Somewhere else I saw a post by someone who uses 1 50 lb bag of DE per year - obviously not a heavy use - just a light sprinkle - I may reconsider, esp if it keeps mites down - but I will probably wear a mask when I use it. I can't imagine the small amounts described by this person would be any more harmful than the dust that's created by my pine shavings. Thanks all for some very knowledgeable comments.