A recent weekend newspaper got my attention with a story about the possible dangers of asbestos in vermiculite. Since I use vermiculite as a rooting medium, I read the entire article and then did a little research.

The EPA, Environmental Protection Agency, reports that, "(Vermiculite)... poses a minimal health risk to consumers.
Vermiculite products may, however, present more serious risks in a work setting where the frequency and duration of exposures are likely to be significantly greater." Read the entire article is on their website at ...
http://www.epa.gov/asbestos/vermfacts.pdf

The EPA suggests the following...
"To further reduce the low risk associated with the occasional use of vermiculite products during gardening activities, EPA recommends that consumers can do the following:
* Use vermiculite outdoors or in a well-ventilated area.
* Keep vermiculite damp while using it to reduce the amount of dust created.
* Avoid bringing dust from vermiculite use into the home on clothing.
Use premixed potting soil, which usually contains more moisture and less vermiculite than a pure vermiculite product, and is less likely to generate dust."

Even though the risk is low, I personally will be looking for a different rooting mixture in the future.