📅 April 2026 · ⏱ 6 min read · BSiO₂ Pty Ltd
When people hear the word "silica" they often think of danger — and that concern is understandable. The link between silica dust and silicosis (a serious, irreversible lung disease) is well-established and well-publicised. Australian WHS regulators have significantly tightened standards around crystalline silica in recent years, and rightly so.
But here is the critical point that is frequently misunderstood: not all silica is the same. The word "silica" covers a family of silicon dioxide compounds with dramatically different molecular structures, properties, and health profiles. The dangerous form — crystalline silica — and the safe form — amorphous silica, found in diatomaceous earth — are as different as ice and liquid water. Same chemistry, entirely different structure and behaviour.
Crystalline silica is silicon dioxide (SiO₂) in which the atoms are arranged in a rigid, repeating, ordered lattice structure — like a crystal. The most common forms are quartz (found in granite, sandstone, and concrete), cristobalite (formed when amorphous silica is heat-treated above 1,000°C), and tridymite.
When fine respirable particles of crystalline silica are inhaled over time, they reach deep into lung tissue. The rigid, angular crystalline structure causes mechanical damage to lung cells, triggering inflammation. Over years of repeated exposure, this leads to fibrosis (scarring) of the lungs — silicosis. There is no cure.
IARC classifies crystalline silica inhaled from occupational sources as a Group 1 carcinogen. Safe Work Australia's Workplace Exposure Standard (WES) for respirable crystalline silica is 0.05 mg/m³ (TWA) — one of the lowest dust standards in Australian WHS regulation.
This is where many buyers make a costly mistake. Not all diatomaceous earth products are the same — and the key question is whether the product has been calcined (heat-treated) or not.
When diatomaceous earth is heated above approximately 1,000°C — a process used to improve filtration performance in pool and industrial filtration grades — the amorphous silica it contains is converted into crystalline silica (primarily cristobalite). Calcined and flux-calcined DE products can contain up to 70% crystalline silica.
BSiO₂ product is never calcined. It goes from our deposit through crushing and screening only. No heat. No chemical treatment. The safe amorphous structure is preserved from ground to bag.
| Property | Crystalline Silica | Amorphous Silica (BSiO₂) |
|---|---|---|
| Molecular structure | Ordered, repeating lattice | Random, disordered |
| Common sources | Quartz, granite, concrete dust | Diatomite, diatom fossils |
| IARC classification | Group 1 — known carcinogen | Group 3 — not classifiable |
| Silicosis risk | Yes — established link | No established link |
| WHS classification | Hazardous substance | Not classified hazardous |
| Food additive approval | Not approved | FSANZ approved E551 |
| BSiO₂ certified level | Respirable quartz <0.5% (below LOR) | Amorphous silica 80.2% |
When evaluating any diatomaceous earth product, always ask three questions:
Full Safety Data Sheet, laboratory reports, and product specifications available on request.
