&EPA
United States
Environmental Protection
Agency
Technical Fact Sheet-
Hexahydro-1,3,5-trinitro-
1,3,5-triazine(RDX)
May 2012
TECHNICAL FACT SHEET - RDX
At a Glance
Introduction
Highly explosive, white crystalline
solid.
Synthetic product that does not
occur naturally in the environment.
Has been used extensively in the
manufacture of explosives and
accounts for a large part of the
explosives contamination at active
and former U.S. military
installations.
Not significantly retained by most
soils and biodegrades very slowly
under aerobic conditions. As a
result, it can easily migrate to
groundwater.
Not expected to persist for a long
period of time in surface waters
because of transformation
processes.
Classified as a Group C (possible
human) carcinogen.
Can damage the nervous system if
inhaled or ingested.
EPA plans to update its toxicity
benchmarks and health risk
assessment.
Basic types of on-site analytical
methods include colorimetric and
EXPRAY.
The primary laboratory methods
include liquid and gas
chromatography.
Potential treatment technologies
include in situ bioremediation,
granular activated carbon
treatment, composting, and
incineration.
This fact sheet, developed by the U.S. Environmental Protection Agency
(EPA) Federal Facilities Restoration and Reuse Office (FFRRO),
provides a brief summary of hexahydro-1,3,5-trinitro-1,3,5-triazine
(RDX), including its 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 and field personnel who may
address RDX contamination at cleanup sites or in drinking water
supplies.
RDX is a secondary explosive that is used extensively by the U.S.
military in manufacturing explosives. Major manufacturing of RDX began
in the U.S. in 1943 during World War II and was produced in enormous
quantities at the Government Owned-Contractor Operated (GOCO)
Holston Army Ammunition Plant (AAP) in Kingsport, Tennessee, for use
in military munitions in World War II and afterwards (AEHA 1985).
During the 1940s through the 1970s, Department of Defense (DoD)
ammunitions plants and depots demilitarized off-specification,
unserviceable, and obsolete munitions based on steam-out and melt-out
processes to recover2,4,6-trinitrotoluene (TNT) and TNT-containing
explosive fillers such as Composition B (TNT/RDX mixture). These
processes often generated significant quantities of explosives-
contaminated wastewaters. The untreated wastewater was discharged
into unlined impoundments, lagoons, ditches, and playas, which resulted
in significant levels of soil and groundwater contamination. Groundwater
contamination from RDX was first reported in the late 1980s (Spalding
and Fulton 1988).
RDX is still widely used in U.S. military munitions and is present in
munitions fillers such as Composition A, Composition B, Composition C,
and Cyclotols. With its manufacturing impurities and environmental
transformation products, this compound accounts for a large part of the
explosives contamination at active and former U.S. military installations
(EPA 1999).
What is RDX?
»> RDX, also known as Royal Demolition Explosive, cyclonite, hexogen,
and T4, is a synthetic product that does not occur naturally in the
environment and belongs to a class of compounds known as
explosive nitramines (ATSDR 2012; CRREL 2006).
»> Production of RDX in the U.S. is limited to Army ammunition plants.
Currently, it is manufactured at one facility in the U.S., the Holston
AAP GOCO facility in Kingsport, Tennessee, from 1943 to present
(AEHA 1985; ATSDR 2012).
United States
Environmental Protection Agency
Office of Solid Waste and
Emergency Response (5106P)
1
EPA 505-F-11-010
May 2012
-------
Technical Fact Sheet - RDX
What is RDX? (continued)
RDX is not produced commercially in the U.S;
however, RDX is used both in military and
commercial applications (ATSDR 2012).
RDX is one of the most powerful high explosives
available and was widely used during World War II.
It is present in more than 4,000 military items, from
large bombs to very small igniters (DoD 2011).
It is a highly explosive, white crystalline solid (in its
pure form) that is often mixed with other
explosives, oils, or waxes to make military
munitions and other products (DoD 2011).
It is commonly used as an ingredient in plastic
explosives and has been used as explosive "fill" in
most types of munitions compounds (DoD 2011;
MMR2001).
RDX can be used alone as a base charge for
detonators or mixed with other explosives such as
TNT to form Torpex, Composition B, H6, and
cyclotols, which produce a bursting charge for
aerial bombs, mines, and torpedoes (ATSDR
2012).
RDX is commonly found at hand grenade ranges,
antitank rocket ranges, bombing ranges, munitions
testing sites, explosives washout lagoons, and
open burn/open detonation (OB/OD) sites (CRREL
2006; CRREL 2007).
