Vermiculite is a naturally occurring mineral, similar in appearance to mica, which has the unusual property of expanding into worm-like accordion-shaped pieces when heated.  The expanded vermiculite is a lightweight, fire-resistant, absorbent, and odorless material.  These properties allow vermiculite to be used to make numerous products, including attic insulation.

All vermiculite ores contain a range of other minerals that were formed along with vermiculite in the rock.  Vermiculite ores from some sources have been found to contain asbestos minerals; but asbestos in not intrinsic to vermiculite and only a few ore bodies contain more than trace amounts.  Prior to its close in 1990, much of the world's supply of vermiculite came from a mine near Libby, Montana.  This mine had a natural deposit of asbestos, which resulted in the vermiculite being contaminated with asbestos.  Attic insulation produced using vermiculite ore that originated from the Libby mine, may contain asbestos fibers.  Today, vermiculite is mined at three U.S. facilities and in other countries, which have low levels of contamination in the finished material.

Asbestos can cause health problems when inhaled into the lungs.  If products containing asbestos are disturbed, thin, lightweight asbestos fibers are released into the air.  Persons breathing the air may breathe in asbestos fibers.  Continued exposure increases the amount of fibers that remain in the lung.  Fibers embedded in lung tissue over time may result in lung diseases such as asbestosis, lung cancer, or mesothelioma.  Smoking increases your risk of developing illness from asbestos exposure.

Vermiculite attic insulation is a pebble-like, pour-in product and is usually light brown or gold in color.  Currently, there are specific technical issues involving vermiculite sampling that can complicate testing for the presence of asbestos fibers and interpreting the risk from exposure.  The Environmental Protection Agency (EPA) and the Agency for Toxic Substances and Disease Registry (ATSDR) are not recommending at this time that homeowners have vermiculite attic insulation tested for asbestos.  It is best to assume that the material may be contaminated with asbestos. 

If vermiculite insulation is present in a home, the safest action is to not disturb it.  Any disturbance has the potential to release asbestos fibers into the air.  Limit the number of trips you make to your attic and shorten the length of those trips.  You should not store boxes or other items in your attic.  If you plan to remodel or conduct renovations that would disturb the vermiculite, hire professionals trained and certified to handle asbestos to safely remove the material.  You should never attempt to remove the insulation yourself.  Common dust masks are not effective against asbestos fibers.  For information on the requirements for wearing a respirator mask, visit:
www.osha.gov/SLTC/etools/respiratory/index.html.

More information is available at: www.epa.gov/asbestos/ and www.atsdr.cdc.gov.