Vermiculite and Asbestos
Recently I was brought to task for suggesting the use of vermiculite: "Vermiculite or "Asbestose" as it is better known, is a well-documented product for its cause of lung cancer and silicosis-like effect on tissues. I would hope that you would mention these particular warnings to anyone that might use the "Vermiculite" idea from your page."
I had not heard of this fact, and was obviously concerned about advocating the use of something potentially harmful to one's health. In doing some on-line research into the question, I discovered that pure vermiculite does not contain asbestos, but that there was a period of time when asbestos contaminated vermiculite mined in Libby, Montana did contain some asbestos. This contaminated vermiculite found its way into some residential insulation products sold up to about 1996 in the U.S. and Canada. If disturbed, this insualtion can become a health hazard if the dust is breathed. That mine in Libby has been closed down for several years and is no longer producing this contaminated vermiculite.
Current sources of vermiculite are carefully monitored for this potential problem, especially because of the alert that has been issued by the U.S. EPA. It is my understanding that unless you go digging in someone's attic to obtain the old contaminated vermiculite, there is little danger in using newly available vermiculite.
Here are some of the links that substantiate this: