Diatomaceous earth (DE) is a naturally occurring substance composed of the fossilized remains of diatoms, single-celled aquatic algae. These microscopic creatures possess skeletons made of silica, a naturally abundant material. Over millennia, diatoms accumulated in the sediments of various water bodies, forming silica-rich deposits that are now mined to produce diatomaceous earth.
Silica, the primary component of diatomaceous earth, is a common element, constituting approximately 26% of the Earth’s crust by weight. It exists in diverse forms, including sand, quartz, and various minerals. Silicon, a key element within silica, is not found in its pure form in nature but readily combines with oxygen and water to form silicon dioxide. Silicon dioxide occurs naturally in both crystalline and amorphous forms. Diatomaceous earth primarily consists of amorphous silicon dioxide, although it may contain trace amounts of crystalline silicon dioxide. Diatomaceous earth first gained recognition as a pesticide ingredient in 1960, when products containing it were registered to combat insects and mites.
Diatomaceous earth is available in various product forms, with dusts being the most prevalent for pesticide applications. Wettable powders and pressurized liquids are also available. Currently, over 150 diatomaceous earth products are registered for use in diverse settings, including indoor and outdoor spaces, farms, gardens, and pet kennels. Certain formulations are even approved for direct application on domestic animals like dogs and cats. These products effectively target a wide array of pests, including bed bugs, cockroaches, crickets, fleas, ticks, and spiders, among many others.
Beyond its pesticidal uses, diatomaceous earth is incorporated into thousands of non-pesticide products. It is found in skin care formulations, toothpastes, food products, beverages, pharmaceuticals, rubber, paints, and water filters. The Food & Drug Administration (FDA) recognizes diatomaceous earth as “Generally Recognized as Safe” (GRAS) for food applications. “Food grade” diatomaceous earth undergoes purification and is utilized as an anti-caking agent in animal feed and as a clarifying agent in wine and beer production.
IMPORTANT SAFETY NOTE: Always adhere to product label instructions and implement measures to minimize exposure when using diatomaceous earth products. In case of accidental exposure, carefully follow the First Aid instructions provided on the product label. For further medical advice, contact the Poison Control Center at 800-222-1222. For concerns regarding pesticide-related issues, reach out to NPIC at 800-858-7378.
Diatomaceous earth’s insecticidal action is non-poisonous. It does not require ingestion to be effective. Instead, it works by causing insects to dehydrate and perish. Diatomaceous earth achieves this by absorbing the essential oils and fats from the insect’s exoskeleton cuticle. The sharp microscopic edges of diatomaceous earth particles further contribute to this process by abrading the exoskeleton, accelerating desiccation. Diatomaceous earth remains effective as long as it remains dry and undisturbed in the application area.
Human exposure to diatomaceous earth can occur through inhalation of dust, ingestion, skin contact, or eye contact. This can happen during product application or when entering treated areas before the dust has settled. Exposure can also arise from accidental access to products by children or pets. Limiting exposure is achievable by diligently reading and following all label directions.
Inhalation of diatomaceous earth can lead to irritation of the nose and nasal passages. Inhaling extremely large quantities may induce coughing and shortness of breath.
Diatomaceous earth can also cause eye irritation due to its abrasive nature. Like any dust, silica dust can be an eye irritant.
Skin contact may result in irritation and dryness.
When ingested, diatomaceous earth exhibits minimal absorption into the body. The unabsorbed portion is rapidly eliminated from the body. Trace amounts of silica are naturally present in all bodily tissues, and silicon dioxide is a normal component of urine. Studies involving human ingestion of small amounts of diatomaceous earth have shown no significant changes in silicon dioxide levels in urine, indicating limited absorption.
Following inhalation of amorphous diatomaceous earth, it is quickly cleared from lung tissue. However, crystalline diatomaceous earth, possessing smaller particles, may accumulate in lung tissue and lymph nodes. Pesticide products may contain very low levels of crystalline diatomaceous earth.
Animal studies involving prolonged inhalation exposure to diatomaceous earth have yielded mixed results. In mice exposed to diatomaceous earth inhalation for one hour daily over a year, an increased incidence of lung cancers was observed. Conversely, rats fed high doses of silica for two years did not show an elevated cancer risk.
The majority of diatomaceous earth is composed of amorphous silicon dioxide. While it may contain minute traces of crystalline silicon dioxide, amorphous diatomaceous earth has not been linked to cancer development in humans.
Rabbit studies investigating dermal exposure to diatomaceous earth, with applications five times weekly for three weeks, revealed no adverse health effects. Similarly, rat studies involving high dietary doses of diatomaceous earth for six months showed no reproductive or developmental effects. Another rat study, feeding rats a 5% diatomaceous earth diet for 90 days, only observed a more rapid weight gain as an effect.
Guinea pigs subjected to prolonged inhalation of diatomaceous earth-containing air for two years exhibited a slight increase in connective tissue in their lungs. However, assessments conducted before the two-year mark found no such effects.
Pesticide products might contain a minimal quantity of crystalline diatomaceous earth. Long-term inhalation of the crystalline form is associated with silicosis, chronic bronchitis, and other respiratory conditions. However, the predominant form in diatomaceous earth is amorphous, not crystalline. The amorphous form is only associated with mild and reversible lung inflammation.
While children may exhibit heightened sensitivity to pesticides compared to adults, current data does not suggest an increased sensitivity specifically to diatomaceous earth in children.
Silicon, a major component of diatomaceous earth, is the second most abundant element in soils. It is a common constituent of rocks, sands, and clays and is also prevalent in plants, playing a role in their growth and development. Diatomaceous earth’s chemical composition renders it resistant to microbial degradation and sunlight breakdown. It also exhibits low vapor emission and limited water solubility.
Oceans harbor vast reserves of diatomaceous earth, with numerous marine organisms utilizing it to construct their skeletons.
Diatomaceous earth is practically non-toxic to fish and aquatic invertebrates. It is commonly encountered by birds and other wildlife and is not known to be harmful to them. Although specific wildlife toxicity evaluations are limited, regulatory agencies have concluded that diatomaceous earth is unlikely to pose harmful effects to birds, fish, or other wildlife.
Diatomaceous earth’s silicon dioxide composition is suggested to play a vital role in bone formation. Studies in chickens fed silicon dioxide-deficient diets showed impaired bone formation, indicating the importance of silicon dioxide in skeletal development.
