Perchlorate is a highly soluble chemical used in solid rocket fuel that has contaminated groundwater sources near military and manufacturing sites, and it may cause health issues by interfering with thyroid hormone production, especially in pregnant women and fetuses. While treatment options exist to remove perchlorate from drinking water, regulating a maximum contaminant level could cost municipalities between $100 million to $2.1 billion depending on the standard set. The document reviews the chemical properties and commercial uses of perchlorate, environmental occurrences and health effects, existing regulations, and available treatment technologies.

1. Current Issues in Environmental Regulation and Public Health:
PERCHLORATE
Carter Franz
Francesco Ramos

2. Table of Contents
I. Executive Summary ............................................................................................. ii
II. Physical and Chemical Properties ....................................................................... 1
III. Common Commercial Applications .................................................................... 4
IV. Commercial and Natural Production ................................................................... 6
V. Environnemental Occurrence .............................................................................. 13
VI. Health Effects ................................................................................................... 16
VII. Regulation......................................................................................................... 20
VIII. Treatment Options........................................................................................... 22
References ................................................................................................................ 29

3. Tables
Table 1: Physical and chemical properties of perchlorate ............................................................................ 3
Table 2: Annual estimated use and production of perchlorate compounds .................................................. 4
Table 3: Estimated annual perchlorate releases from commercial and natural applications......................... 6
Table 4: Selected perchlorate sources, releases and detections .................................................................... 8
Table 5: Selected DOD sites with perchlorate detections ............................................................................. 9
Table 6: Measured perchlorate concentration in common foods ................................................................ 15
Table 7: Relative source contributions remaining for water based on TDS for various sub-groups .......... 15
Table 8: State drinking water regulations ................................................................................................... 20
Table 9: Relative source contributions of perchlorate in drinking water for vulnerable subpopulations ... 21
Table 10: Applicability of common treatment technologies ....................................................................... 23
Table 11: National cost of federal regulation.............................................................................................. 28
Figures
Figure 1: Molecular geometry of perchlorate ............................................................................................... 2
Figure 2: Energy for a chemical reaction ...................................................................................................... 3
Figure 3: Locations of known users and manufacturers of perchlorate ........................................................ 8
Figure 4: Fate and Transport of perchlorate in groundwater aquifer and estimated residence time ........... 10
Figure 5: Schematic of perchlorate plume at Stringfellow Superfund Site................................................. 11
Figure 6: Pathway of Tronox plume in the south west United States ......................................................... 12
Figure 7: Suspected or known perchlorate releases and detections ............................................................ 14
Figure 8: Percent of total U.S. perchlorate detections found in each state ................................................. 14
Figure 9: Perchlorate mode of action and adverse affect when ingested .................................................... 17
Figure 10: The thyroid and its role in hormone secretion ........................................................................... 18
Figure 11: Progression of perchlorate regulation at the federal level in the United States ......................... 20
Figure 12: Quantification and calculations for toxicological effects of perchlorate ................................... 21
Figure 13: Schematic representation of the ion exchange between perchlorate and chloride .................... 23
Figure 14: Ion exchange treatment for perchlorate removal ....................................................................... 24
Figure 15: Schematic representation of a membrane filtration system for the treatment of perchlorate .... 25
Figure 16: Enzymatic pathway of the dissimilatory perchlorate reducing bacteria (DPRB) ..................... 26
Figure 17: Phytoremediation of perchlorate. This process is an emerging technology for perchlorate
remediation ................................................................................................................................................. 27

4. I. Executive Summary
On October 8, 2009 the U.S. Environmental Protection Agency (EPA) accepted the last
public comment (out of 22,000) regarding a federal drinking water regulation for perchlorate, a
‘candidate contaminant’ of the EPA’s since 1998. Perchlorate, a common constituent of solid
rocket fuel, has been linked to adverse health effects related to the hormonal homeostasis of the
thyroid gland in mice. Known to be released in large amounts nearby ground and surface water
supplies at U.S. Department of Defense, NASA research, and manufacturing sites, perchlorate
was chosen for evaluation to determine whether or not it causes adverse health effects in humans
at environmentally present concentrations. If so, a regulatory standard will have to be set which
would require municipal entities to treat water supplies to meet that standard.
This report outlines the chemical and physical properties that make perchlorate popular
among defense contractors and other users, and those properties that make it problematic for
environmental remediation efforts and finally those that possibly cause adverse health effects in
vulnerable populations. Perchlorate rose in popularity beginning with the Second World War
because of its oxidizing potential. Subsequently, it was used in munitions, rocket launchers,
fireworks and other related uses. Commercially viable only as a solid salt, 90% of perchlorate
demand is for ammonium perchlorate, and these salts are highly soluble in water and unable to
adsorb to soil, making them extremely mobile in aqueous medium.
The time period since perchlorate was established as a candidate for regulation, new
research has yielded the following conclusion regarding the health effects of perchlorate: The
vulnerable population group is the fetuses of iodine deficient pregnant women exposed to
concentrations of perchlorate in water of over 15µg/L (ppb). This comes after a body of animal
studies on mice was summarily discounted as non-analogous to healthy adults and adolescents
because of differences in the pituitary gland. In 2005 a Center for Disease Control study
concluded that higher urinary perchlorate concentrations were a positive predictor of unbalanced
hormonal behavior regulated by the thyroid gland in iodide deficient women. However, they
noted that the hormonal behavior was within healthy range, and that there was no precedent in
the research indicating those urinary levels of perchlorate would cause any adverse health
effects.
Various technologies are available to treat perchlorate, and depending on whether or not a
regulatory standard is set, 3.4% or 1.4% of the nation’s public water supply would require
adoption of these unconventional treatment technologies. The cost implications of setting a
Federal drinking water limit for perchlorate are that compliance would cost 2.1 billion USD with
a maximum contaminant level (MCL) of 4 ppb and 100 million USD with an MCL of 24 ppb.
Regulating perchlorate would cost the nation less than previous drinking water standards, and the
costs would fall on a small number of municipalities and private entities.
We conclude that perchlorate is an environmental contaminant which can cause negative
health affects at high doses, especially to the fetuses of iodine deficient pregnant women. While
the cost of implementing a federal drinking water standard is low compared to previous limits,
the cost would fall upon a few individuals. Clearly, there are many stakeholders and we hope the
political process serves both sides of the debate fairly. If a regulation is put in place, we would
recommend the ion exchange method as the most reliable and capable of removing perchlorate
from public drinking water systems.

5. INTRODUCTION
erchlorate is a highly soluble anion used in solid
P
rocket fuel and found naturally in the
environment. Previous disposal methods at U.S.
“As with any Department of Defense and other user sites
consisted of dumping perchlorate salts or liquid
new regulatory waste into the Earth untreated. In the late 1990’s
standard, there is perchlorate was detected in high concentrations in public
water supplies of the American south west and subsequently
debate in the throughout the entire United States. Public health officials
public sphere as were concerned that ingestion of perchlorate may cause
hypothyroidism, a condition characterized by an underactive
to whether or not thyroid and a slowing metabolism. The EPA added
a national perchlorate to its candidate contaminant list in 1998, and the
report that follows is a summary of research concerning the
drinking water health effects, regulatory framework, and environmental
limit for remediation efforts associated with perchlorate up to 2009. As
with any new regulatory standard, there is debate in the public
perchlorate sphere as to whether or not a national drinking water limit for
would improve perchlorate would improve the health of the population. The
first section will elaborate on the chemical and physical
the health of the properties governing the behavior of perchlorate. These
population.” properties are the basis for understanding perchlorates nature
as a commercial commodity, a persistent ground water
contaminant, and a potential human health concern.
II. Physical and Chemical Properties of Perchlorate
Molecular Geometry. Figure 1 shows the sp3 tetrahedral arrangement of the perchlorate anion,
which consists of one chloride bonded to four oxygen atoms. Because of this geometry
perchlorate has a large ionic volume and low charge density. Therefore, it is a poor complexing
agent with cations in aqueous solutions. This low association with cations makes perchlorate
highly soluble and mobile in aqueous environments, and prevents bioaccumulation and soil
sorption. This contributes to perchlorates persistence in aquifer plumes, and confounds
1

