Public Health Statement for Polybrominated Biphenyls (PBBs)
Spanish: Bifenilos Polibromados
PDF Versionpdf icon[135 KB]
This Public Health Statement is the summary chapter from the Toxicological Profile for Polybrominated Biphenyls. 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.
This public health statement tells you about polybrominated biphenyls (PBBs) and the effects of exposure to PBBs.
The Environmental Protection Agency (EPA)
identifies the most serious hazardous waste sites in the nation.
These sites are then placed on the National Priorities List
(NPL) and are targeted for long-term federal clean-up activities.
PBBs have been found in at least nine of the 1,647 current
or former NPL sites. Although the total number of NPL sites
evaluated for these substances is not known, the possibility
exists that the number of sites at which PBBs are found may
increase in the future as more sites are evaluated. This information
is important because these sites may be sources of exposure
and exposure to these substances may harm you.
When a substance is released either from a large area, such as an industrial plant, or from a container, such as a drum or bottle, it enters the environment. Such a release does not always lead to exposure.
You can be exposed to a substance only when you come in contact with it. You may be exposed by breathing, eating, or drinking the substance, or by skin contact.
If you are exposed to PBBs, many factors
will determine whether you will be harmed. These factors include
the dose (how much), the duration (how long), and how you
come in contact with PBBs. You must also consider any other
chemicals you are exposed to and your age, sex, diet, family
traits, lifestyle, and state of health.
What are PBBs?
Polybrominated biphenyls (PBBs) are chemicals
that were added to plastics used in a variety of consumer
products, such as computer monitors, televisions, textiles,
and plastic foams, to make them difficult to burn. Because
PBBs were mixed into plastics rather than bound to them, they
were able to leave the plastic and find their way into the
environment. Commercial production of PBBs began in the 1970s.
Manufacture of PBBs was discontinued in the United States
in 1976. Concern regarding PBBs is mainly related to exposures
resulting from an agriculture contamination episode that occurred
in Michigan over a 10-month period during 1973-1974.
There are no known natural sources of
PBBs in the environment. PBBs are solids and are colorless
to off-white. PBBs enter the environment as mixtures containing
a variety of individual brominated biphenyl (for PBBs) components,
known as congeners. Some commercial PBB mixtures are known
in the United States under the industrial trade name, FireMaster®.
However, other flame retardant chemicals also may be identified
by this name. PBBs are no longer used in North America because
the agriculture contamination episode that occurred in Michigan
in 1973-1974 led to the cessation of its production.
What happens to PBBs when they enter the environment?
In the past, PBBs entered the air, water,
and soil during their manufacture and use. In addition, animal
feed was accidentally mixed with 500-1,000 pounds of PBBs
in lower Michigan in 1973. This contamination of the food
chain affected millions of farm animals and humans living
in Michigan at this time. PBBs entered the environment during
the disposal of contaminated animal feed and animal products
during the agriculture contamination episode. PBBs also entered
the environment from PBB-containing wastes that manufacturers
disposed of in waste sites. Small quantities of PBBs also
entered the environment from accidental spills during transport.
PBBs are no longer manufactured in North America, but very
small amounts of PBBs may be released into the environment
from poorly maintained hazardous waste sites and improper
incineration of plastics that contain PBBs.
How might I be exposed to PBBs?
PBBs are no longer produced or used in
the United States. Thus, the general population exposure to
PBBs will only be from past releases. For people living in
the lower peninsula of Michigan, especially near PBB contaminated
areas, exposure to PBBs may still be occurring today. However,
environmental levels have decreased since the 1970s and current
exposure, if any, will be at low levels. For other regions
of the United States, the levels of exposure will either be
very low or none.
Measured data in air, water, soil, and
food, as well as body burden data (blood, urine, breast milk,
and body fat), indicate that most people within the state
of Michigan who were exposed to PBBs received very low levels
of PBBs. The levels from exposure were slightly higher for
people living in the lower peninsula of Michigan and highest
among people living on contaminated dairy farms. Consumption
of contaminated meat and dairy products caused the higher
levels of PBBs in the body. Monitoring of the workplace environment,
as well as the blood, urine, and body fat of workers indicated
that those in PBB industries were exposed to higher levels
of PBBs than the general population. These workers were exposed
to PBBs by breathing contaminated workplace air and by skin
contact with PBBs. Occupational exposure also could have occurred
from the incineration of materials containing PBBs. Exposure
in workplaces is no longer likely because PBBs are no longer
manufactured. People who live near hazardous waste sites that
contain PBBs may be exposed primarily by breathing air that
contains PBBs.
How can PBBs enter and leave my body?
If you breathe air that contains PBBs,
or swallow food, water, or soil contaminated with PBBs, they
can enter your body through your lungs and stomach and pass
into the bloodstream. We don't know how much of the PBBs will
pass into the blood from the lungs; although most will probably
pass into the blood from the stomach and intestines. If you
touch soil containing PBBs, it is highly unlikely that PBBs
would pass through your skin into the bloodstream. It is not
known how fast PBBs enter the blood from the lungs or stomach.
