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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

This Public Health Statement is the summary 

chapter from the Toxicological Profile for cobalt. 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 this 

substance 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 1-888-422-8737. 

This public health statement tells you about cobalt 

and the effects of exposure. 

The Environmental Protection Agency (EPA) 

identifies the most serious hazardous waste sites in 

the nation. These sites make up the National 

Priorities List (NPL) and are the sites targeted for 

long-term federal cleanup activities. Stable cobalt 

has been found in at least 426 of the 1,636 current 

or former NPL sites. Radioactive cobalt, as 60Co, 

has been found in at least 13 of the 1,636 current or 

former NPL sites. However, the total number of 

NPL sites evaluated for this substance is not known. 

As more sites are evaluated, the sites at which 

cobalt is found may increase. This information is 

important because exposure to this substance may 

harm you and because these sites may be sources of 

exposure. 

When a substance is released from a large area, 

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

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

release does not always lead to exposure. You are 

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. 

External exposure to radiation may occur from 

natural or man-made sources. Naturally occurring 

sources of radiation are cosmic radiation from space 

or radioactive materials in soil or building materials. 

Man-made sources of radioactive materials are 

found in consumer products, industrial equipment, 

atom bomb fallout, and to a smaller extent from 

hospital waste and nuclear reactors. 

If you are exposed to cobalt, many factors 

determine whether you'll be harmed. These factors 

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

long), and how you come in contact with it. You 

must also consider the other chemicals you're 

exposed to and your age, sex, diet, family traits, 

lifestyle, and state of health. 

1.1 WHAT IS COBALT? 

Cobalt is a naturally-occurring element that has 

properties similar to those of iron and nickel. It has 

an atomic number of 27. There is only one stable 

isotope of cobalt, which has an atomic mass number 

of 59. (An element may have several different 

forms, called isotopes, with different weights 

depending on the number of neutrons that it 

contains. The isotopes of an element, therefore, 

have different atomic mass numbers [number of 

protons and neutrons], although the atomic number 

[number of protons] remains the same.) However, 

there are many unstable or radioactive isotopes, two 

of which are commercially important, cobalt-60 and 

cobalt-57, also written as Co-60 or 60Co and 

Co-57 or 57Co, and read as cobalt sixty and cobalt 

fifty-seven. All isotopes of cobalt behave the same 

chemically and will therefore have the same 

chemical behavior in the environment and the same 

chemical effects on your body. However, isotopes 

have different mass numbers and the radioactive 

isotopes have different radioactive properties, such 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

as their half-life and the nature of the radiation they 

give off. The half-life of a cobalt isotope is the time 

that it takes for half of that isotope to give off its 

radiation and change into a different isotope. After 

one half-life, one-half of the radioactivity is gone. 

After a second half-life, one-fourth of the original 

radioactivity is left, and so on. Radioactive isotopes 

are constantly changing into different isotopes by 

giving off radiation, a process referred to as 

radioactive decay. The new isotope may be a 

different element or the same element with a 

different mass. 

Small amounts of cobalt are naturally found in most 

rocks, soil, water, plants, and animals, typically in 

small amounts. Cobalt is also found in meteorites. 

Elemental cobalt is a hard, silvery grey metal. 

However, cobalt is usually found in the 

environment combined with other elements such as 

oxygen, sulfur, and arsenic. Small amounts of these 

chemical compounds can be found in rocks, soil, 

plants, and animals. Cobalt is even found in water 

in dissolved or ionic form, typically in small 

amounts. (Ions are atoms, collections of atoms, or 

molecules containing a positive or negative electric 

charge.) A biochemically important cobalt 

compound is vitamin B12 or cyanocobalamin. 

Vitamin B12 is essential for good health in animals 

and humans. Cobalt is not currently mined in the 

United States, but has been mined in the past. 

Therefore, we obtain cobalt and its other chemical 

forms from imported materials and by recycling 

scrap metal that contains cobalt. 

Cobalt metal is usually mixed with other metals to 

form alloys, which are harder or more resistant to 

wear and corrosion. These alloys are used in a 

number of military and industrial applications such 

as aircraft engines, magnets, and grinding and 

cutting tools. They are also used in artificial hip 

and knee joints. Cobalt compounds are used as 

colorants in glass, ceramics, and paints, as catalysts, 

and as paint driers. Cobalt colorants have a 

characteristic blue color; however, not all cobalt 

compounds are blue. Cobalt compounds are also 

used as trace element additives in agriculture and 

medicine. 