Exhibit 1: Physical and Chemical Properties of RDX
(ATSDR 2012; Major et al. 2007)
Property Value
CAS Number
Physical Description (physical state at room temperature)
Molecular weight (g/mol)
Water solubility (mg/L at 20°C)
Octanol-water partition coefficient (Kow)
Soil organic carbon-water coefficient (Koc)
Boiling point (°C)
Melting point (°C)
Vapor pressure at 25°C (mm Hg)
Specific gravity
Henry's Law Constant at 25°C (atm-m3/mol)
121-82-4
White Crystalline Solid
222
42
0.87
1.80
Decomposes
206
4.0 x10'9
1.816
1.96x10'11
Abbreviations: g/mol - grams per mole; mg/L - milligrams per liter; °C - degrees Celsius;
mm Hg - millimeters of mercury; atm-m3/mol - atmosphere time cubic meter per mole.
What are the environmental impacts of RDX?
RDX can be released to the environment
through spills, firing of munitions, disposal of
ordnance, open incineration and detonation of
ordnance, leaching from inadequately sealed
impoundments, and demilitarization of
munitions. The compounds can also be released
from manufacturing and munitions processing
facilities (ATSDR 2010).
RDX has been identified in at least 31 of the
1,699 hazardous waste sites that have been
proposed for inclusion on the National Priorities
List(NPL) (ATSDR 2012).
In surface soils, RDX is biodegraded very slowly
aerobically. It degrades most easily under
anaerobic conditions (EPA 1999).
Its biodegradation products include hexahydro-
1-nitroso-3,5-dinitro-1,3,5-triazine (MNX),
hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine
(DNX), and hexahydro-1,3,5-trinitroso-1,3,5-
triazine (TNX) (Army 2009; CRREL 2006).
Low soil sorption coefficient (K0c) values
indicate that RDX is not significantly retained by
most soils. However, the rate of migration
depends on the soil composition (ATSDR 2012;
EPA 2005).
RDX can migrate through the vadose zone and
contaminate underlying groundwater aquifers,
especially at source areas that have permeable
soils, a shallow groundwater table, and
abundant rainfall (CRREL 2006).
-------
Technical Fact Sheet - RDX
What are the environmental impacts of RDX? (continued)
RDX dissolves slowly in water because of the
slow rate of dissolution from the solid phase and
does not evaporate from water readily as a
result of its low vapor pressure (EPA 2005).
Phototransformation of RDX in soil is not
significant; however, it is the primary physical
mechanism that degrades RDX in aqueous
solutions. Consequently, RDX is not expected to
persist for a long period of time in surface waters
(ATSDR 2010; CRREL 2006).
Based on its low octanol-water partition
coefficient (K0w) and low experimental
bioconcentration factor, RDX has a low
bioconcentration potential in aquatic organisms
(ATSDR 2012; EPA 2005).
What are the health effects of RDX?
Potential exposure to RDX could occur by
dermal contact or inhalation exposure; however,
the most likely route of exposure at or near
hazardous waste sites is ingestion of
contaminated drinking water (MMR 2001).
EPA has assigned RDX a weight-of-evidence
carcinogenic classification of C (possible human
carcinogen) (IRIS 1993; OSHA2010).
The oral slope factor for carcinogenic risk is 0.11
milligrams per kilogram per day (mg/kg/day)
(IRIS 1993).
EPA assigned RDX an oral reference dose
(RfD) of 3 x 10~3 mg/kg/day (IRIS 1993).
RDX targets the nervous system and can cause
seizures in humans and animals when large
amounts are inhaled or ingested. Human studies
also revealed nausea and vomiting after
inhalation or oral exposure to unknown levels of
RDX (ATSDR 2012; EPA 2005).
EPA is looking to update its toxicity benchmarks
and health risk assessment for RDX in its
database of chemical risk values, the Integrated
Risk Information System (IRIS) (DoD 2011).
Limited information is available regarding
respiratory, reproductive, cardiovascular, or
dermal exposure in humans after any route or
duration of exposure to RDX (ATSDR 2012).
Are there any federal and state guidelines and health standards for RDX?
A minimal risk level (MRL) of 0.2 mg/kg/day has
been derived for acute-duration oral exposure (14
days or less), 0.1 mg/kg/day for intermediate-
duration oral exposure (15 to 364 days), and 0.1
mg/kg/day for chronic-duration oral exposure (365
days or more) to RDX (ATSDR 2012).
The EPA has established a lifetime Health
Advisory guidance level of 2 parts per billion (ppb)
for RDX in drinking water. The health advisory for a
cancer risk of 10~4 is 0.03 milligrams per liter
(mg/L)(EPA2011a).
EPA has calculated a resident soil screening level
of 5.6 milligrams per kilogram (mg/kg) and the
industrial soil screening level of 24 mg/kg (EPA
2011b).
