I'm not really an asbestos expert, but there are low levels of asbestos in vermiculite from Libby, MT. You could send some to a testing lab to know for sure, but it might be near the limit of detection. If the levels are over 1% by weight, EPA says you need to use special precautions to prevent exposure to the environment. OSHA says you need to handle it accoding to special precautions above 0.1% asbestos (most analytical methods can only see down to 1%). There's some kind of homeowner exemption for working around asbestos-containing material, but as a landlord, the exemptions may not hold. The bottom line is you can't breathe any fibers (if there are any) and you need disposable coveralls so you don't contaminate your street clothes. I can't give you risk levels.