vermiculite insulation may contain asbestos.
What is asbestos?
Asbestos is a mineral fiber. Asbestos fibers are long, thin, and
very strong, yet flexible enough to be woven together. Until the
1970ís, asbestos was commonly added to a variety of building materials
to strengthen them, provide heat insulation and make them fire
resistant. Although most products today do not contain asbestos,
some older materials in your home may, including pipe and sprayed-on
insulation, floor tiles, and roofing and siding materials.
What is vermiculite?
Vermiculite is a naturally occurring mineral used in construction,
insulation and gardening products. It looks like shiny, small pieces
of popcorn, and is usually light-brown or gold in
color. Vermiculite came from mines in Libby, Montana (closed in
1990) as well as other mines in the U.S. and other countries.
Vermiculite is still mined and distributed for a number of uses, including
Why should I be concerned about vermiculite insulation?
Much of the Libby vermiculite was used as attic insulation. It was sold
under the product name Zonolite. The Environmental Protection Agency
(EPA) estimated in 1985 that 940,000 American homes contained Zonolite
Over 70% of vermiculite ore mined worldwide came from the Libby,
Montana mine. The ore from this mine also included a natural deposit
of amphibole/tremolite asbestos. Much of the vermiculite from Libby
was contaminated with asbestos. Asbestos fibers are invisible to the
eye and can only be professionally detected. Homeowners should
consider the following:
- Vermiculite used for residential insulation may contain asbestos.
- If you are unsure whether the insulation in your home contains
vermiculite, avoid disturbing it until either you or a professional
can confirm that it is vermiculite.
- Vermiculite mined today for use in insulation is from a source
considered to be free of asbestos contamination.
What might vermiculite insulation in my home look like?
Vermiculite is ideal for attic insulation because of itís properties
as a lightweight, fire-resistant, absorbent and odorless material.
Vermiculite in insulation is a pebble-like, blown-in product and is
usually light-brown or gold in color. Sizes of vermiculite products range
from very fine particles to large (coarse) pieces nearly an inch long.
If you have vermiculite insulation in your attic, you should assume
that the material may contain asbestos. Testing vermiculite
insulation for asbestos is not necessary. Vermiculite sold under the
name Zonolite originated in Libby, Montana, and should be assumed to
If I find vermiculite insulation in my home, should it be removed?
Homeowners may wish to consider the following points:
- First, due to the physical characteristics of vermiculite and where it
may be installed, the potential for contamination of the air throughout
your home may be low.
- Second, if the insulation will not be disturbed and is not
contaminating the home environment (e.g. itís sealed behind tight
walls, floors, or isolated in an unfinished attic, which is vented
outside) it may be best to leave it alone. Furthermore, signs
should be posted inside the attic saying "Cancer Hazard:
Insulation contains asbestos, do not disturb or create dust."
Posting signs will ensure that electricians, plumbers and others doing
work on your home will be notified of the potential for exposure and
can take necessary steps to protect themselves.
- Last, if home renovations involve removal of walls or other areas
where vermiculite insulation is located, extra precaution is necessary
and removal by a trained and certified professional prior to
renovation may be warranted.
What can I do to prevent asbestos exposure?
The following steps can help minimize asbestos exposure during very
minor home renovations (such as installing a ceiling light, bathroom
fan, or computer cable):
- Wear gloves, eye protection and a HEPA respirator (not just a dust
- Tape off rooms with plastic sheeting to prevent contaminating other
areas of the home; keep the vermiculite damp to prevent spreading dust.
- Keep windows open for good ventilation and wipe up all dust and debris
using wet cleaning methods (wet-wiping and wet-mopping).
- A HEPA vacuum can be used for clean up of minor dust or debris.
Do not use a home/shop vacuum.
- If renovations involve more extensive removal or exposure to asbestos
containing insulation, itís best to hire a professional,
state-certified, asbestos removal contractor.
What are the health risks associated with asbestos exposure?
Asbestos fibers must be inhaled to cause disease. Disturbing
vermiculite insulation or dust containing asbestos will result in exposure
unless precautions are taken. When insulation containing asbestos is
disturbed, lightweight asbestos fibers are released into the air and can
be inhaled. In general, the more you are exposed to asbestos, the
greater your risk of developing related diseases. Exposure may not
have immediate health consequences, however. In many cases, individuals do
not develop related diseases for years or even decades after exposure.
Those at highest risk for exposure and disease are long-term
vermiculite processing plant employees or workers regularly installing or
handling products containing asbestos without proper protection.
Those at lower risk include people who occasionally disturb attic
insulation during activity in the attic or minor "handyman"
jobs. The lowest risk would be for people who live in a home where
the vermiculite insulation is isolated and they have had no direct contact
with the materials.
Some asbestos-exposed workers, family members, and those living in the
neighborhoods of asbestos plants have developed mesothelioma.
Mesothelioma is a rare type of cancer that begins in the tissue
surrounding the lungs, stomach, and heart. Mesothelioma has also
been found in individuals who were exposed to asbestos only once decades
earlier. The only known cause of mesothelioma is asbestos.
Exposure to a lot of asbestos over a long time (like in an occupational
setting) can cause permanent lung damage known as asbestosis. Asbestosis
causes shortness of breath and increases the risk of serious lung
infections. Smoking also increases the risk of developing illness
from asbestos exposure.
For more information
For health related questions, contact your local public health agency
or the Wisconsin Division of Public Health at (608) 266-1120. For a
list of state-certified contractors, consultants and labs, call the
and Lead Section at (608) 261-6876.
For more information, follow these links: (exit DHS)
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P-45008 (Rev. 8/03)
July 26, 2013