PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

This Public Health Statement is the summary 

chapter from the Toxicological Profile for 

Perchlorates. It is one in a series of Public Health 

Statements about hazardous substances and their 

health effects. A shorter version, the ToxFAQsTM, 

is also available. This information is important 

because these substances may harm you. The 

effects of exposure to any hazardous substance 

depend on the dose, the duration, how you are 

exposed, personal traits and habits, and whether 

other chemicals are present. For more information, 

call the ATSDR Information Center at 1-800-232-

4636. 

__________________________________________ 

The Environmental Protection Agency (EPA) 

identifies the most serious hazardous waste sites in 

the nation. These sites are then placed on the 

National Priorities List (NPL) and are targeted for 

long-term federal clean-up activities. Perchlorates 

have been found in at least 49 of the 1,581 current 

or former NPL sites. The possibility exists that the 

number of sites at which perchlorates are found may 

increase in the future as more sites are evaluated. In 

addition, perchlorate exposure has been found to be 

more widespread, so that waste sites are only a part 

of the potential perchlorate sources. Other potential 

sources of exposure include food, some water 

supplies, fireworks, road flares, consumer products 

such as bleach and matches, and natural sources. 

When a substance is released either from a large 

area, such as an industrial plant, or from a container, 

such as a drum or bottle, it enters the environment. 

Such a release does not always lead to exposure. 

You can be exposed to a substance only when you 

come in contact with it. You may be exposed by 

breathing, eating, or drinking the substance, or by 

skin contact. 

If you are exposed to perchlorates, many factors 

will determine whether or not you will be affected. 

These factors include the physical form of the 

chemical, the dose (how much), the duration (how 

long), and how you come in contact with them. 

You must also consider any other chemicals to 

which you are exposed and your age, sex, diet, 

family traits, lifestyle, and state of health. 

1.1 WHAT ARE PERCHLORATES? 

The terms perchlorate or perchlorate anion refer to a 

negatively charged group of atoms consisting of a 

central chlorine atom bonded to four oxygen atoms. 

Perchlorate has the molecular formula ClO4

-

. The 

terms perchlorates or perchlorate salts refer to the 

inorganic compounds that contain the perchlorate 

anion bonded to a positively charged group such as 

ammonium or an alkali or alkaline earth metal. 

Perchlorates can form naturally in the atmosphere, 

leading to trace levels of perchlorate in 

precipitation. High levels of perchlorates occur 

naturally in some locations, such as regions of west 

Texas and northern Chile. 

Perchlorates are colorless and have no odor. Five 

perchlorates are manufactured in large amounts: 

magnesium perchlorate, potassium perchlorate, 

ammonium perchlorate, sodium perchlorate, and 

lithium perchlorate. Perchlorates are found in the 

environment in two forms, either as a solid or 

dissolved in water. If no water is present, as in a 

drum or on top of dry ground, then they will exist as 

solids. If water is present, then they will quickly 

dissolve. When perchlorates dissolve, they separate 

into two parts. One part has a positive charge, and 
 PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

the other part has a negative charge. The part with 

the negative charge is called the perchlorate anion 

or just perchlorate. This is the part of the chemical 

that people look for in the environment or in your 

body. 

Perchlorates are stable at normal temperatures, but 

when they are heated to a high temperature, they 

begin to react. Once they begin to react, they 

produce a large amount of heat. This causes more 

of the perchlorates to begin reacting, which makes 

even more heat. This chain reaction process repeats 

itself over and over until an explosion occurs. 

Because perchlorates react this way, they are used 

in rocket motors, fireworks, flares, gunpowder, and 

explosives. 

Because perchlorates can react quickly at high 

temperatures, people did not expect to find them in 

the environment. But at normal Earth temperatures, 

perchlorates react much more slowly. We have 

learned only recently that perchlorates may last in 

the environment unreacted for several years. 

One of the perchlorate salts, ammonium 

perchlorate, is produced in large amounts because it 

is used in rocket fuels. The solid booster rocket on 

the space shuttle is almost 70% ammonium 

perchlorate. Perchlorates are also used in 

explosives. Because perchlorates are used for some 

military applications, many countries consider the 

amounts that they make confidential. This is one 

reason why we do not know the exact amount of 

perchlorates produced or used in the United States 

or around the world. As with most chemicals, 

private companies in the United States are not 

required to provide information on the amount of 

perchlorates that they make or use. We also do not 

know the exact amount of perchlorates brought into 

the United States from other countries, although the 

largest amount probably comes from fireworks. It 

is important to note that production figures for a 

limited set of the larger profile of perchlorate 

applications do not readily translate into 

environmental release data or accurately 

characterize the universe of perchlorate uses and 

potential for release. 