Cobalt can also exist in radioactive forms. A 

radioactive isotope of an element constantly gives 

off radiation, which can change it into an isotope of 

a different element or a different isotope of the 

same element. This newly formed nuclide may be 

stable or radioactive. This process is called 

radioactive decay. 60Co is the most important 

radioisotope of cobalt. It is produced by 

bombarding natural cobalt, 59Co, with neutrons in a 

nuclear reactor. 60Co decays by giving off a beta 

ray (or electron), and is changed into a stable 

nuclide of nickel (atomic number 28). The half-life 

of 60Co is 5.27 years. The decay is accompanied by 

the emission of high energy radiation called gamma 

rays. 60Co is used as a source of gamma rays for 

sterilizing medical equipment and consumer 

products, radiation therapy for treating cancer 

patients, and for manufacturing plastics. 60Co has 

also been used for food irradiation; depending on 

the radiation dose, this process may be used to 

sterilize food, destroy pathogens, extend the shelflife of food, disinfest fruits and grain, delay 

ripening, and retard sprouting (e.g., potatoes and 

onions). 57Co is used in medical and scientific 

research and has a half-life of 272 days. 57Co 

undergoes a decay process called electron capture to 

form a stable isotope of iron (57Fe). Another 

important cobalt isotope, 58Co, is produced when 

nickel is exposed to a source of neutrons. Since 

nickel is used in nuclear reactors, 58Co may be 

unintentionally produced and appear as a 

contaminant in cooling water released by nuclear 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

reactors. 58Co also decays by electron capture, 

forming another stable isotope of iron (58Fe). 60Co 

may be similarly produced from cobalt alloys in 

nuclear reactors and released as a contaminant in 

cooling water. 58Co has a half-life of 71 days and 

gives off beta and gamma radiation in the decay 

process. 

Quantities of radioactive cobalt are normally 

measured in units of radioactivity (curies or 

becquerels) rather than in units of mass (grams). 

The becquerel (Bq) is a new international unit, and 

the curie (Ci) is the traditional unit; both are 

currently used. A becquerel is the amount of 

radioactive material in which 1 atom transforms 

every second, and a curie is the amount of 

radioactive material in which 37 billion atoms 

transform every second. For an overview of basic 

radiation physics, chemistry, and biology see 

Appendix D of the cobalt profile. For more 

information on radiation, see the ATSDR 

Toxicological Profile for Ionizing Radiation. 

1.2 WHAT HAPPENS TO COBALT WHEN 

IT ENTERS THE ENVIRONMENT? 

Cobalt may enter the environment from both natural 

sources and human activities. Cobalt occurs 

naturally in soil, rock, air, water, plants, and 

animals. It may enter air and water, and settle on 

land from windblown dust, seawater spray, volcanic 

eruptions, and forest fires and may additionally get 

into surface water from runoff and leaching when 

rainwater washes through soil and rock containing 

cobalt. Soils near ore deposits, phosphate rocks, or 

ore smelting facilities, and soils contaminated by 

airport traffic, highway traffic, or other industrial 

pollution may contain high concentrations of cobalt. 

Small amounts of cobalt may be released into the 

atmosphere from coal-fired power plants and 

incinerators, vehicular exhaust, industrial activities 

relating to the mining and processing of cobaltcontaining ores, and the production and use of 

cobalt alloys and chemicals. 58Co and 60Co may be 

released to the environment as a result of nuclear 

accidents (i.e, Chernobyl), radioactive waste 

dumping in the sea or from radioactive waste 

landfills, and nuclear power plant operations. 

Cobalt cannot be destroyed in the environment. It 

can only change its form or become attached or 

separated from particles. Cobalt released from 

power plants and other combustion processes is 

usually attached to very small particles. Cobalt 

contained in windborne soil is generally found in 

larger particles than those released from power 

plants. These large particles settle to the ground or 

are washed out of the air by rain. Cobalt that is 

attached to very small particles may stay in the air 

for many days. Cobalt released into water may 

stick to particles in the water column or to the 

sediment at the bottom of the body of water into 

which it was released, or remain in the water 

column in ionic form. The specific fate of cobalt 

will depend on many factors such as the chemistry 

of the water and sediment at a site as well as the 

cobalt concentration and water flow. Cobalt 

deposited on soil is often strongly attached to soil 

particles and therefore would not travel very far into 

the ground. However, the form of the cobalt and 

the nature of the soil at a particular site will affect 

how far cobalt will penetrate into the soil. Both in 

soil and sediment, the amount of cobalt that is 

mobile will increase under more acidic conditions. 

