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Chromium is a naturally occurring element found in rocks, animals, plants, soil, and in volcanic

dust and gases. Chromium is present in the environment in several different forms. The most

common forms are chromium(0), trivalent (or chromium(III)), and hexavalent (or

chromium(VI)). Chromium(III) occurs naturally in the environment and is an essential nutrient

required by the human body to promote the action of insulin in body tissues so that sugar,

protein, and fat can be used by the body. Chromium(VI) and chromium(0) are generally

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produced by industrial processes. No known taste or odor is associated with chromium

compounds. The metal chromium, which is the chromium(0) form, is a steel-gray solid with a

high melting point. It is used mainly for making steel and other alloys. The naturally occurring

mineral chromite in the chromium(III) form is used as brick lining for high-temperature

industrial furnaces, for making metals and alloys (mixtures of metals), and chemical compounds.

Chromium compounds, mostly in chromium(III) or chromium(VI) forms, produced by the

chemical industry are used for chrome plating, the manufacture of dyes and pigments, leather

tanning, and wood preserving. Smaller amounts are used in drilling muds, rust and corrosion

inhibitors, textiles, and toner for copying machines. For more information on the physical and

chemical properties and on the production and use of chromium, see Chapters 3 and 4.

Chromium enters the air, water, and soil mostly in the chromium(III) and chromium(VI) forms

as a result of natural processes and human activities. Emissions from burning coal and oil, and

steel production can increase chromium(III) levels in air. Stainless steel welding, chemical manufacturing,

and use of compounds containing chromium(VI) can increase chromium(VI) levels

in air. Waste streams from electroplating can discharge chromium(VI). Leather tanning and

textile industries as well as those that make dyes and pigments can discharge both chromium(III)

and chromium(VI) into waterways. The levels of both chromium(III) and chromium(VI) in soil

increase mainly from disposal of commercial products containing chromium, chromium waste

from industry, and coal ash from electric utilities.

In air, chromium compounds are present mostly as fine dust particles. This dust eventually

settles over land and water. Rain and snow help remove chromium from air. Chromium

compounds will usually remain in the air for fewer than 10 days. Although most of the

chromium in water binds to dirt and other materials and settles to the bottom, a small amount

may dissolve in the water. Fish do not accumulate much chromium in their bodies from water.

Most of the chromium in soil does not dissolve easily in water and can attach strongly to the soil.

A very small amount of the chromium in soil, however, will dissolve in water and can move

deeper in the soil to underground water. The movement of chromium in soil depends on the type

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and condition of the soil and other environmental factors. For more information about the fate

and movement of chromium compounds in the environment, see Chapters 4 and 5.

You can be exposed to chromium by breathing air, drinking water, or eating food containing

chromium or through skin contact with chromium or chromium compounds. The level of

chromium in air and water is generally low. The concentration of total chromium in air (both

chromium(III) and chromium(VI)) generally ranges between 0.01 and 0.03 microgram (µg) (1 µg

drinking water (mostly as chromium(III)) are generally very low, less than 2 parts of chromium in

a billion parts of water (2 ppb). Contaminated well water may contain chromium(VI). For the

general population, eating foods that contain chromium is the most likely route of chromium(III)

exposure. Chromium(III) occurs naturally in many fresh vegetables, fruits, meat, yeast, and

grain. Various methods of processing, storage, and preparation can alter the chromium content of

food. Acidic foods in contact with stainless steel cans or cooking utensils might contain higher

levels of chromium because of leaching from stainless steel. Refining processes used to make

white bread or sugar can decrease chromium levels. Chromium(III) is an essential nutrient for

humans. On the average, adults in the United States take in an estimated 60 µg of chromium

daily from food. You may also be exposed to chromium from using consumer products such as

household utensils, wood preservatives, cement, cleaning products, textiles, and tanned leather.

People who work in industries that process or use chromium or chromium compounds can be

exposed to higher-than-normal levels of chromium. An estimated 305,000 workers in the United

States are potentially exposed to chromium and chromium-containing compounds in the

workplace.

Occupational sources of chromium exposure (with chemical forms of interest shown in brackets)

may occur in the following industries:

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Examples of other occupations that may involve chromium exposure include these:

disposal of some toner powders from copying machines (chromium(VI))

A list of other industries that may be sources of occupational exposure is given in Section 5.5.

