1.1 What is cadmium? |
1.2 What happens to cadmium when it enters
the environment? |
1.3 How might I be exposed to cadmium? |
1.4 How can cadmium enter and leave my
body? |
1.5 How can cadmium affect my health? |
1.6 How does it affect children? |
1.7 How can families reduce the risk of
exposure to cadmium? |
1.8 Is there a medical test to determine
whether I have been exposed to cadmium? |
1.9 What recommendations has the federal
government made to protect human health? |
1.10 Where can I get more information? |
References |
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July 1999 |
Public Health Statement |
for |
Cadmium |
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This Public Health Statement is the
summary chapter from the Toxicological
Profile for cadmium. It is one in a series of Public Health
Statements about hazardous substances and their health effects.
A shorter version, the ToxFAQs™,
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.
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This public health statement tells you
about cadmium 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 a long-term federal cleanup.
Cadmium has been found in at least 776 of the 1,467 current
or former NPL sites. However, its unknown how many NPL
sites have been evaluated for this substance. As more
sites are evaluated, the sites with cadmium may increase.
This 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 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 cadmium, many factors
determine whether you'll be harmed. These factors include
the dose (how much), the duration (how long), the chemical
or physical form of cadmium present, 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.
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1.1
What is cadmium? |
Cadmium is an element that occurs naturally
in the earth's crust. Pure cadmium is a soft, silver-white
metal. Cadmium is not usually present in the environment
as a pure metal, but as a mineral combined with other elements
such as oxygen (cadmium oxide), chlorine (cadmium chloride),
or sulfur (cadmium sulfate, cadmium sulfide). Cadmium
is most often present in nature as complex oxides, sulfides,
and carbonates in zinc, lead, and copper ores. It is rarely
present in large quantities as the chlorides and sulfates.
These different forms of cadmium compounds are solids that
dissolve in water to varying degrees. The chlorides
and sulfates are the forms that most easily dissolve in water.
Cadmium may change forms, but the cadmium metal itself does
not disappear from the environment. Knowing the particular
form of cadmium, however, is very important when determining
the risk of potential adverse health effects.
Cadmium compounds are often found in
or attached to small particles present in air. Most
people can not tell by smell or taste that cadmium is present
in air or water, because it does not have any recognizable
taste or odor. Soils and rocks contain varying amounts
of cadmium, generally in small amounts but sometimes in larger
amounts (for example in some fossil fuels or fertilizers).
Most cadmium used in the United States
is extracted as a by-product during the production of other
metals such as zinc, lead, or copper. Cadmium has many
uses in industry and consumer products, mainly in batteries,
pigments, metal coatings, plastics, and some metal alloys.
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1.2
What happens to cadmium when it enters the environment? |
It is estimated that about 25,000 to
30,000 tons of cadmium are released to the environment each
year, about half from the weathering of rocks into river water
and then to the oceans. Forest fires and volcanoes also
release some cadmium to the air. Release of cadmium
from human activities is estimated at from 4,000 to 13,000
tons per year, with major contributions from mining activities,
and burning of fossil fuels. Cadmium can enter the air
from the burning of fossil fuels (e.g., coal fired electrical
plants) and from the burning of household waste. Because
of regulations, only small amounts currently enter water from
the disposal of waste water from households or industries.
Fertilizers often contain some cadmium that will enter the
soil when fertilizers are applied to crops. Cadmium
can also enter the soil or water from spills or leaks at hazardous
waste sites if large amounts of dissolved cadmium are present
at the site. The form of cadmium at these sites is important
since many forms do not easily dissolve in water.
Cadmium that is in or attached to small
particles can enter the air and travel a long way before coming
down to earth as dust, or in rain or snow. The cadmium
metal itself does not break down in the environment, but it
can change into different forms. Most forms of cadmium
stay for a long time in the same place where they first entered
the environment. Some forms of the cadmium that goes
into the water will bind to soil, but some will remain in
the water. Some forms of cadmium in soil can enter water
or be taken up by plants. Fish, plants, and animals
can take some forms of cadmium into their bodies from air,
water, or food. Cadmium can change forms in the body,
but it also stays in the body for a very long time (years).