EPA has not established an ambient air level
standard for RDX (MMR 2001).
RDX is on the EPA's Drinking Water Contaminant
Candidate List (CCL) (DoD 2010).
The Occupational Safety and Health Administration
(OSHA) set a construction industry permissible
exposure limit (PEL) of 1.5 milligrams per cubic
meter (mg/m3) of workplace air for an 8-hour
workday for a 40-hour work week (OSHA 2010).
The National Institute for Occupational Safety and
Health (NIOSH) recommended exposure limit
(REL) for RDX during an 8-hour workday, 40-hour
work week is 1.5 mg/m3 (OSHA 2010).
The American Conference of Governmental
Industrial Hygienists (ACGIH) has set a threshold
limit value (TLV) of 0.5 mg/m3 (OSHA 2010).
Numerous states have established regulations on
explosives for air quality control, solid waste
disposal, storage, manufacture, and use.
Tennessee is developing new regulatory standards
for RDX and Massachusetts has established
regulatory cleanup standards for RDX in soil and
groundwater (DoD 2011; Mass DEP 2008).
The Department of Transportation has many
regulations on the transportation of RDX (DOT
1989).
-------
Technical Fact Sheet - RDX
What detection and site characterization methods are available for RDX?
RDX, manufactured in the U.S. by the Bachmann
process at Holston AAP, contains High Melting
Explosive (HMX) as a manufacturing impurity of
RDX at a level of approximately 10 percent.
Therefore, sites potentially containing RDX or RDX
containing explosives fillers (such as Composition
B) should be analyzed for HMX as well (AEHA
1985).
Both RDX and HMX are analytes on U.S. EPA
SW-846 Methods 8330B (high-performance liquid
chromatography - ultraviolet [HPLC-UV]) and 8095
(gas chromatography-electron capture device
[GC-ECD]).
HPLC and high-resolution gas chromatography
(HRGC) have been paired with several types of
detectors, including mass spectrometry (MS),
electrochemical detection (ED), ECD, and
ultraviolet (UV) detector (ATSDR 2012).
Laboratory Method 8330 is the most widely used
analytical approach for detecting RDX in soil. The
method specifies using HPLC with a UV detector. It
has been used to detect RDX and some of its
breakdown products at levels in the low ppb range
(EPA 2006).
Another method commonly used is Method 8095,
which employs the same sample processing steps
as Method 8330, but uses HRGC with an ECD for
detection (EPA 2005).
Specific field screening methods for RDX include
SW4051 to detect RDX in soil by immunoassay
and SW8510 to detect both RDX and HMX using a
colorimetric screening procedure (Army 2009;
USAGE 2005).
Colorimetric methods generally detect broad
classes of compounds such as nitroaromatics or
nitramines. As a result, these methods are able to
detect the presence of the target analytes and also
respond to many other similar compounds.
Immunoassay methods are more compound
specific (EPA 2005).
The EXPRAY kit is a simple colorimetric screening
kit that can be used to provide qualitative tests for
soils. It is also useful for both surfaces and
unknown soils. The tools detection limit is about 20
nanograms (USAGE 2001).
Prototype biosensor methods for RDX have been
field tested and are emerging methods for
explosives analysis in water (EPA 1999).
Tested field-screening instruments for RDX include
FAST 2000, which uses antibodies and
fluorescence, and GC-IONSCAN, which uses ion
mobility spectrometry (IMS) (EPA 2000a, b).
What technologies are being used to treat RDX?
Bioreactors, bioslurry treatments, and passive
subsurface biobarriers have been proven
successful in reducing RDX concentrations
(CRREL 2006; EPA 2005; ESTCP 2010).
Composting has been proven in achieving cleanup
goals for RDX at field demonstrations (EPA 2005).
In situ chemical remediation can also be used to
treat RDX. Fenton oxidation and treatment with
iron metal (FeO) has been used to remediate RDX-
contaminated soil and water but has not been used
as stand-alone, full-scale treatment technology
(EPA 2005; NCER2010).
Other methods of treating waters contaminated
with RDX include activated carbon, UV radiation
and in situ bioremediation (ATSDR 2012).
Where can I find more information about RDX?
Agency for Toxic Substances and Disease
Registry (ATSDR). 2012. Toxicological Profile for
RDX. www.atsdr.cdc.qov/toxprofiles/tp78.pdf
Cold Regions Research and Engineering
Laboratory (CRREL). 2006. Conceptual Model for
the Transport of Energetic Residues from Surface
Soil to Groundwater by Range Activities.
