&EPA
United States
Environmental Protection
Agency
Technical Fact Sheet-
1,4-Dioxane
January 2013
TECHNICAL FACT SHEET - 1,4-DIOXANE
Introduction
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 "likely to be
carcinogenic to humans" by all
routes of exposure.
* 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 the increased
sensitivity needed for dioxane
detection. High-temperature
sample preparation techniques
improve the recovery of dioxane.
* Common treatment technologies
include advanced oxidation
processes and ex situ
bioremediation.
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 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
groundwater 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 2012; EPA 2006).
»> It is used in many products, including paint strippers, dyes, greases,
varnishes, and waxes. 1,4-Dioxane is also found as an impurity in
antifreeze and aircraft deicing fluids and in some consumer products
[deodorants, shampoos, and cosmetics] (ATSDR 2012; EPA 2006;
Mohr2001).
»> 1,4-Dioxane is a likely contaminant at many federal facilities because
of its widespread use.
»> 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 2011).
»> 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).
United States
Environmental Protection Agency
Office of Solid Waste and
Emergency Response (5106P)
1
EPA 505-F-13-001
January 2013
-------
Technical Fact Sheet - 1,4-Dioxane
What is 1,4-Dioxane? (continued)
Exhibit 1: Physical and Chemical Properties of 1,4-Dioxane
(ATSDR 2012; EPA IRIS 2010)
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 at 25 °C (atm cm3/mol)
000123-91-1
Flammable liquid with a faint, pleasant odor
88.11
Soluble in water
101. 1 "Cat 760 mm Hg
38.1
1.033
-0.27
1.23
4.80 X10'6
Notes: g/mol - grams per mole; mg/L - milligrams per liter; °C - degrees Celsius; mm Hg - millimeters of mercury;
atm m3/mol - atmosphere-cubic centimeters 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
(Mohr2001).
It is short-lived in the atmosphere, with a 6- to 10-
hour half-life (Mohr2001). Breakdown products
include aldehydes and ketones.
It may migrate rapidly in groundwater, 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 groundwater
(EPA 2006).
It is relatively resistant to biodegradation and does
not bioconcentrate in the food chain (ATSDR
2012; Mohr2001).
It has been detected in at least 31 of the 1,689
current or former sites on EPA's National Priorities
List (NPL); it may be present (but samples were
not analyzed for it) at many other sites (ATSDR
2012).
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
(DHHS2011).
Exposure may occur through inhalation of vapors,
ingestion of contaminated food and water, or
dermal contact (DHHS 2011).
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 2012).
Workers at industrial sites are at greatest risk of
repeated inhalation exposure (DHHS 2011).
Short-term exposure may result in irritation of the
eyes, and throat (ATSDR 2012).
Chronic exposure may result in dermatitis,
eczema, drying and cracking of skin, and liver and
kidney damage (ATSDR 2012; EPA OSW1996).
1,4-Dioxane is weakly genotoxic and reproductive
effects are unknown; however, a developmental
study on rats indicated that the developing fetus
may be a target of toxicity (ATSDR 2012; EPA
IRIS 2010).
The oral slope factor for carcinogenic risk is
1 x 10~1 milligrams per kilogram per day (mg/kg-
day) and the drinking water unit risk is 2.9 x 10~6
per microgram per liter (ug/L). EPA has classified
1,4-dioxane as "likely to be carcinogenic to
humans" by all routes of exposure (EPA IRIS
2010).
The chronic oral reference dose (RfD) is
0.03 mg/kg-day (EPA IRIS 2010).
The EPA's drinking water equivalent level (DWEL)
is 1 milligrams per liter (mg/L) (EPA 2012a).
-------
Technical Fact Sheet - 1,4-Dioxane
Are there any federal and state standards and guidelines for 1,4-Dioxane?
Federal and State Standards and Guidelines:
• 1,4-Dioxane may be regulated as hazardous
waste when used as a solvent stabilizer (EPA
OSW1996).
• No federal drinking water standards have been
established (DHHS 2011; ATSDR 2012).
However, a maximum contaminant level (MCL)
is not necessary to determine a cleanup level.
• A minimal risk level (MRL) of 2 parts per million
(ppm) was derived for acute-duration inhalation
exposure, 0.2 ppm for intermediate-duration
inhalation exposure, and 0.03 ppm for chronic-
duration inhalation exposure (ATSDR 2012).
• A MRL of 5 mg/kg/day was derived for acute-
duration oral exposure, 0.5 mg/kg-day for
intermediate-duration oral, and 0.1 mg/kg-day
for chronic-duration oral exposure (ATSDR
2012).
• EPA established a 1-day health advisory of 4.0
mg/L and a 10-day health advisory of 0.4 mg/L
for 1,4-dioxane based on a 10-killiogram (kg)
child (EPA 2012a).
• EPA has calculated a screening level of
6.7 x 10~1 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
2012c).
• EPA has calculated a residential soil screening
level of 4.9 milligrams per kilogram (mg/kg) and
an industrial soil screening level of 1.7 x 101
mg/kg (EPA 2012c).
