What Exactly is Diatomaceous Earth?
Diatomaceous earth (DE) is a naturally occurring, fine powder derived from the fossilized remains of microscopic, aquatic organisms called diatoms. The exoskeletons of these tiny creatures are composed of silica. Over millions of years, as diatoms died and their remains settled, they accumulated in lake and ocean beds, forming the deposits that are now mined for commercial use. The raw material is then processed to create various grades of diatomaceous earth, each with unique properties and applications.
The Critical Difference: Amorphous vs. Crystalline Silica
The fundamental distinction between food grade and other forms of diatomaceous earth lies in the type and concentration of silica they contain.
-
Amorphous Silica: This is the state of silica in its natural, unprocessed form. Food grade DE is composed primarily of amorphous silica, which is considered non-toxic and generally safe for ingestion in small amounts. The abrasive, microscopic edges of the amorphous silica are still effective for pest control, but the material is safe to handle with proper precautions.
-
Crystalline Silica: This form of silica is created when diatomaceous earth is exposed to extremely high heat through a process called calcination. This process is used to alter the properties of DE, making it an effective filter for applications like swimming pools. However, the heat-treated crystalline silica is hazardous when inhaled and is not safe for consumption.
Comparing Grades of Diatomaceous Earth
To highlight the key differences, here is a breakdown of the most common types of DE:
| Feature | Food Grade DE | Pool/Filter Grade DE | Garden Grade DE |
|---|---|---|---|
| Composition | Mostly amorphous silica | High levels of crystalline silica | Can vary, but typically similar to food grade |
| Processing | Unheated, uncalcined | Calcined (heat-treated) | Uncalcined |
| Safety (Ingestion) | Safe for human and animal consumption (low levels) | Highly toxic and never safe for consumption | Generally safe, but food-grade is safer due to purity standards |
| Heavy Metals | Strict limits on arsenic and lead content | No specific requirements | Varies depending on source |
| Primary Use | Dietary supplement, pet dewormer, food storage anti-caking agent, and pest control | Water filtration for pools and other liquids | Natural pest control and soil amendment |
| Handling Precautions | Avoid inhaling dust, use mask | Strict safety gear required to prevent inhalation of crystalline silica | Similar to food grade; avoid inhalation |
Practical Applications of Food Grade DE
Food grade diatomaceous earth is celebrated for its versatility and non-toxic nature, making it a popular choice for many home and garden uses. Its effectiveness stems from its mechanical, not chemical, action. The microscopic, sharp edges of the silica particles cut into the exoskeletons of insects, while the powder's absorbent nature dehydrates them, leading to death.
-
Natural Pest Control: For controlling a wide array of crawling pests such as ants, bed bugs, and fleas, food grade DE can be lightly dusted in cracks, crevices, and along baseboards. Its mechanical action ensures that insects cannot build resistance to it.
-
In the Garden: Applied as a barrier or dusted onto leaves, it deters slugs, snails, aphids, and mites from damaging plants. For edible plants, it's recommended to wash produce thoroughly before consumption.
-
Animal Feed Additive: In the agricultural industry, food grade DE is used as an anti-caking agent in animal feed and as a natural dewormer.
-
Dietary Supplement: Some individuals use food grade DE as a dietary supplement for purported benefits such as improved digestion and detoxification, although it's crucial to consult a healthcare professional before doing so.
The Risks of Using the Wrong Type of Diatomaceous Earth
The dangers of using non-food grade DE, especially pool grade, for purposes other than its intended filtration are significant. The high concentration of crystalline silica in calcined DE can cause serious respiratory problems if inhaled, including silicosis, a severe lung disease. For this reason, pool filter DE should never be used for pest control or any application that risks inhalation by humans or pets. The cheaper price of non-food grade products is not worth the potential health risks.
How to Ensure You Have Food Grade Diatomaceous Earth
-
Read the Label: Always check the product label for confirmation that it is specifically marked as "Food Chemical Codex Grade" or "Food Grade". Many manufacturers will also display an OMRI (Organic Materials Review Institute) certification.
-
Check the Source: Food grade DE is sourced from freshwater diatoms, while filter grade is often from saltwater sources and is calcined.
-
Inquire with the Manufacturer: If unsure, contact the manufacturer directly to confirm the product's processing and crystalline silica content.
Conclusion
The notion that all diatomaceous earth is interchangeable is a dangerous misconception. Is food grade diatomaceous earth the same as diatomaceous earth? The definitive answer is no, not when comparing it to grades like pool filter or industrial varieties. The processing method, specifically calcination, fundamentally alters the DE, creating hazardous crystalline silica. While food grade DE is a safe, natural, and versatile product for many uses, it is imperative to use the correct grade for the job. By understanding the critical distinctions, you can effectively and safely leverage the power of diatomaceous earth while protecting your health and the health of your family and pets. For further reading on safety, consult the National Pesticide Information Center fact sheet on Diatomaceous Earth.
How to Properly Apply Diatomaceous Earth
Here are some best practices for applying food grade DE safely and effectively for pest control:
- Wear appropriate personal protective equipment, including a dust mask, goggles, and gloves, to prevent inhalation and skin irritation.
- Apply a fine, light dusting in areas where crawling pests are active. Avoid creating thick piles, as insects may simply walk around them.
- Apply in dry conditions. The efficacy of DE is significantly reduced when wet, so reapply after rain or heavy moisture.
- For indoor use, only apply to cracks, crevices, and areas with minimal airflow to prevent the fine powder from being circulated in the air.
By following these guidelines and always double-checking the product grade, you can avoid unnecessary risks and achieve the desired results from your diatomaceous earth application.
