Understanding the Grades of Diatomaceous Earth
Diatomaceous earth (DE) is a powder derived from the fossilized remains of diatoms, a type of algae. The silica-rich powder comes in two main forms: food-grade and filter-grade (also known as pool-grade). The distinction is critical, as their processing and crystalline silica content dictate their safety profile.
- Food-Grade Diatomaceous Earth: Mined from freshwater sources, this form contains less than 1% crystalline silica and is purified for use as a food additive or anti-caking agent. While considered safe for consumption in small amounts, it is not absorbed by the body in significant quantities and passes through the digestive tract.
- Filter-Grade Diatomaceous Earth: Mined from saltwater and treated with high heat (calcined), this variety has a higher concentration of crystalline silica (up to 60%). Filter-grade DE is highly toxic to humans and should never be ingested or inhaled.
Respiratory Risks: The Most Serious Side Effect
The most significant and well-documented health risk associated with diatomaceous earth comes from inhalation, especially chronic exposure to crystalline silica found in filter-grade DE. The microscopic, sharp-edged particles can cause severe damage to lung tissue.
Short-Term Inhalation Effects
Inhaling even a small amount of DE dust can cause irritation in the nose, nasal passages, and lungs. Symptoms of brief exposure include:
- Coughing
- Sneezing
- Shortness of breath
- Irritation of the throat
Long-Term Respiratory Complications
Frequent, prolonged inhalation, particularly in occupational settings or with filter-grade products, poses serious long-term health risks. These include:
- Silicosis: An incurable lung disease caused by inhaled silica dust, which leads to inflammation and scarring of the lungs.
- Chronic Obstructive Pulmonary Disease (COPD): Increased risk for those with pre-existing lung conditions like asthma.
- Lung Cancer: Studies have shown a potential link between occupational crystalline silica exposure and an increased risk of lung cancer.
Gastrointestinal and Digestive Side Effects
While proponents suggest digestive benefits, some users report experiencing negative gastrointestinal side effects, especially when first starting to take diatomaceous earth.
- Digestive Discomfort: Some individuals report stomach upset, bloating, and gas. This can be a result of its abrasive nature and the body's reaction to a new substance.
- Constipation: Insufficient fluid intake while taking DE can lead to dehydration and constipation, as the powder is highly absorbent. It is crucial to drink plenty of water.
- Herxheimer-Like Reaction: Anecdotal reports describe flu-like symptoms, including headaches and fatigue, attributed to a "die-off" reaction from microorganisms. There is no scientific evidence to support this claim, and symptoms may simply indicate the body's adjustment.
External and Topical Side Effects
Applying diatomaceous earth directly to the skin or eyes can cause irritation, dryness, and minor abrasions. The abrasive texture that makes it effective as an insecticide can also irritate human tissue.
- Skin Irritation and Dryness: Direct skin contact can cause dryness and minor rashes, especially with repeated exposure.
- Eye Irritation: Getting DE dust in the eyes can cause discomfort and irritation. Protective eyewear is recommended during application.
Comparative Risk of Food-Grade vs. Filter-Grade DE
| Feature | Food-Grade Diatomaceous Earth | Filter-Grade Diatomaceous Earth |
|---|---|---|
| Source | Freshwater deposits | Saltwater deposits |
| Processing | Minimally processed | Heat-treated (calcined) |
| Crystalline Silica Content | Less than 1% | Up to 60% |
| Ingestion Safety | Generally recognized as safe (GRAS) for incidental consumption | Toxic; Never ingest |
| Inhalation Risk | Low risk for mild, reversible inflammation | High risk; can cause silicosis and lung cancer |
| Regulatory Status | FDA approved as a food additive | Industrial use only; EPA regulates pesticide products |
Minimizing Risks and Precautions
To safely use diatomaceous earth, especially in pest control applications, it is essential to take the following precautions:
- Verify the Grade: Always purchase food-grade DE for any use around humans and pets. Check for a food-grade label and EPA registration number if used as a pesticide.
- Avoid Inhalation: Wear a NIOSH-approved dust mask and ensure good ventilation when applying DE. Avoid creating large clouds of dust and do not use a fan or vacuum cleaner immediately after application.
- Protect Skin and Eyes: Wear gloves and goggles to prevent skin dryness and eye irritation, especially during prolonged use.
- Stay Hydrated (for internal use): If taking food-grade DE orally, start with a small dose and drink plenty of water to prevent dehydration and constipation.
- Consult a Professional: If you have respiratory issues like asthma or COPD, or if you are pregnant or breastfeeding, consult a healthcare provider before using DE.
Conclusion
While food-grade diatomaceous earth is generally considered safe for incidental ingestion in low amounts, its side effects are not negligible and depend heavily on the type and handling of the product. The most severe risks are tied to inhalation of crystalline silica found in filter-grade DE, which can cause life-threatening lung conditions. Even with food-grade products, respiratory protection is essential during application. Digestive issues can occur, but these are often mild and temporary. The key to safe use lies in proper product selection, careful handling to minimize dust, and respecting the substance's abrasive nature both internally and externally. When in doubt, always prioritize safety and consult a medical professional.
