Emerging  Contaminant  - Perchlorate
                                                                                April 2008
                                                                                           FACT SHEET
At a Glance
    White crystalline solid or colorless

    Explosive at high temperatures.

    Short-term exposure to high doses
    may cause eye and skin irritation,
    coughing, nausea, vomiting, and

    Highly soluble in water; migrates
    quickly from soil to ground water.

    Primary pathways for human
    exposure to perchlorate are
    ingestion of food and contaminated
    drinking water.

    Sampling at current federal sites as
    well as Formerly Used Defense
    Sites has detected perchlorate
    primarily in association with sites
    historically involved in the
    manufacture, maintenance, use,
    and disposal of ammunition and
    rocket fuel.

    Perchlorate is both naturally
    occurring and man-made.

    Health-based goals or drinking
    water standards have been
    developed by various states.

    The presence of high amounts of
    other anions, such as chloride,
    sulfate, or carbonate, may interfere
    with the analysis of perchlorate.

    Common treatment technologies
    include ion exchange, bioreactors,
    and in situ bioremediation.
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 a
new source or a new pathway to humans has been discovered or a new detection
method or treatment technology has been developed. This fact sheet, developed
by the U.S. Environmental Protection Agency (EPA) Federal Facilities
Restoration and Reuse Office (FFRRO), provides a brief summary for
perchlorate, including physical and chemical properties; environmental and
health impacts; existing federal and state guidelines;  detection and treatment
methods; and additional sources of information.

Perchlorate is a persistent contaminant of concern that has presented a number of
issues to the government, the private sector, and other organizations and
interested parties.  These issues include health effects and risk, regulatory
standards and cleanup levels, degradation processes,  and treatment technologies
(EPA FFRRO 2005). This fact sheet provides basic information on perchlorate
to site managers and other field personnel who are addressing perchlorate
contamination at a cleanup site or in a drinking water supply.

What is perchlorate?	

*> Perchlorate is a naturally occurring and man-made anion (C1O4~) that
   consists of one chlorine atom bonded to four oxygen atoms (EPA FFRRO
   2005; ITRC 2005).

*> Perchlorate is commonly used as an oxidizer in solid propellants, munitions,
   fireworks, airbag initiators for vehicles, matches, and signal flares (ITRC
   2005; EPA FFRRO 2005).  It is also found in some disinfectants and some
   herbicides (ITRC 2005).
*> Perchlorate is found as a natural impurity in nitrate salts from Chile, which
   are imported used to produce nitrate fertilizers and a number of other
   products (ITRC 2005; EPA FFRRO 2005).

*> Perchlorate may occur naturally, particularly in arid regions such as the
   southwestern United States. (Rao 2007).

*> Manufactured forms of perchlorate include perchloric acid and salts such as
   ammonium perchlorate, sodium perchlorate, and potassium perchlorate
   (EPA FFRRO 2005; ITRC 2005).

*> Of the domestically produced (high grade) perchlorate, 90 percent of
   perchlorate is estimated to be used in the defense and aerospace industries in
   the form of ammonium perchlorate  (ITRC 2005; GAO 2005).
*> Perchlorate has been used by the U. S. Department  of Defense (DoD) as an
   oxidizer in munitions and missiles since the 1940s  (Mendiratta, et al 1996).
   United States
   Environmental Protection
        Solid Waste and
        Emergency Response
EPA 505-F-07-003
       April 2008

What are the environmental impacts of perchlorate?
    Recent surveys have detected perchlorate in food
    crops and milk (FDA, 2008).
    Perchlorate is highly soluble, relatively stable and
    mobile in water. As a result, perchlorate plumes in
    ground water can be extensive.  For example, the
    perchlorate plume at a former safety flare site (the
    Olin Flare Facility) in Morgan Hill, California,
    extends more than 9 miles (EPA FFRRO 2007).
    Perchlorate compounds and the perchlorate anion do
    not volatilize from water to air (ITRC 2005, EPA
    IRIS 2005).
Sampling at current and Formerly Used Defense Sites
has detected perchlorate primarily in association with
sites historically involved in the manufacture,
maintenance, use, and disposal of ammunition and
rocket fuel (EPA FFRRO 2007).
Perchlorate has been detected at nearly 270 sites;
more than 45 of these sites are on the National
Priorities List (EPA FFRRO 2007).
                     Exhibit 1: Physical and Chemical Properties of Perchlorate Compounds
                                  (EPA FFRRO 2005; NIOSH 2007; ITRC 2005)
CAS Numbers
Physical Description
(Physical state at
room temperature)
Molecular weight
Water solubility (g/L
at 25°C)
Melting / Boiling
point (°C)
Vapor pressure at
Specific gravity
partition coefficient
(log Kow)
Ammonium Potassium
Perchlorate Sodium Perchlorate Perchlorate Perchloric Acid
White orthorhombic
Melting Point: 65.6 to
Not available
White orthorhombic
deliquescent crystal
Melting Point: 482
Not available
orthorhombic crystal
or white
Melting Point: 400
Not available
Colorless liquid
Miscible in cold water
Melting Point: -112
Boiling Point: 19
g/mol - gram per mole; g/L - grams per liter; mg/L - milligrams per liter; °C - degrees Celsius; mm Hg - millimeters of mercury.

