Diatomaceous earth is a chalky power derived from the fossilised remains of microscopic plankton. Although not dangerous to the touch, diatomaceous earth contains silica, which, if inhaled, can lead to respiratory illness.
The inhalation of large amounts of the powder may cause mucus membranes in the nose and the throat to become dry and irritated. Earth that contains silica may also cause severe lung diseases, including cancer.
Dryness of the throat will set in immediately, while more severe respiratory illness can take years to show.
Diatomaceous earth has a number of common uses, including as an insecticide, and should therefore be handled with caution.
Although diatomaceous earth is often described as a carcinogen, according to "Proctor and Hughes' Chemical Hazards of the Workplace," the silica contained in it is only a probable carcinogen.
According to a data sheet supplied by Science Stuff, Inc., those with pre-existing respiratory conditions may be more susceptible to the negative effects of inhalation.
Masks should be worn around diatomaceous earth. A person who inhales the dust should be moved to fresh air.