Other uses of perchlorates include temporary 

adhesives, electrolysis baths, batteries, air bags, 

drying agents, etching agents, cleaning agents and 

bleach, and oxygen generating systems. Little data 

are available on the nature, amount, and potential 

for release of these possible sources of perchlorate 

to the environment. Perchlorates are also used for 

making other chemicals. Many years ago, 

perchlorates were used as a medication in the 

United States to treat overactive thyroid glands, and 

they still have some medical uses in the United 

States and other parts of the world. Perchlorate is 

also used in treatment of side effects of amiodarone, 

a drug used in the treatment of cardiac arrhythmias 

and angina. 

1.2 WHAT HAPPENS TO PERCHLORATES 

WHEN THEY ENTER THE 

ENVIRONMENT? 

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 
 PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

periods of time; however, there is evidence that 

microorganisms found in soil and water may 

eventually reduce perchlorate to other substances. 

If perchlorates are released to air, then they will 

eventually settle out of the air, primarily in rainfall. 

Perchlorates do not appear to accumulate in 

animals. Our understanding of perchlorates 

continues to evolve, and scientific understanding 

related to perchlorates will continue to be reviewed 

and re-evaluated when new information becomes 

available. 

Before 1997, it was very hard to measure 

perchlorates in the environment. In 1997, a much 

better method was developed, and low levels of 

perchlorates in water and other media can now be 

measured. Scientists first began looking for 

perchlorates near sites where they had been used or 

discarded, and were surprised when they found 

them in many other places, including areas where 

there was no known perchlorate use. They did not 

think that perchlorates would last very long in the 

environment because of perchlorate’s reactivity. 

Since then, scientists have been looking for 

perchlorates in water at more and more places. 

Perchlorates have recently been found in 

environmental media such as soil, plants, and 

animals located in areas where perchlorate was used 

and released, and in areas where there was no 

known use or man made releases of perchlorates. 

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. When rockets 

undergo successful launches, the intense heat leads 

to nearly complete reaction of the perchlorate. 

Therefore, release of perchlorate to the environment 

often occurs when its intended use does not occur 

(for example, dismantling and disposal of rockets, 

accidental release from manufacturing facilities, or 

unsuccessful rocket launches). In the past, some of 

these activities resulted in high levels of perchlorate 

contamination of soil and groundwater at many 

military installations and rocket manufacturing 

facilities. Today, great effort is made to minimize 

the release of perchlorates when rockets or missiles 

are dismantled or when perchlorates are 

manufactured. Other human-made sources for 

perchlorate release into the environment include 

road-side safety flares and fireworks. Perchlorate 

has also been detected at low levels as an impurity 

in certain consumer products such as bleach, and 

the use and disposal of these products could also 

lead to releases. Perchlorate is a natural component 

of a nitrate fertilizer from Chile that was imported 

and regularly used in the United States for many 

years. Although the use of this fertilizer has 

declined in recent years, perchlorate was released 

directly to soil and plants in areas where this 

fertilizer was applied. In addition, there appear to 

be natural sources of perchlorate in the 

environment. Perchlorates can form naturally in the 

atmosphere, leading to trace levels of perchlorate in 

rainfall. Higher than expected levels of perchlorates 

occur naturally in some locations such as regions of 

west Texas, New Mexico, and northern Chile. A 

combination of human activities and natural sources 

has led to the widespread presence of perchlorates 

in the environment. 
 PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

1.3 HOW MIGHT I BE EXPOSED TO 

PERCHLORATES? 

You may be exposed to perchlorates if you eat food 

or drink water that contains perchlorates. 

Perchlorates have been found in food and milk. 

Some plants, especially leafy green vegetables, have 

been found to have elevated levels of perchlorate. 

When water containing perchlorate is used to 

irrigate the plants, perchlorate is left behind when 

water evaporates from the leaves of the plants. 