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1.3
How might I be exposed to cadmium? |
Food and cigarette smoke are the biggest
sources of cadmium exposure for people in the general population.
Average cadmium levels in U.S. foods range from 2 to 40 parts
of cadmium per billion parts of food (2–40 ppb). Lowest
levels are in fruits and beverages, and highest levels are
in leafy vegetables and potatoes. Air levels of cadmium
in U.S. cities are low, ranging from less than 1 to 40 nanograms
per cubic meter (ng/m³) (a nanogram is one billionth
of a gram). Air levels greater than 40 ng/m³
may occur in urban areas with high levels of air pollution
from the burning of fossil fuels. The level of cadmium
in most drinking water supplies is less than 1 ppb, well below
the drinking water standard of 50 ppb. Levels in drinking
water, however, may vary greatly depending on local conditions.
The average level of cadmium in unpolluted soil is about 250
ppb. At hazardous waste sites, cadmium levels have been
measured in soil at about 4 parts cadmium per million parts
(4 ppm; a part per million is 1,000 times more than a ppb)
and in water at 6 ppm. In the United States, the average
person eats food with about 30 micrograms (µg) of cadmium
in it each day, but only about 1–3 µg per day of that
cadmium from food is absorbed and enters the body. Cadmium
exposure from smoking cigarettes may be a more serious health
concern than cadmium in food. Smokers may double their
daily intake of cadmium compared with nonsmokers. Each
cigarette may contain from 1 to 2 µg of cadmium, and
40–60% of the cadmium in the inhaled smoke can pass through
the lungs into the body. This means that smokers may
take in an additional 1–3 µg of cadmium into their body
per day from each pack of cigarettes smoked. Smoke from
other people's cigarettes probably does not cause nonsmokers
to take in much cadmium.
Aside from tobacco smokers, people who
live near hazardous waste sites or factories that release
cadmium into the air have the potential for exposure to cadmium
in air. However, numerous state and federal regulations
control the amount of cadmium that can be released to the
air from waste sites and incinerators so that properly regulated
sites are not hazardous. The general population and
people living near hazardous waste sites may be exposed to
cadmium in contaminated food, dust, or water from unregulated
releases or accidental releases. Numerous regulations
and use of pollution controls are enforced to prevent such
releases.
Workers can be exposed to cadmium in
air from the smelting and refining of metals, or from the
air in plants that make cadmium products such as batteries,
coatings, or plastics. Workers can also be exposed when
soldering or welding metal that contains cadmium. Approximately
512,000 workers in the United States are in environments each
year where a cadmium exposure may occur. Regulations
that set permissible levels of exposure, however, are enforced
to protect workers and to make sure that levels of cadmium
in the air are considerably below levels thought to result
in harmful effects.
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1.4
How can cadmium enter and leave my body? |
Cadmium can enter your body from the
food you eat, the water you drink, from particles it may be
attached to in the air you breathe, or from breathing in cigarette
smoke that contains cadmium. Higher amounts of cadmium
can enter your body from the cadmium in air or smoke that
you inhale (25 to 60% of the cadmium present) than from cadmium
in foods you eat (about 5–10% enters the body). The
cadmium not taken into your body through the lungs is breathed
out. The cadmium not taken into your body from food
or water leaves your body in feces. If you do not eat
foods that contain enough iron or other nutrients, you are
likely to take up more cadmium from your food than usual.
Virtually no cadmium enters your body through your skin.
Most of the cadmium that enters your
body goes to your kidney and liver and can remain there for
many years. A small portion of the cadmium that enters
your body leaves slowly in urine and feces. Your body
can change most cadmium to a form that is not harmful, but
too much cadmium can overload the ability of your liver and
kidney to change the cadmium to a harmless form, and the harmful
form may damage your health.
