Advertisement I am taking a course at a comunity college and our teacher showed us some pictures of fibres that are said to cause cancer. Included were pics of asbestos fibres and vermiculite fibres, as well as many others. He said vermiculite is dangerous if you breath the dust over a period of time. I have read many threads in which people have stated using vermiculite in their T tanks. I am not so worried about the Ts getting cancer because I haven't heard it was a possibility for them to get cancer. But If you are using it as a substrate I you might want to rethink it. Any additional info. anyone could provide would be welcome. Thanks.