Cows may eat fodder containing perchlorate and 

pass them on in their milk. The Food and Drug 

Administration (FDA) recently published the results 

of measurements of perchlorate and iodine levels in 

the food supply. The FDA found that 74% of the 

foods analyzed had at least one sample in which 

perchlorate was detected. The perchlorate dietary 

intake was estimated for 14 different age/gender 

groups in the United States. The lowest intake 

range was estimated as 0.08–0.11 μg/kg/day 

(micrograms/kilogram/day) for males aged 25–30 

years, and the highest estimated intake was to be 

0.35–0.39 μg/kg/day for children 2 years old. 

These levels are not expected to affect human 

health. The FDA did not recommend any changes 

in eating habits of Americans based upon the 

measured levels of perchlorate. 

Perchlorates have been found in lakes, rivers, and 

groundwater wells. Perchlorate has been identified 

at least once in approximately 4% of over 

3,800 community water systems sampled 

throughout the United States. From 26 different 

states and 2 territories, the detectable levels 

averaged 9.8 μg/L (micrograms/liter) and ranged 

from the minimum reporting level of 4 μg/L to a 

maximum at 420 μg/L. 

Additional potential sources of perchorate may be 

found if you live near a rocket manufacturing or 

testing facility, if you live near or work at a factory 

where they are made, or if you live near a factory 

that makes fireworks, flares, or other explosive 

devices. As mentioned earlier, perchlorate is being 

found in small amounts in areas where it has not 

been known to be manufactured, used, or released 

by humans. Exposure to perchlorates at these 

locations may be possible because natural levels of 

perchlorates occur in the environment. 

Perchlorate has been detected at low levels as an 

impurity in certain products that are commonly used 

by humans. Some of these products include bleach 

and cleaning products that may contain bleach, 

bottled water, and tobacco products; even some 

nutritional supplements (vitamins and minerals) 

have been found to contain perchlorates. However, 

vitamin and mineral supplements are typically 

formulated to include iodine, a factor that would 

provide protection against any possible effect of 

perchlorate. 

1.4 HOW CAN PERCHLORATES ENTER 

AND LEAVE MY BODY? 

Perchlorates can enter the body after you have 

swallowed food or water containing them. Since 

they easily dissolve in water, they quickly pass 

through the stomach and intestines and enter the 

bloodstream. If you breathe in air containing dust 

or droplets of perchlorate, it can pass though your 

lungs and enter the bloodstream. Perchlorates 

probably do not enter the body directly through the 
 PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

skin, but if present on your hands, hand-to-mouthactivity could contribute to oral exposure. 

The blood stream carries perchlorate to all parts of 

the body. Perchlorate is not changed inside 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 perchlorates are 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 then release it into the urine. 

The body begins to clear itself of perchlorate 

through the kidneys within 10 minutes of exposure. 

Although most of the perchlorate that is taken into 

the body is quickly eliminated, the presence of 

perchlorate in many foods and in some drinking 

water sources means that exposure may continue to 

occur on a daily basis. 

1.5 HOW CAN PERCHLORATES AFFECT 

MY HEALTH? 

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. Although not 

demonstrated in humans, it is anticipated that 

people exposed to excessive amounts of perchlorate 

for a long time may develop a decreased production 

of thyroid hormones. The medical name for this 

condition is hypothyroidism. Hypothyroidism is 

usually caused by conditions totally unrelated to 

perchlorates. In hypothyroidism, the lower amounts 

of thyroid hormones in your blood cause increases 

in pituitary hormones that can lead to an increase in 

the size of the thyroid gland. The medical name for 

this condition is goiter. Because thyroid hormones 

perform important functions throughout the body, 

many normal body activities also are affected by the 

lower hormone levels. Because perchlorates were 

known to lower thyroid hormone levels, at one time, 

perchlorates were given as a drug (more than 

400 mg per day, which is many times higher than 

the doses that people receive from environmental 

exposures) to treat people with overactive thyroid 

glands (a condition known as hyperthyroidism). 

Side effects seen in a small number of treated 

patients were skin rashes, nausea, and vomiting. A 

few patients developed severe shortages of blood 

cells, and some of them died. Healthy volunteers 

who took approximately 35 mg of perchlorate every 

day (equivalent to drinking 2 liters of water 

containing 17 mg/L or 17 parts per million [ppm] 

perchlorate every day) for 2 weeks or 3 mg daily for 

6 months (equivalent to drinking 2 liters of water 

containing 1.5 mg/L [1.5 ppm] perchlorate every 

day) showed no signs of abnormal functioning of 

their thyroid gland. A study of adults in Nevada 

found that the number of cases of thyroid disease in 

a group of people who drank water contaminated 

with perchlorate was no different than the number 

of cases found in a group of people who drank 

water without perchlorate. This means that levels 

of perchlorate in the water were not the cause of the 

thyroid disease, and a search of the literature 

confirms no evidence of perchlorate inducing 

thyroid disease. Two studies of people who worked 

for years in the production of perchlorate found no 
 PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

evidence of alterations in the workers’ thyroids, 

livers, kidneys, or blood. One of these studies 

estimated that the workers may have taken up about 

34 mg of perchlorate per day. A recent study 

showed that perchlorate levels to which the general 

population of the United States is exposed via food 

and drinking water, were associated with changes in 

thyroid hormone levels in women with low iodine 

intake, suggesting that the effect of perchlorate in 

people depends on gender, the length of exposure, 

and how much iodine the people consume. Further 

research is recommended to affirm these findings. 

As mentioned in the preceding sections, perchlorate 

is a naturally occurring chemical that has been 

found in some foods and in some drinking water 

supplies. Other naturally occuring chemicals, such 

as thiocyanate (in food and cigarette smoke) and 

nitrate (in some food), are also known to inhibit 

iodide uptake. Further studies are needed to 

completely answer all questions about potential 

toxicity of perchlorate. 

The thyroid gland is also the main target organ for 

perchlorate toxicity in animals. The thyroid 

changes caused by perchlorate in animals may lead 

to tumors in the thyroid after a long period. This 

has occurred after administering high amounts 

(928 to 2,573 milligrams perchlorate/kg/day) of 

perchlorate to the animals. The National Academy 

of Sciences (NAS) concluded that based on the 

understanding of the biology of human and rodent 

thyroid tumors, it is unlikely that perchlorate poses 

a risk of thyroid cancer in humans. Perchlorates 

have not been classified for carcinogenic effects by 

the Department of Health and Human Services 

(DHHS) or the International Agency for Research 

on Cancer (IARC). The EPA has determined that 

perchlorate is not likely to pose a risk of thyroid 

cancer in humans, at least at doses below those 

necessary to alter thyroid hormone homeostasis, 

based on the hormonally-mediated mode of action 

in rodent studies and species differences in thyroid 

function. 

Studies in animals also showed that perchlorate did 

not affect the reproductive organs or the animals’ 

capacity to reproduce. The NAS found that the 

studies in animals provided important information, 

but their usefulness to predict whether harmful 

effects could occur in humans is small. 

1.6 HOW CAN PERCHLORATES AFFECT 

CHILDREN? 

This section discusses potential health effects in 

humans from exposures during the period from 

conception to maturity at 18 years of age. 

Children and developing fetuses may be more likely 

to be affected by perchlorate than adults because 

thyroid hormones are essential for normal growth 

and development. Two studies were conducted of 

newborn babies and school-age children from an 

area in Chile where levels of perchlorate in the 

drinking water were much higher than those 

detected in some U.S. water supplies due to natural 

sources of perchlorate. No evidence of abnormal 

thyroid function was found among the babies or the 

children. The mothers and the children may have 

taken approximately 0.2 mg of perchlorate per day 

in the drinking water. Some studies of newborn 

babies in areas from Arizona, California, and 

Nevada, where perchlorate has been found in the 

drinking water, have not provided convincing 

evidence of thyroid abnormalities associated with 
 PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

perchlorate. A Centers for Disease Control and 

Prevention (CDC) study of people all over the 

United States showed that all of the people that 

were tested had detectable concentrations of 

perchlorate in their urine, thus making it difficult to 

find an unexposed comparison group as a control 

population. 

As indicated above, perchlorate has been found in 

breast milk, so that nursing mothers can transfer 

perchlorate to their babies. Nevertheless, the 

beneficial aspects (biological and psychological) of 

breast-feeding outweigh any risks from exposure to 

perchlorate from mother’s milk, especially if they 

consume adequate iodine from food and 

supplements. 

