February 2001 |
ToxFAQs™ |
for |
Polychlorinated Biphenyls (PCBs) |
(Bifenilos
Policlorados (BPCs)) |
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This fact sheet answers the most frequently
asked health questions about polychlorinated biphenyls (PCBs).
For more information, you may call the ATSDR Information Center
at 1-888-422-8737. This fact sheet is one in a series of summaries
about hazardous substances and their health effects. 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.
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HIGHLIGHTS: Polychlorinated
biphenyls (PCBs) are a mixture of individual chemicals
which are no longer produced in the United States, but
are still found in the environment. Health effects that
have been associated with exposure to PCBs include acne-like
skin conditions in adults and neurobehavioral and immunological
changes in children. PCBs are known to cause cancer in
animals. PCBs have been found in at least 500 of the 1,598
National Priorities List sites identified by the Environmental
Protection Agency (EPA). |
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What
are polychlorinated biphenyls (PCBs)? |
Polychlorinated biphenyls are mixtures
of up to 209 individual chlorinated compounds (known as congeners).
There are no known natural sources of PCBs. PCBs are either
oily liquids or solids that are colorless to light yellow.
Some PCBs can exist as a vapor in air. PCBs have no known
smell or taste. Many commercial PCB mixtures are known in
the U.S. by the trade name Aroclor.
PCBs have been used as coolants and lubricants
in transformers, capacitors, and other electrical equipment
because they don't burn easily and are good insulators. The
manufacture of PCBs was stopped in the U.S. in 1977 because
of evidence they build up in the environment and can cause
harmful health effects. Products made before 1977 that may
contain PCBs include old fluorescent lighting fixtures and
electrical devices containing PCB capacitors, and old microscope
and hydraulic oils.
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What
happens to polychlorinated biphenyls (PCBs) when they enter
the environment? |
- PCBs entered the air, water, and soil during their manufacture,
use, and disposal; from accidental spills and leaks during
their transport; and from leaks or fires in products containing
PCBs.
- PCBs can still be released to the environment from hazardous
waste sites; illegal or improper disposal of industrial
wastes and consumer products; leaks from old electrical
transformers containing PCBs; and burning of some wastes
in incinerators.
- PCBs do not readily break down in the environment and
thus may remain there for very long periods of time. PCBs
can travel long distances in the air and be deposited in
areas far away from where they were released. In water,
a small amount of PCBs may remain dissolved, but most stick
to organic particles and bottom sediments. PCBs also bind
strongly to soil.
- PCBs are taken up by small organisms and fish in water.
They are also taken up by other animals that eat these aquatic
animals as food. PCBs accumulate in fish and marine mammals,
reaching levels that may be many thousands of times higher
than in water.
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How
might I be exposed to polychlorinated biphenyls (PCBs)? |
- PCBs entered the air, water, and soil during their manufacture,
use, and disposal; from accidental spills and leaks during
their transport; and from leaks or fires in products containing
PCBs.
- PCBs can still be released to the environment from hazardous
waste sites; illegal or improper disposal of industrial
wastes and consumer products; leaks from old electrical
transformers containing PCBs; and burning of some wastes
in incinerators.
- PCBs do not readily break down in the environment and
thus may remain there for very long periods of time. PCBs
can travel long distances in the air and be deposited in
areas far away from where they were released. In water,
a small amount of PCBs may remain dissolved, but most stick
to organic particles and bottom sediments. PCBs also bind
strongly to soil.
- PCBs are taken up by small organisms and fish in water.
They are also taken up by other animals that eat these aquatic
animals as food. PCBs accumulate in fish and marine mammals,
reaching levels that may be many thousands of times higher
than in water.
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How
can polychlorinated biphenyls (PCBs) affect my health? |
The most commonly observed health effects
in people exposed to large amounts of PCBs are skin conditions
such as acne and rashes. Studies in exposed workers have shown
changes in blood and urine that may indicate liver damage.
PCB exposures in the general population are not likely to
result in skin and liver effects. Most of the studies of health
effects of PCBs in the general population examined children
of mothers who were exposed to PCBs.
Animals that ate food containing large
amounts of PCBs for short periods of time had mild liver damage
and some died. Animals that ate smaller amounts of PCBs in
food over several weeks or months developed various kinds
of health effects, including anemia; acne-like skin conditions;
and liver, stomach, and thyroid gland injuries. Other effects
of PCBs in animals include changes in the immune system, behavioral
alterations, and impaired reproduction. PCBs are not known
to cause birth defects.
