What is Diatomaceous Earth?
Diatomaceous earth (DE) is a fine, off-white powder composed of the fossilized remains of tiny, aquatic organisms called diatoms. These microscopic skeletons are primarily made of natural silica. Diatomaceous earth is characterized by its sharp, abrasive edges, which make it effective for various mechanical applications. Depending on its intended use, DE is processed into several grades, with food and feed-grade being two of the most common for nutritional and pest-control purposes.
The Defining Distinction: Purity and Regulations
The fundamental difference between food and feed-grade diatomaceous earth is the level of purity and the regulatory oversight governing its production and use. Food-grade DE must adhere to the rigorous standards set by agencies like the Food Chemical Codex (FCC) in the U.S. to be considered safe for consumption and food processing. These standards dictate not only the crystalline silica content but, most importantly, set stringent limits on heavy metals. Feed-grade DE, while still a low-crystalline silica product, is subject to less strict manufacturing guidelines because it is intended for animal, not human, consumption.
Strict Heavy Metal Content
Food-grade diatomaceous earth has very tight specifications regarding heavy metal content. For instance, to be considered food-grade, the product must not contain more than 10 mg/kg of arsenic and 10 mg/kg of lead. This low threshold is critical for ensuring human safety, as these toxic heavy metals can pose serious health risks. Feed-grade products do not have to meet these same strict heavy metal specifications, meaning their levels may be higher and potentially unsafe for human consumption, even if they are safe for animals.
Crystalline vs. Amorphous Silica
Both food and feed-grade DE products must contain less than 1% crystalline silica and remain uncalcined. The primary form is amorphous silica, which is non-toxic and safe for consumption. Calcined DE, often referred to as filter-grade or pool-grade DE, has been heat-treated, which significantly increases its crystalline silica content, making it toxic and only suitable for industrial applications like water filtration.
Uses of Food Grade and Feed-Grade DE
The specific grade of diatomaceous earth dictates its safe and appropriate uses.
Uses for Food-Grade DE:
- As a dietary supplement: Marketed for human consumption, typically mixed with water, for its silica content.
- Food processing aid: Used as a filtering agent during the processing of certain food products.
- Anti-caking agent: Added to animal feed and grain storage to prevent clumping.
- Natural insecticide: Safe for use around humans and pets to control pests like fleas, bed bugs, and ants.
Uses for Feed-Grade DE:
- Animal feed additive: Used to prevent caking and as a supplement to support animal health.
- Natural insecticide: Effective for pest control in and around animal housing, barns, and gardens.
Comparison Table: Food Grade vs. Feed Grade DE
| Feature | Food-Grade Diatomaceous Earth | Feed-Grade Diatomaceous Earth |
|---|---|---|
| Purity Standards | Adheres to strict food-grade regulations (e.g., Food Chemical Codex) for human use. | Meets less stringent standards suitable for animal use. |
| Heavy Metal Content | Very strict limits on toxic heavy metals like arsenic and lead (<10 mg/kg). | Less strict regulations on heavy metal content. |
| Crystalline Silica | Low percentage (less than 1%) and remains uncalcined. | Low percentage (less than 1%) and remains uncalcined. |
| Intended Use | Safe for human consumption, food processing, and both human and animal pest control. | Intended for animal feed and pest control in animal environments. |
| Primary Goal | To ensure maximum purity and safety for human and animal applications. | To provide a safe and effective additive for animal nutrition and pest control. |
The Importance of Correct Grading
Knowing the correct grade of diatomaceous earth is not merely a formality; it is a critical safety consideration. The rigorous testing and certification process for food-grade products ensure that they are free from harmful levels of contaminants. While feed-grade products are safe for their intended use with animals, their lower purity standards mean they are not guaranteed to be safe for human consumption. Furthermore, it is essential to distinguish both food- and feed-grade from filter-grade DE, which is processed differently and is toxic if inhaled or ingested due to high crystalline silica content. Always read the label carefully to ensure you are purchasing the correct grade for your specific application.
Conclusion
In summary, the key difference between food grade and feed-grade diatomaceous earth is the degree of purity mandated by regulatory standards. Food-grade DE is held to a higher standard, with strict limits on heavy metal content, making it safe for human consumption and food processing. Feed-grade DE is safely used in animal feed and for pest control but lacks the same level of heavy metal scrutiny, and should not be used for humans. For any application involving humans or pets, selecting the certified food-grade product is the only safe option.
For more detailed information on food safety standards, you can refer to the Food and Drug Administration's resources on food additives and ingredients. https://www.fda.gov/food/food-additives-petitions/food-ingredients-and-packaging-fda
