Vermiculite is one of the best-known potting-mix additives or amendments. It's a naturally occurring mineral that's been used for decades to aerate heavy soil and to hold in moisture and nutrients. While it looks harmless enough, though, it may actually pose a hidden health risk to gardeners.
Recent tests conducted by EPA investigators found that five of 16 randomly purchased bags of vermiculite contained deadly asbestos; in one sample, asbestos fibers actually became airborne (meaning it's breathable).
You don't necessarily have to stop using vermiculite, but you should take precautions against possible asbestos contamination. Asbestos has been linked to a number of deadly diseases, including asbestosis and lung cancer. Master gardener Paul James suggests ways you can protect yourself:
- Always work outside when using vermiculite.
- Cover your face and nose with a mask capable of trapping asbestos fibers.
- Keep the vermiculite and other potting-mix materials moist to minimize dust.
- Wash your clothes after coming in contact with vermiculite, but don't shake the dust off your clothes in the house. Once asbestos gets into your house, chances are it's going to be there forever.
The EPA says that placing a ban on products containing vermiculite would be irresponsible without further study, and James tends to agree. After all, not all vermiculite products contain asbestos. So, just to be on the safe side, be sure to take precautions when handling the substance or consider switching to perlite, a volcanic substance that works as well as vermiculite.
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