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How
likely are polychlorinated biphenyls (PCBs) to cause cancer? |
Few studies of workers indicate that
PCBs were associated with certain kinds of cancer in humans,
such as cancer of the liver and biliary tract. Rats that ate
food containing high levels of PCBs for two years developed
liver cancer. The Department of Health and Human Services
(DHHS) has concluded that PCBs may reasonably be anticipated
to be carcinogens. The EPA and the International Agency for
Research on Cancer (IARC) have determined that PCBs are probably
carcinogenic to humans.
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How
do polychlorinated biphenyls (PCBs) affect children? |
Women who were exposed to relatively
high levels of PCBs in the workplace or ate large amounts
of fish contaminated with PCBs had babies that weighed slightly
less than babies from women who did not have these exposures.
Babies born to women who ate PCB-contaminated fish also showed
abnormal responses in tests of infant behavior. Some of these
behaviors, such as problems with motor skills and a decrease
in short-term memory, lasted for several years. Other studies
suggest that the immune system was affected in children born
to and nursed by mothers exposed to increased levels of PCBs.
There are no reports of structural birth defects caused by
exposure to PCBs or of health effects of PCBs in older children.
The most likely way infants will be exposed to PCBs is from
breast milk. Transplacental transfers of PCBs were also reported
In most cases, the benefits of breast-feeding outweigh any
risks from exposure to PCBs in mother's milk.
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How
can families reduce the risk of exposure to polychlorinated
biphenyls (PCBs)? |
- You and your children may be exposed to PCBs by eating
fish or wildlife caught from contaminated locations. Certain
states, Native American tribes, and U.S. territories have
issued advisories to warn people about PCB-contaminated
fish and fish-eating wildlife. You can reduce your family's
exposure to PCBs by obeying these advisories.
- Children should be told not play with old appliances,
electrical equipment, or transformers, since they may contain
PCBs.
- Children should be discouraged from playing in the dirt
near hazardous waste sites and in areas where there was
a transformer fire. Children should also be discouraged
from eating dirt and putting dirty hands, toys or other
objects in their mouths, and should wash hands frequently.
- If you are exposed to PCBs in the workplace it is possible
to carry them home on your clothes, body, or tools. If this
is the case, you should shower and change clothing before
leaving work, and your work clothes should be kept separate
from other clothes and laundered separately.
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Is
there a medical test to show whether I've been exposed to polychlorinated
biphenyls (PCBs)? |
Tests exist to measure levels of PCBs
in your blood, body fat, and breast milk, but these are not
routinely conducted. Most people normally have low levels
of PCBs in their body because nearly everyone has been environmentally
exposed to PCBs. The tests can show if your PCB levels are
elevated, which would indicate past exposure to above-normal
levels of PCBs, but cannot determine when or how long you
were exposed or whether you will develop health effects.
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Has the federal government made recommendations to protect human health? |
The EPA has set a limit of 0.0005 milligrams
of PCBs per liter of drinking water (0.0005 mg/L). Discharges,
spills or accidental releases of 1 pound or more of PCBs into
the environment must be reported to the EPA. The Food and
Drug Administration (FDA) requires that infant foods, eggs,
milk and other dairy products, fish and shellfish, poultry
and red meat contain no more than 0.2-3 parts of PCBs per
million parts (0.2-3 ppm) of food. Many states have established
fish and wildlife consumption advisories for PCBs.
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References |
Agency for Toxic Substances and Disease
Registry (ATSDR). 2000. Toxicological
Profile for polychlorinated biphenyls (PCBs). Atlanta,
GA: U.S. Department of Health and Human Services, Public Health
Service.
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Where can I get more information? |
ATSDR can tell you where to find occupational
and environmental health clinics. Their specialists can recognize,
evaluate, and treat illnesses resulting from exposure to hazardous
substances. You can also contact your community or state health
or environmental quality department if you have any more questions
or concerns. For more information, contact:
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Agency for Toxic Substances and Disease Registry
Division of Toxicology
1600 Clifton Road NE, Mailstop F-32
Atlanta, GA 30333
Phone: 1-888-42-ATSDR (1-888-422-8737)
FAX: (770)-488-4178
Email: ATSDRIC@cdc.gov
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