• EPA has also calculated residential air
screening level of 3.2 x 10~1 micrograms per
cubic meter (ug/m3) and an industrial air
screening level of 1.6 ug/m3 (EPA 2012c).
• The soil-to-groundwater risk-based soil
screening level (SSL) is 1.4 x10"4 mg/kg (EPA
2012c).
Workplace Exposure Limits:
• The Occupational Safety and Health
Administration (OSHA) set an average 8-hour
time-weighted average (TWA) airborne
permissible exposure limit (PEL) of 360
milligrams per cubic meter (mg/m3) or 100 mg/L
(NIOSH 2007; 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 TWA
(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 2007).
Other State and Federal Standards and
Guidelines:
• 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 50 ug/L in drinking water.
Colorado has established an interim
groundwater quality cleanup standard of 0.35
ug/L (ATSDR 2012; CDPHE 2012).
• The Food and Drug Administration set 10 ppm
as the limit for 1-4-dioxane in glycerides and
polyglycerides for use in products such as
dietary supplements. FDA also surveys raw
material and products contaminated with 1,4-
dioxane (ATSDR 2012).
• 1,4-Dioxane is exempted from tolerances for
pesticide chemicals in or on raw agricultural
commodities, and it has been classified as a
toxic inert ingredient of pesticide products
(EPA 2012b).
• 1,4-Dioxane is listed as a hazardous air
pollutant under the Clean Air Act (CAA) (EPA
2012b).
• A reportable quantity of 100 pounds has been
established under CERCLA (EPA 2012b).
-------
Technical Fact Sheet - 1,4-Dioxane
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 (VOCs) (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 8261A); and
azeotrophic distillation (SW-846 Method 5031)
(EPA 2000, 2006).
It is recommended that groundwater 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 is 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).
Phytoremediation is being explored as a means to
remove the compound from shallow groundwater.
Research on hybrid poplars has demonstrated
their ability to take up and effectively degrade or
deactivate 1,4-dioxane (EPA 2001, EPA 2012b).
Microbial degradation in engineered bioreactors
has been documented under enhanced conditions
or where selected strains of bacteria capable of
degrading 1,4-dioxane are cultured
(EPA 2006, 2010).
Photocatalysis has been shown to remove 1,4-
dioxane in aqueous solutions (Purifies ES Inc.
2006; Vescovietal. 2010).
Other in-well combined treatment technologies
being assessed include air sparging; soil vapor
extraction; and dynamic subsurface groundwater
circulation (Odah et al. 2005).
Where can I find more information about 1,4-Dioxane?
Agency for Toxic Substances and Disease
Registry (ATSDR). 2012. "Toxicological Profile for
1,4-Dioxane."
www.atsdr.cdc.qov/toxprofiles/tp187.pdf
Alexeeff, G. 1998. Office of Environmental Hazard
Assessment. Memorandum: 1,4-Dioxane Action
Level.
http://oehha.ca.qov/water/pals/pdf/PAL14DIOXAN.
Edf
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). 2012. Notice of Public
Rulemaking Hearing. Regulation No. 31 and No.
41.
http://www.sos.state.co.us/CCR/Upload/NoticeOfR
ulemakinq/ProposedRuleAttach2012-00387.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.
-------
Technical Fact Sheet - 1,4-Dioxane
Where can I find more information about 1,4-Dioxane? (continued)
National Institute for Occupational Safety and
Health (NIOSH). 2007. "Pocket Guide to Chemical
Hazards." Cincinnati, Ohio. Page 120.
www.cdc.gov/niosh/docs/2005-149/pdfs/2005-
149.pdf
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.
U.S. Department of Health and Human Services
(DHHS). 2011. 1,4-Dioxane, CAS No. 123-91-1,
Report on Carcinogens, 12th 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. 2006. "Treatment Technologies for 1,4-
Dioxane: Fundamentals and Field Applications."
EPA 542-R-06-009.
www.epa.gov/tio/download/remed/542r06009.pdf
EPA. 2012a. 2012 Edition of Drinking Water
Standards and Health Advisories.
http://water.epa.gov/action/advisories/drinking/uplo
ad/dwstandards2012.pdf
EPA. 2012b. "1,4 Dioxane" www.clu-in.org/
contaminantfocus/default.focus/sec/1,4-
Dioxane/cat/Overview/
EPA. 2012c. Regional Screening Level (RSL)
Summary Table.
http://www.epa.gov/region9/superfund/prg/
EPA Integrated Risk Information System (IRIS).
2010. "1,4-Dioxane (CASRN 123-91-1)."
www.epa.gov/iris/subst/0326.htm
Vescovi T., H. Coleman, and R. Amal. 2010. "The
Effect of pH on UV-based advanced oxidation
technologies- 1,4-dioxane degradation." Journal of
Hazardous Materials. Volume 182. Pages 75 to
79.
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 email at cooke.maryt@epa.gov.
------- |