Diatomaceous Earth (DE) is a fine, powdery substance derived from the fossilized remains of ancient, single-celled aquatic organisms called diatoms. These fossils are composed primarily of silica, resulting in a naturally occurring sedimentary rock powder. The safety of using this material around humans and pets depends entirely on the grade of the product and how it is applied. This article examines the distinctions between the different forms of DE and assesses the safety profile for human and domestic animal exposure.
Understanding Diatomaceous Earth Grades and Function
The critical distinction in DE safety lies in how the raw material is processed, which creates two primary grades. Food Grade Diatomaceous Earth is minimally processed and contains mostly amorphous silica, a non-crystalline form of silicon dioxide. This grade is recognized as safe for use in food storage, pest control, and as a dietary supplement for humans and animals.
Filter Grade, often called Pool Grade, is rendered dangerous by a high-heat treatment process called calcination. This heating converts the amorphous silica into crystalline silica, which is highly abrasive and poses a significant respiratory hazard. Filter Grade DE is intended exclusively for industrial uses like water filtration and should never be used for pest control or in any situation where humans or pets could inhale it.
DE functions as an insecticide through a physical, non-chemical mechanism. The microscopic particles have sharp, jagged edges that abrade the waxy outer layer of an insect’s exoskeleton. This damage, combined with the DE’s absorbent nature, causes the insect to lose moisture rapidly and die from dehydration (desiccation). Since the action is mechanical, insects cannot develop resistance to it as they can with chemical pesticides.
Safety Profile for Human Exposure
Food Grade DE is regulated by the Food and Drug Administration (FDA) and is classified as Generally Recognized as Safe (GRAS) for use in food and feed. The primary safety concern for humans, regardless of the grade, is the inhalation of the fine powder. The tiny particles can irritate the respiratory system, leading to coughing and shortness of breath, especially for individuals with pre-existing conditions like asthma or COPD.
Inhaling Filter Grade DE, with its high concentration of crystalline silica, carries a severe long-term risk. Chronic or repeated exposure can lead to silicosis, a debilitating lung disease characterized by inflammation and scarring of the lung tissue. Studies on workers have shown a risk of lung disease and cancer linked to cumulative exposure to respirable crystalline silica dust.
Food Grade DE is considered non-toxic if accidentally swallowed in small amounts, though excessive ingestion can cause minor digestive issues. The powder can also lead to mild irritation upon contact with the skin or eyes. When handling DE, minimize dust clouds to protect the delicate tissues of the eyes and nasal passages.
Safety Profile for Domestic Animals
Food Grade DE is generally considered safe for use around domestic animals, provided the grade is verified and proper application methods are followed. Many pet owners use the powder topically to control external parasites, such as fleas, ticks, and mites. When applying DE directly to a pet’s coat, avoid dusting near the animal’s face, eyes, and nose to prevent irritation and inhalation.
Accidental consumption of Food Grade DE is typically not a major health concern for dogs and cats, as it is often included in animal feed. Ingestion of large amounts, however, can cause minor gastrointestinal upset or constipation due to its absorbent qualities. Some owners use Food Grade DE as a purported internal dewormer, but this should only be done after consulting with a veterinarian, as supporting scientific evidence is limited.
Smaller domestic animals, such as birds and reptiles, are more susceptible to airborne particulates due to their smaller lung capacity. For these sensitive species, the risk of respiratory irritation from any fine dust is amplified. Extra caution is necessary to ensure the powder is applied in a way that minimizes dust creation, or to use alternative pest control methods entirely.
Proper Handling and Application to Minimize Risk
The single most important safety measure is confirming the product is explicitly labeled as Food Grade Diatomaceous Earth. Never use Filter Grade DE for any purpose other than pool filtration, as its high crystalline silica content makes it hazardous for home use. Store the product in its original, clearly labeled container, away from food and out of reach of children and pets to prevent accidental exposure.
When applying DE, protective gear is necessary to mitigate inhalation risks. A disposable dust mask, such as an N95 respirator, and safety goggles should be worn, especially when treating large areas or indoors. Apply the powder lightly, creating only a thin, invisible film, rather than a thick, visible layer or dust cloud.
Applications should be made when pets and other people are not in the immediate area. After application, allow 30 to 60 minutes for any airborne dust to settle completely before reintroducing pets or humans to the treated space. This careful application and waiting period reduces the risk of respiratory irritation for everyone in the household.