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1.5
How can cadmium affect my health? |
The potential for cadmium to harm your
health depends upon the form of cadmium present, the amount
taken into your body, and whether the cadmium is eaten or
breathed. There are no known good effects from taking
in cadmium. Breathing air with very high levels of cadmium
can severely damage the lungs and may cause death. Breathing
air with lower levels of cadmium over long periods of time
(for years) results in a build-up of cadmium in the kidney,
and if sufficiently high, may result in kidney disease.
Other effects that may occur after breathing cadmium for a
long time are lung damage and fragile bones.
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 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.
We do not have many good studies on the
health effects of cadmium in people. Exposures to cadmium
throughout most of the world are currently regulated so there
are relatively few people receiving high levels, and the effects
from long-term low-level exposure to cadmium are hard to determine
with the many other factors that can come into play.
A number of studies on workers exposed to cadmium in the air
have not resulted in convincing evidence that cadmium can
cause lung cancer in humans. In animals studies, mice
or hamsters that breathed in cadmium did not get lung cancer,
but rats that breathed in cadmium did develop lung cancer.
There is no good information on people to suggest that breathing
cadmium can affect your ability to have children. Female
rats and mice, however, that breathed high levels of cadmium
had fewer litters, and their babies may have had more birth
defects than usual. Breathing cadmium has also been
shown to cause liver damage and changes in the immune system
in rats and mice. There is no reliable information on
people to indicate that breathing cadmium harms peoples' liver,
heart, nervous system, or immune system.
Eating food or drinking water with very
high cadmium levels severely irritates the stomach, leading
to vomiting and diarrhea, and sometimes death. Eating
lower levels of cadmium over a long period of time can lead
to a build-up of cadmium in the kidneys. If the levels
reach a high enough level, the cadmium in the kidney will
cause kidney damage, and also causes bones to become fragile
and break easily. We do not have good direct information
from people who have been exposed to cadmium to know if eating
cadmium at levels, below which other toxic effects are not
seen, might effect your ability to have children. Animals
eating or drinking cadmium sometimes get high blood pressure,
iron-poor blood, liver disease, and nerve or brain damage.
We have no good information on people to indicate that the
levels that people would need to eat or drink cadmium to result
in these diseases, or if they would occur at all. Studies
of humans or animals that eat or drink cadmium have not found
increases in cancer, although additional research is needed
to be more certain that eating or drinking cadmium definitely
does or does not cause cancer. Skin contact with cadmium
is not known to affect the health of people or animals because
virtually no cadmium can enter the body through the skin under
normal circumstances (i.e., without exposure to very high
concentrations for long times or exposure to skin that was
not damaged).
As a conservative approach, and based
on the limited human data and the studies in rats, the United
States Department of Health and Human Services (DHHS) has
determined that cadmium and cadmium compounds may reasonably
be anticipated to be carcinogens. The International
Agency for Research on Cancer (IARC) has determined that cadmium
is carcinogenic to humans. The EPA has determined that
cadmium is a probable human carcinogen by inhalation.
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1.6
How can cadmium affect children? |
This section discusses potential health
effects from exposures during the period from conception to
maturity at 18 years of age in humans. Potential effects
on children resulting from exposures of the parents are also
considered.
The health effects seen in children from
exposure to toxic levels of cadmium are expected to be similar
to the effects seen in adults (kidney, lung, and intestinal
damage depending on the route of exposure). These effects
are most easily seen in short-term high-level exposures.
Harmful effects on child development or behavior have not
generally been seen in populations exposed to cadmium, but
more research is needed. It is also difficult to determine
the cause of harmful effects on child behavior or development
from exposures to low levels over long periods of time, which
are the most likely exposures for children as well adults
in the general population.
We do not know whether cadmium can cause
birth defects in people. Studies in animals exposed
to high enough levels of cadmium during pregnancy have resulted
in harmful effects in the young. The nervous system
appears to be the most sensitive target. Young animals
exposed to cadmium before birth have shown effects on behavior
and learning. There is also some information from
animal studies that high enough exposures to cadmium before
birth can reduce body weights and affect the skeleton in the
developing young. Similar effects, however, have not
been observed in humans. Humans may respond differently
or the exposure levels in humans may be considerably below
the levels that produced these adverse effects in animals.
