Perchlorate: Contamination in Water and an Assessment of Regulations
Chesten Chong, Maryam Mortezai, Antonio Machado
Department of Environmental and Occupational Health, California State University, Northridge
LEVELS IN ENVIRONMENTAL MATRICES
ABSTRACT
Perchlorate naturally occurs in the environment and has been found in food and water. Perchlorate is introduced
into the environment when rockets were made, tested, and disassembled and from fireworks, explosives, flares,
and similar products. Perchlorate is also an impurity in certain industrial and consumer products, such a cleansers
and bleaches, which also may result in its discharge to the environment.
Perchlorate released to the environment is deposited in soil or water (rivers, streams, lakes, and ponds) and can
leach into groundwater from soil. The main target organ for perchlorate toxicity in humans is the thyroid gland.
Perchlorate inhibits the thyroid’s uptake of iodine. Iodine is required as a building block for the synthesis of
thyroid hormone.
Groundwater Quality Status, 2006-2008
120
100
80
60
40
20
0
Antelope
Valley
Coachella
Valley
Colorado
River Basins
Indian Wells Owens Valley Mojave Area
Low or Not Detected
Perchlorate is a relatively well-studied chemical due its pharmacological uses. The relatively low levels found in
some wells and public water systems are unlikely to cause adverse effects in humans. Perchlorate is not a known
carcinogen, does not accumulate in the body and is excreted from the body within hours.
Moderate
Perchlorate Peak Level (µg/L) from 2010-2013
 The monitoring results showed perchlorate to be a widespread
drinking water contaminant, occurring in several hundred
wells, mostly in southern California. Domestic wells (used for
private wells for household drinking water) were sampled and
are included in these monitoring results. They are not
regulated under the EPA. The homeowners are responsible for
the water quality. Perchlorate has affected sources of drinking
water (domestic wells) in both monitoring done by the CDPH.
108
120
94
100
INTRODUCTION
High
68
80
60
40
 Perchlorate and its salts are mainly used in solid propellants and for
manufacturing matches, rockets, explosives and fireworks. It occurs
naturally in certain fertilizers and potash ores. Perchlorate is a white
crystalline solid or a colorless liquid. It is highly soluble in water and
is a concern in water, soil and food contamination.
20
7.9
4.5
14
4.8
13
9
9.9
10
4.6
According to a 2005 Journal of Environmental Science and Technology study using ion chromatography to find
contaminants in agricultural products found quantifiable levels of perchlorate in 16 percent of conventionally
produced lettuces and other leafy greens and in 32 percent of otherwise similar but organically produced samples.
Perchlorates have been shown to accumulate in the leaves of some food crops, tobacco plants, and more generally in
broad leaf plants. As water transpires from the leaves, perchlorate remains behind in the leaf due to it in volatility
under most environmental conditions. Although experimental studies detailing the environmental fate of perchlorates
are limited, the current consensus indicates that they are persistent under most environmental conditions.
DIPOSITION AND METABOLISM
 The perchlorate anion (ClO4-) commonly originates as a
contaminant in the environment from the improper
disposal of solid salts of ammonium, potassium, or sodium
perchlorate.
 Perchlorates are released to the environment from a
combination of human-made (anthropogenic) and natural
sources. Perchlorate releases from accidents at
manufacturing facilities and unsuccessful rocket launches,
as well as activities related to the manufacture, disposal, or
Whittaker-Bermite , Santa Clarita, CA
research of propellants, explosives, or pyrotechnics, are well
documented.
 Compounds containing perchlorate include the oxidant in solid rocket fuel as well as that in fireworks, military
ordinance, flares, airbags, and other applications where an energetic oxidant is required.
Perchlorates can enter the body after swallowing food or water contaminated with perchlorate. Since they easily
dissolve in water, they quickly pass through the stomach and intestines and enter the bloodstream. Breathing in air
containing dust or droplets of perchlorate, causes the particles to pass through the lungs and enter the bloodstream. It
is unlikely for perchlorates to enter the body directly through the skin, but if present on your hands, hand-to-mouthactivity could contribute to oral exposure.
Perchlorate is not changed inside the body and the blood stream carries perchlorate to all parts of the body. A few
internal organs (for example, the thyroid, breast tissue, and salivary glands) can take up relatively large amounts of
perchlorate from the bloodstream. Perchlorate generally leaves these organs in a few hours.
When perchlorate is swallowed, a small percentage is eliminated in the feces. More than 90% of perchlorate taken in
by mouth enters the bloodstream. In the blood, perchlorate passes into the kidneys, which is then release into the
urine. The body begins to clear itself of perchlorate through the kidneys within 10 minutes of exposure. Most of the
perchlorate that is taken in to the body is quickly eliminated. Perchlorate can occur on the daily basis since it is
present in many foods and in some drinking water sources.
FATE AND TRANSPORT
HEALTH EFFECTS
Perchlorates can enter the environment from several sources, both human-made (called anthropogenic) and
natural sources. Since perchlorate is used in rockets and certain military applications, the manufacture, use,
and disposal of products like rockets and missiles has led to perchlorate being released into the
environment.
 The main target organ for perchlorate toxicity in humans is the
thyroid gland. Perchlorate has been shown to partially inhibit the
thyroid’s uptake of iodine. Iodine is required as a building block for
the synthesis of thyroid hormone. Thyroid hormones regulate certain
body functions after they are released into the blood.
 Perchlorate disrupts one or more steps in the synthesis and
secretion of thyroid hormones, resulting in subnormal levels of
T4 and T3 and an associated compensatory increase in secretion
of TSH. 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 (NIS), a transport
mechanism in the membranes of thyroid cells.
Perchlorates are soluble in water and generally have high mobility in soils. This characteristic results in
their ability to move from soil surfaces into groundwater (a process called leaching) when they enter the
environment. Perchlorates are ionic substances and therefore, do not volatilize from water or soil surfaces.
Perchlorates are known to remain unreacted in the environment for long periods of time. Perchlorates
released to air will eventually settle out of the air, primarily in rainfall.
REMEDIATION
 Perchlorate treatment technologies may be generally
classified into categories of destruction or removal
technologies. Destructive processes include biological
reduction, chemical reduction, and electrochemical
reduction. Physical removal processes include anion
exchange, membrane filtration (including reverse
osmosis and nanofiltration), and electrodialysis, which
all require subsequent disposal of removed perchlorate.
2,000,000,000
1,500,000,000
1,000,000,000
500,000,000
0
4 µg/L
24 µg/L
5.2
ECOTOXICOLOGY
PRODUCTION AND USE
2,500,000,000
20
0
 The presence of perchlorate in groundwater and drinking water is a
potential health concern because perchlorate can impair proper
functioning of the thyroid gland. The thyroid gland produces hormones
that are maintained within narrow concentration limits by an efficient
regulatory mechanism. Hormones required for normal development of
the central nervous system of fetuses and infants are secreted by the
thyroid gland. These hormones are required for normal skeletal growth
and development.
Estimate Cost
10
 The results from the sampling done by the USGS illustrated
that most desert regions have either low/no detect or
moderate concentrations of perchlorate in their groundwater
with the exception of the Coachella Valley. Levels of
perchlorate are due to perchlorate naturally occurring in
groundwater. The concentrations found in groundwater are
generally stable, or change slowly compared to organic
constituents. It is not as critical to have an early warning
groundwater contamination alert since perchlorate is
naturally occurring.
 If the federal stand is to be lowered, costs will have to
be justified. Compliance cost, new standard reduction
and upgrading of public water systems will be needed
if the standard is lowered significantly.
Perchlorate uptake by plants, trees, forage and edible vegetation is known to occur and is another natural attenuation
and redistribution pathway. In fact, phytoremediation of perchlorate has been proposed as a technology to remove
perchlorate from contaminated soils and groundwater, particularly for shallow contamination.
 Besides its potential to cause endocrine system and reproductive problems, perchlorate is considered a “likely
human carcinogen” by the U.S. Environmental Protection Agency (EPA).
REGULATIONS
Summary of proposed state drinking water standards or action levels for perchlorate
Country/State
PHG/MCLG
Proposed
Standard
Arizona
California
6
Maryland
Massachusetts
New Jersey
2
Action Level
Remarks
14
Based on child
exposures
6
Notification level
1
Advisory level
1
5
Health based value
New Mexico
1
New York
5
Nevada
18
Oregon
4
Texas
17
51
U.S. EPA
15
Canada
6
According to a study, microorganisms have been shown to be capable of reducing perchlorate (Cl O−4) to chloride
(Cl−) and oxygen, thus transforming perchlorate into harmless end-products. This study focused on microbialmediated perchlorate reduction, and discusses issues of importance to the remediation of perchlorate contamination
in groundwater.
CONCLUSIONS
The exposure and risk of perchlorate that are found in drinking water are extremely low. Unless taken in at high
levels and exposed for a prolonged period of time, most of the perchlorate levels taken in by the human body are
secreted through the urinary system. The greatest risks to high levels of perchlorate concentrations are sensitive
individuals and those with nutrition deficiency. Perchlorate is found in food and water, but concentration levels are
not high enough to cause adverse health effects in humans Alteration of diet or iodine supplements are not needed to
reduce exposure to perchlorate. A healthy diet including fruits, vegetables and nutrient dense foods should be
followed and the U.S. population consumes the adequate amounts of iodine.
Advisory Level for
children and other atrisk populations for
Bourne
Drinking water
screening level
Drinking water
planning level
Public notice
standard
Residential protective
clean up level (PCL)
Industrial/commercia
l PCL
Interim drinking
water health advisory
level
 The limit of detection for perchlorate is
between 0.01 ppb and 4ppb.
 The highest level in the United States
to date is 3,700,000 ppb, found in
ground water near Las Vegas, Nevada.
 California Department of Public
Health (CDPH) has set the standard
and action level to 6 µg/L.
 Other states have taken a more
stringent action level or standard since
Federal EPA only has an interim action
level and has not finalized a regulation
for perchlorate. Perchlorate is an
unregulated contaminant under the
EPA.
Guidance Level
EPA has developed a Reference Dose (RfD) of 0.0007 mg/kg/day for perchlorate. The RfD is an estimate
of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be
without appreciable risk of deleterious effects during a lifetime. This RfD leads to a drinking water
equivalent level (DWEL) of 24.5 ppb.
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