Breathing certain forms of diatomaceous earth can cause silicosis and other lung problems: http://npic.orst.edu/factsheets/degen.html http://npic.orst.edu/fact

Breathing certain forms of diatomaceous earth can cause silicosis and other lung problems: http://npic.orst.edu/factsheets/degen.html http://npic.orst.edu/factsheets/degen.html Apparently breathing the amorphous form causes only mild and reversible lung inflammation. Breathing the crystalline form can be more dangerous.