You may be exposed to higher-than-normal levels of chromium if you live near the following:

compounds

textile industries

converters contain chromium

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In addition, you may be exposed to higher levels of chromium if you use tobacco products, since

tobacco contains chromium. For additional information about chromium exposure, see

Chapter 5.

Chromium can enter your body when you breathe air, eat food, or drink water containing

chromium. In general, chromium(VI) is absorbed by the body more easily than chromium(III),

but once inside the body, chromium(VI) is changed to chromium(III). When you breathe air

containing chromium, chromium particles can be deposited in the lungs. Particles that are

deposited in the upper part of the lungs are likely to be coughed up and swallowed. Particles

deposited deep in the lungs are likely to remain long enough for some of the chromium to pass

through the lining of the lungs and enter your bloodstream. Once in the bloodstream, chromium

is distributed to all parts of the body. Chromium will then pass through the kidneys and be

eliminated in the urine in a few days. Everyone normally eats or drinks a small amount of

chromium daily. Most of the chromium that you swallow leaves your body within a few days

through the feces and never enters your blood. A small amount (about 0.4–2.1%) will pass

through the lining of the intestines and enter the bloodstream. Chromium(III) present in food

can attach to other compounds that make it easier for chromium to enter your bloodstream from

your stomach and intestines. This form of chromium is used by your body to carry out essential

body functions. If your skin comes into contact with chromium, very little will enter your body

unless your skin is damaged. For more information, please read Chapter 2.

To protect the public from the harmful effects of toxic chemicals and to find ways to treat people

who have been harmed, scientists use many tests.

One way to see if a chemical will hurt people is to learn how the chemical is absorbed, used, and

released by the body; for some chemicals, animal testing may be necessary. Animal testing may

also be used to identify health effects such as cancer or birth defects. Without laboratory

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animals, scientists would lose a basic method to get information needed to make wise decisions

to protect public health. Scientists have the responsibility to treat research animals with care and

compassion. Laws today protect the welfare of research animals, and scientists must comply

with strict animal care guidelines.

Chromium(III) is an essential nutrient that helps the body use sugar, protein, and fat. An intake

of 50–200 µg of chromium(III) per day is recommended for adults. On the average, adults in the

United States take in an estimated 60–80 µg of chromium per day in food. Therefore, many

people's diets may not provide enough chromium(III). Without chromium(III) in the diet, the

body loses its ability to use sugars, proteins, and fat properly, which may result in weight loss or

decreased growth, improper function of the nervous system, and a diabetic-like condition.

Therefore, chromium(III) compounds have been used as dietary supplements and are beneficial

if taken in recommended dosages.

The health effects resulting from exposure to chromium(III) and chromium(VI) are fairly well

described in the literature. In general, chromium(VI) is more toxic than chromium(III).

chromic acid or chromium(VI) trioxide, can cause irritation to the nose, such as runny nose,

sneezing, itching, nosebleeds, ulcers, and holes in the nasal septum. These effects have

primarily occurred in factory workers who make or use chromium(VI) for several months to

many years. Long-term exposure to chromium has been associated with lung cancer in workers

exposed to levels in air that were 100 to 1,000 times higher than those found in the natural

environment. Lung cancer may occur long after exposure to chromium has ended.

Chromium(VI) is believed to be primarily responsible for the increased lung cancer rates

observed in workers who were exposed to high levels of chromium in workroom air. Breathing

in small amounts of chromium(VI) for short or long periods does not cause a problem in most

people. However, high levels of chromium in the workplace have caused asthma attacks in

people who are allergic to chromium. Breathing in chromium(III) does not cause irritation to the

nose or mouth in most people. In the same way, small amounts of chromium(VI) that you

swallow will not hurt you; however, accidental or intentional swallowing of larger amounts has

caused stomach upsets and ulcers, convulsions, kidney and liver damage, and even death. The

