ToxFAQs™ for Synthetic Vitreous Fibers
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This fact sheet answers the most frequently
asked health questions about synthetic vitreous fibers. For
more information, you may call the ATSDR Information Center
at 1-800-232-4636. 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.
fibers are manmade fibrous materials used for thermal
and sound insulating purposes. Short-term exposure can
cause reversible skin, eye, and lung irritation. Workers
from factories making synthetic vitreous fibers used in
home insulation showed no increased rates of lung problems.
Some refractory ceramic fiber workers showed changes in
their chest x-rays, but these changes are not associated
with breathing problems. There is no clear association
between exposure to synthetic vitreous fibers and cancer
in humans. Synthetic vitreous fibers have not been detected
in any of the 1,647 National Priorities List sites identified
by the Environmental Protection Agency (EPA).
What are synthetic vitreous fibers?
Synthetic vitreous fibers are a group
of fibrous, inorganic materials that contain aluminum or calcium
silicates, and are made from rock or stone, clay, slag, or
glass. They do not occur naturally in the environment, but
are widely used for thermal and sound insulating purposes
and to reinforce other building materials. There are three
categories of synthetic vitreous fibers: 1) glass fibers (fiberglass),
including glass wool and continuous filament glass, 2) mineral
wool, which contains stone wool and slag wool, and 3) refractory
Insulation that is used in homes and
buildings is composed of synthetic vitreous fibers. Refractory
ceramic fibers are not widely used for building insulation.
They are used to insulate furnaces, in replacement of asbestos.
What happens to synthetic vitreous fibers when they enter the environment?
- Synthetic vitreous fibers can enter the air, water, and
soil from the manufacture, use, and disposal of fiber-containing
- Synthetic vitreous fibers are generally not broken down in the environment.
- Synthetic vitreous fibers do not dissolve in water or move through soil.
How might I be exposed to synthetic vitreous fibers?
- When insulation materials containing synthetic vitreous
fibers are disturbed, fibers can be suspended in the air
and inhaled. Installing your own fiberglass insulation in
your home may expose you and your family to synthetic vitreous
- Workers who install or remove insulation or who are involved
in building maintenance or repair are expected to have the
highest levels of exposure to synthetic vitreous fibers.
How can synthetic vitreous fibers affect my health?
When synthetic vitreous fibers are suspended
in air they can cause irritation of the eyes, the nose and
throat, and parts of the lung. When these fibers contact the
skin, they may also cause irritation. These effects are reversible
and disappear shortly after exposure stops.
Animal studies show that repeatedly breathing
air containing a lot of synthetic vitreous fibers can lead
to inflammation and fibrosis of the lung. If pulmonary inflammation
continues over a long period of time, a slow build up of scar
tissue may occur in the lungs and in the membrane encasing
the lungs called the pleura. This effect is called pulmonary
fibrosis or pleural fibrosis. Glass fibers commonly used in
home insulation materials did not cause fibrosis in animals,
but refractory ceramic fibers did.
You are unlikely to develop long-term
pulmonary inflammation or pulmonary fibrosis from synthetic
vitreous fibers, unless you are exposed to very dusty conditions
daily for many years. Studies of workers from factories that
make synthetic vitreous fibers used in home insulation materials
did not find abnormal numbers of cases of long-term pulmonary
inflammation, breathing problems, or changes in chest x-rays.
Some workers who made refractory ceramic fibers showed changes
in chest x-rays that are called pleural plaques, but their
ability to breathe was normal. Pleural plaques are small areas
of very mildly scarred pleural tissue.
How likely are synthetic vitreous fibers to cause cancer?
You are unlikely to develop cancer from
breathing in air with small amounts of synthetic vitreous
fibers. Studies of workers from factories that make synthetic
vitreous fibers have not found increased rates of lung cancer
or cancer of the pleura, called mesothelioma. Animals exposed
for life to air containing refractory ceramic fibers showed
increased rates of lung cancer and mesothelioma, but animals
exposed to insulation glass wools and stone wools did not.
The International Agency for Research
on Cancer (IARC) determined that insulation glass wool, stone
wool, and slag wool, and continuous filament glass are not
classifiable as to carcinogenicity to humans because of the
inadequate evidence of carcinogenicity in humans and the relatively
low biopersistence of these materials. IARC determined that
refractory ceramic fibers are possibly carcinogenic to humans
because of their relatively high biopersistence and the findings
of cancer in animals that repeatedly breathed in high levels
of refractory ceramic fibers. The EPA has classified refractory
ceramic fibers as a probable human carcinogen.
How can synthetic vitreous fibers affect children?
There are no unique exposure pathways
to synthetic vitreous fibers for children. It is likely that
children exposed to these types of fibers will experience
the same effects as adults, such as eye, skin, and upper respiratory
There are no studies that examined whether
exposure to synthetic vitreous fibers affect the developments
of the fetus, infants, or young children.
How can families reduce the risk of exposure to synthetic vitreous fibers?
Insulating material in attics or walls
is the most common source of synthetic vitreous fibers in
a home. Avoid disturbing or contacting these materials.
If you install your own insulation, wear
protective clothing, respiratory protection, and eye protection,
and follow recommendations provided by the manufacturer for
installing this material.
If you are exposed to these fibers at
work, you may carry fibers home on your skin, clothes, or
tools. You can avoid this by showering, and changing clothing
before leaving work. Your work clothes should be kept separate
from other clothes and laundered separately.
Is there a medical test to show whether I've been exposed to synthetic vitreous fibers?
There are currently no tests specific for synthetic vitreous fibers. A chest x-ray is a common method
to determine if you have certain conditions, such as pleural plaques, lung or pleural fibrosis, or mesotheliomas.
Has the federal government made recommendations to protect human health?
The Occupational Safety and Health Administration
(OSHA) has set a limit of 5 milligrams of synthetic vitreous
fibers as inert or nuisance dust per cubic meter (5 mg/m3)
of air for the respirable fraction and 15 mg/m3 for total
dust. The voluntary limit for fiberglass and mineral wool
is 1 fiber per cubic centimeter.
Agency for Toxic Substances and Disease Registry (ATSDR). 2004. Toxicological Profile for Synthetic Vitreous Fibers. 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
Office of Innovation and Analytics, Toxicology Section
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.