6. environmental engineers because sodium and potassium perchlorates
precipitation and sorption are ruled out as (Urbansky, 1998). Perchloric acid (HClO4)
treatment options (Srinivasan, 2009). is miscible in water and has an octanol-
Perchlorate’s ionic radius is similar to that water partition coefficient of -4.63 (EPA,
of the iodine anion. When in the 2008). Perchlorate is non-volatile and does
bloodstream, perchlorate competes with not bind readily to mineral surfaces, which
iodine for uptake into the thyroid gland, indicates that perchlorate will travel rapidly
which can ultimately reduce radioiodine over soil with surface water runoff or be
uptake and disrupt the normal hormone transported through soil with infiltration
secretion of the thyroid when ingested in (ATDSR, 2008). Therefore, adsorption
large doses. techniques used in water treatment plants are
ruled out as a possible treatment option.
(1) NH4ClO4(s) water NH4+ (aq) + ClO4- (aq)
Subsequent discussion will talk about the
commercial applicability of perchlorate
containing salts, but the following statement
makes an important distinction: “Given that
perchlorates completely dissociate at
environmentally significant concentrations,
their cations are, for all practical purposes,
spectators in the aqueous fate of perchlorate.
Figure 1: Molecular Geometry of Therefore, the environmental fate of
Perchlorate perchlorate salts is dominated by the
Perchlorates tetrahedron geometry contributes
perchlorate ion (ATDSR, 2008).” This
to the large ionic volume and low charge
density of ClO4 -. The negative charge is property is important, because
equally distributed among the 4 outer oxygen environmental engineers are concerned with
atoms. Consequently, it is a poor complexing the removal of perchlorate, and therefore the
agent and highly soluble in aqueous perchlorate anion, from the environment
environments, making it difficult to remediate (especially drinking water sources).
by conventional methods. Research shows that this task is further
Image: CAS, 2009 complicated by the chemical kinetics of
perchlorate.
Thermodynamics and Kinetics. Figure 2
Solubility. Perchlorates are commercially
depicts the ‘energy hump’ that reactants in a
viable as solid salts, in white or clear crystal
chemical reaction must surpass to become
form stored at ambient temperature. These
products. Perchlorate represents the highest
salts fully dissociate in water (Equation 1)
oxidized form of chlorine (+7), and has a
and some organic solvents, with solubility’s
high reduction potential. Perchlorate can
ranging from 2.06 x 104 to 2.10 x 106 mg/L
react explosively at high temperatures, and
in fresh water at 25ºC, and 1.00 x 101 to
is a powerful oxidant when combined with
1.82 x 106 mg/L in standard organic solvents
fuel sources. Ammonium perchlorate, the
(See Table 1). Log octanol-water partition
most widely produced perchlorate salt,
coefficients (log Kow) are -5.84 for
thermally decomposes at temperatures of
ammonium perchlorate, and -7.18 for
439ºC, and then combusts in a self-
2

7. propagating manner (CDTSC, 2005). Standard
reduction potentials show that the reduction of
perchlorate to (Eq. 2) chloride, or (Eq. 3)
chlorate, is thermodynamically favorable
(Urbansky, 1998).
(2) ClO4- + 8 H+ + 8 e- ↔ Cl- + 4 H2O
-----E° = 1.287 V
(3) ClO4- + 2 H+ + 2 e- ↔ ClO3- + H2O
E° = 1.201 V
Though perchlorate is
thermodynamically favored to be easily
reduced, it is highly non-reactive in aqueous Figure 2: Energy for a Chemical Reaction
solution at ambient temperatures. “The low This general graph depicts the transgression of a chemical
reactivity is a matter of kinetic lability rather reaction. In the case of perchlorate as a reactant, it has
than thermodynamic stability (Urbansky, high activation energy, so it takes a large amount of
1998).” The activation energy needed to energy to reach the “transition state”. Consequently, the
break down perchlorate is high: 123.8 reduction of perchlorate with typical reducers is too slow
kJ/mol below 240 ºC; 79.1 kJ/mol from 240 (days to weeks) to be used in water treatment plants.
to 200 ºC; 307.1 kJ/mol between 400 and Image: sparknotes.com/figures
440 ºC (ATDSR, 2008). This kinetic barrier
is difficult for environmental engineers
This also implies the main path of perchlorate in the
working towards remediation because
environment is aqueous, and the primary risk to
typical reducing agents cannot reduce
humans will be via ingestion. Perchlorate
perchlorate economically (Urbansky, 1998).
compounds are denser than water, a property that
Table 1 shows that all common
affects the transport of perchlorate in groundwater
perchlorate compounds have an extremely
aquifer plumes. Table 1 also lists the specific
low vapor pressure, and do not volatize from
gravities.
water to air (Sellers, 2007). Therefore, air
stripping is ruled out as a treatment option.
Table 1: Physical and chemical properties of perchlorate (EPA, 2005 & IDTC, 2005)
Perchlorate Compounds Ammonium Potassium Sodium Perchloric Acid
Colorless orthorhombic
Physical state at White orthorhombic White orthorhombic
crystal or white Colorless liquid
ambient temperature crystal deliquescent crystal
crystalline powder
Molecular weight
117.49 122.44 138.55 100.47
(g/mol)
Water solubility (g/L at
200 2,096 15 Miscible in cold water
25oC)
Melting / Boiling point Melting Point: 65.6 to Melting Point: -112
Melting Point: 482 Melting Point: 400
(oC) 439 Boiling Point: 19
Vapor pressure at 25oC
Not available 4.8 Not available 3.5
(mm Hg)
Specific gravity 1.95 2.52 2.53 1.664
Octanol-water partition
-5.84 -7.18 -7.18 -4.63
coefficient (log Kow)
Sorption Capacity Very low Very low Very low 3
Very low
Volatility Nonvolatile Nonvolatile Nonvolatile Nonvolatile

8. III. Common Commercial glass etching (ATDSR, 2008).
Applications Worldwide production of
perchlorates was less than 3.6 million total
The most widely used perchlorates pounds up until 1940. However, with the
are in the form of solid salts, including onset of World War II, annual production of
ammonium, potassium, magnesium, sodium, perchlorate increased to 36 million pounds,
and lithium perchlorate (see Table 2) . The due to the increased demand for rocket and
Department of Defense (DOD), the National missile propellants. Advancements in space
Aeronautics and Space Administration exploration technology and cold war
(NASA), and the defense industry have used innovations further increased demand. U.S.
perchlorate for decades in the perchlorate production alone reached 50
manufacturing, testing, and firing of missiles million pounds annually by 1974, and in
and rockets. Their primary uses are as 1994 was estimated at around 22 million
oxidants in combination with fuel sources. pounds, or 34% of capacity (ATDSR, 2008).
The approximate percentages sold for Because perchlorate is considered a
specific end users are 92% as an oxidizer, “strategic chemical” due to its military
7% as an explosive, and 1% for other uses applications, and because the U.S. does not
(CDTSC, 2005). The DOD uses 6-8 million log perchlorate as a separate good on
pounds of ammonium perchlorate annually, import/export logs, exact U.S. production
of which roughly 4 million pounds is and disposal volumes are difficult to gauge
recovered and recycled for use in (ATDSR, 2008).
commercial applications such as blasting or Ammonium perchlorate accounts for
90% of perchlorate production in the U.S.,
Table 2: Estimated Annual Production and Use of Perchlorate Compounds
U.S.
Chemical Production
Compound Use
Formula in 1951-1997
(million lb.)
Ammonium NH4ClO4 609 Energetic booster in rocket fuel, used primarily by the DOD, national
perchlorate aeronautic space, and space administration. The high solubility of
NH4ClO4 makes this material useful as an intermediate for production
of all other perchlorates by double metathesis reactions and controlled
crystallization (Kirk, 2004).
Sodium NaClO4 20 Strong oxidizing agent used in the explosives and chemical industry
perchlorate (Kirk, 2004).
Potassium KClO4 22 Solid oxidant for rocket production; also used in pyrotechnics
perchlorate (ATSDR, 2008).
Lithium LiClO4 No data Electrolyte in voltaic cells and batteries involving lithium anodes; thin
perchlorate found film polymers used in certain electrochemical devices, may be doped
with lithium perchlorate to induce conductive properties; used as a
synthetic of certain organic compounds (Seller et al, 2004).
Magnesium Mg(ClO4)2 0.7 Drying agent for industrial gases; electrolyte for magnesium batteries;
perchlorate used in synthesis of certain organic compounds (Kirk, 2004).
Perchloric HClO4•2H2O No data Analytical reagent; used hot and concentrated as oxidizing and
acid found dehydrating agent (Merck, 1983).
4