More research on human health effects is needed to answer
these questions.
Most cadmium taken into the stomach and
intestines passes through without being absorbed. At
high enough levels, however, damage to the stomach and intestines
can occur. A few studies in animals indicate that younger
animals absorb more cadmium than adults. Animal studies
also indicate that the young are more susceptible than adults
to a loss of bone and decreased bone strength from exposure
to cadmium. Animal studies also indicate that more cadmium
is absorbed into the body from the diet if the diet is low
in calcium, protein, or iron, or if the diet is high in fat
(because fat slows down the passage of food in the gut and
allows more time for absorption). Children who do not
get enough iron, calcium, or protein may also absorb more
cadmium.
Women with low levels of calcium or iron,
due to multiple pregnancies and/or dietary deficiencies, may
also absorb more cadmium when exposed to cadmium in food or
water. Cadmium does not readily go from a pregnant woman's
body into the developing child, but some can cross the placenta.
Cadmium levels in human milk can also be from 5 to 10% of
the levels found in the mother's blood.
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1.7
How can families reduce the risk of exposure to cadmium? |
If your doctor finds that you have been
exposed to significant amounts of cadmium, ask your doctor
if children may also be exposed. When necessary, your
doctor may need to ask your state public health department
to investigate.
You can reduce the risk of your family
being exposed to cadmium by identifying potential sources
of cadmium exposure (in or around your home, at work, or where
your children play), and by taking measures to prevent your
family members from being exposed. A balanced diet that
includes enough calcium, iron, protein, and zinc will also
help reduce the amount of cadmium that may be absorbed into
the body from food or drink.
Take an inventory of items in and around
your home that might contain cadmium. Examples include
fungicides (cadmium chloride), batteries (nickel-cadmium batteries
also called Ni-Cad batteries), and hobbies that use materials
that contain cadmium (electroplating or welding of metals,
some fabric dyes, ceramic and glass glazes). Generally,
the label of ingredients for a product will list cadmium or
a cadmium compound as an active ingredient, or you can contact
the manufacturer and ask whether the item contains cadmium.
If you think that a fertilizer might contain cadmium, ask
the supplier or the manufacturer. The cadmium in these
items would have to get into your body before it could do
any harm. This could happen if, for example, a fungicide
containing cadmium was accidentally or intentionally swallowed,
or if Ni-Cad batteries were being burned in a waste incinerator
and a family member was breathing in the smoke, or if you
were welding metal alloys that contain cadmium or using a
cadmium glaze on a piece of pottery and were breathing in
fumes that contained cadmium. You can prevent these
exposures by making sure that you and your family members
do not accidentally swallow substances that contain cadmium
or breathe in air contaminated with cadmium. All cadmium-containing
fungicides or dyes should be properly stored, safely out of
the reach of children. If you or your family members
have a hobby where metals or materials that contain cadmium
are being heated or welded, you should seek advice on proper
ventilation of your workspace and the proper use of a safety
respirator.
Nickel-cadmium batteries are not harmful
when properly used, but can release cadmium fumes if burned
in an incinerator or waste fire. Breathing in these
fumes may be harmful to your health. Small children
also may mistake Ni-Cad batteries for toys and may accidentally
swallow them. If the battery case is damaged, then some
cadmium could escape and come in contact with the stomach
or intestines. Keep Ni-Cad batteries out of the reach
of small children, and teach your older children that the
contents in Ni-Cad batteries can be harmful to their health
if swallowed or burned. Teach your family how to properly
dispose of the batteries. Information on where to dispose
of Ni-Cad batteries is available from your city or county
waste disposal office or the office for a waste disposal service.
If you are using fungicides or fertilizers
that contain cadmium on your lawn or garden, read the instructions
to learn the safe way to use these materials. One possible
route of exposure from fungicides or fertilizers would be
from breathing in small particles of cadmium-containing dusts.
Protective safety gear including dust masks are available
at hardware and building supply stores.