Ultimately, most cobalt ends up in the soil or 

sediment. 

Plants can accumulate very small amounts of cobalt 

from the soil, especially in the parts of the plant that 

you eat most often, such as the fruit, grain, and 

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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

seeds. While animals that eat these plants will 

accumulate cobalt, cobalt is not known to 

biomagnify (produce increasingly higher 

concentrations) up the food chain. Therefore, 

vegetables, fruits, fish, and meat that you consume 

will generally not contain high amounts of cobalt. 

Cobalt is an essential element, required for good 

health in animals and humans, and therefore, it is 

important that foodstuffs contain adequate 

quantities of cobalt. 

60Co and 58Co are moderately short-lived, 

manufactured radioactive isotopes that are produced 

in nuclear reactors. Although these isotopes are not 

produced by nuclear fission, small amounts of these 

radioisotopes are also produced by the neutron 

interaction with the structural materials found in the 

reactor of nuclear plants, and are produced during 

the routine operation of nuclear plants. Small 

amounts may be released to the environment as 

contaminants in cooling water or in radioactive 

waste. Since these isotopes are not fission products, 

they are not produced in nuclear weapons testing 

and are not associated with nuclear fallout. In the 

environment, radioactive isotopes of cobalt will 

behave chemically like stable cobalt. However,

60Co and 58Co will also undergo radioactive decay 

according to their respective half-lives, 5.27 years 

and 71 days. 

1.3 HOW MIGHT I BE EXPOSED TO 

COBALT? 

Cobalt is widely dispersed in the environment in 

low concentrations. You may be exposed to small 

amounts of cobalt by breathing air, drinking water, 

and eating food containing it. Children may also be 

exposed to cobalt by eating dirt. You may also be 

exposed by skin contact with soil, water, cobalt 

alloys, or other substances that contain cobalt. 

Analytical methods used by scientists to determine 

the levels of cobalt in the environment generally do 

not determine the specific chemical form of cobalt 

present. Therefore, we do not always know the 

chemical form of cobalt to which a person may be 

exposed. Similarly, we do not know what forms of 

cobalt are present at hazardous waste sites. Some 

forms of cobalt may be insoluble or so tightly 

attached to particles or embedded in minerals that 

they are not taken up by plants and animals. Other 

forms of cobalt that are weakly attached to particles 

may be taken up by plants and animals. 

The concentration of cobalt in soil varies widely, 

generally ranging from about 1 to 40 ppm 

(1 ppm=1 part of cobalt in a million parts of soil by 

weight), with an average level of 7 ppm. Soils 

containing less than about 3 ppm of cobalt are 

considered cobalt-deficient because plants growing 

in them do not have sufficient cobalt to meet the 

dietary requirements of cattle and sheep. Such 

cobalt-deficient soils are found in some areas in the 

southeast and northeast parts of the United States. 

On the other hand, soils near cobalt-containing 

mineral deposits, mining and smelting facilities, or 

industries manufacturing or using cobalt alloys or 

chemicals may contain much higher levels of 

cobalt. 

Usually, the air contains very small amounts of 

cobalt, less than 2 nanograms (1 nanogram=onebillionth part of a gram) per cubic meter (ng/m3

). 

The amount of cobalt that you breathe in a day is 

much less than what you consume in food and 

water. You may breathe in higher levels of cobalt 

in dust in areas near cobalt-related industries or near 

certain hazardous waste sites. 

The concentration of cobalt in surface and 

groundwater in the United States is generally low— 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

between 1 and 10 parts of cobalt in 1 billion parts of 

water (ppb) in populated areas; concentration may 

be hundreds or thousands times higher in areas that 

are rich in cobalt-containing minerals or in areas 

near mining or smelting operations. In most 

drinking water, cobalt levels are less than 1–2 ppb. 

For most people, food is the largest source of cobalt 

intake. The average person consumes about 

11 micrograms of cobalt a day in their diet. 

Included in this food is vitamin B12, which is found 

in meat and diary products. The recommended 

daily intake of vitamin B12 is 6 micrograms 

(1 microgram=one-millionth part of a gram). 