What are the health effects of perchlorate?
    The chronic oral reference dose (RfD) is 0.0007
    milligrams per kilogram body weight per day (Note:
    A reference dose is an estimate (with uncertainty
    spanning perhaps an order of magnitude) of a daily
    oral exposure to the human population (including
    sensitive subgroups) that is likely to be without
    appreciable risk of deleterious  effects over a
    lifetime.) (EPA IRIS 2005).
    Short-term exposure to high doses may cause eye and
    skin irritation, cough, nausea, vomiting, and diarrhea
    (NIOSH 2007).
    Primary pathways for human exposure to perchlorate
    are ingestion of food and contaminated drinking
    water (EPA FFRRO, 2007).
                                                          At high enough exposures, perchlorate can interfere
                                                          with iodide uptake into the thyroid gland, disrupting
                                                          the functions of the thyroid and potentially leading to
                                                          a reduction in the production of thyroid hormones.
                                                          Thyroid hormones play an important role in
                                                          regulating metabolism. In fetuses, infants, and young
                                                          children, thyroid hormones are critical for normal
                                                          growth and development (NAS 2005).
                                                          Because of its ability to inhibit thyroid iodide uptake,
                                                          potassium perchlorate was historically used to treat
                                                          hyperthyroidism and Grave's Disease (NAS 2005)
                                                          Based on studies conducted on rodents, it was found
                                                          that perchlorate at levels below those required to alter
                                                          thyroid hormone equilibrium is unlikely to cause
                                                          thyroid cancer in human beings (EPA IRIS 2005).
Are there any existing federal and state guidelines and health standards for
    The RfD established by EPA equates to a Drinking
    Water Equivalent Level (DWEL) of 24.5 micrograms
    per liter (ug/L), or parts per billion (ppb) (EPA
    FFRRO 2005). A DWEL is a lifetime exposure
    concentration protective of adverse, non-cancer
    health effects that assumes all of the exposure to a
    contaminant is from drinking water.  (Note: The
    DWEL is calculated based on a 70 kg body weight
    and a drinking water consumption of 2 liters/day.)

    Massachusetts (2 ug/L) and California (6 ug/L) have
    established enforceable standards for perchlorate in
    drinking water (Massachusetts DEP 2006, California
    DHS 2007).
                                                          The Office of Solid Waste and Emergency Response
                                                          (OSWER) has established a preliminary remediation
                                                          goal (PRO) at NPL sites of 24.5 ug/L.  PRGs are
                                                          developed based on readily available information and
                                                          are modified, as necessary, before final cleanup goals
                                                          are established, based on information that becomes
                                                          available during the remedial investigation/feasibility
                                                          study. (EPA FFRRO 2007)
                                                          Certain states have developed advisory levels or
                                                          health-based goals ranging from 4 to 51 ug/L (ITRC
What detection and site characterization methods are available for perchlorate?
                                                              •    EPA Method 3 31.0—Liquid
                                                                  Chromatography/Electrospray lonization/ Mass
                                                                  Spectrometry (EPA OGWDW 2007).
                                                              •    EPA Method 6850—High Performance Liquid
                                                                  Chromatography/Electrospray lonization/Mass
                                                                  Spectrometry (EPA 2007).
                                                              •    EPA Method 6860—Ion Chromatography/
                                                                  Electrospray lonization/Mass Spectrometry
                                                                  (EPA 2007).
The following methods can be used to analyze for
perchlorate in drinking water, in addition to ground
water, surface water, and irrigation water:
•   EPA Method 314.0—Ion Chromatography (EPA
    OGWDW 2007).
•   EPA Method 314.1—Inline Column
    Concentration/Matrix Elimination Ion
    Chromatography with Suppressed Conductivity
    Detection (EPA OGWDW 2007).
•   EPA Method 332.0—Ion Chromatography with
    Suppressed Conductivity and Electrospray
    lonization Mass Spectrometry  (EPA FFRRO
                                                                  The presence of high amounts of other anions,
                                                                  such as chloride, sulfate, or carbonate may
                                                                  interfere with the analysis of perchlorate (EPA
                                                                  Researchers have demonstrated the ability to
                                                                  distinguish man-made and natural sources of
                                                                  perchlorate using chlorine and oxygen stable
                                                                  isotope analysis (Bohlke, et al. 2005).