Animal studies have shown a low level of thyroid 

activity in developing animals exposed to 

perchlorates through the placenta before birth or 

through the mother’s milk after birth. Modern 

studies of the effects of perchlorate on developing 

animals have been conducted mostly in rats. Several 

studies in which pregnant rats were given relatively 

low amounts of perchlorate have shown that 

perchlorate can alter the thyroid gland in the 

newborn animals. This has generally occurred 

when perchlorate also affected the thyroid of the 

mothers. In addition, a study suggested an alteration 

in an area of the brain of pups born to rats. The 

NAS (2005) indicated that rats are more sensitive to 

agents that disturb thyroid function than are 

humans, so the relevance of rat studies in 

quantitative terms to humans is limited. 

1.7 HOW CAN FAMILIES REDUCE THE 

RISK OF EXPOSURE TO 

PERCHLORATES? 

Although perchlorate is present in food, milk, and 

drinking water, it is very unlikely that it will be 

present in the air of the average home or apartment. 

Perchlorates are found in some consumer products 

that people use. They are present in highway and 

marine signal flares, small fireworks, gunpowder, 

and matches. Storing these items out of the reach of 

children and not igniting them in a closed 

environment, such as inside the house or the garage, 

will decrease the potential for exposure. 

Although perchlorate has been detected in a few 

samples of bottled water, the levels have been very 

low. Therefore, if you live near a location where 

perchlorates have been found in drinking water at 

high levels, using bottled drinking water may 

reduce the risk to your family, particularly if you 

drink well water that may contain perchlorate. If 

you live in one of these areas, prevent your children 

from playing in dirt and from eating dirt. Make 

sure your children wash their hands frequently, and 

before eating. Discourage your children from 

putting their hands in their mouths or doing other 

hand-to-mouth activities. You may also contact 

local public health authorities and follow their 

advice. 

If you work in a factory that makes or uses 

perchlorates, it is possible to carry perchlorate dust 

from work on your clothing, skin, or hair. You may 

then get perchlorate dust in your car, home, or other 

locations outside of work where family members 

might be exposed. You should know about this 

possibility if you work with perchlorates. Taking a 
 PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

shower will remove any perchlorate dust from your 

skin or hair. Washing your clothes will remove any 

perchlorates dust from them. 

1.8 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO PERCHLORATES? 

Methods to measure perchlorate in the body are not 

routinely available, but perchlorate can be measured 

in the urine. Because perchlorate leaves the body 

fairly rapidly (in a matter of hours), perchlorate in 

the urine can only indicate very recent exposure. 

Levels of thyroid hormones in the blood can be 

monitored. Such tests will tell you if your hormone 

levels are altered, but will not tell you the cause 

(exposure to perchlorate is only one of many 

possibilities). Medical tests can also measure the 

capacity of the thyroid gland to take iodide from the 

blood to manufacture thyroid hormones. Exposure 

to perchlorate can decrease this capacity, but so can 

exposure to other chemicals, as well as iodine 

deficiency and medical conditions unrelated to any 

exposure to chemicals. 

1.9 WHAT RECOMMENDATIONS HAS THE 

FEDERAL GOVERNMENT MADE TO 

PROTECT HUMAN HEALTH? 

The federal government develops regulations and 

recommendations to protect public health. 

Regulations can be enforced by law. The EPA, the 

Occupational Safety and Health Administration 

(OSHA), and the Food and Drug Administration 

(FDA) are some federal agencies that develop 

regulations for toxic substances. Recommendations 

provide valuable guidelines to protect public health, 

but cannot be enforced by law. The Agency for 

Toxic Substances and Disease Registry (ATSDR) 

and the National Institute for Occupational Safety 

and Health (NIOSH) are two federal organizations 

that develop recommendations for toxic substances. 

Regulations and recommendations can be expressed 

as “not-to-exceed” levels, that is, levels of a toxic 

substance in air, water, soil, or food that do not 

exceed a critical value that is usually based on 

levels that affect animals; they are then adjusted to 

levels that will help protect humans. Sometimes 

these not-to-exceed levels differ among federal 

organizations because they used different exposure 

times (an 8-hour workday or a 24-hour day), 

different animal studies, or other factors. 

Recommendations and regulations are also updated 

periodically as more information becomes available. 

For the most current information, check with the 

federal agency or organization that provides it. 

Some regulations and recommendations for 

perchlorates include the following: 

The EPA is currently undertaking efforts to make a 

determination as to whether or not a national 

primary drinking water regulation is needed for 

perchlorate. To make this determination, EPA is 

evaluating information to more fully characterize 

perchlorate exposure to determine if regulation of 

perchlorate in drinking water would represent a 

meaningful opportunity for reducing risks to human 

health as required under the Safe Drinking Water 

Act (SDWA). 