9. and is the largest component of solid rocket (Seller et al, 2004). Other uses of
(~70%) and missile propellants (Lieberman perchlorates include fireworks, road flares,
et al, 2008). Being the only common matches, photography, etching and
perchlorate that does not leave behind a engraving, and blasting explosives used for
solid by-product as well as the ease of mining and other civilian applications.
disposal from rocket encasings adds to its Fireworks can contain up to 70% (wt)
widespread use (CDTSC, 2005 & Atikovic, potassium or ammonium perchlorate, and
2007). Solid rocket fuels that use over 221 million pounds of pyrotechnics
perchlorate, as opposed to liquid fuels that were consumed in 2003 in the U.S. (Seller et
use other oxidizers, can provide a high thrust al, 2004). Sodium perchlorate is employed
for a low cost (ITRC, 2005). Average annual in airbag inflator systems. Due to their low
production rates for ammonia perchlorate weight and high energy density, lithium and
between 1951 and 1997 estimated to be magnesium perchlorate have been used in
roughly 1.06 x 107 kg per year. The sole batteries. Potassium perchlorate can be
producer of ammonium perchlorate in North mixed with reactive metals such as
America is American Pacific Corporation zirconium or iron, and used in heat pellets to
(AMPAC) near Cedar City, Utah (ATDSR, activate reserve battery cells (ATDSR,
2008). Ammonium perchlorate is also used 2008).
in small amounts in ammunition, mixed with In 1998, the FDA approved the use
sulfamic acid to produce smoke and dense of potassium perchlorate as an additive in
fog for tactical military operations, and as a rubber gaskets of food containers.
component of temporary adhesives used Ammonium, potassium, and sodium
with steel and other metallic plates perchlorate have also been used as
(ATDSR, 2008). stimulants to increase the weight of poultry
Nitrate and perchlorate containing and other farm animals, and as weed killers
Chilean salt pepper is used in the production and growth stimulants in leguminous plants
of fertilizer. The United States has been (ATDSR, 2008).
importing Chilean caliches since 1830, and Another common form of
the use continues today with the U.S. commercially available perchlorate is
importing more than 75,000 tons containing perchloric acid (HClO4). Applications
0.01% perchlorate annually between 2002 include etching of liquid crystal displays,
and 2004 for use mainly on tobacco, cotton, polymerization catalysis, critical electronics
and some fruit crops (Seller et al, 2004). applications, and ore extraction. Perchloric
This accounts for approximately 1% of the acid is also used routinely for many
total fertilizer used per year in the U.S. industrial and testing laboratory chemical
(ATDSR, 2008). analyses, including isolation, separation,
titration, deproteinization, dehydration, and
Other Commercial Applications of as a solvent and oxidizing agent. Analytical
Perchlorate. While perchlorate’s major use chemists use perchlorates to adjust the ionic
is in the production of rocket propellant, strength of aqueous metal solutions.
munitions, explosives and fireworks, Perchlorates are unreactive as a ligand (do
manufacturers also use perchlorate not complex with metals) so they do not
compounds in small amounts for some interfere with the chemical dynamics of the
consumer products (see Table 3). Since investigation (Urbansky, 1998)
1976, over 14,000 patents have been issued Perchlorates used medically during
for various perchlorate-containing materials the 1950s and early 1960s, for the treatment
5

10. of hyperthyroidism, or Graves’ disease. In
the United States, perchlorate is still used salivary glands. In addition, treatment to
during medical imaging of the brain, blood, counter effects of the drug amiodarone on
and placenta, in order to block radioiodine the thyroid includes potassium perchlorate
uptake in the thyroid, choroid plexus, and (ATDSR, 2008).
Table 3: Estimated annual perchlorate releases from commercial and natural applications
le
Application Est. Perchlorate Additional Information
Release (lb/year)
Chilean 15,000 About 75,000 tons of fertilizer including 0.01 (wt) % perchlorate was used
nitrate annually between 2002 and 2004 (Seller et al., 2004).
fertilizer
Fireworks No data found Environmental releases of perchlorate are difficult to predict due to variability in
the decomposition of perchlorate during combustion. Concentrations as high as
44.2 μg/L have been observed in nearby surface waters following a fireworks
display in Oklahoma (Wilkin et al, 2007).
Safety flares 240,000 Preliminary research indicates that unburned and burned flares can leach 3.6 g and
1.9 mg respectively perchlorate. Estimated 20-40 million flares used annually
(Seller et al., 2004).
Blasting No data found Blasting agents used in coal mining, quarrying, and other uses can contain
explosives perchlorate up to 30 (wt) %. The U.S. produces around 2.5 million tons of
explosives annually (Seller et al., 2004). Environmental releases of perchlorate are
difficult to predict due to variability in the decomposition of perchlorate during
combustion. Wells at the Kennecott copper mines in Magna, Utah have measured
13 ng/L perchlorate (Urbansky, 1998).
Chemical 1,700 Electrochemical production of sodium chlorate can generate perchlorate as an
Production impurity at 50-230 mg/kg chlorate. The annual consumption of sodium chlorate in
the U.S. is around 1.2 million tons (Seller et al, 2004).
Defoliant 1,600 Perchlorate released as a defoliant between 1991 and 2003 is estimated at around
20,000 lb (Seller et al, 2004).
IV. Commercial and Natural saltpeter deposits contain concentrations
Production from 300 to 1,000 mg/kg in the soil. Natural
perchlorate has been detected in the Bolivian
Natural Sources. Perchlorate occurs Playa crust high in the Andes, at
naturally in the environment, but its exact concentrations of 500 mg/kg of soil (Seller
origin and mechanisms of formation are not et al, 2004). Research on perchlorate
known. Isotopic ratios in the nitrate deposits containing soils has concluded that
suggest that perchlorate formed in the perchlorate and nitrate co-occur naturally, so
atmosphere by a process involving ozone as perchlorate is extracted from deposits of
the oxidant (Brown, 2005). It has typically nitrate ores, and is distributed in sodium
been discovered in high concentrations in nitrate fertilizer. Dry deposits of perchlorate
the soils of arid climates. Historically, the are also found naturally within potash
largest known natural source of perchlorate (potassium ore deposit) in mines close to
is found in Atacama Desert in Chile, where Carlsbad, New Mexico and in
6

11. central Canada. The concentrations of Perchlorate could also be an intermediate
perchlorate in these deposits range from 25 by-product from the interaction of two
to 2,700 mg/kg of soil. Reservoirs of natural hypochlorite degradation pathways, for
perchlorate in the arid American southwest instance degradation to chlorate and
are estimated at up to 1 kg/ha (Seller et al, degradation to oxygen and sodium chloride
2004). (MDEP, 2009).
Industrial Preparation. Sodium Waste Streams. Figure 3 shows a map of
perchlorate is the most soluble salt, and known perchlorate users and table 4 shows
therefore the principal salt produced. The some typical waste stream volumes. One of
most common method of producing sodium the advantages of ammonium perchlorate
perchlorate is electrolysis of an aqueous compared to other oxidizers is that it is
solution of sodium chloride, with the easily washed out of old rocket boosters and
following two electron oxidation series can be reused in other commercial
(ATDSR, 2008): applications (after being re-crystallized).
The washout operation generates wastewater
(4) Cl- → ClO2- → ClO3- → ClO4- that because of perchlorates low solubility
and other properties persists in the
All other perchlorate compounds are formed environment for decades (Atikovic, 2007).
by adding other salts to a sodium nitrate Two methods of solid propellant disposal
solution, to selectively re-crystallize the used in the past, open burning and hydro-
perchlorate salts that are less soluble than mining, discharged perchlorate directly into
sodium perchlorate: the environment. With open burning, un-
combusted fuel material was allowed to seep
Na+ (aq) + ClO4- (aq) + M+ (aq) + X- (aq) → into the soil and water. Current practice is to
MClO4 (s) ↓ + Na+ (aq) + X- (aq) collect unburned material and re-burn it “to
ensure complete combustion of energetic
where X is chloride, sulfate, or carbonate; M material (ITRC, 2005).” Hydro-mining is a
is magnesium, potassium, lithium, or method of using high pressured water jets to
ammonium; and MClO4 (s) is the desired wash out the rocket booster, so the hard
perchlorate (ATDSR, 2008). ware can be recycled. Current practice it to
Degradation of other compounds is capture and treat the waste streams prior to
another way to produce perchlorate. discharge (see section VIII), but in the past
Perchlorate can be found as a breakdown the waste water was discharged untreated to
product in solutions of sodium hypochlorite, the ground or into retention pounds prone to
which is used as a swimming pool leakage (USEPA, 2005). Measured
disinfectant, and can be incidentally formed perchlorate levels in ground and surface
in corrosion control applications. The water near munitions and rocket fuel plants
mechanism hypothesized for perchlorate have been shown to range from 4000 mg/L
formation commences with the initial to as high as 3700 mg/L (Urbansky, 1998).
degradation of hypochlorite to chlorate.
7

