Diatomaceous Earth (DE) is a naturally occurring, soft, sedimentary rock composed of the fossilized remains of microscopic aquatic organisms called diatoms. These skeletons are primarily made of silica. Once mined and ground into a fine white powder, DE is used widely as a natural insecticide, a filtration aid, and even as a dietary supplement. Whether DE is dangerous depends entirely on its specific form and how a person is exposed to it.
Defining the Forms Amorphous and Crystalline
Diatomaceous Earth exists in two primary forms of silica that determine its safety profile. The natural, unheated state is amorphous silica, found in certified Food Grade DE, which is relatively safe and contains less than 2% of the hazardous crystalline form. Crystalline silica is created through calcination, where DE is heated to extremely high temperatures (over 1,800 degrees Fahrenheit). This heat reorganizes the structure into sharp, crystalline cristobalite. Filter Grade or Pool Grade DE, used for industrial filtration, is calcined and can contain high percentages of crystalline silica, sometimes ranging from 40% up to 75%.
Health Risks from Inhalation Exposure
The primary danger associated with Diatomaceous Earth is the inhalation of its fine dust particles, especially the crystalline form. Airborne crystalline silica particles travel deep into the lungs and become permanently lodged in the tissue. The body’s response to these sharp particles initiates inflammation and scarring, leading to silicosis, a severe and incurable lung disease. Long-term occupational exposure to high concentrations of this dust is clearly linked to this condition. Even amorphous, Food Grade DE can cause mild, reversible irritation if inhaled in large amounts, so minimizing airborne dust is the most important safety measure.
Safety Profile of Ingestion and Topical Use
When certified Food Grade Diatomaceous Earth is used for ingestion or topical application, the risk profile is dramatically lower than the inhalation risk. The Food and Drug Administration (FDA) lists food-grade DE as “Generally Recognized as Safe” (GRAS) for approved uses, such as an anticaking agent in feed. Amorphous silica passes through the digestive system without being absorbed into the bloodstream or body tissues and is non-toxic to mammals upon ingestion. For topical use, amorphous DE is generally considered safe, though its highly absorbent nature can sometimes lead to skin dryness or mild irritation. This low-risk status applies only to the certified Food Grade product, which must contain minimal levels of crystalline silica.
Guidelines for Safe Handling and Application
Safe handling of Diatomaceous Earth begins with verifying the product label to ensure it is certified Food Grade for household use. The most important step is controlling the dust, as inhalation is the main route of exposure. Users should wear a NIOSH-approved dust mask or respirator (such as an N95) and protective eyewear when applying the powder, especially indoors. Application should be done sparingly, aiming for a light, barely visible layer rather than thick piles that can easily be disturbed. Any excess or spilled powder should be cleaned up with a damp cloth or rag, not a standard household vacuum cleaner, which can re-suspend the fine particles into the air.