Diatomaceous earth is a substance made from the fossilized remains of tiny, aquatic organisms called diatoms. Its use is widespread, found in everything from industrial filters and insecticides to food products and dietary supplements. This wide range of applications often leads to questions about its safety and a potential link to cancer. The relationship between diatomaceous earth and cancer is complex, hinging entirely on the specific type of the substance in question.
The Two Types of Diatomaceous Earth
The most important factor for its health implications is its two primary forms: food-grade and filter-grade. Their fundamental difference is their silica composition, which is altered by how they are processed. This processing dictates their safe and appropriate uses.
Food-grade diatomaceous earth is sourced from fresh water and is uncalcined, meaning it is not heat-treated. Its composition is primarily amorphous silica, a non-crystalline structure. This type contains very low levels of crystalline silica, typically less than 2%. It is purified and used as an anti-caking agent in foods and animal feed, a natural insecticide, and is sometimes marketed as a health supplement.
Filter-grade diatomaceous earth, also known as industrial or pool-grade, is created by heating the raw earth to very high temperatures in a process called calcination. This heat treatment converts the amorphous silica into crystalline silica, which can comprise over 60% of the final product. This process hardens the diatom skeletons, making it a highly effective filtration medium for swimming pools, water purification, and in the production of beverages like beer and wine. This form is not safe for consumption.
Silica Dust Inhalation and Cancer Risk
The primary health concern associated with diatomaceous earth is not from ingestion but from the long-term inhalation of its dust, specifically the crystalline form. The International Agency for Research on Cancer (IARC) classifies inhaled crystalline silica as a Group 1 carcinogen, meaning it is recognized as causing cancer in humans. This classification is based on extensive evidence from occupational studies.
The risk is predominantly linked to filter-grade diatomaceous earth due to its high concentration of crystalline silica. When microscopic crystalline silica particles are inhaled over long periods, they can become embedded in lung tissue. The body struggles to clear these sharp, durable particles, leading to sustained inflammation and scarring, a condition known as silicosis. This chronic inflammation can eventually lead to the development of lung cancer.
This cancer risk is an occupational hazard for workers in industries like mining, construction, and manufacturing, where they are consistently exposed to airborne silica dust from filter-grade DE or other silica-containing materials. The risk associated with amorphous silica, the type found in food-grade DE, is not classified in the same way, as it does not have the same disease-causing potential upon inhalation.
Claims of Curing Cancer
Separate from the risks of causing cancer, there are claims circulating, particularly within alternative health communities, that ingesting food-grade diatomaceous earth can treat or cure cancer. Proponents suggest it can “detoxify” the body or that its physical properties can destroy cancer cells. These assertions are not supported by scientific or medical evidence.
Medical experts clarify that any substance capable of killing cancer cells would also likely be toxic to healthy cells; this is the central challenge in developing chemotherapy drugs. The idea that a natural compound can selectively target cancer cells without clinical validation is unfounded, and no clinical research has demonstrated its efficacy as a cancer treatment.
While laboratory research has explored using the unique, porous structure of diatom silica shells as a potential mechanism for targeted drug delivery, this is fundamentally different from ingesting the raw material. This research is in preclinical stages and involves modifying the silica particles to act as carriers for established anticancer drugs, not using the diatomaceous earth itself as the active treatment.
Safe Use and Regulatory Standing
The key to safely using any type of diatomaceous earth is to minimize inhaling its dust by avoiding creating airborne dust, especially in enclosed or poorly ventilated spaces. Using a mask can provide an additional layer of protection when handling larger quantities.
The U.S. Food and Drug Administration (FDA) has designated purified, food-grade diatomaceous earth as “Generally Recognized as Safe” (GRAS). This status applies to its approved uses as an anti-caking agent in food and animal feed and as a filtering aid in beverage production.
This regulatory approval, however, does not extend to its use as a dietary supplement or medical treatment. The FDA does not regulate dietary supplements for effectiveness, so the GRAS classification should not be interpreted as an endorsement of health claims. The established safety risk remains with the inhalation of crystalline silica found in industrial-grade products.