12. Figure 3: Locations of known users and manufacturers of perchlorate (USEPA, 2005)
Table 4: Selected perchlorate sources, releases and detections (Mayer, 2004)
State Location Suspected Source Type of Contamination Max. Conc.
ppb
NV Kerr-McGee/BMI Perchlorate Public Water System 24
Henderson, Nevada Manufacturing Monitoring Well 3,700,000
Surface Water 120,000
NV PEPCON Perchlorate Monitoring Well 600,000
Henderson, Nevada Manufacturing
(former)
CA Aerojet General Rocket Public Water Supply Well 260
Rancho Cordova, CA Manufacturing Monitoring Well 640,000
CA Rialto-Colton Plume Fireworks Facility Public Water Supply Well 811
Rialto, CA Flare Manufacturing
Rocket Research and
Manufacturing
CA Stringfellow Hazardous Waste Monitoring Well 682,000
Superfund Site Glen Disposal Facility Private Well 37
Avon, CA
IA Ewart, IA Unknown Source Livestock Well 29
NY Westhampton Unknown Source(s), Public Water Supply Well 16
Suffolk County, NY possibly agricultural Monitoring Well 3,370
8

13. Perchlorate can also be released into run-off becomes mobile in the environment
the environment at sites where perchlorate (ATSDR, 2008). Changes in land use
salts are used in manufacturing processes. patterns from natural settings to irrigated
As mentioned above, there is only one agricultural land are mobilizing natural
producer of ammonium perchlorate today, deposits of perchlorate into surface and
but there were many more that operated in ground waters in these locations (Rao et al,
the past but have now closed or ceased 2007). In wet and humid climates that
perchlorate production (see Table 4). Those coincide with agricultural applications of
former sites of manufacture are current imported perchlorate-containing fertilizers,
locations of perchlorate plume tracking and there can be leaching from solid perchlorate
remediation. at the soil surface (Seller et al, 2004).
Other anthropogenic waste streams One study shows estimated source
have occurred from munitions strength of 1.4 x 105 kg/year for perchlorate
manufacturing & disposal and the launching released to the environment from road
of solid fuel launch vehicles. Natural waste flares. If perchlorate is released into the air,
streams may occur when sand or soil it will eventually settle out, primarily in
containing perchlorate erodes and by way of rainfall (ATSDR, 2008).
The US-EPA documents that 63
DOD sites or installations have detectable
(meaning over the minimum detection
Table 5: Selected DOD sites with perchlorate range of .5 ppb-1 ppb) perchlorate
detections (extracted from ITRC, 2005) concentrations in soil, and/or
Perchlorate ground water. Racca et al (2008) reports
State Installation Branch
Type of
detection 56 installations had detections of over 4
Contamination
(ppb) ppb by 2007. A 2001 DOD survey of
weapons systems containing perchlorate
Edwards Air Air listed 259 different munitions. There is
CA GW 160,000
Force Base* Force
also a ‘perchlorate replacement program’
Holloman Air Air underway to replace perchlorate in some
NM SW 16,000
Force Base Force existing munitions when possible (ITRC,
2005).
Aberdeen
MA Army DW, GW 5, 24 DOD site prioritization began in
Proving Ground
2004 to determine which DOD
Redstone establishments posed the greatest risk to
AL Army GW 160,000
Arsenal* drinking water contamination. Sites were
evaluated based on reported detections
White Sands
NM Army GW 21,000 over 4 ppb, whether or not perchlorate
Missile Range
related activities had occurred at the site,
Naval Air and site proximity to drinking water wells
Weapons (less than 1 mile, between 1 and 5, or
CA Navy GW 560 greater than 5 miles) (Racca et al., 2008).
Station, China
Lake This list is not comprehensive,
but representative of detections at select
Naval Surface DOD facilities.
MA Warfare Center, Navy SW 1,000
Indian Head* (*) perchlorate cleanup is underway as of
September, 2005.
9

14. Transport in the Environment. As Flowers et al (2001) examined the
mentioned above perchlorate compounds are behavior of perchlorate plumes in
highly soluble in aqueous solution and the groundwater aquifers (see Figure 4). Their
perchlorate ion does not bind to soil model assumed dense brine was released at
particles. Perchlorate has been released to a disposal site. Since a large density
the environment in solid form, as (1.11g/cm3) contrast exists between the
ammonium, sodium, potassium, and other concentrated brine and ambient
perchlorate salts, as well as in liquid form. groundwater, in the vadose zone the
These concentrated releases form highly perchlorate solution will sink vertically by
density perchlorate brines once in contact the force of gravity at the same velocity as
with moisture. In soil, the movement of water, and horizontally by way of capillary
perchlorate is a “function of the amount of forces. As perchlorate disperses it begins to
water present. (ITRC, 2005)” move faster than the average groundwater
velocity (Flowers et al, 2001).
Figure 4: Fate and transport of perchlorate in groundwater aquifer and estimated residence time
(adapted from Flowers et al, 2001)
10

15. In arid regions perchlorate “may options would be an economically
accumulate at various horizons in the soil inefficient way to treat perchlorate, and that
due to evaporation of infiltrating rainfall that “isolating and removing the source” of
leached perchlorate from shallower depths. contamination is recommended (Flowers et
(ITRC, 2005)” al, 2001).
After subsurface migration in the As mentioned above, under ambient
vadose zone, the concentrated brine will conditions perchlorate is kinetically stable
pool on top of a low-permeability confining and does not react or decompose.
layer and eventually penetrate the layer Biodegradation of perchlorate will not occur
byway of diffusion (at a lower velocity than unless significant levels of organic carbon
in the vadose zone). Once confined in the are present. Taking into account perchlorates
low-permeability layer, perchlorate will high solubility, low sorption, and lack of
become a long-term source of aquifer degradation plumes tend to be large and
contamination (appx. 100 year retention persistent. For example, the perchlorate
time) because of mass-transfer limitations plume at the Stringfellow Superfund site
(Flowers et al, 2001). Even when (Figure 5) in California persists for 5 miles
perchlorate discharge at the surface is from the Pyrite Canyon to the Santa Ana
stopped, and the pool above the low- River (Kenoyer et al, 2007.) According to
permeability layer stops growing, the California-EPA, wastes from rocket fuel
perchlorate will still diffuse back into the users/manufacturers were transported and
aquifer from the confining layer. They dumped in unlined pounds for evaporation at
conclude that long-term pump and treatment Stringfellow throughout the years.
Figure 5: Schematic of Perchlorate Plume at Stringfellow Superfund Site
(CDTSC, 2006)
Average of
detected
perchlorate
concentrations
18 ppb
12 ppb
Image: www.ccaej.org (Center for Community Action and Environmental Justice)
11

