What is Vermiculite, and Does it Contain Asbestos?
On its own, vermiculite is non-toxic and known for its fire-resistant properties. However, vermiculite and many other building materials can contain asbestos, which is a mineral fiber that has been linked to an increased risk of lung diseases and other health concerns.
But what is vermiculite, exactly, and what is its risk of containing asbestos?
What Is Vermiculite?
Vermiculite is a lightweight, highly absorbent, fire-resistant mineral. It looks silvery, light brown or gray in appearance and is sometimes compared to popcorn. Technically, it’s called a hydrated magnesium aluminum silicate mineral.
Incredibly, vermiculite doesn’t burn—even up to 1,000 degrees. When heated, it puffs up to 30 times its original size.
How Is Vermiculite Used?
Because of its absorbent and fire-resistant properties, exfoliated vermiculite is used for building construction, insulation, gardening soil and packing material.
In building construction and insulation applications, it adds to the fire-resistance of the building material. Treated vermiculite expands and is full of air pockets that trap heat. Being both fire-resistant and insulating makes it a great building material.
For gardening soils, vermiculite doesn’t contain any nutrients on its own. However, it traps nutrients and moisture for the plant to access as needed. It also lightens heavy or compacted soils without disrupting the soil’s pH level.
In packaging applications, it protects objects that are sensitive to moisture. Being highly absorbent, it keeps chemicals safe that have violent reactions to water. Vermiculite is also compressible in its expanded form to absorb shocks in transit. Additionally, because it contains a lot of air, it provides thermal insulation.
What’s the Problem With Vermiculite?
On its own, vermiculite is non-toxic. But it’s not safe to assume that all vermiculite is safe.
Between 1919 and 1990, over 70 percent of all vermiculite sold in the United States was mined near Libby, Montana. You could buy the vermiculite under the brand name Zonolite.
In 1999, the EPA investigated the area and discovered asbestos contamination. Cleanup began immediately and was concluded in 2018 after removing more than one million cubic yards of contaminated soil but the effects of the asbestos-containing vermiculite still live on. (Read more about the Libby, Montana contamination event here.)
It’s likely that vermiculite from any year prior to 1990 contains asbestos. You should assume that any vermiculite that you discover and you didn’t order or place yourself comes with a threat of asbestos.
What to Do About Vermiculite
The only way to know that vermiculite is free from asbestos is to test a sample. When in doubt, do not disturb insulation. Asbestos is most harmful when airborne because it gets inside your lungs.
4 Tips When Collecting a Vermiculite Sample
- Wear a lung-protecting mask. Don’t take risks with your health. If you have been exposed to asbestos, it may be 20-50 years before health concerns manifest and there is no known safe level of exposure.
- Collect your sample from the bottom of the attic floor. Asbestos settles to the bottom of insulation because it is one of the heavier materials.
- Collect about a cup’s worth of vermiculite from a variety of locations in the attic. To know if there is asbestos in your insulation, we need representative samples and enough of them to test correctly.
- Be careful about spreading asbestos. Do your best to minimally disturb the insulation to prevent asbestos from becoming airborne and affecting other people who are not wearing masks.
Contact EHS to Test Your Vermiculite for Asbestos
EHS provides asbestos testing that is accredited in 16 states. We can confidently tell you if your sample of vermiculite contains asbestos.
Contact us today or visit our asbestos-testing services page for more information.