Chapter 3: Builders and water softeners · Part 3: Zeolites and silicates
Zeolite A
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The worst fact: the dust is small enough to reach the lungs. In monkeys breathing 1 mg per cubic metre for 6 hours a day, 5 days a week, for up to 2 years, sporadic lung inflammation cleared within 90 days of stopping. At higher doses it didn't fully clear. A few company reports to Europe's chemicals agency class it as a respiratory irritant, but most notifications for sodium aluminosilicate don't classify it.
Why brands use it: it swaps the calcium in hard water for sodium. In Europe, most phosphate-free laundry powders are based on it.
Take care if: you breathe the dust when pouring powder.
Comes from: silica and alumina (from sodium silicate and aluminium hydroxide), heated with caustic soda.
Myth check: "Zeolites are harmful to breathe, like silica": partly. It's an irritant dust, but unlike quartz it didn't cause lung scarring in tests. Industry measurements put the dust from pouring one cup of powder at about 0.27 µg, of which up to 0.09 µg is zeolite.
Contaminants: nil.
Fair to say: the industry's risk assessment found it poses no risk to the environment, and about 90% is removed in sewage plants.
Correct as of November 2026. What the badges mean
Sources
- Safe Work Australia. Hazardous Chemical Information System (HCIS): classifications for each chemical, and for formaldehyde.
- HERA. Risk assessments: STPP (2003) and STPP eutrophication note (2003); phosphonates (2004); zeolite A (2004); soluble silicates (2005); polycarboxylates parts I and II (2014).
The full source list is at the end of Chapter 3.