If you have a water well and are concerned
that your water may contain cadmium, you can have your water
tested. Water filters that remove cadmium, as well as
lead and other metals, from drinking water are also available
at your local stores. You should ask for advice from
your public health officials or from knowledgeable suppliers
of water filters on the proper filter or filters to use for
your water system.
It is sometimes possible to carry cadmium-containing
dust from work on your clothing, skin, hair, tools, or other
objects removed from the workplace. This is particularly
true when working in buildings where there is smelting or
refining of cadmium-containing metal ores, soldering or welding
of metals that contain cadmium, or where cadmium batteries,
coatings, or plastics are made. You may contaminate
your car, home, or other locations outside work where children
might be exposed to cadmium.
Your occupational health and safety officer
at work can and should tell you whether chemicals you work
with are dangerous and likely to be carried home on your clothes,
body, or tools and whether you should be showering and changing
clothes before you leave work, storing your street clothes
in a separate area of the workplace, or laundering your work
clothes at home separately from other clothes. If cadmium
is being used in your workplace, there should be a material
safety data sheet (MSDS) available at your place of work,
as required by the Occupational Safety and Health Administration
(OSHA). The MSDS information will include the chemical
name(s) of any hazardous cadmium ingredients, fire and explosion
data, potential health effects, how you get the chemical(s)
in your body, how to properly handle the materials, and what
to do in an emergency.
Your employer is legally responsible
for providing a safe workplace and should freely answer your
questions about hazardous chemicals. Your OSHA-approved
state occupational safety and health program or OSHA can answer
any further questions, and help your employer identify and
correct problems with hazardous substances. Your OSHA-approved
state occupational health program or OSHA will also listen
to formal complaints you would like to make about workplace
health hazards and will inspect your workplace, if necessary.
Employees have a right to seek safety and health on the job
without fear of punishment.
Potential sources of exposure to cadmium
away from home include exposures at hazardous waste sites
or from air near waste incinerators. Young children
should not play near or in hazardous wastes sites, and regulations
that prevent this activity are generally enforced. Proper
enforcement of regulations also prevents releases of cadmium
to the air from waste incinerators or to water from hazardous
waste sites. If you or your family live near a hazardous
waste site and you have reason to believe that regulations
are not being enforced and that you or your children are being
exposed to cadmium, contact your local health official and
report your concern.
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1.8
Is there a medical test to determine whether I have been exposed
to cadmium? |
You can be tested for exposure to cadmium
in several ways. The amount of cadmium in your blood,
urine, hair, or nails can be measured by some medical laboratories.
The amount of cadmium in your blood shows your recent exposure
to cadmium. The amount of cadmium in your urine shows
both your recent and your past exposure. Cadmium levels
in hair or nails are not as useful as an indication of when
or how much cadmium you may have taken in, partly because
cadmium from outside of your body may attach to the hair or
nails. Tests are also available to measure the amount
of cadmium inside your liver and kidneys. The results
of these tests can help a doctor evaluate the risk of liver
or kidney disease. However, these tests are too costly
and inconvenient for routine use. Your urine can be
tested to see if your kidneys are damaged. If you do
have kidney damage, the urine tests do not prove that cadmium
caused the damage.
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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), 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).
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 cadmium include the following:
The government has taken steps to protect
humans from excessive cadmium exposure. The EPA allows
only up to 5 parts of cadmium per billion parts of water (5
ppb) in drinking water. The EPA also limits how much
cadmium can be put into lakes, rivers, dumps, and cropland,
and does not allow cadmium in pesticides. The FDA limits
the amount of cadmium in food colors to 15 parts per million
(ppm).
OSHA now limits the amount of cadmium
in workplace air to 5 micrograms per cubic meter (µg/m³).
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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 or:
Agency for Toxic Substances and Disease Registry
Division of Toxicology
1600 Clifton Road NE, Mailstop F-32
Atlanta, GA 30333
Information line and technical assistance:
Phone: 888-422-8737
FAX: (770)-488-4178
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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References |
Agency for Toxic Substances and Disease
Registry (ATSDR). 1999. Toxicological profile
for cadmium. Atlanta, GA: U.S. Department of Health and
Human Services, Public Health Service.
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