What technologies are being used to treat perchlorate?
    Ex Situ Treatment:
    •   Ion exchange using perchlorate-selective or
        nitrite-specific resins (EPA FFRRO 2005;
        GWRTAC 2001; Boodoo 2003).
    •   Bioremediation using packed-bed or fluidized-
        bed bioreactors (EPA FFRRO 2005; GWRTAC
        200 l;Hatzinger 2005).
    •   Liquid phase carbon adsorption using granular
        activated carbon (GAC) to remove low levels of
        perchlorate; pretreatment may be necessary to
        make it suitable for perchlorate removal (EPA
        FFRRO 2005; ITRC 2005; GWRTAC 2001).
•   Membrane technologies (electrodialysis and
    reverse osmosis) (EPA FFRRO 2005; ITRC
    2005; GWRTAC 2001).
In Situ Treatment:
•   Bioremediation using perchlorate-selective
    microbes (EPA FFRRO 2005; ITRC 2005;
    GWRTAC 2001).
•   Permeable reactive barrier (EPA FFRRO 2005;
    ITRC 2005; GWRTAC 2001).
•   Phytoremediation may also be used, although the
    mechanism of phytoremediation of perchlorate is
    yet to be established (EPA FFRRO 2005;
    GWRTAC 2001).
Where can I find more information about perchlorate?
    Boodoo, F. 2003.  POU/POE Removal of
    Perchlorate. Water Conditioning & Purification.
    Pages 1-4.
    Bohlke, J. K., N.C. Sturchio, B. Gu, J. Horita, G.M.
    Brown, W.A. Jackson, J. Batista, and P.B. Hatzinger.
    2005. Perchlorate isotope forensics. Anal. Chem.,
    77, 7838-7842.
    California DHS (Department of Health Services)
    2006 Press Release.
    EPA (Environmental Protection Agency). 1999.
    Method 314.0 Determination of Perchlorate in
    Drinking Water Using Ion Chromatography.
    EPA.  2007. New Test Methods On-line.
    EPA FFRRO (EPA Federal Facilities Restoration and
    Reuse Office). 2005. Perchlorate  Treatment
    Technology Update - Federal Facilities Forum Issue
    Paper. EPA 542-R-05-015.
    EPA FFRRO.  2007.
    EPA IRIS (Integrated Risk Information System).
    2005. www.epa.gov/iris/subst/1007.htm.
    EPA OGWDW (Office of Groundwater and Drinking
    Water).  2007. www.epa.gov/safewater/
    FDA (Food and Drug Administration) 2008. U.S.
    Food and Drug Administration's Total Diet Study:
    Dietary intake of Perchlorate and Iodine.
GAO (U.S. Government Accountability Office).
2005. Perchlorate: A System to Track Sampling and
Cleanup Results is Needed. GAO-05-462.
GWRTAC (Ground Water Remediation
Technologies Analysis Center). 2001. Technology
Status Report: Perchlorate Treatment Technologies.
1st edition.
Hatzinger, P.B. 2005. Perchlorate Biodegradation
for Water Treatment. Environmental Science &
Technology.  Vol. A. Pages 239-247.
ITRC (Interstate Technology Regulatory Council).
2005. Perchlorate: Overview of Issues, Status, and
Remedial Options.
Massachusetts DEP (Department of Environmental
Protection). 2006. Press Release.
Mendiratta, S.K., R.L. Dotson, and R.T. Brooker.
1996. Kirk-Othmer Encyclopedia of Chemical
Technology.  Vol.  18. Pages 157-170.
NAS (National Research Council of the National
Academies). 2005. "Health Implications of
Perchlorate Ingestion."
http://www.nap.edu/catalog.php7record id=l 1202
NIOSH (National Institute for Occupational Safety and
Health).  2007.
Rao, B.,  Anderson, T. A., Orris, et al. 2007.
Widespread natural perchlorate in unsaturated zones of
the Southwest United States. Environmental  Science
Technology41 (13), 4522 -4528, 2007.
Additional information on perchlorate can be found at EPA's www.cluin.org/perchlorate.
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.