ERDC/CRREL TR-06-18. www.dtic.mil/cqi-
bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&
AD=ADA472270
CRREL. 2007. Protocols for Collection of Surface
Soil Samples at Military Training and Testing
Ranges for the Characterization of Energetic
Munitions Constituents. ERDC/CRREL TR-07-10.
www.dtic.mil/cq i-bin/GetTRDoc?Location=
U2&doc=GetTRDoc.pdf&AD=ADA471045.
Environmental Security Technology Certification
Program (ESTCP). 2010. Passive Biobarrierfor
Treating Comingled Perchlorate and RDX in
Groundwater at an Active Range (ER-1028).
-------
Technical Fact Sheet - RDX
Where can I find more information about RDX? (continued)
Massachusetts Department of Environmental
Protection (Mass DEP). 2008. Massachusetts
Contingency Plan. 310 CMR 40.0000.
www.mass.gov/dep/cleanup/laws/mcptoc.htm
Massachusetts Military Reservation (MMR) 2001.
Impact Area Groundwater Study Program.
Chemical Fact Sheet - RDX. Fact Sheet 2001 -04.
http://imc2.armv.mil/wastewater/communitv/facts/rd
x.pdf
Major, M., Reddy, G., and Leach, G. 2007
Reevaluation of the toxicity and carcinogenicity of
RDX within the guidelines of modern risk
assessment. Health Effects Research Program.
2007 JSEM Conference.
Occupational Safety & Health Administration
(OSHA). 2010. Cyclonite (RDX).
www.osha.gov/dts/chemicalsampling/data/CH 231
075.html
Spalding, R. and J. Fulton. 1988. Groundwater
Munition Residues and Nitrate near Grand Island,
Nebraska, USA. Journal of Contaminant
Hydrology. Volume 2 (2), Pages 139-153.
U.S. Army. 2009. Military Munitions Response
Program. Munitions Response Remedial
Investigation/Feasibility Study Guidance.
U.S. Army Corps of Engineers (USAGE). 2001.
Field-Based Analytical Methods for Explosive
Compounds. Clu-ln Seminar. August 28, 2001.
http://www.clu-in.org/conf/tio/explosives 082801 /
prez/aug01BW.pdf
USAGE. 2005. Military Munitions Center of
Expertise. Technical Update. Munitions Constituent
(MC) Sampling.
www.hnd.usace.army.miI/oew/MMTecliUpdat.es/M
C Tech Update Final.pdf
U.S. Army Environmental Hygiene Agency
(AEHA). 1985. Water Pollution Aspects of
Explosive Manufacturing. Technical Guide No.
140.
U.S. Department of Defense (DoD). 2011.
Emerging Chemical & Material Risks.
www.denix.osd.mil/portal/page/portal/CMRMD/EC
MR
U.S. Department of Transportation (DOT). 1989.
Hazardous materials table and hazardous
materials communications regulations. Code of
Federal Regulations. 49 CFR 172.101.
U.S. Environmental Protection Agency (EPA).
1999. Office of Research and Development.
Federal Facilities Forum Issue. Field Sampling and
Selecting On-site Analytical Methods for
Explosives in Water. EPA-600-S-99-002.
EPA. 2000a. Office of Research and Development.
Barringer Instruments. GC-IONSCAN.
Environmental Technology Verification Report.
EPA/600/R-00/046.
EPA. 2000b. Office of Research and Development.
Research International, Inc. FAST 2000.
Environmental Technology Verification Report.
EPA 600-R-00-045EPA. 2005.
EPA Handbook on the Management of Munitions
Response Actions. EPA 505-B-01-001
http://nepis.epa.gov/EPA/html/DLwait.htm?url=/Ad
obe/PDF/P100304J.PDF
EPA. 2006. 8330b. Nitroaromatics, Nitramines, and
Nitrate esters by High Performance Liquid
Chromatography (HPLC) Revision 2.
EPA. 2011 a. 2011 Edition of the Drinking Water
Standards and Health Advisories.
http://water.epa.gov/action/advisories/drinking/uplo
ad/dwstandards2011 .pdf
EPA. 2011b. Regions 3,6, and 9. Regional
Screening Levels Table.
www.epa.gov/reg3hwmd/risk/human/index.htm
EPA. Integrated Risk Information System (IRIS).
1993. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)
(CASRN 121-82-4). Last Revised 1993.
www.epa.gov/IRIS/subst/0313.htm
EPA. National Center for Environmental Research
(NCER). 2010. Final Report: Fate and Transport of
Munitions Residues in Contaminated Soil.
http://cfpub.epa.gov/ncer abstracts/index.cfm/fuse
action/display.abstractDetail/abstract/5251/report/F
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.
------- |