You may also be exposed to higher levels of cobalt 

if you work in metal mining, smelting, and refining, 

in industries that make or use cutting or grinding 

tools, or in other industries that produce or use 

cobalt metal and cobalt compounds. If good 

industrial hygiene is practiced, such as the use of 

exhaust systems in the workplace, exposure can be 

reduced to safe levels. Industrial exposure results 

mainly from breathing cobalt-containing dust. 

When we speak of exposure to 60Co, we are 

interested in exposure to the radiation given off by 

this isotope, primarily the gamma rays. The general 

population is rarely exposed to this radiation unless 

a person is undergoing radiation therapy. However, 

workers at nuclear facilities, irradiation facilities, or 

nuclear waste storage sites may be exposed to 60Co 

or 58Co. Exposures to radiation at these facilities 

are regulated and carefully monitored and 

controlled. 

1.4 HOW CAN COBALT ENTER AND 

LEAVE MY BODY? 

Cobalt can enter your body when you breathe in air 

containing cobalt dust, when you drink water that 

contains cobalt, when you eat food that contains 

cobalt, or when your skin touches materials that 

contain cobalt. If you breathe in air that contains 

cobalt dust, the amount of inhaled cobalt that stays 

in your lungs depends on the size of the dust 

particles. The amount that is then absorbed into 

your blood depends on how well the particles 

dissolve. If the particles dissolve easily, then it is 

easier for the cobalt to pass into your blood from the 

particles in your lungs. If the particles dissolve 

slowly, then they will remain in your lungs longer. 

Some of the particles will leave your lungs as they 

normally clean themselves out. Some of the 

particles will be swallowed into your stomach. The 

most likely way you will be exposed to excess 

cobalt is by eating contaminated food or drinking 

contaminated water. Levels of cobalt normally 

found in the environment, however, are not high 

enough to result in excess amounts of cobalt in food 

or water. The amount of cobalt that is absorbed into 

your body from food or water depends on many 

things including your state of health, the amount 

you eat or drink, and the number of days, weeks, or 

years you eat foods or drink fluids containing 

cobalt. If you do not have enough iron in your 

body, the body may absorb more cobalt from the 

foods you eat. Once cobalt enters your body, it is 

distributed into all tissues, but mainly into the liver, 

kidney, and bones. After cobalt is breathed in or 

eaten, some of it leaves the body quickly in the 

feces. The rest is absorbed into the blood and then 

into the tissues throughout the body. The absorbed 

cobalt leaves the body slowly, mainly in the urine. 

Studies have shown that cobalt does not readily 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

enter the body through normal skin, but it can if the 

skin has been cut. 

1.5 HOW CAN COBALT AFFECT MY 

HEALTH? 

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. In the case of a radioactive 

chemical, it is also important to gather information 

concerning the radiation dose and dose rate to 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 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. 

Cobalt has both beneficial and harmful effects on 

human health. Cobalt is beneficial for humans 

because it is part of vitamin B12, which is essential 

to maintain human health. Cobalt 

(0.16–1.0 mg cobalt/kg of body weight) has also 

been used as a treatment for anemia (less than 

normal number of red blood cells), including in 

pregnant women, because it causes red blood cells 

to be produced. Cobalt also increases red blood cell 

production in healthy people, but only at very high 

exposure levels. Cobalt is also essential for the 

health of various animals, such as cattle and sheep. 

Exposure of humans and animals to levels of cobalt 

normally found in the environment is not harmful. 

When too much cobalt is taken into your body, 

however, harmful health effects can occur. 

Workers who breathed air containing 0.038 mg 

cobalt/m3

 (about 100,000 times the concentration 

normally found in ambient air) for 6 hours had 

trouble breathing. Serious effects on the lungs, 

including asthma, pneumonia, and wheezing, have 

been found in people exposed to 0.005 mg 

cobalt/m3 while working with hard metal, a cobalttungsten carbide alloy. People exposed to 0.007 mg 

cobalt/m3 at work have also developed allergies to 

cobalt that resulted in asthma and skin rashes. The 

general public, however, is not likely to be exposed 

to the same type or amount of cobalt dust that 

caused these effects in workers. 

In the 1960s, some breweries added cobalt salts to 

beer to stabilize the foam (resulting in exposures of 

0.04–0.14 mg cobalt/kg). Some people who drank 

excessive amounts of beer (8–25 pints/day) 

experienced serious effects on the heart. In some 

cases, these effects resulted in death. Nausea and 

vomiting were usually reported before the effects on 

the heart were noticed. Cobalt is no longer added to 

beer so you will not be exposed from this source. 