16. In addition, quarry blasting in Pyrite perchlorate concentrations (60ppb) in the
Canyon (since 1904) may have included Ogallala aquifer of the Texas southern High
explosives that contained perchlorate dust Plains. Their studied showed that
that was washed into the soil and creeks, and perchlorate was found beneath natural
then into groundwater. Irrigation of the Glen grassland and shrub land ecosystems (2.7-
Avon area may have occurred from sources 7.2 ppb), and that its correlation with
such as the Colorado River, and many tons chloride concentrations suggests dry fallout
of nitrate fertilizer was used in the area and precipitation are the likely sources.
during the twentieth century (CDTSC, Further, they determine that perchlorate
2006). Since these activities span over a plumes reach a maximum depth of 8.3
century, and are all considered ‘possible’ meters in a downward direction under rain
sources, exact numbers on releases in the fed agricultural areas, and again correlate
vicinity of the Stringfellow site are not perchlorate concentrations with chloride
available. However, current perchlorate concentrations (Scanlon et al, 2007).
concentrations measured in nearby A 2007 study by Wilkin et al (2007)
groundwater wells are shown in the figure looked at perchlorate concentrations in a
below. lake following fireworks displays. It
An abstract from the American concluded that before the fireworks displays,
Geophysical Union’s fall 2007 meeting lake concentration of perchlorate rose from a
indicates that “groundwater perchlorate mean value of .043 ppb to a maximum
contamination is likely to increase in the concentration of 44.2 ppb after the display.
future with more widespread flushing of Perchlorate concentrations returned to
naturally occurring perchlorate beneath previous levels within 20 to 80 days after the
cultivated regions.” Their study was display, “with the rate of attenuation
motivated by the discovery of high correlating to surface water temperature.”
water contamination,
Tronox Plume Management. Figure 6: Pathway of Tronox Plume in the Southwest
In mid-1997 the United States (USEPA, 2005)
Metropolitan Water District of
Southern California discovered
perchlorate in the lower Colorado
River and traced contamination to
Lake Mead and the Las Vegas
Wash (see Figure 6). Ultimately,
the source of the perchlorate was
traced to the Kerr McGee (now
Tronox) Chemical Plant in
Hendersen, Nevada (USEPA,
2005). Tronox ground water
aquifer plume released about 900
to 1000 pounds per day (average)
of perchlorate to Las Vegas Wash
prior to controls being
implemented (USEPA, 2005).
After revelations of the drinking
12

17. Tronox suspended the production of to a federal drinking water limit for
perchlorate and began remediation. The cost perchlorate. The occurrence maps that have
of remediation is 124 million dollars, and been produced from studies by Brandhuber
has resulted in a 90% decrease in et al (2005) (occurrence in public drinking
perchlorate entering the LVW since 1999 water systems) and the USEPA (2005)
(Aqueduct Mag., 2008). (users, manufacturers and releases) show
Their control strategy aims to that perchlorate is many times present in
capture and treat perchlorate on Tronox public water systems where no known or
property where it is most concentrated by likely anthropogenic releases into the
means of a slurry wall, at a narrow environment have occurred.
subsurface channel between the plant and
LVW, and near LVW where capture will Public Water Systems. Current analytical
have the most immediate impact on reducing techniques have achieved detection limits as
releases to LVW. The Tronox releases low as 0.5 ppb for perchlorate. In 1999
described above, which ended up in Lake perchlorate was added to the EPA’s
Mead and the lower Colorado River had an Unregulated Contaminant Monitoring List
impact on the drinking water supply of 15 to (UCML), and public water systems (PWSs)
20 million people in Arizona, southern serving more than 10,000 people were
California, southern Nevada, Tribal nations required to monitor perchlorate levels
and Mexico (USEPA, 2005). beginning in 2001. As part of the EPA’s
UCMR 1 program, conducted between 2001
IV. Environmental Occurrence and 2005, data was compiled from 34,331
samples collected at the entry points (where
Perchlorate Exposure in the United water goes from the source into the
States. The U.S. EPA has been tracking the distribution system) of 3,865 of the nations
manufacturing, use and release of PWSs. The minimum detection limit for the
perchlorate to the environment since the late UCMR 1 program was 4 ppb, and
1990’s (Brandhuber, 2005). In addition, the perchlorate was detected in 637 (1.9%) of
DOD is currently in the process of going those samples, which equated to 160 (4.1%)
through historical records of possible of PWSs.
perchlorate containing production processes In addition to PWS’s that serve more
to estimate the total amount of perchlorate than 10,000 people, 800 samples (2.3% of
that has been released throughout the the total) were taken from PWSs that serve
century (ITRC, 2005). Occurrence mapping populations less than 10,000. Therefore, the
for perchlorate attempts to pinpoint the UCMR 1 accounted for roughly 80% of the
location of users and manufacturers of U.S. population (Brandhuber et al, 2005).
perchlorate (Figure 3), known or suspected According to Russell et al (2009), a recent
releases of perchlorate into the environment study (an update of Brandhuber et al (2005)
(Figure 7), and its detection in public water to be published in AWWA Journal at the
systems (concs. > 4ppb, Figure 7). In end of 2009) points out that because the
addittion, its occurrence in food can be UCMR 1 only accounted for 1.8% of small
mapped from various studies, but PWSs (pop. < 10,000) a “more complete
establishing the cause and effect relationship sampling effort” is needed to fully assess
between perchlorate releases and its perchlorate concentrations in those systems,
pathway to food products is a challenge. and it is likely the levels are higher than
Further, its occurrence in food is not related previously assumed from the UCMR 1.
13

18. Figure 7: Suspected or known perchlorate releases and detections
(Brandhuber, 2005).
Known perchlorate release Drinking Water Detections: 4µg/L < 10 µg/L >10 µg/L
Figure 8: Percent of total U.S. perchlorate detections found in each state (Russell et al, 2009)
14

19. Of the positive detections, the perchlorate concerning studies related to perchlorate in
concentrations ranged from 4 ppb to more food, since it is not related to a federal
than 3.7 million ppb, with an average of standard for perchlorate in drinking water,
9.85 ppb. More than half of detections and because the studies have found it hard to
occurred in California and Texas (see Figure track sources of most perchlorate containing
8 above), with the highest concentrations foods.
found in Arkansas, California, Texas,
Nevada and Utah. Figure 4 shows the share
Table 7: Relative source contributions remaining for
of total PWSs with perchlorate detections water based on TDS for various sub-groups (extracted
allotted to each state (and Puerto Rico). from US EPA, 2008)
Figure 7 shows detections of perchlorate
Population Food intake RfD RSC for
between 4bb and 10 ppb, and those above 10 Group (ug/kg/day) remaining DW (%
ppb (Brandhuber et al (2005). (ug/kg/day) of RfD)
Table 6: Measured perchlorate concentration Infants .26-.29 041-.44 59%-
in common foods (compiled from FDA, 2004 63%
& Jackson et al, 2005) Children, 2yr .35-.39 .31-.35 44%-
50%
Children, 6yr .25-.28 .42-.45 60%-
Type of Minimum Maximum Mean 64%
sample (ppb) (ppb) Perchlorate Children, 10 .17-.20 .50-.53 71%-
(ppb) yr 76%
Teen Girls .09-.11 .59-.61 84%-
Vegtables 2.38 228.25 19.43
87%
Bottle 0.45 0.56 ND Teen Boys .12-.14 .56-.58 80%-
water 83%
Women, 25- .09-.11 .59-.61 84%-
Cow milk 3.16 11.30 5.76 30 87%
Fruit 0.85 144.48 ND Men, 25-30 .08-.11 .59-.62 84%-
Apple 1.39 3.45 2.15 89%
juice Women, 40- .09-.11 .59-.61 84%-
45 87%
Orange 2.27 3.15 2.59 Men, 40-45 .09-.11 .59-.61 84%-
juice 87%
Sweet 0.85 2.07 1.24
Potatoes Occupational Exposure. In two widely
cited occupational studies (Lamm et al,
Fish 12.22 17.70 6.61 1999 & Gibbs et al, 1998) there were no
adverse health effects on factory workers
Food Exposure. Perchlorate is common in exposed to perchlorate. While there was
many foods. Table 6 and Table 7 list reduced iodine uptake, there was not any
perchlorate concentrations found in food signs of hypothyroidism (i.e. no changes in
samples, and the relative source contribution TSH, T4, and T3 levels) (ATDSR, 2008). A
of food to perchlorate in our diets. The more recent study, Bravermen et al (2005),
relative source contribution will become found similar results. The study found that
important in the health section of this report workers experienced a decrease in iodide
when developing the subchronic health uptake during their shifts when exposed to
advisory. This report does not go into detail high doses, as well as fluctuations in T3 and
15

20. T4 levels, but that these effects went away “The median estimated absorbed
when the worker was away from the factory. dose was 0.167 mg/kg/day, equivalent to
They concluded that “long-term, drinking approximately 2L of water
intermittent, high exposure to ClO4- does not containing 5 mg perchlorate/L. It should be
induce hypothyroidism or goiter in adults mentioned that perchlorate workers are
(Braverman et al, 2005).” These terms will exposed during an unusual schedule of three
be described in more detail in the Health 12-hour shifts followed by 3 days without
Effects section of this report. In exposure (long-time, intermittent exposure).
occupational settings, the main risk factor Given the relatively short elimination half-
would be via inhalation. Finally, it is worth life of chlorine in worker of approximately 8
repeating that ammonium perchlorate is hours (Lamm et al, 1999) perchlorate would
90% of perchlorate sold, and all ammonium not be expected to accumulate to levels that
perchlorate produced occurs in a single would cause thyroid problems (ATSDR,
production plant in Henderson, Nevada (as 2008).” No data were found on levels of
mentioned above). These studies were all perchlorate in ambient air, but workers at an
carried out at that plant. Therefore, the ammonium perchlorate production facility
implications of the numbers that follow who were exposed to perchlorate dust had
would apply only for workers at that single single shift absorbed doses measured at 0.2–
plant, who would be experiencing the most 436 μg/kg, with a 35 μg/kg average.
frequent doses of perchlorate and maybe the Cumulative lifetime doses for these workers
only doses in the United States at any given over an average of 8.3 years ranged from
time. Needless to say, a federal regulation 8,000 to 88,000 μg/kg (ATDSR, 2008).
for occupational exposure of perchlorate
would be irrelevant.
VI. Health Effects
action, and not the adverse health affect. In
The main health concern regarding this respect, perchlorate is treated differently
the perchlorate ion is its ability, when in the than other ‘candidate contaminants’ that the
human blood stream, to inhibit the uptake of EPA evaluates for regulation (US EPA,
iodide by the thyroid. The EPA considers 2008). Therefore, since the reference dose of
this inhibition the mode of action rather than perchlorate is not based on the adverse
the adverse affect. Srinivasan et al (2009) health effect, but a precursor to the adverse
states that the mode of action is considered health effect, it can be considered an added
the factors that cause the inhibition of iodide safety factor to protect vulnerable groups
uptake, and the potential adverse health (see Figure 12).
affect is hypothyroidism. The flow chart to It is important to point out that the
the left, adapted from Seller et al (2007), available clinical studies in many cases
illustrates this distinction (see Figure 9). The show that perchlorate affects thyroid
EPA’s reference dose for perchlorate and all functioning (ie. iodide uptake inhibition)
discussion regarding exposure to vulnerable while exposure is occurring, but no study
groups is always referring to the mode of has proven any long term adverse health
16

21. effects of perchlorate at doses that are likely Figure 9: Perchlorate mode of action and
to be consumed by humans from drinking adverse affect when ingested (adapted from
water or food supplies. This section will Seller et al, 2007)
discuss further important human studies
over the past ten years, the relevance of
animal studies, and finally potentially
vulnerable groups of the human population.
Perchlorate and Thyroid Function. When Mode of Action
idodide uptake is reduced, one or more steps
in the synthesis and secretion of thyroid
hormones can be interrupted, resulting in
subnormal levels of T3 (triiodothyronine)
and T4 (thyroxin) and an associated
compensatory increase in secretion of TSH
(thyroid stimulating hormone). Perchlorate
has been found to induce this precursor to
the adverse effect (iodide uptake inhibition)
and subsequent adverse affect in humans
when administered at doses much higher
than those found in the environment (greater
Adverse Affect
than 500 ppb). The perchlorate ion, because
of its similarity to iodide in ionic size and
charge, competes with iodide for uptake into
the thyroid gland by the sodium-iodide
symporter, a transport mechanism in the
membranes of thyroid cells. This
competitive inhibition results in reduce
production of the thyroid hormones T3 and
T4 and a consequent increase in THS where
thyroid, pituitary and hypothalamus are
involved (see figure 10) (ATDSR, 2008).
Subsequent events include decreases
in serum T4 and T3. In mice studies, this
decrease has led to the potential for altered
neurodevelopment if observed in either perturbation of thyroid hormone economy as
mothers, fetuses or neonates, and increase in the primary biological effect of perchlorate
serum TSH leading to the potential for in rats (CDTSC, 2005)
thyroid hyperplasia and tumors (ATDSR,
2008). The repeat observation of thyroid Human Studies. In the US Department of
effects such as alterations of hormones, Health and Human Service’s Toxicological
increase thyroid weight, and alterations of Profile for Perchlorate, studies are
thyroid histopathology from a large number summarized that aimed to determine “does-
of rat studies on perchlorate provide response relationships at low doses of and to
supporting evidence for the propose mode- define no-effect level of exposure to
of-action, and confirms that the perchlorate (ATSDR, 2008).”
17

22. Their summary concludes that no study thus based in Washington D.C.) are cited widely
far has shown perchlorate to cause adverse in the blogosphere and in newspapers,
health effects in humans at doses would indicate that perchlorate has been
encountered in the environment. G. determined highly dangerous to women with
Charnley (2009), Srinivasan et al (2009), low iodide levels, and that the lack of a
and Hagstrom (2006) back up this claim Federal perchlorate regulation is a result of
with their summaries. Defense Department lobbyists and other
special interests. The keystone study cited in
Figure 10: The thyroid and its role in hormone this sphere of information is a 2005 CDC
secretion (image: www.clarion.com) report that establishes a positive relationship
between iodide deficient women,
perchlorate levels in their urine, increasing
serum concentrations of TSH, and
decreasing serum concentrations of T4 (ie.
perchlorate was a predictor for the
imbalance of these hormones in iodine
deficient women).
The study (Blount et al, 2006)
evaluated the relationship between levels of
perchlorate in the urine and serum levels of
TSH and T4 in 2,299 men and women (>11
years old). The study concluded that in
women with urinary iodine < 100µg/L,
perchlorate was a predictor of T4 and TSH.
A previous study on women in Chile (avg.
iodine 269µg/L) exposed to perchlorate
Greer et al (2002) conducted the concentrations of up to 114 µg/L showed no
most widely cited study (under the auspices adverse affect, but their iodine
of the National Academy of Sciences), one concentrations were sufficient. However, the
that is also the basis for the EPA’s Blount study recognized that the low levels
perchlorate reference dose (RfD). 37 human of perchlorate that produced the adverse
volunteers were separated into four groups affect in iodide deficient women did not
and served drinking water amounting to produce adverse affects in numerous
0.007, 0.02, 0.1, and .5 mg/kg-day levels of previous studies. As they put it: “(The
perchlorate for 14 days. Using various adverse affects of this study) are found at
statistical measures of radioiodine uptake perchlorate exposure levels that were
inhibition they determined a true no effect unanticipated based on previous studies
level of 5.2 and 6.4 µg/kg-day measured 8 (Blount et al, 2006).” Furthermore, they
and 24 hours after exposure, respectively. establish a predictor, but the change in T4
For comparison, this would correspond to a and TSH was still within the healthy range
drinking water supply concentration of for a human being. Finally, a New York
about 180 and 220 µg/L (ppb), respectively. Times article quotes the author of the CDC
The levels detected in U.S. drinking water study as follows: “The study did not
supplies generally range from 5-20 µg/L as establish a cause-and-effect relationship but
seen in section IV (Greer et al (2002). pointed to a need for more research
Reports released by the (Goodman, 2009).”
Environmental Working Group (a non-profit
18

23. In addition, and something these time than in rats to affect the circulation of
researchers seemed to have over looked or at T4 and T3 hormones (ATSDR, 2008). There
least considered, is that an iodine deficiency are also physiological differences between
in and of itself is a cause of hypothyroidism, rats and humans related to the pituitary
with or without the perchlorate. Any online thyroid axis, which “makes rats
medical dictionary will explicitly state the inappropriate for quantifying predicted
main adverse affect of iodine deficiency is changes in humans for risk assessment
hypothyroidism. The CDC study removed purposes (Srinivasan, 2009).”
91 women from a total of 1,226 because In the June 2009 Environmental
they had reported a history of Health Perspectives there is a discussion of
hypothyroidism. This indicates that the an article by Gilbert et al (2008) in which he
authors assumed that the majority of women claims neurological development effects of
with a thyroid disorder or out of the ordinary perchlorate in drinking water consumed by
T4 and TSH have been diagnosed. They do adult rats. Though the discussion is not peer
not offer a justification for that assumption. reviewed, it is a discourse about a peer
The authors controlled for many variables reviewed article between the authors of the
that could also be positive predictors of T4 article, and employees from Novice who
or TSH, but none of those include low were contracted to assess the claims of the
iodide levels. The authors also state that the article. While they go back and forth about
World Health Organization defines implications of the article, they both agree
sufficient iodine intake as 100µg/L or more. on one thing: “…the purpose of our study
So by concluding that women with iodide was not to emulate human exposures to
levels below the accepted standard showed perchlorate.” The study found a reduction in
the typical adverse affect of low iodide synaptic functioning at a dose of 4.5 mg/kg-
content, the authors are stating the obvious. day, which is much higher than the
maximum concentration of .5 mg/kg-day in
Animal Studies. Most of the concern about Greer’s study (Gilbert et al, 2009).
perchlorate’s possible adverse effect on
human health stems from extensive research At-risk subpopulations. The main concern
on animals where perchlorate doses have and basis of the perchlorate regulatory
instigated hypothyroidism and tumors. debate is on possible congenital effects.
Generally, the animals in these studies are Since fetuses of hypothyroidic women are at
given doses 10-times or more the amount a greater risk for abnormal growth and
likely to be encountered by humans in the development, the concern is that perchlorate
environment (Srinivasan, 2009). Rats and induced hypothyroidism will produce the
mice are used because in some cases their same effects. “(According the National
response mechanisms to perchlorate would Research Council) because the fetus
be similar to humans. Specifically, rats and depends on an adequate supply of maternal
humans have thyroids that function thyroid hormone for its central nervous
similarly, and the mode of action of system development during the first
perchlorate (i.e., iodide uptake inhibition) is trimester of pregnancy, iodide uptake
analogous. However, the main difference inhibition from low-level perchlorate
between human and animals represented in exposure has been identified as a concern in
the studies is the dose-response connection with increasing the risk of
relationships. In humans, perchlorate neurodevelopmental impairment in fetuses
dosages must occur over a longer period of of high-risk mothers (USEPA, 2008).”
19

24. VII: Regulation
Figure 11: Progression of Perchlorate Regulation at the Federal level in the United States
(self-generated graphic)
Perchlorate Regulation in the United Federal regulation (US EPA, 2009). “The
States. Figure 11 illustrates the history of U.S. Congress is considering two pieces of
perchlorate regulation at the Federal level. legislation, one that would compel the US
Because debate exists regarding its health EPA to establish a drinking water standard
effects at environmentally present doses, for perchlorate and one that would compel
there is not a federal drinking water limit US EPA to determine whether perchlorate
established for perchlorate. California and should be regulated (G. Charnely, 2008).”
Massachusetts are the only two states to
establish an enforceable regulation for According to the EPA, in order to
perchlorate, as shown in Table 8. The Safe regulate a contaminant three conditions must
Drinking Water Act was amended in 1996 to be met:
include section 1412, which mandates the
EPA to evaluate at least five contaminants 1) The contaminant may have an
from its candidate list every 5 years and adverse affect on human health.
determine whether or not they require 2) The contaminant is known to
occur or there is a substantial
Table 8: State Drinking Water Regulations likelihood that the contaminant
(USEPA, 2008) will occur in public water
Advisory Levels systems with a frequency and at
Enforceable Regulations in Other States
levels of public health concern.
2 4‐51 ppb 3) Regulation of such contaminant
Massachusetts presents a meaningful
ppb
opportunity for health risk
California 6 reduction for persons served by
ppb
the public water system.
20

25. Table 9: Relative source contributions of perchlorate in drinking water
for vulnerable subpopulations (USEPA, 2008)
Sub population Body Drinking Water RSC From Potential
Weight Consumption Drinking HA level
Water as %
RfD
Women of 70 kg 2 liters 84‐87% 21 µg/L
Childbearing
Age
Pregnant 70 kg 2 liters 62% 15 µg/L
Women
Figure 12: Quantification and calculations for toxicological effects of
perchlorate (self generated from USEPA, 2008)
NOAEL
RfD =
UF
RfD x BW
DWEL =
DWI
Subchronic HA = DWEL x RSC
7 µg/kg/day
RfD = = 0.7 µg/kg/day
10
0.7 µg/kg/day x 70
DWEL = kg = 24.5 µg/L
2 L/day
Subchronic
= 24.5 µg/L x 0.62 = 0.0152 µg/L (rounded 15 µg/L)
HA
RfD = Reference Dose (mg/kg bw/day)
DWEL = Drinking Water Equivalent Level
RSC = Relative Source Contribution
NOAEL = No Adverse Effect Level (mg/kg bw/day)
UF = Uncertainty factor established for vulnerable subpopulations
BW= Assumed body weight of an adult (70 kg)
DWI = Assumed daily water consumption for an adult (2 L/day)
21

26. In October, 2008 the EPA 90th percentile rather than mean food
determined perchlorate did not meet the 2nd exposure data “to ensure that the interim HA
and 3rd conditions, and asked for public protects highly exposed pregnant women
feedback. They received nearly 33,000 and their fetuses (USEPA, 2008).”
public comments, but as of October, 2009
have not made a final determination on a VIII: Treatment Options
federal regulation. Currently, there is a
Federal Register notice asking for “comment In order for the EPA to set a
on a broader range of alternatives” for regulation for a contaminant they must
evaluating all available data on conditions 1 assess and put forth the most economical
thru 3. remediation and treatment technologies. The
perchlorate treatment technologies can be
2005 Reference Dose & 2009 Health classified according the environmental
Advisory. The EPA assigned a Reference setting of perchlorate. The treatments in this
Dose (RfD) of 0.007 mg/kg/day for section will separate the perchlorate from
perchlorate recommended by the National the medium of interest or degrade it. The
Research Council (NRC, 2005) based off of physical and chemical properties, cost,
the NOEL from Greer et al (2002). A feasibility and source of the contamination
composite uncertainty factor (UF) of 10 was will dictate which treatment is the best.
used to protect the fetuses of pregnant Table 10 summarizes the technologies
woman who might have hypothyroidism or discussed in this section and their range of
iodide deficiency. The RfD represents the effective treatments.
maximum safe oral dose of a
noncarcinogenic substance that can be Ion exchange. Ion exchange (IX) is the
consumed by a human. To correlate this most common used ion exchange. Ion
dose with drinking water safety, a Drinking exchange is a physical-chemical process in
Water Equivalent Level (DWEL) is which charged functional groups, resins, on
established, which is the concentration of a the surface of a solid attracted and thereby
contaminant in drinking water that will have remove ions from water via electrostatic
no adverse effect. The DWEL assumes that forces. Resins are macroporous of which
a 70 kg adult drinks 2 L of water per day contain positively charge surface functional
with no exposure from other sources. Hence, group sorbed with counter ions, usually Cl‫־‬
24.5 ppb (µg/L) is the DWEL recommended anions. When it is exposed to a solution that
by the US-EPA in their integrated risk contains ions like perchlorate, the ions in
information system (see Figure 12) (Gu et solution will enter the ion exchange, in
al, 2006). exchange for Cl‫ ־‬from the resin bead, see
The 2009 interim health advisory figure 13 (Chiang, 2005).
covers a period of more than 30 days, but
less than one year. The subchronic health
advisory is directed towards the fetuses of
iodine deficient pregnant women, and
includes a relative source contribution from
drinking water of 62% specifically for
pregnant women, as their food intake varies
from non-pregnant women and other
populations (see Table 9). The EPA used the
22

27. Table 10: Applicability of common treatment technologies (adapted from Seller, 2007)
Effective
treatment
Type of Technology Soil Water
concentration
treatment
(ppb)
Ion exchange ● 10-100,000
Separation GAC ● 1-10
Membrane filtration ● 10-5,000
Bioreactors ● 100-10,000
In situ 100-500,000
● ●
biodegradation
Thermal destruction ● ● 10-10,000
Destruction Electrochemical 1-10
●
destruction
Iron particles ●
Phytoremediation ● ● 100-10,000
Catalytic reactor ● 10-1,000
Figure 13: Schematic representation of the ion exchange between perchlorate and chloride
(extracted from Gu, 2006)
Ion exchange technology can use multiple (lag beds). Using multiple beds can also
beds in series to reduce the need for bed allow continuous operation because some
regeneration; beds first in the series (lead beds can be regenerated while others
beds) require regeneration first, and fresh continue to treat water, see figure 14 (EPA,
beds can be added at the end of the series 2005).
23

