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Vermiculite and Asbestos: how to minimize the risks

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Vermiculite which is accompanied by a great deal of dust likely has residual asbestos in its contents and should be used with caution

By James O'Shea Posted Apr 3, 2009

VermiculiteWhen we hear the word “asbestos” we often think back on the controversy of the late 1970’s when it became common knowledge that asbestos was indeed a human health hazard. Since then, many steps have been taken to remove asbestos from buildings and commercial products in an effort to reduce human exposure to this mineral. Asbestos however, is still a relevant hazard today in a number of different capacities. While most asbestos containing products were banned by the Consumer Product Safety Commission and regulated by the Environmental Protection Agency, unfortunately it still exists in hundreds of older products as well as in trace amounts in newly manufactured products. Among new products that may still contain asbestos are soil retention enhancers, particularly vermiculite.

Vermiculite is mined from natural deposits across the globe and has a myriad of uses not only for commercial and private gardening, but also as an insulation compound. Vermiculite forms over millions of years due to the weathering of the mineral, biotite. Unfortunately, former biotite deposits are often in close proximity to deposits of diopside, which upon being subjected to the same weathering and age conditions becomes asbestos.

In Libby, MT one particular mine shipped hundreds of thousands of tons of asbestos-contaminated vermiculite across the country. However, they were not the only manufacturers of vermiculite to ship asbestos with their products. Many other manufacturers were doing the same thing before EPA testing and regulations finally forced them to limit the amount of residual asbestos dust in the vermiculite. In the early 1990’s the W.R. Grace Company closed its mine in Libby, Montana and over 20 processing plants located across the country. As a result, there are many regions where there simply isn’t a local vermiculite processing plant. Because of a lot of bad publicity about Libby and the Libby vermiculite mine, many of the larger “box stores” no longer stock and supply vermiculite.

Today, most vermiculite is safe. However, that is not to say it cannot contain asbestos.

Today, most vermiculite is safe. However, that is not to say it cannot contain asbestos. Vermiculite which is accompanied by a great deal of dust likely has residual asbestos in its contents and should be used with caution. Current EPA regulations ban products which contain 1% or more asbestos. Unfortunately even products containing less that 1% asbestos are still extremely hazardous, particularly when in loose dust form as vermiculite often is manufactured.

It is no surprise then that hundreds of the Libby mine’s employees and residents of the town were diagnosed with mesothelioma, a rare and aggressive cancer that is known only to be caused by asbestos exposure. Options for mesothelioma treatment are limited, so many of these residents were able to secure financial compensation for their families through litigation. Mesothelioma incidence is also known to be high in commercial gardeners and other occupations which deal with large amounts of loose vermiculite.

Fortunately, exposure to asbestos-contaminated vermiculite can be avoided if consumers follow these simple precautions:

  • Note the appearance of the vermiculite. If it seems to carry a great deal of residual dust, dispose of it outdoors.
  • Read the label. Most manufacturers of vermiculite mark their products packaging with “Non Dusty” labels. These refined granules are often slightly more expensive but they are certainly the safest.
  • Apply vermiculite on non-windy days to minimize airborne particulate matter. Wet-down soil once applied.

Environmental Protection Agency. EPA Asbestos Materials Ban.1989
Consumer Product Safety Commission. Asbestos Consumer Products.

Article written by James O’Shea for

Posted in Organic Garden Tags , ,
  • Landscaping

    Given the minimal ammounts that appear in vermiculite, I would say this is generally a non issue. Plus if you using it as a gardening supplment then it is going to be somewhat broken down/absorbed / filtered through the dirt. I think Greg Seaman hit the nail on the head.

  • Jon M

    Yeah, seriously. In the Spring I work with Pro-mix non stop and I always blow out black boogers because I inhale so much of the stuff. I never heard of vermiculite being a "carrier" of asbestos. Now, I'm sure it's only trace amounts. Besides, vermiculite is heavy and doesn't float in the air like peat moss, so I'm sure I don't inhale much of the bad stuff. I'd be more concerned with tiles.

  • Mesothelioma

    This is the great blog, I'm reading them for a while, thanks for the new posts!

  • Guest

    No, Greg is right. It's the same risk that smoking one cigarette has – very unlikely to cause cancer unless you were exposed several times or to large amounts. My grandfather worked around asbestos while young, and died at the age of 86 from a heart attack. He smoked for several years as well – so he was a prime candidate for getting lung diseases… but never did. It's not something to panic about. Just be smart.

  • Guest

    The vermiculite i work with has a small amount of asbestos.  I’ve worked with it 10+ years. Exposed to it over years could cause problems. I know from experience that if  it’s left on skin causes dry peeling skin on my hand. The less of it that i inhale or get on my skin the better. I recommend wearing a face mask to protect against fine floating particles and gloves.  

  • Muhammad Sulman

    that is not to say it cannot contain asbestos. Vermiculite which is
    accompanied by a great deal of dust likely has residual asbestos in its
    contents and should be used with caution.

  • Shanon Kerr

    Thank you for the information. 🙂

  • Janie Wise

    As an organic gardener, do I need to be concerned with asbestos uptake in my plants? Is it only considered harmful if you breath it? I have some asbestos which came out of a building we were renovating. I would like to amend the soil in my gardens with it if it’s safe.

    • It is not recommended. Better to find a location to bury the asbestos or dispose of it at a facility equipped for this material.

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