123-91-1
Flammable liquid with a faint, pleasant odor
88.10
Soluble in water
101.1°Cat760mmHg
38.1
1.033
-0.27
1.23
4.80X10'6
Notes: g/mol - gram per mole; mg/L - milligrams per liter; °C - degrees Celsius; mm Hg - millimeters of mercury;
Atm m3/mol - atmosphere-cubic meters per mole.
What are the environmental impacts of 1,4-Dioxane?
1,4-Dioxane is typically found at solvent release
sites and PET manufacturing facilities (Mohr
2001).
It is short-lived in the atmosphere, with a 6- to 10-
hour half-life (Mohr 2001). Breakdown products
include aldehydes and ketones.
It may migrate rapidly in ground water, ahead of
other contaminants, and does not volatilize rapidly
from surface water bodies (EPA 2006).
It is weakly retarded by sorption to soil particles
and may move rapidly from soil to ground water
(EPA 2006).
It is relatively resistant to biodegradation and does
not bioconcentrate in the food chain (ATSDR
2006; Mohr 2001).
It has been identified at 31 of the 1,689 sites on
EPA's National Priorities List (NPL); it may be
present (but samples were not analyzed for it) at
many other sites (ATSDR 2006).
What are the health effects of 1,4-Dioxane?
Potential exposure could occur during production
and use of 1,4-Dioxane as a stabilizer or solvent
(DHHS 2002).
Exposure may occur through inhalation of vapors,
ingestion of contaminated food and water, or
dermal contact (DHHS 2002).
Inhalation is the most common route of human
exposure; it is also 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 (DHHS 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 (ATSDR 2006; EPA
OS W1996).
Weakly genotoxic; reproductive effects are
unknown (ATSDR 2006).
Classified as a Group B2 (probable human)
carcinogen (EPA IRIS 2005; IARC 1999) and is
"reasonably anticipated to be a human
carcinogen" (DHHS 2002).
Toxicity currently being reassessed under the EPA
Integrated Risk Information System (IRIS) (EPA
IRIS 2005).
-------
Emerging Contaminant- 1,4-Dioxane
What are the health effects of 1,4-Dioxane? (continued)
The carcinogenic Oral Slope Factor is 1.1 X 10-2
milligrams/kilogram/day (mg/kg/day), with a
lifetime cancer risk of 1 in 10-4 for a drinking water
concentration of 0.3 milligrams per liter (mg/L)
(ATSDR 2006; EPA IRIS 2005).
Are there any federal and state standards and guidelines for 1,4-Dioxane?
Water Standards and Guidelines:
• 1,4-Dioxane may be regulated as hazardous
waste when used as a solvent stabilizer (EPA
OS W1996).
• No federal drinking water standards have been
established (DHHS 2002). However, a
maximum contaminant level (MCL) is not
necessary to determine a cleanup level.
• EPA Regions 3 and 6 have calculated a
screening level of 6.1 micrograms per liter (ug/L)
for 1,4-Dioxane in tap water, based on a 1 in 10"
6 lifetime excess cancer risk. This screening
level is not enforceable but provides a useful
gauge of relative toxicity (EPA 2008a and b).
• State regulators often use drinking water action
levels and health advisories to establish site
cleanup goals. Cleanup levels vary by state,
ranging from 3 to 85 ug/L in drinking water or
ground water. Only Colorado has established
an enforceable cleanup standard: facilities must
achieve a 6.1 ug/L level by March 2005 and a
3.2 ug/L level by March 2012 (CDPHE 2009).
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 mg/L
(EPA OSW 1996; OSHA 1998).
• The American Conference of Governmental
Industrial Hygienists (ACGIH) threshold limit
value (TLV) for dermal exposure is 25 mg/L, and
the recommended airborne exposure limit is 20
mg/L averaged over an 8-hour work shift
(ACGIH 1998; EPA OSW 1996).
• The National Institute for Occupational Safety
and Health (NIOSH) has set 500 mg/L as the
concentration that is immediately dangerous to
life or health (IDLH) and recommended 1 mg/L
as the airborne exposure limit (NIOSH 1997).
What detection and site characterization methods
are available for 1,4-Dioxane?
As a result of the limitations in the analytical
methods to detect 1,4-Dioxane, it has been
difficult to identify its occurrence in the
environment. Modifications to existing sample
preparation procedures may be needed to
achieve increased sensitivity for 1,4-Dioxane
detection (EPA 2006).
Conventional analytical methods produced
sensitivity levels that were about 100 times greater
for 1,4-Dioxane as compared with those for volatile
organic compounds (VOC) (Mohr2001).
High-temperature sample preparation
techniques improve the recovery of 1,4-Dioxane.
These techniques include purging at elevated
temperature (SW-846 Method 5030C);
equilibrium headspace analysis (SW-846
Method 5021); vacuum distillation (SW-846
Method 8261 A); and azeotrophic distillation
(SW-846 Method 5031) (EPA 2000, 2006).
It is recommended that ground water samples
be analyzed for 1,4-Dioxane where TCA is a
known contaminant.
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 1,4-Dioxane
(EPA 2006).
Commercially available advanced oxidation
processes (AOP) using hydrogen peroxide with
ultraviolet (UV) light or ozone have been used to
treat 1,4-Dioxane (EPA 2006; EPA OSW 1996).
Ex situ bioremediation using a fixed-film,
moving-bed biological treatment system is also
used to treat 1,4-Dioxane (EPA 2006).
-------
Emerging Contaminant- 1,4-Dioxane
What technologies are being used to treat 1,4-Dioxane? (continued)
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, 2006; Purifies ES Inc.
2006; Odah et al. 2005).
Where can I find more information about 1,4-Dioxane?
Agency for Toxic Substances and Disease
Registry (ATSDR). 2007. "Toxicological Profile
for 1,4-Dioxane." http://www.atsdr.cdc.gov/
toxprofiles/tp187.pdf.
Alexeeff, G. 1998. Office of Environmental
Hazard Assessment. Memorandum: 1,4-Dioxane
Action Level, http://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.
Colorado Department of Public Health and the
Environment (CDPHE). 2009. Notice of Public
Rulemaking Proceeding before the Colorado
Water Quality Control Commissions.
http://www.cdphe.state.co.us/op/wqcc/MeetingsandN
otices/hearingnotices/Rulemaking/WrittenComment/
31 41WCRMnotice.pdf.
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. Volume 71. Pages
589 to 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. Volume 15 (3), Pages 51 to 64.
Purifies ES Inc. 2006. Case History: 1,4 Dioxane
Remediation 1. www.purifics.com/solutions/
pdf/Case%20Historv%20-%201.4-
Dioxane%201 .pdf.
U.S. Department of Defense (DoD). 2008.
Emerging Contaminants. Web site accessed
September 8. https://www.denix.osd.mil/
portal/page/portal/denix/environment/MERIT.
U.S. Department of Health and Human Services
(DHHS). 2002. 1,4-Dioxane, CAS No. 123-91-1,
Report on Carcinogens, 10th Edition.
U.S. Environmental Protection Agency (EPA)
Office of Solid Waste (OSW). 1996. Solvents
Study. 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. http://www.epa.gov/tio/
download/remed/542r06009.pdf.
EPA. 2008a. Region 6. Human Health Medium-
Specific Screening Level. March, www.epa.gov/
region6/6pd/rcra c/pd-n/screen.htm.
EPA. 2008b. Region 3. Human Health Risk
Assessment - Risk-Based Concentrations Table.
September.
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.
------- |