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levels of chromium(VI) that caused these effects were far greater than those that you might be

exposed to in food or water. Although chromium(III) in small amounts is a nutrient needed by

the body, swallowing large amounts of chromium(III) may cause health problems. Workers

handling liquids or solids that have chromium(VI) in them have developed skin ulcers. Some

people have been found to be extremely sensitive to chromium(VI) or chromium(III). Allergic

reactions consisting of severe redness and swelling of the skin have been noted. Exposure to

chromium(III) is less likely than exposure to chromium(VI) to cause skin rashes in chromiumsensitive

people. The metal, chromium(0), is less common and does not occur naturally. We do

not know much about how it affects your health, but chromium(0) is not currently believed to

cause a serious health risk. We have no reliable information that any form of chromium has

harmful effects on reproduction or causes birth defects in humans, though it does not seem likely

that the amount of chromium that most people are exposed to will result in reproductive or

developmental effects.

In animals that breathed high levels of chromium, harmful effects on the respiratory system and

a lower ability to fight disease were noted. However, we do not know if chromium can lower a

person's ability to fight disease. Some of the female mice that were given chromium(VI) by

mouth had fewer offspring and had offspring with birth defects. Some male mice that were

given chromium(VI) or chromium(III) by mouth had decreased numbers of sperm in the testes.

The birth defects or the decrease in sperm occurred in mice at levels about several thousand

times higher than the normal daily intake by humans. Some chromium(VI) compounds produced

lung cancer in animals that breathed in the particles or had the particles placed directly in their

lungs. In animals that were injected with some chromium(VI) compounds, tumors formed at the

site of injection.

Because some chromium(VI) compounds have been associated with lung cancer in workers and

caused cancer in animals, the Department of Health and Human Services has determined that

certain chromium(VI) compounds (calcium chromate, chromium trioxide, lead chromate,

strontium chromate, and zinc chromate) are known human carcinogens. The International

Agency for Research on Cancer (IARC) has determined that chromium(VI) is carcinogenic to

humans, based on sufficient evidence in humans for the carcinogenicity of chromium(VI)

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compounds as found in chromate production, chromate pigment production, and chromium

plating industries. IARC's determination is also based on sufficient evidence in experimental

animals for the carcinogenicity of calcium chromate, zinc chromate, strontium chromate, and

lead chromate; and limited evidence in experimental animals for the carcinogenicity of

chromium trioxide (chromic acid) and sodium dichromate. IARC has also determined that

chromium(0) and chromium(III) compounds are not classifiable as to their carcinogenicity to

humans. The EPA has determined that chromium(VI) in air is a human carcinogen. The EPA

has also determined that there is insufficient information to determine whether chromium(VI) in

water or food and chromium(III) are human carcinogens.

For more information on the health effects of chromium, please see Chapter 2.

This section discusses potential health effects from exposures during the period from conception

to maturity at 18 years of age in humans.

Children who live near wastes sites where chromium is found are likely to be exposed to higher

environmental levels of chromium through breathing, touching soil, and eating contaminated

soil. Children at age five years or younger have higher levels of chromium in their urine than do

adults and children living outside of contaminated areas. Very few studies have looked at how

chromium can affect the health of children. Children need small amounts of chromium(III) for

normal growth and development. It is likely that the health effects seen in children exposed to

high amounts of chromium will be similar to the effects seen in adults. We do not know whether

children differ from adults in their susceptibility to chromium.

We do not know if exposure to chromium will result in birth defects or other developmental

effects in people. Birth defects have been observed in animals exposed to chromium(VI).

Death, skeletal deformities, and impaired development of the reproductive system have been

observed in the newborn babies of animals that swallowed chromium(VI). Additional animal

studies are needed to determine whether exposure to chromium(III) will result in birth defects.

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One animal study showed that more chromium(III) will enter the body of a newborn than an

adult. We do not know if this is also true for chromium(VI). We have no information to suggest

that there are any differences between children and adults in terms of where chromium can be

found in the body, and how fast chromium will leave the body. Studies with mice have shown

that chromium crosses the placenta and concentrates in fetal tissue. Therefore, pregnant women

who were exposed to chromium in the workplace or by living near chromium waste sites may

transfer chromium from their blood into the baby where it may build up at levels greater than in

the mother. There is some evidence in humans that chromium can be transferred from mother to

infant through breast milk.

If your doctor finds that you have been exposed to significant amounts of chromium, ask

whether your children might also be exposed. Your doctor might need to ask your state health

department to investigate.