The 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 
 PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

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. EPA calculates the DWEL using the RfD, 

multiplied by an adult body weight of 70 kg, and 

divided by a tap water consumption value of 2 

L/day. EPA’s Office of Solid Waste and 

Emergency Response has provided guidance for 

perchlorate that indicates that the RfD and its 

corresponding DWEL of 24.5 ppb are respectively 

the recommended “to be considered” (TBC) value 

and the preliminary remediation goal (PRG) for 

cleanup under the Comprehensive Environmental 

Response, Compensation, and Liability Act of 1980 

(CERCLA). The EPA is also responsible for 

developing guidelines for controlling hazardous 

waste from the time it is generated until its ultimate 

disposal—in effect, from “cradle to grave”. 

The Department of Transportation (DOT) has 

designated perchlorate as a hazardous material and 

limits the quantity that is transported aboard aircraft 

and vessels. The DOT also provides identification 

and protective guidance for an emergency response 

to a transportation incident involving a hazardous 

material. 

The Department of Defense (DOD) must comply 

with any EPA cleanup standards and processes 

under all applicable environmental laws and 

regulations, including CERCLA, the Resource 

Conservation and Recovery Act (RCRA), the Clean 

Water Act (CWA), and the SDWA. DOD policy 

requires the testing of perchlorate when it is 

reasonably expected that a release has occurred. 

Specifically, the DOD’s policy states that in the 

absence of federal or state standards, if perchlorate 

levels in water exceed 24 ppb (current level of 

concern for managing perchlorate), a site-specific 

risk assessment must be conducted. When an 

assessment indicates that the perchlorate 

contamination could result in adverse health effects, 

the site must be prioritized for risk management. 

DOD will also comply with applicable state or 

federal promulgated standards, whichever is more 

stringent. Additionally, DOD established the 

Emerging Contaminants Directorate in 2006 to help 

the department proactively approach emerging 

contaminants to enable a fully informed, risk-based 

investment decision process that protects human 

health and DOD operations capabilities; perchlorate 

is one of seven emerging contaminants included on 

DOD’s Action List. 

The FDA has developed Dietary Guidelines that 

promote health and reduce risk for chronic diseases 

through diet and physical activity. FDA is not 

recommending any changes to infants’ and 

children’s diets and eating habits based on current 

perchlorate data. FDA continues to recommend a 

healthy eating plan, consistent with the Dietary 

Guidelines for Americans, that emphasizes fruits, 

vegetables, whole grains, and fat-free or low-fat 

milk and milk products; includes lean meats, 

poultry, fish, beans, eggs, and nuts; and is low in 

saturated fats, trans fats, cholesterol, salt (sodium), 

and added sugars. Additionally, adequate intake of 

iodine has previously been recognized as important 

for healthy thyroid function. 

1.10 WHERE CAN I GET MORE 

INFORMATION? 

If you have any more questions or concerns, please 

contact your community or state health or 
 PUBLIC HEALTH STATEMENT 

 Perchlorates CAS#: 10034-81-8, 7778-74-7, 7790-98-9, 7601-89-0, 7791-03-9 

Division of Toxicology and Environmental Medicine September 2008

__________________________________________________________________________________________

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 

environmental quality department, or contact 

ATSDR at the address and phone number below. 

ATSDR can also tell you the location of 

occupational and environmental health clinics. 

These clinics specialize in recognizing, evaluating, 

and treating illnesses that result from exposure to 

hazardous substances. 

Toxicological profiles are also available on-line at 

www.atsdr.cdc.gov and on CD-ROM. You may 

request a copy of the ATSDR ToxProfilesTM CDROM by calling the toll-free information and 

technical assistance number at 1-800-CDCINFO 

(1-800-232-4636), by e-mail at cdcinfo@cdc.gov, 

or by writing to: 

Agency for Toxic Substances and Disease Registry 

Division of Toxicology and Environmental 

Medicine 

1600 Clifton Road NE 

Mailstop F-32 

Atlanta, GA 30333 

Fax: 1-770-488-4178 

Organizations for-profit may request copies of final 

Toxicological Profiles from the following: 

National Technical Information Service (NTIS) 

5285 Port Royal Road 

Springfield, VA 22161 

Phone: 1-800-553-6847 or 1-703-605-6000 

Web site: http://www.ntis.gov/