28. Figure 14: Ion exchange treatment for perchlorate removal (Extracted from EPA, 2005)
Granular Activate Carbon (GAC). It is small treatment capacity for perchlorate
one of the oldest means of treatment water removal, and research is underway to
process. GAC is a granular porous that has a identify methods to improve the treatment
sorption capacity of contaminant as capacity of a GAC system for perchlorate
perchlorate. Thus, liquid phase carbon removal, including use of “tailored GAC
adsorption using granular activated carbon (Srinivasan 2009).”
(GAC) is an ex situ technology to remove Rapid Small-Scale Column Test
perchlorate from contaminated groundwater (RSSCT) were dry packed with virgin
and surface water. The mechanism of activate carbon. Water passes onto virgin
perchlorate sorption is not well understood. GAC utilizing RSSCTs containing (180 x
Conceptually, perchlorate interacts with the 250 µm) GAC. The challenge for tailored
positively charged surfaces of the GAC GAC is the regeneration of the medium
particles rather than adsorbing to the inner because it can be regenerated. Hence, any
surfaces of pores in the GAC as would a spent tailored GAC must be removed for
large organic molecule. See figure 14 and disposal. It can be used organic clay and
swap ion exchange resin for a sorbent zone. zeolites instead of GAC (Gu, 2006).
Nevertheless, GAC has a comparatively
Membrane Filtration. Membrane filtration Two streams are produced in the membrane
treatment includes reverse osmosis (RO), process, see figure 15: the filtrate or
nanofiltration (NF), ultrafiltration (UF) and permeate which is nearly deionized water
electrodialysis (ED). Process based on and the brine concentrate or rejectate, which
membrane, water is forced through a semi- contains all reject salts or dissolved material
permeable membrane while dissolved salts including perchlorate.
are unable to pass through the membrane.
24

29. Figure 15: Schematic representation of a membrane filtration system for the treatment of
perchlorate, adapted from (Gu 2006).
ClO4 → Cl − + 2O2
−
Bioreactors. A bioreactor is a situ The first enzymatic step of the pathway,
biological treatment system that degrades perchlorate reduction to chlorite, is
contaminants in extract groundwater using performed by perchlorate reductase. The
microorganisms. Biological treatment can be chlorite produced is subsequently converted
aerobic, or anaerobic. Anaerobic system is to chloride and oxygen, this conversion is
used to treat perchlorate. The done by chlorite dismutase, see figure 16.
microorganisms are facultative anaerobes
and they can use electron acceptor other
than dissolved oxygen such as: nitrate,
perchlorate and sulfate. The dissimilatory
perchlorate reducing bacteria (DPRB) has a
perchlorate reduction pathway consisting of
two key enzymes perchlorate reductase and
chlorite dismutase. These two enzymes
govern the following anaerobic reduction
process (EPA, 2006).
25

30. Organic carbon
ClO4-/ClO3-
e-
ClO2-
e-
Cl- CO2
O2
H2O
Figure 16: Enzymatic pathway of the dissimilatory perchlorate reducing bacteria (DPRB),
adapted from (Gu 2006).
More than 30 different strains of As in bioreactor, bacteria use perchlorate as
perchlorate-degrading microbes have been electron acceptor (Srinivasan 2009). ISB has
identified, with many classified in the reduced perchlorate concentrations less than
Proteobacteria class of the bacteria kingdom.
4 μg/L in groundwater (EPA 2005).
Soil and groundwater samplings have
confirmed the pervasiveness of perchlorate- Thermal Destruction. This process can
reducing bacteria (EPA 2005). remove perchlorate from soil to the vapor
phase and subsequently destroy it. Remove
perchlorate from soil requires temperatures
In situ biodegradation (ISB). ISB comes
between 315 to 650 ºC. This technology is
together hydrogeology, chemistry, also time depending because perchlorate
engineering and microbiology into an volatilizes over a period of time once a
approach for planned and controlled target temperature is achieved. The exhaust
microbial degradation of perchlorate. ISB from this system is accumulated by an air
normally involves nutrients to the cleaning system and heated to temperatures
of approximately 816 ºC to destroy it
subsurface to promote the biodegradation of
completely. It can treat samples with
the perchlorate by the DPRB. The electron concentration from 1 to 110 µg/kg. It can
donors can be substance based on carbon reduce to 4 µg/kg, if the sample is more this
such as: alcohols, organic acids, or sugars. concentration (Seller 2006).
Electrochemical destruction and Iron in concentrated solutions of hypochlorous
particles. This process reduces perchlorate acid is been reduced. Titanium metal is also
into chloride ion. When a cell has nickel used as a chemical reductant to remove
electrode and a platinum counter electrode perchlorate in water. The activation of
26

31. titanium was achieved by eliminating the contaminants by natural processes occurring
localized surface oxide film using within the plant body. This process for
electrochemically induced pitting corrosion. perchlorate removal gain attention in the late
The titanium metal ions in the vicinity of the 1990s, and it was considered for surface,
pits results in a higher rate of perchlorate groundwater and soil. The process, see
reduction. The surface of the bare Ti inside figure 17, ahs two mechanisms: rhizosphere
the pits induces further electrochemical degradation where the perchlorate is present
reactions and causes faster rate of chloride in soil adheres to the root system of the
oxidation to chlorine by increasing the plant. The root system contains various
current (Srinivasan 2009). microbial communities that, thus, provide
Stabilized elemental iron biomass to biodegrade perchlorate. Second
nanoparticles can remove perchlorate mechanism is phytoaccumulation or
knowing that temperature played a critical phytoextraction. Shoots and trees take up
role in perchlorate degradation process. and harvest the perchlorate and the
Perchlorate removal is achieved by iron perchlorate is accumulated in leaves as a
particle at temperature around 200 ºC result of evapotranspiration. The water is
(Srinivasan 2009). evaporated but the perchlorate not, hence,
under anoxic conditions certain
Phytoremediation. Phytoremediation is in microorganism can degrade perchlorate.
situ mechanism that uses plants to remove
Figure 17: Phytoremediation of perchlorate. This process is an emerging technology for
perchlorate remediation (taken from EPA 2005).
also used to reduced perchlorate. Perchlorate
Catalytic reactor. This technology uses absorbs ultraviolet (UV) light in the
hydrogen gas to reduce perchlorate
completely to chloride has been reported. wavelength range shorter than 185
Methylthrioxorhenium is added to combine nanometers, and consequently UV light can
with 5% Pd-carbon powder. Metallic iron be used to catalyze the reduction reaction
and goethite (FeO·OH) or other metal are (seller 2007).
27

32. Cost Implications of Regulating
Perchlorate Conclusions
The American Water Works Perchlorate is an environmental
Association (AWWA) published in March, contaminant which can cause negative
2009 the first report on the national cost health affects at high doses, especially to the
implications of regulating perchlorate with a fetuses of iodine deficient pregnant women.
maximum contaminant level (MCL) at the While the cost of implementing a federal
national level (Russell et al, 2009). If the drinking water standard is low compared to
Federal Government implemented a MCL of previous limits, the cost would fall upon a
4µg/L, 3.4% of public water systems (PWS) few individuals. Clearly, there are many
would be affected, and the net present value stakeholders and we hope the political
(NPV) of compliance costs would be 2.1 process serves both sides of the debate
billion USD. An MCL of 24µg/L would fairly. If a regulation is put in place, we
affect 1% of PWS’s, and the NPV for would recommend the ion exchange method
compliance would be 100 million USD. See as the most reliable and capable of removing
Table 11. perchlorate from public water systems.
According to the AWWA, the
national cost for perchlorate remediation
would be cheaper than previous contaminant
regulations in the United States, but “…a
small number of systems are carrying this
cost burden and the cost implications to an
individual system having to install
perchlorate treatment would likely be
significant (Russell et al, 2009).” They also
say that if Congress decides to pursue a
federal regulation for perchlorate in the
future, this report will be a “key building
block” for subsequent discussions of
national cost.
Table 11: National Cost of Federal
Regulation
MCL % PWS Cost (USD)
affected
4 3.4 2.1 billion
ppb
24 1 100 million
ppb
28