Children living near chromium waste sites are likely to be exposed to higher environmental

levels of chromium through breathing, touching soil, and eating contaminated soil. Some

children eat a lot of dirt. You should discourage your children from eating dirt. Make sure they

wash their hands frequently and before eating. Discourage your children from putting their

hands in their mouths or hand-to-mouth activity. Although chromium(III) is an essential nutrient

that helps the body use sugar, protein, and fat, you should avoid excessive use of dietary

supplements containing chromium such as chromium picolinate. You should only use the

recommended amount if you choose to use these products and store these products out of

children’s reach in order to avoid accidental poisonings.

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Chromium can be measured in the hair, urine, serum, red blood cells, and whole blood.

However, since chromium(III) is an essential nutrient, low levels of chromium are normally

found in body tissues and urine. Tests for chromium exposure are most useful for people

exposed to high levels. These tests cannot determine the exact levels of chromium you may have

been exposed to or predict whether or not health effects will occur. High chromium levels in the

urine and red blood cells indicate exposure to chromium(VI) or chromium(III) compounds.

Since the body changes chromium(VI) to chromium(III), the form of chromium that you were

exposed to cannot be determined from levels in the urine. Much more chromium(VI) can enter

red blood cells than chromium(III), but chromium(VI) can be changed to chromium(III) within

these cells. Therefore, chromium levels in the red blood cells indicate exposure to

chromium(VI). Because red blood cells last about 120 days before they are replaced by newly

made red blood cells, the presence of chromium in red blood cells can show whether a person

was exposed to chromium 120 days prior to testing but not if exposure occurred longer than

120 days before testing. Skin patch tests may indicate whether a person is allergic to some

chromium salts. For more information, please see Chapters 2 and 6.

The federal government develops regulations and recommendations to protect public health.

Regulations can be enforced by law. Federal agencies that develop regulations for toxic

substances include the Environmental Protection Agency (EPA), the Occupational Safety and

Health Administration (OSHA), and the Food and Drug Administration (FDA).

Recommendations provide valuable guidelines to protect public health but cannot be enforced by

law. Federal organizations that develop recommendations for toxic substances include the

Agency for Toxic Substances and Disease Registry (ATSDR) and the National Institute for

Occupational Safety and Health (NIOSH).

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Regulations and recommendations can be expressed in not-to-exceed levels in air, water, soil, or

food that are usually based on levels that affect animals; then they are adjusted to help protect

people. Sometimes these not-to-exceed levels differ among federal organizations because of

different exposure times (an 8-hour workday or a 24-hour day), the use of different animal

studies, or other factors.

Recommendations and regulations are also periodically updated 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 chromium include the following:

EPA has set the maximum level of chromium(III) and chromium(VI) allowed in drinking water

at 100 µg chromium/L. According to EPA, the following levels of chromium(III) and

chromium(VI) in drinking water are not expected to cause effects that are harmful to health:

1,400 µg chromium/L for 10 days of exposure for children, 240 µg chromium/L for longer term

exposure for children, 840 µg chromium/L for longer term exposure for adults, and 120 µg

chromium/L for lifetime exposure of adults.

OSHA regulates chromium levels in the workplace air. The occupational exposure limits for an

chromium (chromium(0)), and insoluble salts. The level of chromium trioxide (chromic acid)

and other chromium(VI) compounds in the workplace air should not be higher than 52 µg

For chromium(0), chromium(II), and chromium(III), NIOSH recommends an exposure limit of

chromium(VI) compounds (including chromic acid) to be potential occupational carcinogens and

workweek.

For more information, please see Chapter 7.

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If you have any more questions or concerns, please contact your community or state health or

environmental quality department or

Agency for Toxic Substances and Disease Registry

Division of Toxicology

1600 Clifton Road NE, Mailstop E-29

Atlanta, GA 30333

* Information line and technical assistance

Phone: 1-888-42-ATSDR (1-888-422-8737)

Fax: (404) 639-6359

ATSDR can also tell you the location of occupational and environmental health clinics. These

clinics specialize in recognizing, evaluating, and treating illnesses resulting from exposure to

hazardous substances.

* To order toxicological profiles, contact

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

Phone: (800) 553-6847 or (703) 605-6000

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