There are no known current sources of PBBs because they are
no longer produced and used in North America. They are rarely
found in air and drinking water away from production plants
and contaminated sites. Once PBBs are in your body, they can
partially change into breakdown products called metabolites.
Some metabolites and unchanged PBBs could leave your body,
mainly in the feces and in very small amounts in the urine,
within a few days. Other unchanged PBBs might stay in your
body for many years. PBBs are stored mainly in your body fat,
tend to concentrate in breast milk fat, and can enter the
bodies of children through breast feeding. PBBs also can enter
the bodies of unborn babies through the placenta.
How can PBBs affect my health?
Scientists use many tests to protect
the public from harmful effects of toxic chemicals and to
find ways for treating persons who have been harmed.
One way to learn whether a chemical will
harm people is to determine how the body absorbs, uses, and
releases the chemical. That sometimes involves animal testing.
Animal testing may help identify health effects such as cancer
or birth defects. Without laboratory animals, scientists would
lose a basic method for getting information needed to make
wise decisions that protect public health. Scientists have
the responsibility to treat research animals with care and
compassion. Scientists must comply with strict animal care
guidelines because laws today protect the welfare of research
animals.
Much of what is known about the health
effects of PBBs in people comes from studies of ingestion
in Michigan in the early-to-mid 1970s, where feed for farm
animals was accidentally contaminated with a fire retardant
containing PBBs. People were exposed to PBBs for several months
when they ate meat, milk, and eggs from the contaminated animals.
After news of the contamination episode became widespread,
many Michigan residents complained of various health problems,
including nausea, abdominal pain, loss of appetite, joint
pain, fatigue, and weakness. However, it could not be clearly
established that any of the problems were caused by eating
the food contaminated with PBBs. PBBs also did not cause any
definite changes in the livers or immune systems of the Michigan
residents. However, some people who ate the contaminated food
developed skin disorders, such as acne and hair loss. It is
likely that PBBs caused the skin problems because other chemicals
similar to PBBs also cause these effects. Workers who were
exposed to PBBs for a few days to months by breathing and
skin contact also developed acne, although not all persons
exposed to PBBs developed acne. Very little is known about
the health of people who are exposed to low levels of PBBs
for long periods by eating, breathing, or skin contact.
Laboratory animals fed PBBs had body
weight loss, skin disorders, and nervous system effects, and
their livers, kidneys, thyroid glands, and immune systems
were seriously injured. Some animals fed high amounts died.
PBBs also caused birth defects in animals, but it is not known
for sure whether PBBs make males or females infertile. Most
of the effects in animals occurred after they ate large amounts
of PBBs for short periods or smaller amounts for several weeks
or months. Body weight loss and effects on the livers, kidneys,
and thyroid glands were observed. A lifetime study of rats
and mice fed PBBs at doses higher than those expected from
environmental exposure. A few studies tested animals exposed
to PBBs by skin contact. These animals had injuries to the
liver and skin. Only one study tested animals exposed to PBBs
by breathing, and no health effects were observed.
We do not know if PBBs caused or will
cause cancer in people who ate food contaminated with PBBs.
Rats developed cancer in their livers after eating a large
amount of a PBB mixture only once. The babies of exposed rats
developed cancer in their livers after eating a large amount
of the same PBB mixture only once. Liver cancer also developed
in rats and mice that ate smaller amounts of the PBB mixture
for several months. Mice that had skin contact with a small
amount of a PBB mixture for several months did not develop
skin cancer. There are no cancer studies in animals that breathed
PBBs. Because animals fed PBBs did develop cancer, the National
Toxicology Program (NTP) of the Department of Health and Human
Services (DHHS) determined that PBBs may reasonably be anticipated
to be carcinogens. Similarly, the International Agency for
Research on Cancer (IARC) has determined that PBBs are possibly
carcinogenic to humans. The EPA has not classified the carcinogenicity
of PBBs.
We do not know whether the effects found
in animals exposed to PBBs would also occur in people exposed
in the same way. The amounts of PBBs that caused health effects
in animals are much greater than levels of PBBs normally found
in the environment. Long-term exposure to these chemicals
has a greater potential to cause health effects than does
short-term exposure to low levels because they tend to build
up in your body over many years.
How can PBBs affect children?
This section discusses potential health
effects in humans from exposures during the period from conception
to maturity at 18 years of age.
Children are exposed to PBBs in generally
the same way as are adults, mainly by eating contaminated
food. Because of their smaller weight, children's intake of
PBBs per kilogram (or pound) of body weight may be greater
than that of adults. The most likely way that infants will
be exposed is from breast milk that contains PBBs, although
fetuses in the womb are also exposed. Children who live near
hazardous waste sites might accidentally eat some PBBs by
putting dirty hands or other soil/dirt-covered objects in
their mouths, by eating without washing their hands, or similar
behavior. Some children also eat dirt on purpose. It is not
possible that children could be exposed to PBBs following
transport of the chemical on clothing from the parent's workplace
to the home because PBBs are no longer being produced or used.