The effects on the heart, however, may have also 

been due to the fact that the beer-drinkers had 

protein-poor diets and may have already had heart 

damage from alcohol abuse. Effects on the heart 

were not seen, however, in people with anemia 

treated with up to 1 mg cobalt/kg, or in pregnant 

women with anemia treated with 0.6 mg cobalt/kg. 

Effects on the thyroid were found in people exposed 

to 0.5 mg cobalt/kg for a few weeks. Vision 

problems were found in one man following 

treatment with 1.3 mg cobalt/kg for 6 weeks, but 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

this effect has not been seen in other human or 

animal studies. 

Being exposed to radioactive cobalt may be very 

dangerous to your health. If you come near 

radioactive cobalt, cells in your body can become 

damaged from gamma rays that can penetrate your 

entire body, even if you do not touch the radioactive 

cobalt. Radiation from radioactive cobalt can also 

damage cells in your body if you eat, drink, breathe, 

or touch anything that contains radioactive cobalt. 

The amount of damage depends on the amount of 

radiation to which you are exposed, which is related 

to the amount of activity in the radioactive material 

and the length of time that you are exposed. Most 

of the information regarding health effects from 

exposure to radiation comes from exposures for 

only short time periods. The risk of damage from 

exposure to very low levels of radiation for long 

time periods is not known. If you are exposed to 

enough radiation, you might experience a reduction 

in white blood cell number, which could lower your 

resistance to infections. Your skin might blister or 

burn, and you may lose hair from the exposed areas. 

This happens to cancer patients treated with large 

amounts of radiation to kill cancer. Cells in your 

reproductive system could become damaged and 

cause temporary sterility. Exposure to lower levels 

of radiation might cause nausea, and higher levels 

can cause vomiting, diarrhea, bleeding, coma, and 

even death. Exposure to radiation can also cause 

changes in the genetic materials within cells and 

may result in the development of some types of 

cancer. 

Studies in animals suggest that exposure to high 

amounts of nonradioactive cobalt during pregnancy 

might affect the health of the developing fetus. 

Birth defects, however, have not been found in 

children born to mothers who were treated with 

cobalt for anemia during pregnancy. The doses of 

cobalt used in the animal studies were much higher 

than the amounts of cobalt to which humans would 

normally be exposed. 

Nonradioactive cobalt has not been found to cause 

cancer in humans or in animals following exposure 

in the food or water. Cancer has been shown, 

however, in animals who breathed cobalt or when 

cobalt was placed directly into the muscle or under 

the skin. Based on the animal data, the 

International Agency for Research on Cancer 

(IARC) has determined that cobalt is possibly 

carcinogenic to humans. 

Much of our knowledge of cobalt toxicity is based 

on animal studies. Cobalt is essential for the growth 

and development of certain animals, such as cows 

and sheep. Short-term exposure of rats to high 

levels of cobalt in the air results in death and lung 

damage. Longer-term exposure of rats, guinea pigs, 

hamsters, and pigs to lower levels of cobalt in the 

air results in lung damage and an increase in red 

blood cells. Short-term exposure of rats to high 

levels of cobalt in the food or drinking water results 

in effects on the blood, liver, kidneys, and heart. 

Longer-term exposure of rats, mice, and guinea pigs 

to lower levels of cobalt in the food or drinking 

water results in effects on the same tissues (heart, 

liver, kidneys, and blood) as well as the testes, and 

also causes effects on behavior. Sores were seen on 

the skin of guinea pigs following skin contact with 

cobalt for 18 days. Generally, cobalt compounds 

that dissolve easily in water are more harmful than 

those that are hard to dissolve in water. 

Much of what we know about the effects of 

radioactive cobalt comes from studies in animals. 

The greatest danger of radiation seen in animals is 

the risk to the developing animal, with even 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

moderate amounts of radiation causing changes in 

the fetus. High radiation doses in animals have also 

been shown to cause temporary or permanent 

sterility and changes in the lungs, which affected 

the animals’ breathing. The blood of exposed 

animals has lower numbers of white blood cells, the 

cells that aid in resistance to infections, and red 

blood cells, which carry oxygen in the blood. 

Radioactive cobalt exposures in animals have also 

caused genetic damage to cells, cancer, and even 

death. 

1.6 HOW CAN COBALT AFFECT 

CHILDREN? 

This section discusses potential health effects from 

exposures during the period from conception to 

maturity at 18 years of age in humans. 

Children can be exposed to cobalt in the same ways 

as adults. In addition, cobalt may be transferred 

from the pregnant mother to the fetus or from the 

mother to the infant in the breast milk. Children 

may be affected by cobalt the same ways as adults. 

Studies in animals have suggested that children may 

absorb more cobalt from foods and liquids 

containing cobalt than adults. Babies exposed to 

radiation while in their mother’s womb are believed 

to be much more sensitive to the effects of radiation 

than adults. 

1.7 HOW CAN FAMILIES REDUCE THE 

RISK OF EXPOSURE TO COBALT 

If your doctor finds that you have been exposed to 

significant amounts of cobalt, ask whether your 

children might also be exposed. Your doctor might 

need to ask your state health department to 

investigate. 

Since cobalt is naturally found in the environment, 

people cannot avoid being exposed to it. However, 

the relatively low concentrations present do not 

warrant any immediate steps to reduce exposure. If 

you are accidentally exposed to large amounts of 

cobalt, consult a physician immediately. 

Children living near waste sites containing cobalt 

are likely to be exposed to higher environmental 

levels of cobalt 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. 

You are unlikely to be exposed to high levels of 

radioactive cobalt unless you are exposed as part of 

a radiotherapy treatment, there is an accident 

involving a cobalt sterilization or radiotherapy unit, 

or there is an accidental release from a nuclear 

power plant. In such cases, follow the advice of 

public health officials who will publish guidelines 

for reducing exposure to radioactive material when 

necessary. Workers who work near or with 

radioactive cobalt should follow the workplace 

safety guidelines of their institution carefully to 

reduce the risk of accidental irradiation. 

1.8 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO COBALT? 

We have reliable tests that can measure cobalt in the 

urine and the blood for periods up to a few days 

after exposure. The amount of cobalt in your blood 

or urine can be used to estimate how much cobalt 

you had taken into your body. The tests are not able 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

to accurately predict potential health effects 

following exposure to cobalt. 

It is difficult to determine whether a person has 

been exposed only to external radiation from 

radioactive cobalt unless the radiation dose was 

rather large. Health professionals examining people 

who have health problems similar to those resulting 

from radiation exposure would need to rely on 

additional information in order to establish if such 

people had been near a source of radioactivity. It is 

relatively easy to determine whether a person has 

been internally exposed to radioactive cobalt. 

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. Federal 

agencies that develop regulations for toxic 

substances include the Environmental Protection 

Agency (EPA), the Occupational Safety and Health 

Administration (OSHA), the Food and Drug 

Administration (FDA), and the U.S. Nuclear 

Regulatory Commission (USNRC). 

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), the National Institute for Occupational 

Safety and Health (NIOSH), and the FDA. 

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; 

they are then 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 cobalt include the following: 

EPA requires that the federal government be 

notified if more than 1,000 pounds of cobalt (as the 

bromide, formate, and sulfamate compounds) are 

released into the environment in a 24-hour period. 

OSHA regulates levels of nonradioactive cobalt in 

workplace air. The limit for an 8-hour workday, 

40-hour workweek is an average of 0.1 mg/m3

. The 

USNRC and the Department of Energy (DOE) 

regulate occupational exposures as well as 

exposures of the general public to radioactive 

cobalt. 

1.10 WHERE CAN I GET MORE 

INFORMATION? 

If you have any more questions or concerns, please 

contact your community or state health or 

environmental quality department, your regional 

Nuclear Regulatory Commission office, 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 resulting from exposure to 

hazardous substances. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov 
 

 

 

 

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PUBLIC HEALTH STATEMENT 

Cobalt 

CAS#: 7440-48-4 

Division of Toxicology April 2004 

Toxicological profiles are also available on-line at 

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

request a copy of the ATSDR ToxProfiles 

CD-ROM by calling the information and technical 

assistance toll-free number at 1-888-42ATSDR 

(1-888-422-8737), by email at atsdric@cdc.gov, or 

by writing to: 

Agency for Toxic Substances and Disease Registry 

Division of Toxicology 

1600 Clifton Road NE 

Mailstop F-32 

Atlanta, GA 30333 

Fax: 1-770-488-4178 

For-profit organizations may request a copy of final 

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/ 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov