baalmaiden -
Have used it for years, and never thought about it's make-up until your thread - Thank you.
Found out this though, "Make sure the DE you use is AMORPHOUS DIATOMACEOUS EARTH (ADE). In an article on DE in COMMON SENSE PEST CONTROL QUARTERLY, published by BIRC, Volume III, Number 1, Winter 1987, the matter of safety is explored. We quote:

"Both swimming pool grade and natural diatomaceous earth come from the same fossil sources but they are processed differently. The natural grades are mined, dried, ground, sled and bagged. The pool grade is chemically treated and partially melted and consequently contains crystalline silica which can be a respiratory hazard. Thus, IT IS IMPERATIVE THAT ONLY NATURAL DIATOMACEOUS EARTH BE USED FOR INSECT CONTROL. This noncrystalline silica is not a hazard as the human body apparently can dissolve it. "

"Silicosis refers to lung contamination and irritation by crystalline of free silica (Si02). Crystalline describes the orientation of the Si02 molecules which occur in a fixed pattern in contrast to the non periodic, random molecular arrangement defined as amorphous. Exposure to free silica is an occupational hazard to workers. "

Step Two:

Make sure the DE you use meets World Health Organization (WHO) safety standards. WHO cautions that DE with a crystalline silica content over three percent (3%) is dangerous for ingestion by humans or animals. Safe Solutions, Inc. DE has less than 1% free silica. Swimming pool DE ranges from 60% to 70% free silica."
Found it here: http://www.safe2use.com/safe-products/diatomaceous/diatomaceous_Earth.htm

Best and Thank you,
PP