Some information on health effects of
PBBs in children is available from studies of the Michigan
contamination episode. Symptoms of ill health were not associated
with increased exposure to PBBs, and general neurological
examinations did not show any abnormalities. More detailed
studies of physical and neuropsychological development showed
no effects that were clearly related to PBBs among Michigan
children exposed during the episode. Changes in nerve and
brain function have been seen in animals that were exposed
to PBBs in the womb and by nursing. Animal studies also found
that exposure to PBBs during pregnancy or lactation caused
changes in thyroid hormone levels in the newborn animals and,
at high doses, increases in prenatal death and structural
birth defects.
As indicated above, children can be exposed
to PBBs before birth and from breast milk. PBBs are stored
in the mother's body and can be released during pregnancy,
cross the placenta, and enter fetal tissues. Because PBBs
dissolve readily in fat, they can accumulate in breast milk
fat and be transferred to babies and young children. PBBs
have been found in breast milk; however, in most cases, the
benefits of breast-feeding outweigh any risks from exposure
in mother's milk. You should consult your health care provider
if you have any concerns about PBBs and breast feeding. Because
the nervous system and thyroid are still developing in the
fetus and child, the effects of PBBs on these target systems
might be more profound from exposure before and soon after
birth. That could mean fetuses and children are more susceptible
to PBBs than are adults.
How can families reduce the risk of exposure to PBBs?
If your doctor finds that you have been
exposed to substantial amounts of PBBs, ask whether your children
might also have been exposed. Your doctor might need to ask
your state health department to investigate.
Because PBBs are no longer produced or
used, the risk of exposure to these compounds is limited.
You and your children could be exposed to PBBs by eating fish
or wildlife caught from contaminated locations. Children who
live near hazardous waste sites should be discouraged from
playing in the dirt near these sites because they could still
contain PBBs. Children should also be discouraged from eating
the dirt, and careful handwashing practices should be followed.
Is there a medical test to determine whether I have been exposed to PBBs?
Special tests can determine whether PBBs
are in the blood, body fat, and breast milk. These are not
regular or routine clinical tests, but could be ordered by
a doctor to detect PBBs in people exposed to them in the environment
and at work. If your PBB levels are higher than the normal
levels, this will show that you have been exposed to high
levels of the chemicals. However, these measurements cannot
determine the exact amount or type of PBBs that you have been
exposed to, or how long you have been exposed. Although these
tests can indicate whether you have been exposed to PBBs to
a greater extent than the general population, they do not
predict whether you will be harmed. Blood tests are the easiest,
safest, and probably the best method for detecting recent
or past exposures to large amounts of PBBs. Results of such
tests should be reviewed and carefully interpreted by physicians
with a background in environmental and occupational medicine.
Exposures to PBBs have been of greatest concern in Michigan
as explained in Sections 1.3 and 1.5.
What recommendations has the federal government made to protect human health?
The federal government develops regulations
and recommendations to protect public health. Regulations
can be enforced by law. The EPA, the Occupational Safety
and Health Administration (OSHA), and the Food and Drug Administration
(FDA) are some federal agencies that develop regulations for
toxic substances. Recommendations provide valuable guidelines
to protect public health, but cannot be enforced by
law. The Agency for Toxic Substances and Disease Registry
(ATSDR) and the National Institute for Occupational Safety
and Health (NIOSH) are two federal organizations that develop
recommendations for toxic substances.
Regulations and recommendations can be expressed as "not-to-exceed" levels, that is, levels of a toxic substance in air, water, soil, or food that do not exceed a critical value that is usually based on levels that affect animals; they are then adjusted to levels that will help protect humans. Sometimes these not-to-exceed levels differ among federal organizations because they used different exposure times (an 8-hour workday or a 24-hour day), different animal studies, or other factors.
Recommendations and regulations are also updated periodically as more information becomes available. For the most current information, check with the federal agency or organization that provides it. Some regulations and recommendations for PBBs include the following:
At present, there are no federal guidelines or recommendations for protecting human health from exposure to PBBs.
References
Agency for Toxic Substances and Disease Registry (ATSDR). 2004. Toxicological Profile for Polybrominated Biphenyls and Polybrominated Diphenyl Ethers (PBBs and PBDEs). Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.
Where can I get more information?
If you have questions or concerns, please contact your community or state health or environmental quality department or:
For more information, contact:
Agency for Toxic Substances and Disease Registry
Division of Toxicology and Human Health Sciences
4770 Buford Highway
Chamblee, GA 30341-3717
Phone: 1-800-CDC-INFO 888-232-6348 (TTY)
Email: Contact CDC-INFO
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.